Hydrotherm HC boiler won't fire


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Old 10-30-10, 11:31 AM
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Boiler won't fire

I arrived home last night to find that my boiler won't fire the burners. The thermostat seems to send the on/off signal correctly as I can see the vent damper open and hear the circulator pump running. But, no flame appears. I can smell a very tiny hint of propane just then so it seems everything is ok with getting fuel to the burners. My propane tank is full.

When things were working correctly, I think I used to hear a click when the spark occurs to ignite the burners but now I don't hear any such sound. I just hear the circulator pump running so, until I can figure this out, I've switched off the AC current to the system.

Here are the photos and specifications for my system:
Boiler HydroTherm model HC-145D-PV pictures by fromhollywood - Photobucket


Any ideas on what might be the problem on why the burners are not igniting? I have a multimeter so can test whatever you guys suggest.

Thanks very much.
 

Last edited by fromhollywood; 10-30-10 at 11:52 AM.
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Old 10-30-10, 12:35 PM
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First, let's rule out whether or not your a'stat is getting power because if you hear the circ running, it's pretty obvious it is.

I think since you said that you did not hear ignition, that the pilot is not lit, correct?

Does the light on the damper control box indicate that the damper is open?

Check the grounds to the 8600 control and make sure clean and tight.

Since it's been shut down for a while, try turning it back on and initiate a call for heat and see what happens...

You know that you should hear the ignition, the pilot should light, followed by the main burner after the flame rod proves the pilot.

If no ignition attempt, set your meter on the lowest AC scale (200) and measure between 24(GND) and 24 on the 8600. You should have 24 VAC there if there is a call for heat, the vent damper is open, and the rollout switch is closed.

If you don't have 24VAC there, suspect the VD endswitch, or the rollout switch. You can leave one meter lead on 24(GND), and move to the point BETWEEN the Rollout and the VD endswitch. If you have voltage between the two, suspect the rollout. If you still don't have 24VAC, then the problem is the VD endswitch.

If you DO have 24VAC there (at the 24 on the 8600), check from MV/PV to PV. If you have 24VAC there, it means that the control has opened the gas valve. I'm not sure how long the 'timeout' is (looking at your pics, it appears to be 90 seconds), but if the 8600 does not sense a pilot flame, it will close the PV, and you will probably have to 'recycle' the power to the unit to reset it.

Do these and get back... I'll be in and out of the house all afternoon, I'll check from time to time for answers.
 

Last edited by NJT; 10-30-10 at 02:14 PM.
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Old 10-30-10, 02:04 PM
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Thanks for the response Trooper.

I cannot see any pilot or spark while turning on the system. I'm fairly certain this unit has the spark ignition system and not a standing pilot.

All the wiring to the 8600, including the green ground wire, appears to be secure when tugging slightly on them.

I haven't used a multimeter much but I tried the 200AC setting and touched the black lead to 24(GND) and the red to 24V. It read zero. I doubt it matters which color lead goes to which terminal but I then tried switching the red/black leads but still got zero. I had the multimeter leads on those terminals while turning on the main AC switch to the boiler (with the thermostat making it's call for heat). I did not disconnect the wires to the 8600 while doing this but just touched the metal spade terminals with the multimeter leads.

Again, I immediately heard the vent damper opening and the circulator pump running but absolutely no other sounds. The vent damper control shows a green light so I assume it's opening fully.

You mentioned that I "should hear the ignition". I suppose I've been hearing it for the four years since I bought this house but the only sounds I can recollect are the ignition click and then the burners igniting. Does the 8600 make some other sounds?

If you don't have 24VAC there, suspect the VD endswitch, or the rollout switch. You can leave one meter lead on 24(GND), and move to the point BETWEEN the Rollout and the VD endswitch.
Sorry for my ignorance, but I wasn't exactly sure what you meant by "between the rollout and the VD endswitch". Is a "VD endswitch" the same thing as what Hydrotherm calls the "spill switch"? I wasn't sure how to find the "between" location.

My Photobucket boiler album is better organized than when I posted earlier. My multimeter is the last image----I put the multimeter on the "200", two stops to the right of "OFF"----hopefully that is the correct setting you wanted.

Boiler HydroTherm model HC-145D-PV pictures by fromhollywood - Photobucket

I really appreciate your help!
 

Last edited by fromhollywood; 10-30-10 at 02:24 PM.
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Old 10-30-10, 02:25 PM
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I just edited my last post because I thought it might be a bit unclear...

I wasn't exactly sure what you meant by "between the rollout and the VD endswitch". Is a "VD endswitch" the same thing as what Hydrotherm calls the "spill switch"?
The 'spill switch' is a different part, and if you hear the damper opening, the spill switch is OK...

Take a look at the schematic... I'm going to insert here to make easier...
(for some reason my browser is making it tiny!)



...follow the wire coming out of the 24 on the 8600... it stops first at the rollout switch, then to the VD (Vent Damper) endswitch.

Both of these are of course safety controls. If either one of them is 'open', you will get nada at the boiler. The VentDamper endswitch proves that the the damper is open. The rollout is basically a temp switch. If it gets hot because of flame 'rollout' from a blocked flue, it will shut the system down.

Yes, 200 VAC scale is correct...

Correct, do not disconnect the wires from the control.

Correct, meter polarity does not matter with AC voltage.

If you got ZERO on those terminals, it is telling us one or more of the following:
  • that the vent damper either isn't opening fully, or the endswitch isn't 'making'.
  • that the rollout switch has either tripped, or is defective.
  • that there is a broken, loose, corroded connection somewhere in that 'path'

To track down which component is spazzing, leave the one lead on 24(GND) and move the other back along the circuit path... if you have ZERO volts on both terminals of the rollout switch, the VD endswitch is probably the culprit. If you have ZERO on one lead of the rollout switch, and 24VAC on the other, the rollout switch is suspect.
 
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Old 10-30-10, 03:31 PM
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I can see the black wire leaving 24V on the 8600 and then going to the rollout switch. A red wire leaves the other side of the rollout and then joins three other wires, all four of which run to the vent damper control box right in-line with the venting above the boiler. I suppose the "end switch" you are referring to is inside that damper control box as I didn't see any other small switch after the wire left the rollout.

I just put a photo of that vent damper control box on the PhotoBucket page (the first image).
Boiler HydroTherm model HC-145D-PV pictures by fromhollywood - Photobucket

At the 8600, I kept one lead of the multimeter on the 24(GND). I then touched the other lead to the black wire (that left 24V) at the rollout switch. That tested zero. I then moved that lead to the other side of the rollout (red wire) and got 24 volts.

So, I guess that means my rollout switch is either defective or it did it's job and my venting is plugged somewhere? As a test, can I bypass the rollout and connect the two wires going to it just to see if the boiler fires up? Wouldn't that tell me that the problem is clearly the rollout switch? Obviously it wouldn't be safe to leave it that way for more than a few seconds.

At the vent damper control box, the green light goes on momentarily as soon as I apply AC to the boiler. It then goes off for a few seconds and I can see the mechanical thing turn the damper open. The green light then comes on and stays on. Doesn't that mean the vent damper is working correctly?
 

Last edited by fromhollywood; 10-30-10 at 03:54 PM.
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Old 10-30-10, 06:08 PM
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I suppose the "end switch" you are referring to is inside that damper control box
Yes.

So, I guess that means my rollout switch is either defective or it did it's job and my venting is plugged somewhere? As a test, can I bypass the rollout
Yes, as a TEST only! you may bypass it. While the burner is running, look for any unusual operation... such as flames rolling out of the combustion area. The switch might just be defective.

Doesn't that mean the vent damper is working correctly?
Maybe... it would depend on whether or not that LED was triggered by the endswitch. It probably is not. The endswitch is most likely a switch all by it's lonesome, with nothing else connected to it, a 'dry contact'. The LED is probably triggered by one of the other switches on that PC board.
 
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Old 10-30-10, 07:23 PM
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Trooper, I bypassed the rollout switch, using a small piece of 12 gauge and then turned on the AC switch to the boiler. Sure enough, the boiler fired up and I heard the familiar sounds. The flame did come out very slightly over the front edge and the system shut off immediately and then fired up again. I shut it off after four times of it doing this (which probably comprised about fifteen seconds total).

Here's a photo I tried to take while the flame was coming out over the edge:


It's hard to make-out the flame but you can see the dark charred area on the metal on the right side.

The Hydrotherm manual said the rollout switch is a one-time use switch so I'd need to get another one but I'm unclear what is causing the boiler to switch on/off during this test.
 
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Old 10-30-10, 07:30 PM
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There's something else that's fairly bothersome about this pic... the fact that the flames appear to be ORANGE? That's bizzaro... they're kinda 'pumpkin' colored, aren't they?

You need to check the flue passes in the boiler are all clear, the vent pipe to the chimney, and the chimney itself are all clear...

The other shutdowns might could be caused by the 'spill switch'... if it's rolling out at the bottom, it might be rolling out at the top too... the spill switch is self-resetting I believe. If it is the spill switch shutting it down, that would indicate the blockage is not in the boiler flue passes, but rather the chim or flue connector pipe... or maybe both? Did a Heron nest on top yer chimney?

You can see the 'hot spots' better in this pic:

 
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Old 10-30-10, 07:53 PM
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Could it be that propane burns more orange than natural gas? I guess I've never really paid much attention to the color of any flames. Does the orange color signify something else?

This summer, I tried to open the boiler cabinet so I could vacuum it out but I couldn't figure out how----some simple screws on each side would make it much easier. The manual doesn't make it clear how to open the unit or in what order to remove things. If I could get it all open, I could see if anything is plugged-up. Opening the vent above the boiler seems straight-forward and I'll climb on the roof and check the chimney too. Any hints on how to open the boiler unit itself would be appreciated.

The spill switch is way up above the boiler on the vent hood. Do you really think the flames would shoot up that high above the bottom of the boiler? I can do the test again to see. I tried earlier today to push that spill switch but it doesn't seem to give under my thumb so you must be correct that it resets itself. Do you think that spill switch is what is recycling the boiler on/off every few seconds?

Here is the rollout switch. It has a different part number than what is in the Hydrotherm manual. It also has a "152C" which, I assume, means 152 celsius which translates to 306F. Since I have to replace the switch, do I need to get an exact match to this one or are these switches pretty generic?

 
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Old 10-30-10, 08:01 PM
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Follow-up to my last post a few minutes ago-----I just ran the test again and watched the vent hood where the spill switch is located----no flames at all there and cold to the touch. The unit cycled on/off again several times over ten seconds---- the burner only runs for a split second before it shuts off and cycles again. So, I don't think the spill switch is causing the cycling but I'm not sure exactly what the spill switch is sensing. I also noticed more of a propane odor during these short tests than I've ever noticed before around the boiler.
 
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Old 10-30-10, 08:25 PM
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Do you really think the flames would shoot up that high above the bottom of the boiler?
No, not the flames, but the flue gases... if the vent were blocked, the gases would 'spill' from the atmospheric hood and it would get hot... but you said it's cool, so the problem is probably the flue passes in the boiler.

Do you think that spill switch is what is recycling the boiler on/off every few seconds?
No... not if you said the vent hood is cold.

I also noticed more of a propane odor during these short tests than I've ever noticed before around the boiler.
The more you say, the more nervouser and nervouser I'm getting... something is obviously wrong... and if yer gettin' the flame sputtering around like that... I dunno, maybe time to get on the phone? I'm uncomfortable about this... propane is heavier than air and can 'pool' in the low spots... not good...
 
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Old 10-30-10, 08:27 PM
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I wonder if you mighta got a bad tank of gas... did you just get a delivery? and did this start right after that delivery?

That rollout switch should be available from multiple sources/manufacturers. They come in all different temps. This one is a 167C model... and yikes! it's pricey ! That silver thing is a one time thermal fuse. There's one in your coffee maker too. If ya ask me, that price is a rip...

Patriot Supply - 44-20037-03

Somethin' wrong here... take a look at this one, TEN TIMES cheaper, yet, the same durn thing (different temp)

Patriot Supply - STC5257

OK, here's your 152C model...
Patriot Supply - STC5300
 
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Old 10-30-10, 08:33 PM
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It's just a slight wiff of propane I'm noticing, nothing strong. I don't detect a leak anywhere in the main piping (with soapy water) and I don't smell any odor other than that slight amount when the boiler fired-up during that test. It's gone in a few seconds. I think it's normal to smell a bit if the boiler isn't firing-up as expected during the time the valve releases some fuel.

Luckily, I have a wood stove I'm using in the meantime for heat so I can take my time to figure this out.

I'll climb up on the roof tomorrow and run a brush down the chimney and will open the vent line around the damper control unit to make sure it all looks clear.

I'd like to start with opening-up the boiler case and make sure everything is clean. Is there a procedure to follow in opening up the thing? The boiler shuts off in such a split-second that I doubt it is anything too high-up causing the problem.
 
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Old 10-30-10, 08:47 PM
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Those flames should not be orange... that's another symptom of the problem... but there aren't any other safety controls that would act the way you say it's acting... so there's something else probably wrong also. Might be something like the flame rod is dirty... cuz if it's burning poorly, it might be sooting...

I'm pretty sure you have to pull that top sheet metal, which means the flue pipe has to come off... and then there's probably a cast iron 'hood' inside that has to come out... but I've never tore into one of them... I think in another thread Grady said they are a major PITA to get apart... mebbee the G man will jump in.

Here's a link to the literature library at Hydrotherm... yours is the HC-D I believe?

cast iron, boiler, hot water, hydrotherm, heating, efficient, residential, commercial, industrial, stainless steel
 
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Old 10-30-10, 09:09 PM
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My last propane delivery was a few weeks ago and I didn't notice any problem until last night when I returned home after a few days away. (My cat insists on having the stat at 55 when home alone and my cat sitter emailed saying the house seemed extra cold a few days ago). I've never paid attention to the flame colors so it could have been orange for years. Is it supposed to be mostly blue?

You mentioned the "flame rod" might be dirty. I don't see that term in the parts list. Do you mean the four tubes at the very bottom of the boiler that are part of the burner? I want to pay particular attention to the part you're mentioning while cleaning out the unit tomorrow.

Yes, I have the HC-D model. Thanks for that link to the literature. That one HC series document they have online is a slight update to the printed one that came with the unit. It doesn't make things too clear on how to take it all apart but I'll do my best and start with the top, as you suggest.

By the way, I noticed the parts list says the spill switch for my unit has a "manual reset". Could the spill switch be sensing flue gases in the vent hood which would cause the unit to shut off immediately? As I mentioned, I couldn't push that switch with my thumb as it wouldn't give at all.
 
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Old 10-31-10, 08:50 AM
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This PDF covers the operation of the 8600 module. Page 14 has some troubleshooting info... in particular, note step 2, and double check that green ground wire to the burner. I can't stress enough how important that ground wire is... so I'm going to repeat myself a lot... (I might make this my second mantra...) But, in your case, it's very possibly just sooted up... there is a step in the troubleshooting that tells to clean the flame rod with emery cloth. But, you need to first have proper combustion, or the problem will return.

The 'flame rod' is part of the ignitor circuit. They call that circuit 'flame rectification', which basically means that a current is passed through the pilot flame and the control senses that current in order to determine that there is a pilot flame. That ground wire is very important, because any dirty connections in that circuit will really effect the miniscule currents that the flame rod produces. You've got almost nothing to start with, so even a small problem with the ground can totally pooch the operation.

So, to directly answer the question, the 'flame rod' is part of the ignitor and pilot assembly. The graphics in the I&O for the 8600 should help to locate the part.

Is it supposed to be mostly blue?
Yes.

Could the spill switch be sensing flue gases in the vent hood which would cause the unit to shut off immediately?
I do believe that the spill switch is a manual reset. It's a TEMPERATURE sensing device with a bi-metal disc in it that will 'pop' out when the temp is too high. The reset button will then need to be pushed to reset... so, if the button is not up, the switch has not tripped. This doesn't mean that the 'switch' part is making good contact though, but it probably is not part of the problem. You could do the same TEST that you did with the rollout switch to rule out a problem with it. Of course as always, do NOT run the unit with any safety controls bypassed for any more time than it takes to perform the test.

In addition to whatever problem is causing the poor combustion, it's a very real possibility that your 8600 module is ready to bite the soot... but rule everything else out first.
 
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Old 10-31-10, 02:49 PM
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Thanks Trooper for the link to the 8600 manual. That will be helpful. I didn't think to look for that. I really appreciate your help in this little project.

Well, I got the thing mostly apart----now I understand that I did not need to worry about removing the side and rear panels of the boiler----there's nothing there except the side of the big cast-iron monster. All the working, serviceable parts are on the front panel and below where the burners are.

There wasn't much ash inside the venting above the boiler but I'm still struggling trying to figure out how to remove the vertical vent section (hood) that attaches to the top of the boiler itself.

There was some rust at the bottom of the unit but this thing hasn't been serviced or cleaned in over five years---maybe longer. This is the rainy Northwest too so lots of moisture in the air so things tend to rust. See photos below.

You can see the black charring marks on the burner tube to the far right (as you're facing the front of the boiler). You can see black marks inside the firebox too at the back and on the inside of the access door. I'm not sure if that pilot device looks the way it is supposed to or not.

Why do you think the flame in one or more tubes is extending onto the areas that are black? My guess is that its due to accumulated soot, rust, dirt, etc in lots of areas.

There doesn't seem to be much to the burner tubes other than a hollow piece of metal with tiny holes on-top. I'll start cleaning things up now. Does this stuff (tubes, pilot, etc) regularly get replaced or just cleaned-up?








 
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Old 10-31-10, 04:10 PM
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Shouldn't be soot...

... maybe a teensy-eensy bit, but nothing like that.

Caution: it looks like that combustion chamber is lined with refractory material. The dust should not be breathed! I hope it's not too late to tell you that... In fact, I might not even bother to try and clean the soot off of it. That layer of soot should soon disappear once the combustion is right.

Take a mirror and look up, inside the flue passes in the boiler... my bet is that there is significant rust flakes blocking the passages.

I'm not sure what you mean by "still struggling trying to figure out how to remove the vertical vent section (hood) that attaches to the top of the boiler itself." If you mean the cast iron piece on top that has the opening for the flue pipe, it probably lifts off... it will be heavy being cast iron... there will be (should be / may be) sealing strips around the perimeter made of that same sorta refractory material. Don't damage them! Don't put the burners back in until you have had a chance to brush down the flue passes... because all that crap is gonna fall back on them... if it's too late to tell you this, then at least cover them with newspaper so you can collect all the crap that falls down.

Take a picture of the top of the boiler that you are puzzling about.

You need to clean out each and every hole on those burner tubes! An old teethbrush might come in handy for this... Also, they should be brushed on the INSIDE as well.

Clean all the rust and stuff that looks like it's sitting on and around the flame rod.

Take a mirror and a bright light and have a good look at the gas orifices in the manifold. See if they are partially plugged.

One thing I'm wondering about... does the plate on your boiler say specifically that it is set up for LP ? It's remotely possible that it's set up with the orifices for NG ... and that could explain the really bad combustion... maybe... cuz I ain't really a gas guy...
 
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Old 10-31-10, 04:39 PM
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I figured that white stuff wasn't too healthy to breathe. I'm an air-quality control nut so I pulled out my professional HEPA vacuum and donned my mask and gloves before touching it.

I vacuumed a tiny bit of the junk at the very bottom of the boiler and before continuing to clean, I put the burners & vent back and temporarily hooked up the unit and fired it up to see the burn pattern. Interestingly, this time it kept running without immediately shutting off and cycling like yesterday. So, maybe I either got enough junk loose from something or my ground wires had a better connection after touching them.

I took a quick photo during the ten seconds I let it run to show you the flames. The flames coming out of the tubes looked fairly even (blue at their base but more yellow at their top) but there is a long yellow flame coming out of the pilot area.

Here also is a photo of the pilot assembly. I'm not sure how it's supposed to look but the dark thing on the right side doesn't seem to line-up with the silvery thing on the left side.

The vent hood doesn't seem to easily come loose. It's not screwed into the boiler at its base so probably just stuck from being in one place for so many years. I hope it's not cemented onto the boiler.

That's a good idea to check into the orifices to see if they are for LP. The Hydrotherm label does say "NAT" but don't all heaters come from the factory that way and the installer does the LP conversion? (UPDATE: I looked closely at those orifices and they have a "51" on them. The Hydrotherm parts list says these are the ones to use for my model if you're using propane)





 

Last edited by fromhollywood; 10-31-10 at 05:59 PM.
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Old 10-31-10, 06:22 PM
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Oh my... that's about the worst gas flame I've ever seen!

You need to get all those slots in the burners clean. Time for some painstaking brush work... one thing I'm thinking is that the slots are going to be oversized when you are done cleaning them due to the loss of metal to the rust... I think a teethbrush might be the best bet, rather than wire. They look like plain steel, not stainless?

The pilot thing not lining up may be the way it is designed... I don't know for sure... but you do need to get that rust stuff off of it. The ceramic part is an insulator, and rust is conductive. The part on the right is where the pilot gas comes out. The ignition spark travels from the tip of the rod to the bracket above. Make sure the gas outlet on the pilot is clean inside.

That vent pipe should not be cemented on, I'm sure it's just stuck from rust. It should just wiggle loose.

As for the data plate saying NAT, you need to verify if that unit WAS converted for LP, and when you do verify, permanently mark the dataplate to indicate that it was converted. There is an orifice size difference! It will definitely not burn properly if you have the wrong orifices installed.
 
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Old 10-31-10, 06:31 PM
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The instruction manual for my boiler says that the flame should be blue with occasional orange.

Did you look up the flue passages with a mirror like Trooper suggested?
 
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Old 10-31-10, 06:42 PM
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You may well have a pressure problem also... if the conversion wasn't done properly; from the manual:

11. If boiler input needs to be corrected, adjust the combination
gas valve pressure regulator. (Regulator is factory
set at 3.5" W.C. for natural gas or 10" W.C. for
propane.) Turn adjusting screw clockwise to increase
gas flow (increase input). Turn adjusting screw counterclockwise
to decrease gas flow (decrease input). In no
case, should final manifold pressure setting vary more
than .2" W.C. from factory-set pressures. If rated input
cannot be obtained with regulator adjustment, gas supply
pressure or orifice size may be the cause. Consult
your local utility and Hydrotherm.

12. The gas burner orifices supplied with the boiler have
been carefully designed to provide the correct gas input
rate for most gas conditions typically found in the U.S.
Occasionally, however, the local gas characteristics may
not allow the unit to be properly adjusted for input. If this
is the case, the local utility or Hydrotherm may recommend
the orifices be changed. When changing orifices,
follow the procedures in Section 3 of this manual.
 
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Old 10-31-10, 06:49 PM
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More about maintenance... note that they are recommending either furnace cement, or high temp silicone to seal the 'dome' when done cleaning.

2. Check boiler flue passageways in the boiler sections
for any blockage or soot accumulation. Remove draft
hood, jacket top and cast iron dome. Using a flash light,
examine all flue passageways.

a. If passageways are free of soot and obstructions,
replace dome and seal with furnace cement or high
temperature silicone adhesive/sealant.

b. If passageways need cleaning, remove burners as
described in paragraph 3 below. Insert long-handle
bristle flue brush down between section tubes and
upward through sections from combustion chamber in
both diagonal directions to remove carbon from finned
surfaces. Vacuum debris. Replace dome and
seal with furnace cement or high temperature silicone
adhesive/sealant.

c. Reinstall jacket top panel and draft hood.
 

Last edited by NJT; 10-31-10 at 07:53 PM.
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Old 10-31-10, 06:57 PM
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Examine the orifices, the orifice size should be stamped on the body...

35 is the size for NG, 51 for LP.

larger number, smaller orifice.

35 = 0.110 "
51 = 0.067 "

NG orifice almost TWICE as large as LP.

And the pressure setting is RADICALLY different also.
 
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Old 10-31-10, 07:05 PM
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Trooper, Using a mirror, I noticed the upper part of the combustion chamber (or whatever the area is where the burners are) is mostly solid black. I can't get that galvanized vent off the boiler so maybe the installer did use furnace cement around it's base where it attaches to the boiler. If so, that probably means previous owners have only been able to stick a vacuum into that upper hood instead of brushing out the areas----I doubt a vacuum would do much good being that high from the boiler itself.

I'm thinking of cutting the galvanized vent about 2" above the boiler which would then give me access to cleanout the insides. I could then use a wide galvanized band (of the same thickness) around the cut to seal it back together using sheet metal screws all around. I don't know any other way to get inside since that vent is not going to budge off of the boiler---I've tried everything I can think of. There is probably a sheet metal adapter available too (with female ends on both sides) that I could use to put it back together after cutting.

Those orifices have a "51" stamped on them (all 4) which the Hydrotherm manual says is the right thing to use for my model if you're using LP.

I'll study that pressure issue you mentioned in more detail.

I'm done using a toothbrush and soap & water on all 4 burner tubes. I have them sitting on my wood stove drying out right now. I also washed that access cover which made that refratory material soak up water so that's drying out there too.

Thanks for all your help.
 

Last edited by fromhollywood; 10-31-10 at 07:39 PM.
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Old 10-31-10, 07:20 PM
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Just looking at the parts list in the PDF... there's a bunch of parts that are different, depending on the gas...

The pilot assembly itself, the pilot gas orifice, the main orifices, the control box (the 8600), the GAS VALVE itself...

One thing is encouraging, the NG model uses an S8600F while the LP model uses an S8600M, and yours IS an 'M'

The GAS VALVE:

Gas Valve-24v NG VR8204H1006
Gas Valve-24v LP VR8204H1014

Can you find any such numbers on the valve?
 
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Old 10-31-10, 07:24 PM
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OK, I'm encouraged that the orifices are correct, and the ignition control is correct. I'm hoping that means that the gas valve and pilot assembly / orifice are also correct.

Can you lift the entire dome off with the vent pipe attached? You need to take that off anyway... you can't just vacuum, you need to brush... and being a 'pin' type boiler that means that you need to get between the diagonal rows of pins from both angles, top and bottom...
 
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Old 10-31-10, 07:36 PM
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You're good Trooper! I had not thought to look so carefully through the parts list in the Hydrotherm manual to compare LP to NG. I just took the above photo of the gas valve.

It has that beige colored thing to the right that I always see on LP converted valves (with it's sticker saying it's been converted). I'm not sure what those add-on things do to the original valve. But, you can see the model number of the silvery gas valve is one that Hydrotherm says is for Natural Gas (VR8204H1006).

Does that mean the original installer should have replaced that gas valve with the ...1014 model AND also put that other LP gadget to the right of it?

That entire 2+ foot section of galvanized vent that you see in the earlier photo is one piece----it can't be taken apart without cutting it. I can't budge it at all without moving the entire boiler itself. I've tried prying it loose too. I think cutting it and using an adapter for reconnection is my best bet to get it off.
 
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Old 10-31-10, 07:50 PM
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I haven't checked the gas valve specs at Honeywell yet... but the fact that it says it's been converted is a good sign too... the difference in the two valves could well be simply the factory set pressure.

The 'twist' you see on the pilot assembly is intentional. They are made in either RIGHT, CENTER, or LEFT configurations. I'm hoping that since someone obviously knew enough to change all them other parts, that the pilot gas orifice was also changed. The number should be stamped on the orifice, and it should be a BBR10, and NOT a BCR18.

The whole dome top that the vent pipe is connected to needs to come off. You need access to the entire heat exchanger area. You can not clean it through the vent hole. See the part diagram in the PDF file. The entire domed top should lift off. It may be cemented on, but it should come off. DON'T BREAK IT! (duhhhhhh....)
 
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Old 10-31-10, 08:51 PM
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Honeywell has an LP conversion kit for that valve... it consists of the parts needed to allow the pressure regulator section to go up to 10" WC for LP, a new spring, adjusting screw, o-ring, and cap. The cap is BLACK for LP, and SILVER for NG.

I'm confident that whoever did the conversion did it right.

I think that after you get it all cleaned up, you should be OK, but when all is said and done, it would be a good idea to get a tech in to check the regulator setting (and combustion with a CO meter).
 
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Old 11-03-10, 08:39 AM
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Hi Trooper, Thought I'd update you on what steps I've done so far. I finally did get the top off the boiler. What I did not understand until yesterday is that I did not need to remove the 7" galvanized vent pipe from the boiler. I didn't understand the term "dome" but I do now----I finally realized there were some bolts holding down the top piece of cast iron (the dome). Once my brain clicked into gear, I quickly had it all apart. Here's what it looked like below the dome:



I bought a wire "tube" brush, about 7/8" diameter and two feet long and today will push it down through all the openings as far as I can get. Will get on the roof and push a chimney brush down too.

I called Hydrotherm yesterday and they said the rollout switch for my unit was changed to be a manual reset switch (instead of the one-time switch that I have) with a limit of 350F instead of the 305F that I have. They said I could change it to a 350F. I'm wondering if perhaps they changed something else about the boiler (after mine was made) that allowed a 350F limit where mine should still be at 305F.

Are all these rollout switches basically the same except for the temperature setting? I've noticed these switches also have ratings based on 15amps or 20amps. My boiler is on a 20amp circuit.

Do you think the amount of rust on the cast iron is normal? The burner tubes themselves look rusty but only on the part that sits inside the combustion chamber, not the ends that are exposed to the basement air. Maybe it's condensation from the water inside the boiler after it cools. Anyway, it seems that the unit will rust away before too long but maybe that's normal with a boiler?

Thanks for all your help. I couldn't have gotten this far without it.

 
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Old 11-03-10, 04:53 PM
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Good Lawd that's a mess! no wonder you had rollout, that thing is probably at least 50% plugged!

Take a look back at the manual and familiarize yourself with the layout of the 'pins' inside the boiler sectons.

When you clean it, remember that those 'pins' on this inside are arranged diagonally, so you need to brush between the pins from two angles. Of course you will want to get as much as you can from the top, but you are going to need to brush from the bottom also. (I hope you are limber and have short arms!) You might do well to start with the 7/8 brush to knock most of the crap down, but really, a wider brush that will fit between the sections would make life a bit easier. Take a look inside with a flashlight and eye up the spacing between the pins. If you can find one that is kinda 'oval' shaped, it will go between the sections, and between the pins. It will be much less 'work' for you because you won't have to hold the brush against the iron... it should be a sorta snug fit and you can brush both sides at one time. If you have a heating supply in town, see what they have, there's tons of different shapes and sizes. The right brush will make your day.

you are going to need to brush from the bottom also
And for this you will need a shorter brush... maybe you can cut a hunk off the handle of the 7/8" ... and if it's a twisted wire brush, and the brush part is long enough, don't be afraid to bend the business end into a 'U' shape... and that might just work for going down from the top also. You could also wire two of the 7/8" brushes side by side...

a manual reset switch (instead of the one-time switch that I have) with a limit of 350F instead of the 305F that I have. They said I could change it to a 350F
So, were you able to convince them to send you one for free? Did they at least give you the part number, and tell you where to get it?

Are all these rollout switches basically the same except for the temperature setting?
Sorta... aside from the fact that the one you have is one time, non-resettable. I don't think you need to worry about the current rating, it's only switching the burner circuit, not the main AC input to the boiler, so it won't be anywhere near 15 or 20 amps.

Do you think the amount of rust on the cast iron is normal?
Yeah, looks fine. At that rust rate, we'll both be long gone before it rusts through from the outside. That's just surface rust.

When you reinstall the dome, those two metal 'clips' aren't really necessary. They can't hurt of course, but it is obvious that your boiler has never been cleaned, as I doubt they would have been re-installed. The weight of the dome will hold itself in place, those are mainly there for shipping purposes. When you put the dome back, run a bead of that 1200 Hi-Temp silicone around the lip, but don't go crazy with it, because you will want to be able to get it off again maybe in five years or so... personally, I would opt for "Kaowool" strips just layed on top... so if you do hit up a heating supply looking for brushes, see if they have any 3/4 to 1 inch wide precut strips. Here is a source for the strips, 300" is enough to last ya a while!

Patriot Supply - 9501
 
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Old 11-05-10, 12:19 AM
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Trooper, thanks for the cleaning tips. Using your suggestions, I'm confident I did a good job of cleaning from both above and below.

Today, I put everything back together and fired up the boiler. Everything went fine.

-The burner tubes now put out flames that are mostly blue in-color. There is still some yellow but not much. They are about 8-10 inches in height. Is that flame height normal? They probably touch the bottom of the cast-iron boiler inside the combustion chamber, or at least get very close to it.

-The pilot area still has a long, yellow flame. From what you see in the photo, does it look ok? I thought yellow meant it wasn't getting enough air or venting.





-At the front of each burner tube, there is a separate metal piece that moves back-and-forth about one-inch. I'm not sure what they are for. Is it an adjustment of some sort? Maybe to adjust the amount of air that gets into the burner tube?

-The orange spark wire seems awfully close to the fourth burner tube. The wire physically touches the burner. This is how it was before and the cable it too short to do anything else. Is the insulation on a spark wire safe for touching a burner tube?

-I noticed the 15 gallon expansion tank seemed very heavy. I had not drained it since you helped me with that in March 2009. About 10 gallons drained-out. Once it was empty, I opened the fill-valve and it seemed to fill up and get as heavy as it was prior to draining it. Does that sound normal? I thought the expansion tanks were mostly empty until the boiler needs to use them but this one filled-up with water right away.

-My new rollover switch is on-order so I'm not using the boiler until it arrives. While taking the above photos, I had the burner access cover removed and, even though it was running just five minutes, it melted the insulation off three of the wires which you can see in the photo below. I'm using electrical tape in the meantime but will need to replace those.



I'd like to get ALL the wires and the ignition module off of the boiler and mounted on a wall somewhere. I could then use longer cables and run them more safely and keep them away from any heat. Is that advisable or does the module really need to be attached to the boiler itself?

Thanks for your help Trooper!
 
  #34  
Old 11-05-10, 02:50 PM
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Is gas flame too high? 'gas guys' take a look pleeze!

Is that flame height normal?
Well... I ain't zackly a gas guy, but my gut feel tells me it's a little high. In the boiler manual PDF there is a procedure for 'clocking' the gas meter to compare the BTU input to the boiler rating, but I'm wondering if you are on LP you might not even have a meter? It might not be a bad idea to get a tech in with a manometer and set the pressure up for ya. Mayhaps one of the gasser guys will take a look and let us know if that looks OK.

I think the amount of yellow 'tipping' on the main flame is OK.

Also in the manual I think there was a section on the pilot height... and there is an easy adjustment for that. I'm wondering if the pilot is set too high and maybe that's why we're seeing that yellow plume.

Is it an adjustment of some sort? Maybe to adjust the amount of air that gets into the burner tube?
Exactly. Air and gas must be mixed in the proper proportion to burn cleanly. If/when you get a tech to adjust the gas pressure, he should also do a CO check, and from that determine if the air shutter setting is correct.

Is the insulation on a spark wire safe for touching a burner tube?
I will say 'probably'. Think of the spark plug wires on yer car...

Does that sound normal? I thought the expansion tanks were mostly empty until the boiler needs to use them but this one filled-up with water right away.
I hafta confess, I don't recall what we worked on last... but it sounds as though you have a conventional steel tank? Normal operation of those you will have about 2/3 to 3/4 full of water. As long as you are sure that you had all the water out to start with, when the pressure is back on it will compress the air inside the tank to the proper level. The 'tell' if it is OK is the pressure difference from cold to hot.

I had the burner access cover removed and, even though it was running just five minutes, it melted the insulation off three of the wires which you can see in the photo below. I'm using electrical tape in the meantime but will need to replace those.
Thus the reasoning for the label on the manifold that says not to operate without the cover in place!

Pay strict attention to the temperature rating on the wire you use to replace them. Don't skimp on that...

Is that advisable or does the module really need to be attached to the boiler itself?
I wouldn't advise that (remote mounting the control)... you really need that good solid ground, and as short a spark wire as possible. (in fact, Honeywell in the install manual says that the spark wire should be no longer than 36" I think)
 

Last edited by NJT; 11-05-10 at 06:19 PM.
  #35  
Old 11-05-10, 03:14 PM
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Yellow pilot flame...

When you had it all apart... did you clean up the pilot assembly? where the pilot gas line attaches to that assembly, there is an orifice treaded into the bottom of that part. If you didn't scrub-a-dub that assembly when you were brushing the burners teeth, there could be some 'crud' inside the pilot assembly.

I'm wondering if this is contributing to the yella pilot flame...

Also, if you removed the pilot gas tube to get that burner out, please make sure the connection is tight by painting some soap solution on the fitting to be sure nothing is leaking.
 
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Old 11-05-10, 03:20 PM
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You can't go by the size and color of the pilot flame when the main burner is firing. Best to post another pix of the pilot firing all by itself.

The main burner flames look quite hard to me, indicating possibly too much air. The round things you asked about are for adjusting the air - and it looks like they are wide open. Do you remember how they were set before?

It's reasonably easy to tell if there is way too much or way too little air. But to do it right, one needs a combustion analyzer.
 
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Old 11-05-10, 04:12 PM
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To get a continuous pilot flame without the main burners coming on, you can disconnect the wire from the MV terminal on the control module. There are some steps for troubleshooting in this PDF:

http://customer.honeywell.com/TechLi...0s/68-0094.pdf

See page 18...

I'm putting my bet on a dirty pilot orifice.
 
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Old 11-05-10, 04:15 PM
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Mike, you don't think that 'hard' flame is because it's LP gas? just wonderin'...

If my eyes ain't deceivin' me, the shutters are at various different settings... I don't think Hollywood changed them though...
 
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Old 11-08-10, 01:09 PM
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I pulled out the MV wire and took some photos of the pilot flame----here are three from different views (I kept them large so you can see the details). It waves about quite a bit and changes its height from about 2 inches to 4 inches while burning. Most of the flame, as you can see comes from the left side of the pilot assembly with very little coming out the right side.

Trooper, there is no meter for my propane. It's a 500 gallon tank outside with a line going directly to the boiler----that's the only thing I use the propane for. There is a gauge on the tank itself but its not accurate enough to do the clocking test outlined in the Hydrotherm manual.

I did brush the pilot assembly and spark plug gadget with a wire brush and some sandpaper. I got it very clean on the outside. But, I did NOT clean-out any orifice on the pilot----I will look and see if there is something I can push a needle or wire through.

I'll double-check the gas tube connections for any leaks.

I have those air vent shutters mostly closed since I've put everything back together (the things that control the air flow into the burner tubes). They are more closed now than they were before I did the cleaning job.

I'd be happy buying a "combustion analyzer" if you could recommend a decent one for up to $300. ----I see they go much higher. Propane is expensive so it might pay for itself before too long. On one cold month a couple of years ago, I had a monthly usage bill of $600!





 
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Old 11-08-10, 02:35 PM
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In this pic:



is it the camera angle that makes is appear as though the left side of the pilot thingy is actually bent and maybe pinched partially closed?

Before you take that apart... stand by for a minute... I think there's stuff you should know about the assembly before you start... take a look at fig 15 in that PDF on the pilot assembly that I posted earlier. Apparently the compression fitting is a one time use part. If you remove the tubing from the assembly, you might not be able to get it leak free again...
 
 

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