Oil Boiler Aquastat problem?


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Old 01-16-11, 01:48 PM
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Oil Boiler Aquastat problem?

I have a boiler (Crane HMT) that uses a Triple Aquastat relay 8124. I set the HI to 180 and when the thermometer calls for heat, it will go just over 200, releasing the relief valve throwing steam and water out. When i lowered he HI down to 140, it would fire up to 185 and stop burning, circ pump would run. I set the tstat to 15C and i woke up it was at 20C, I also heard the burner fire up ever 20 or so minutes going from 160ish up to little 180-190. Today i shut down the boiler and want the house to drop a bit in temperature to see if it calls for heat and when it stops. I disconnected the LO on the astat today aswell and see of that helps any. But if I set the HI to 180, shouldnt the burner quite when the temperature of the water reaches 180? Also, I am troubleshooting why the temperature was greater than what i set the tstat at as well.

Also, the boiler was used to heat a small apartment building, would I have to change the nozzle to accomodate my 1400 sqft house?
 
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Old 01-16-11, 03:14 PM
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First thing... you took a boiler (used) from an APARTMENT BUILDING and installed it in your 1400 sq ft HOME? That thing must be at least 3 or 4 times as much boiler as you need.

Give us the info off the dataplate... BTU's etc...

Are you sure that the temperature sensing bulb on the aquastat is fully inserted into the well and that there is no damage to the thin capillary tube that connects it?

It's not the TEMPERATURE that is opening the relief valve, it is the PRESSURE.

Disconnecting the LOW is not going to help.

Are you sure everything is wired properly?
 
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Old 01-16-11, 06:29 PM
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The wiring is as follows-

L1-black
L2-White
B1-Black
B2-White
C1-Black
C2-White

Clark HMT-14 145,000 btu. hot water boiler

Is there a way to see if the capillary tube is damaged? I am assuming its the copper wire coming from the back of the relay into the boiler?

Here are some images to help if needed









I turned the LO and HI down while the boiler was off, I havent started it up yet until I get some opinions first
 
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Old 01-16-11, 07:06 PM
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Is this GAS or OIL fired?

OK, 145,000 BTU is smaller than I thought you were going to tell me... but still, it's likely at least 2X more than you need... you asked about 'downfiring'... it's usually not something that is advisable. Boilers are designed to fire at the rate that the manufacturer determined was correct. You can sometimes go down a little bit... but at a point you start to lose more than you gain... it's all about the combustion... the chamber is sized for a certain size flame and that's where it performs best.

It's not something that a DIYer should fool with anyway, because you need to have the instruments to measure the CO2, the draft in the chimney, all that stuff...

You've only got one zone? (thermostat)

Sounds (and looks) from what I can see, that the wiring is OK... B1 and B2 are going to the burner? C1 and C2 are going to the circulator?

Did you install it or did you have someone do that?
 
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Old 01-16-11, 07:11 PM
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Is there a way to see if the capillary tube is damaged? I am assuming its the copper wire coming from the back of the relay into the boiler?
Yes, it looks like a wire, but it's a very small tubing... the only way to tell is by carefully examining it... looking for 'kinks' in the tubing.

If the first picture is the tubing coming out of the aquastat, and into the boiler, then yes, that is the capillary tube.

Was the aquastat taken off when the boiler was moved?

And this is just installed in your home and this is the first time you've fired it up?
 
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Old 01-16-11, 07:48 PM
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Yes it was removed because I did not need the coil for the DHW...I removed the LO and fired up the boiler, the burner cut off at 150, but the pressure was high at 30

I fired it up last night, but like i said, the dials were at 180/140 and it would run up to 200. The pressure is obviously too high
 
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Old 01-16-11, 08:33 PM
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My self and a friend installed it. It worked fine last night. Could pressure be high because of air in the lines?
 
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Old 01-16-11, 08:56 PM
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I just ran it. I set the lO to 120 and ran the burner until temp was 90, and high is set to 180, pressure is about 22psi

Also, when the burner cuts off, the circ pump is not running
 
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Old 01-16-11, 09:04 PM
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Originally Posted by NJ Trooper
Is this GAS or OIL fired?
The furnace is OIL fired////////////////////////////////////////////////
 
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Old 01-16-11, 09:21 PM
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There is a pressure problem. The relief valve as gone twice tonight, pressure going over 30. Expansion tank problem? When i tap on it, bottom does not seem to sound hollow. I tried pressing in on the schrader valve, nothing at all came out, water or air. Should I replace it?

I cant get the temp up to 90 without the pressure going to 30psi

I'm trying to do my best at troubleshooting myself and with help
 

Last edited by soaddrummer; 01-16-11 at 10:22 PM.
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Old 01-17-11, 05:52 AM
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When i tap on it, bottom does not seem to sound hollow. I tried pressing in on the schrader valve, nothing at all came out, water or air. Should I replace it?
The 'tap test' doesen't really tell you anything.

Your pressure problem is the fact that the expansion tank is not properly charged with air, and if it was a used one that came with the system, it may have a defective bladder... but first, try to charge it...

You must follow these steps...

1. Turn off boiler and allow to cool to 100F or less. CLOSE the water feed manual shut off to the boiler.

2. DRAIN ONLY ENOUGH WATER FROM THE BOILER TO DROP THE PRESSURE GAUGE TO ZERO. DO NOT DRAIN THE BOILER COMPLETELY! ONLY DROP TO ZERO ON THE GAUGE!

3. With an accurate tire pressure gauge and a small air compressor or bicycle pump, add air to the schraeder valve until you have 15 PSI in the tank.

4. Check the boiler gauge again, it will probably have risen from zero... Drain more water until it is again at zero.

5. Check the tank air pressure again. If it has fallen from 15, add more air to the tank.

6. Repeat steps 4 & 5 until you have 15 PSI in the tank, and ZERO pressure in the boiler.

7. When step 6 is satisfied, open the water fill and pressurize the boiler to 12-15 PSI when cold, and turn it back on. If the bladder in the tank is OK, the pressure should not rise more than say 8 PSI or so when it gets hot.
 
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Old 01-17-11, 10:06 AM
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I had the tank at 15 psi with no pressure in the boiler, fired it up, maybe got up to 60 degrees and the pressure was at 26psi, i shut it down before the PRV blew...any thoughts? Bad expansion tank? I tapped on the bottom and sounds like there is air in it, and the top of the tank was hot. I also let the boiler cool down, did the steps to make sure the tank was still at 15psi, shut off the water feed to see if it was a faulty auto feed valve and ran the boiler, again, same problem, went up to 26, so i shut it down.
 

Last edited by soaddrummer; 01-17-11 at 11:04 AM.
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Old 01-17-11, 11:18 AM
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After you charged the tank, and then re-opened the water fill valve, did the system pressurize itself back to 12 PSI when it was cold? Or did it go over that before you started the boiler back up?

Do this:

CLOSE the manual fill valve.

While watching the boiler pressure gauge, open a drain and drop the pressure on the gauge back to 12 PSI with the boiler at or below 100F.

KEEP THE MANUAL FILL VALVE CLOSED and fire the boiler up again and see what happens...

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Old 01-17-11, 11:33 AM
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i drained it until it went to 12psi, took a bit of time to get there though, all that water that left, will it need to be fed back to it again? I am firing it up now the manual fill valve CLOSED

yes the system was at 12psi right on when it was cold.

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Old 01-17-11, 11:39 AM
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Okay so with the manual fill vavle closed i fired it up and still the same problem, pressure went up to 26 psi, the temp is reading only 75F

I am also noticing that when i move the LO to 120 it "clicks" on and the reading is showing 85F and pressure is 24 psi and no circ pump running, the high is set to 140. I can manually turn the LO up and it will click on, but if i leave it run the pressure gets too high so i turn it down to 120

Also, the temp gauge reads 80F and the pipes are too hot to touch, i lick my finger and it evaporates right away, could the temp gauge on the boiler be wrong? I had the boiler running for about 45 min turning it on and off because of the pressure being to high.

I then let the system cool down and there was ZERO pressure. I opened up the water fill valve to let water into the system. Now i am back to square one with 15 psi still in the x-tank
 

Last edited by soaddrummer; 01-17-11 at 12:36 PM.
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Old 01-17-11, 12:40 PM
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Yeah, if you can't touch a pipe that the gauge says is at 80F then something is definitely wrong! A human can generally grab a 120 pipe for a second or two... 80F you should be able to hang onto forever... And if the boiler is getting that hot, then it makes sense that the pressure keeps going up and up...
 
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Old 01-17-11, 12:48 PM
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Originally Posted by NJ Trooper
Yeah, if you can't touch a pipe that the gauge says is at 80F then something is definitely wrong! A human can generally grab a 120 pipe for a second or two... 80F you should be able to hang onto forever... And if the boiler is getting that hot, then it makes sense that the pressure keeps going up and up...
So could this problem be the aquastat? When the boiler is filled to the correct temperature cold, and pressure is still rising while the boiler is only at 80F initially and the x tank is at proper psi, i'm not sure what else could be happening
 
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Old 01-17-11, 12:56 PM
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Basically while the system is at regular psi cold, during heating up the pressure gets too high, seems like a pressure problem still, unles the a stat is telling the boiler to heat up pass the HI point and the tstat on the boiler is wrong?
 
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Old 01-17-11, 03:31 PM
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Let's back up a bit and analyze this...

It seems that the temperature gauge is bad... if as mentioned earlier you can't grab an 80F pipe... that something is very wrong there. You need to determine that problem first...

Next, your aquastat doesn't seem to be in control of the temperature... and that also needs fixing. I've recommended that you check that the temp sensing bulb is fully inserted into the well and that the capillary tube has no kinks in it for it's full length.

I believe that what is happening is that the boiler is overheating and the pressure is going out of control. In a NORMAL situation, expansion tanks are PROPERLY SIZED for a certain temperature range. Water will expand a bit under 4% in volume when heated from room temp up to 180. THIS, with a bit of safety margin is what the tanks are sized for. If you heat the water PAST the safety margin, the expansion tank can't handle that extra volume, because the water will continue to expand, the hotter it gets...

So, the FIRST thing to do is to get an accurate temperature gauge on there. You are peeing into the wind if you try to troubleshoot without knowing what's going on...

SOAD yes! Love them
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Old 01-17-11, 03:33 PM
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By the way... the LOW setting on the a'stat will NOT run the circulator... that is normal. Also, the LOW setting should always be at LEAST 20 BELOW the HIGH setting.

Leave the LOW all the way down. You won't be using that.
 
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Old 01-17-11, 03:39 PM
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Let's see some more pictures of the installation...

I'd like to see:

The water fill piping... do you have a 'pressure reducing valve' installed properly?

The gauge and how it's mounted.

The expansion tank and how it's mounted.
(also tell us what SIZE the expansion tank is, and what type of radiators are in the home, whether fin-tube baseboard, or big ole cast iron rads with huge pipes...)

Pull back with the camera and let us see the WHOLE boiler system.
 
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Old 01-18-11, 12:17 PM
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I have fin-tube baseboards. I havent changed anything with the setup of the pipes or expansion tank, i left all the pipping the same as to the way the old boiler was set up. Circ pump and xtank are the same used on the previous boiler system.

I maybe had the burner running for 10 mins and pressure began to build up to about 25 psi, as you can see in the picture. I'm sure the water would show some sort of reading if the pressure is building.









 
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Old 01-18-11, 03:12 PM
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I think I will have to remove the a stat and see if everything is alreight with the capullary tube and bulb. How can this be done correctly?
 
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Old 01-18-11, 03:41 PM
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First, I'm kinda surprised to see a '15' expansion tank there. That was probably 'marginal' with the old system... and could well be too small with this one. I would recommend you go up to a '30' size tank.

I would replace that gauge... It looks to be about a million years old.

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I think I will have to remove the a stat and see if everything is alreight with the capullary tube and bulb. How can this be done correctly?
Not sure what you mean; "how can this be done correctly?"
 
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Old 01-18-11, 03:42 PM
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By the way, that boiler is neither a CRANE, or a CLARK, but a CLARE... maybe that's why I couldn't find anything on it? (I've never heard of Clare anyway!)

Here's something I found... they don't have a website... another reason I couldn't find anything if I tried!

Clare (also known as Clare Brothers) is a product line of oil furnaces, and is owned by International Comfort Products(ICP) (which in turn is owned by Carrier, which is a wholly-owned subsidiary of United Technologies Corporation). ICP markets furnaces under the brand names of Arcoaire, Clare, Comfortmaker, Dettson, Heil, KeepRite, Lincoln, and Tempstar. Clare makes residential furnaces and is headquartered in Canada. Clare does not have a public website.
 
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Old 01-18-11, 03:49 PM
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One more 'by the way' ... I don't put a lot of stock in that other website that you posted your question to... the one that's initials are ' T L ' ... lots of bad info I've found there... yes, some good... but lots bad...
 
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Old 01-18-11, 03:53 PM
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Let's back up here a bit...

You said you 'removed the hot water coil' ? How did you do that? Can you explain a bit more exactly what you did to 'modify' this boiler?

Did you install that well that the bulb from the aquastat is in? or was that already there, and had the aquastat already installed in it?
 
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Old 01-18-11, 03:54 PM
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Okay I will get a bigger expansion tank and see if that works out

Do I just unscrew the prob from the boiler after the boiler has been drained to inspect it? Is there a way to set it into the boiler when I put it back in?
 
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Old 01-18-11, 03:58 PM
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Originally Posted by NJ Trooper
Let's back up here a bit...

You said you 'removed the hot water coil' ? How did you do that? Can you explain a bit more exactly what you did to 'modify' this boiler?

Did you install that well that the bulb from the aquastat is in? or was that already there, and had the aquastat already installed in it?
I removed the aquastat by disconnect the wires, unscrewed the bulb, took it out, replaced a plate and put the bulb back in. The bulb and capillary tube is attached to the aquastat. The bulb i pulled out was about 5" long, im guessing the well is the long piece
 
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Old 01-18-11, 04:07 PM
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Originally Posted by NJ Trooper
One more 'by the way' ... I don't put a lot of stock in that other website that you posted your question to... the one that's initials are ' T L ' ... lots of bad info I've found there... yes, some good... but lots bad...
I understand, I'v been sticking to this site primarily, i am getting more input from here than another site which is remarkable
 
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Old 01-18-11, 04:11 PM
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Originally Posted by NJ Trooper
By the way, that boiler is neither a CRANE, or a CLARK, but a CLARE... maybe that's why I couldn't find anything on it? (I've never heard of Clare anyway!)

Here's something I found... they don't have a website... another reason I couldn't find anything if I tried!
I am sorry, that was a typo I had missed, yes it is a CLARE
 
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Old 01-18-11, 04:17 PM
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I removed the aquastat by disconnect the wires, unscrewed the bulb, took it out, replaced a plate and put the bulb back in. The bulb and capillary tube is attached to the aquastat. The bulb i pulled out was about 5" long, im guessing the well is the long piece
So that bulb went back into the same place it came out of then?

The 'well' is the tube in the boiler that the bulb is inserted into.
 
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Old 01-18-11, 04:22 PM
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Originally Posted by NJ Trooper
So that bulb went back into the same place it came out of then?

The 'well' is the tube in the boiler that the bulb is inserted into.
yes in the picture where you see the capillary tube behind the aquastat is where the bulb was origionally
 
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Old 01-18-11, 04:22 PM
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OK, here's the thing... the type of aquastat that you have is designed to be used on a boiler with the coil. Not to say that it won't work on a boiler without one, it will... BUT, it is designed to keep the boiler warm 24/7, and you do NOT need, OR WANT that... because it will burn fuel for no reason at all.

I would recommend that you change it out for an aquastat that will allow what we call COLD START. ESPECIALLY because it doesn't seem to be working properly anyway. Take a look at this unit:

L7224U1002 - Honeywell L7224U1002 - 120 Vac Oil Electronic Aquastat

I'm not SURE that the tank change is going to 'solve' anything, but it will most likely help the situation... the new boiler might have more water in it... and if the tank was marginal on the old system, the extra water might have pushed it over the edge.
 
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Old 01-18-11, 04:26 PM
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Another thought... it's pretty easy to get the circ pump turned around and pumping the wrong direction... Yours should be pumping DOWN and INTO the boiler. Is it?
 
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Old 01-18-11, 04:44 PM
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Yes it is pumping IN the direction of flow shows that it is.

I will try a new aquastat and new tank
 
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Old 01-18-11, 04:46 PM
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And a new gauge too....................
 
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Old 01-18-11, 05:57 PM
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would it be worth taking the aquastat i have in my old boiler and use that? The old boiler used a cold start one as well or just buy a new one?
 
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Old 01-18-11, 06:25 PM
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Assuming that the old boiler was also OIL fired, yes, as long as it works... why not?

Be sure to treat that little tubing gently!

What model is it? L8148A ?
 
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Old 01-19-11, 06:54 AM
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Yes it is oil fires, it is an older one i think, L8048A, seemed to have worked fine before
 
 

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