Slant/Fin V-120-EP combustion inside tubes

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Old 01-17-15, 04:35 PM
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Slant/Fin V-120-EP combustion inside tubes

Earlier last fall my parents boiler was not lighting reliably and we tracked it down to a dirty orifice. Things were going smoothly, and we thought it was smooth sailing. lol

So now it is intermittently burning inside the tubes. It effects 2 or 3 of the 7 tubes. It makes a loud sound too. When it happens my dad turns it off and back on and it normally fires without a problem. He cleans the tubes religiously every fall with a wire brush. In researching this I found and bought a nylon bristle brush for cleaning the inside of the tubes, but it is still doing it.

The only thing not cleaned routinely is the heat exchanger. Could this be the problem? He's going to try to clean it. Can anyone provide some tips here?

I would like to know if anyone could tell me what causes this?

Thanks!

ps what happened to the older posts?
 
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Old 01-17-15, 04:55 PM
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I think this is typically a gas pressure problem... but I'm not a gas-head, only going by what I've read.

You should get a tech in to check the gas pressure.

ps what happened to the older posts?
What older posts?
 
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Old 01-17-15, 05:02 PM
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Burning in the tubes is often a gas pressure problem. I suggest calling either your gas company or a service company who would have the instruments to test it.
Are you sure of the model number? I can't find it anywhere.
 

Last edited by NJT; 01-17-15 at 06:18 PM.
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Old 01-17-15, 05:51 PM
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Thanks Trooper, I will have the propane company come out and test it.

The older posts, meaning nothing is showing up before around December of 2014.

Grady, the U is probably a V. Sorry about that.
 
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Old 01-17-15, 06:16 PM
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Here's a link to the installation manual. Page 14 addresses cleaning the heat exchanger.
http://www.slantfin.com/images/stori...ctory_v_40.pdf
 
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Old 01-17-15, 06:29 PM
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The older posts, meaning nothing is showing up before around December of 2014.
There is a setting in your "Edit Profile" page that controls how many messages you see. I'm trying to figure out how to get to it myself... something has changed and I can't seem to find it now!

All the messages are still there...

OK, I found it.

In the tool bar across the top find the one that says "FORUM ACTIONS", then "GENERAL SETTINGS" and you will find a selection that allows you to change how many messages you see.
 
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Old 01-17-15, 06:45 PM
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Thanks Grady, so do you really have to take the top off to clean the heat exchanger? I was hoping it could be cleaned from below.

Trooper, thanks a lot!
 
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Old 01-17-15, 07:29 PM
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He's going to try to clean it
Who "he"? Dad?

do you really have to take the top off to clean the heat exchanger? I was hoping it could be cleaned from below.
Yeah... It's a 'pin boiler' and to clean it properly you need to get the brush in between the rows of diagonal 'pins'. Take a mirror and look up inside from the bottom and you'll see what I mean...

It's not as bad as is sounds taking the top stuff off.
 
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Old 01-17-15, 08:36 PM
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When/if you decide to clean the heat exchanger, be sure to cover or better remove the burners.
 
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Old 01-18-15, 07:12 AM
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Trooper, yeah he's a diy kinda guy. Grady, will do! You guys are the best! Thank you so much for your awesome help! I will post back here what the gas guy finds. This is one of my favorite forums!
 
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Old 01-25-15, 06:50 AM
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Hi guys, back again. He had the propane guy over to check the pressure and they found nothing wrong. The pressure is good at the input to the boiler. When the guy was there it worked perfectly, when he left dad said it fired up and all 7 tubes were howling and burning inside. He has not cleaned the heat exchanger, could that be causing it? What else could be the culprit? Thanks!
 
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Old 01-25-15, 05:06 PM
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Did the service guy also check the output side of the gas valve?
If the heat exchanger were plugged, I would expect to see flame roll out.
You could have a gas valve not opening enough to allow the full flow of gas to the burners themselves.
There could also be a restriction in the manifold.
 
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Old 01-25-15, 05:10 PM
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What about inadequate combustion air?

When the service guy was there, was the basement bilco door open?

Or maybe the clothes dryer was not running?
 
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Old 01-25-15, 09:19 PM
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Once or twice I've seen a gas regulator stick & cause an intermittnet problem. Is there any pattern to when this happens? I'm thinking maybe moisture in the regulator freezing/thawing. Any other gas appliances?
 
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Old 01-27-15, 03:05 PM
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Grady, the guy was from the propane company. He tested the pressure up to the boiler. The burners always light up along the length of the tubes, but intermittently there is flame inside some or all of the tubes. With a terrible noise along with it. How does one test for restrictions in the manifold?

Trooper, the boiler is in the basement of a 40 year old home. The unit was replaced about 20 years ago. The doors were all closed like normal. The service guy was only there to check the gas pressure. The problem occurs according to my dad, when it's cold in the unheated basement. At night, like 3am. lol So no laundry drying in the dryer.

He also added when it happens he turns it off, then back on and it lights and burns normally. We are pretty handy and can replace parts, and they don't have much cash to pay a guy to find nothing. :/

I'm not sure of the regulator freezing cause we're in central Illinois, and we've been below freezing for days on end already this year without this happening. Any other ideas.
 
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Old 01-27-15, 03:42 PM
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The problem occurs according to my dad, when it's cold in the unheated basement. At night, like 3am.
I've seen indication that this is often when problems with LP occur.

LP in your tank is a liquid that 'boils' into a gas.

When it's colder out it doesn't turn to gas as readily apparently and the pressure may in fact be low at that point in time.

I would think the gas guy would know this. Was he made aware that this is when the problem occurs?

How full is the tank?
 
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Old 01-27-15, 03:47 PM
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The more I read, the more I'm leaning toward a gas valve not opening fully. Rare but not unheard of.

The thing that bothers me is the fact it occurs in the early morning hours. This is when it would be coldest & most likely to have a regulator problem. Trying to catch something like this in the act will drive a service guy nuts. Trooper makes a good point about vaporization.

Checking the manifold for a restriction involves removal of the gas valve & completely taking apart the manifold then fishing a flexible brush thru it. Before I did that, I would suggest taking out all of the orifices cleaning & inspecting for cobwebs or rust flakes.
 

Last edited by Grady; 01-27-15 at 04:08 PM.
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Old 01-27-15, 04:18 PM
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Just doing a bit more learning... and I pulled this from one of the sites I've read:

Sounds to me like we are way below the effective vaporization capacity of a pair of 100 pounders. A pair of 80 gallon (420lbs) tanks would be border line small for continuious load that big in cold weather.
That 'boiling' of the LP to a gas is the 'vaporization capacity'.

Is there a "LOW GAS PRESSURE CUTOFF SWITCH" installed on the boiler? Does it work? (been tested?)

How big is the tank?
 
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Old 01-27-15, 04:28 PM
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Propane can be a big problem in cold temperatures. As propane evaporates, it further cools the remaining liquid in the tank - worse with small tanks. Industrial and large commercial propane users often have a heated evaporator for the propane.
 
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Old 01-27-15, 06:22 PM
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Surface area of the liquid LP is the key. Sometimes multiple tanks will be manifolded together, even if useage doesn't justify the extra storage capacity, just for more surface area for vaporization.
 
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Old 01-28-15, 09:15 AM
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You know I worked for a cable company in my youth and learned a valuable lesson on human nature. The customer, "the problem only happens at night." Me, "do you watch tv during the day?" The customer, "no, only in the evening." My dad uses a wood burner to offset the propane costs. It's likely the problem happens at night cause it's used more at night.

All this talk of propane tank size and outside temperature. The system is properly sized for a typical home in this area, and has been providing adequate gas pressure for the boiler and cooking stove for 40 years. The system provided adequate gas pressure last year when we had 40 consecutive days of below freezing temperatures reaching as low as -15. It's doing this intermittent behavior now at only 20 degrees F. The tank is probably 200g but I'm not sure.

Grady, I don't know if the boiler has a low pressure cutoff? I'm not completely familiar with the names of these parts. The manifold is the part that feeds gas to all the long tubes. I'm sure it has not been touched. The tubes have been cleaned from the outside with a wire brush, and from the inside with a large brush I purchased online designed for cleaning these tubes.

It's been quite frustrating trying to get accurate info from my dad. I wasn't able to be there when the propane guy was there. I'm going over there and take some pictures. I will try to video the ignition process, but doubt it will fail when I do it. lol

Thanks all for the help!
 
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Old 01-28-15, 11:38 AM
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Believe me, I know what you mean about trying to fix something when you can't get it to fail.

With what you are telling us about the tank, it would seem to rule out a tank size / temperature problem.

If you live close enough to get some pictures of the gas system near & into the boiler we could tell if there is a low pressure switch or not. It would likely look like the one pictured here:
AOL Search

In the manual I linked to earlier, on page 19, there is a list of possible causes for burning at the orifices.
 
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Old 01-28-15, 12:07 PM
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Here are some pictures. I am uploading two videos now.

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Old 01-28-15, 12:39 PM
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I know, I know, I should have had the cover off. I can do it again if needed.

http://youtu.be/IhSOqCRzogw
 
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Old 01-28-15, 12:42 PM
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Old 01-28-15, 01:24 PM
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Does anything in the pictures or video show anything obvious?

Hi Grady, I looked at the troubleshooting part, but didn't know what the problem was called. (flashback) It appears the most common problem is number one, and many of the rest are what could cause number one to happen.

1. Manifold gas pressure too low. (no way to test this)
2. Improper primary air adjustment. (I dunno what this is)
3. Gas regulator bleed too slow. (assume gas man tested)
4. Burrs on orifice. (not likely, tubes are clean)
5. Improperly drilled orifice plugs. (I dunno what this is)
6. Leaking automatic gas valve. (Is this the main and pilot gas valve box intermittently not opening fully?)
7. Adverse draft condition in boiler room. (Nothing's changed regarding the venting)
8. Low main gas pressure. (gas man tested)
9. Safety pilot improperly installed. (I dunno what this is)
 
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Old 01-28-15, 03:57 PM
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Those flames certainly don't look balanced. It appears the center 3 or 4 are higher than the rest. The 2 ends look a lot lower. This is usually an air shutter adjustment but can also be a symptom of a dirty heat exchanger. I'd suggest cleaning the heat exchanger before someone messes with the air shutters.
 
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