boiler help


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Old 02-15-05, 06:40 PM
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boiler help

I have a problem with my crane boiler. It's gas fired 2 zones and the problem is the relief valve lets go intermittenly. I have replaced the gauge on the boiler with a new one and turned the aquastat down to @190. It was up around 220.

The pressure is well under 30 lbs most of the time but I guess when the valve pops it is up around 30. There is a bladder type extrol tank with an air scoop installed.

I have never had this trouble in the 4 years I have lived here and the only thing that changed was the system was expanded to 2 zones in Nov 04. The new zone is in the basement. This problem did not start until 2 weeks ago?????

Also I have completely turnes down the the auto-fill valve to min pressure and this does not change anything.
 
  #2  
Old 02-16-05, 01:47 PM
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The expansion tank is most likely bad. Tap it with a wrench does it ping (empty sound) or does it thud ( full sound) if it thuds its probably full of water and no good.
 
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Old 02-16-05, 02:37 PM
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Wink

Like said check the expansion tank there. You have just a small bladder tank . So check on the schrader valve on it and see if you get water out of it .If so have to get a new tank.

ED
 
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Old 02-16-05, 04:43 PM
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Nope no water just air comes out.
 
  #5  
Old 02-16-05, 06:11 PM
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Johnjohn

Was the schrader up or down? If up, the bladder could still be bad. In order to really check the tank it should be removed from the system. Is there a valve between the boiler & the tank?
 
  #6  
Old 02-16-05, 06:16 PM
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Boiler Help

1) The fill valve might be shot; check it by turning the on/off fresh water supply shutoff valve all the way off & draining some water out of the drain valve at the base of the boiler until the gauge reads 15 psi; if this clears up the problem, change the fill valve.

2) The expansion tank may be too small for the system now that a new zone has been added; check the label on the expansion tank to see if you have a #15 (small size) or #30 (larger size); the #15 is designed for boilers up to 50,000 btu, the #30 for boilers up to 150,000 btu.
 
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Old 02-16-05, 06:27 PM
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The schrader valve is down and no there is no valve between the boiler and tank except for the PRV and air seperator.
 
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Old 02-17-05, 06:16 PM
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When they added the zone valves did they isolate the extrol tank between the zone valves and a flocheck? Is the extrol tank avalible to both zones even if only one is operating? Is the extrol tank installed between the boiler and the zone valves?
 
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Old 02-19-05, 05:04 PM
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The tank is located before both zone valves.
 
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Old 02-20-05, 03:24 PM
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Help!.....................................
 
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Old 02-21-05, 12:03 PM
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Extrol tank

Why would the tank refill with air when fully discharged?? I thought it only had air because of the pre-pressurization.
 
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Old 02-21-05, 04:56 PM
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JohnJohn

Getting a little impatient are we? We are trying to help you. Things like this are not easy to fix in person, let alone on the web. Any idiot can keep changing parts until he gets the right one, even if it means replacing the whole boiler. We are trying to help you dianose & fix the problem without replacing every part on the boiler.
Now if you are ready, to start: Drop the pressure on the boiler to zero. Use a tire gauge to check the pressure on the tank. If not 12#, make it so. Repressurize the system & fire it up. What happens to the pressure gauge?
 
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Old 02-21-05, 05:01 PM
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An extrol tank is cheap compared to the damage high pressure is doing to your boiler. Call a pro to take a look.
 
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Old 02-21-05, 06:16 PM
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When you say drop the pressure on the boiler to zero how should I go about this?
 
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Old 02-21-05, 06:23 PM
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Turn the switch off (not just the thermostat). Turn off the water to the reducing valve (feed valve). Connect a hose to one of the hose bibs on the boiler & run the water into a bucket until the water coming out has little to no pressure.
 
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Old 02-21-05, 06:56 PM
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I will do this tomorrow and post back. Thanks. Oh by the way I shut both valves feed and return for the new zone and turned the thermostat all the way down so it wouldn't call for heat and I'm still having the same problem so I'm pretty sure it's not directly related to the new zone.
 
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Old 03-07-05, 06:15 AM
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Well now I'm confused. I installed a new auto fill valve set at 12psi and a new expansion tank watts 60. My ? is if you add more air to the tank will that decrease boiler pressure? or the opposite? The way I see it if the tank pressure is lower than the water will fill and push the bladder more hence not alot of room for compression? Thanks.
 
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Old 03-07-05, 11:39 AM
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If your only heating a one story house, 12 PSI is fine, Just leave the tank and the feed valve the way they are when you take them out of the box and you will be fine
 
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Old 03-08-05, 06:20 PM
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Well I have just about run out of options. No matter how much or little air is in the new expansion tank the stupid boiler eventually builds up too much pressure and pops off.

I can set it to where there is 12 psi and then cycle the boiler a few times with both zones and it will climb maybe to 20 psi then when it cools it drops back down to 12. Then over the course of 12-24 hours i'll get a little water out of the relief valve. I just looked at it now and there was 27 psi . What gives????
 
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Old 03-08-05, 06:22 PM
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Oh by the way Al G. the reason i messed around with the new tank was when It came out of the box I checked with a gauge and there was no air in it so i put 12 pounds but then I was having the same issue so I started trying diff pressures.
 
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Old 03-09-05, 10:22 AM
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Is your auto feed leaking???? shut the water supply to it off and see if you keep the same psi.

ED
 
  #22  
Old 03-09-05, 12:54 PM
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I would guess that your tire gauge is off. My bet is that the tank out of the box was pre charged correctly. Your tire gauge indicated no pressure so you pumped it up to a pressure higher then 12psi.

Watch the pressure gauge as your boiler heats the water from cold to hot. If the pressure is steadily increasing with temperature you probably have to much pre-charge in the tank. If for example your tank is pre-charged to 25 psi then no expansion into the tank takes place until your boiler pressure is at 25 psi.

You can iteratively adjust the pre-charge by watching the pressure gauge on your boiler as it heats up. The point at which the pressure stops rising quickly is the point at which the pre charge is equal to the boiler pressure. At this point the expansion tank will begin to do its job. Each time you can bleed a little air until you get to a point where that equilibrium point is where you want it. Ideally this would be the boiler pressure but if it's a couple psi (say 13-15 psi in your case) greater there's no harm.
 
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Old 03-10-05, 06:38 PM
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Is it possible that when I added the new zone in my basement I did it incorrectly or forgot to add a device bleeder or something and thats why I'm having a pressure problem?
 
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Old 03-10-05, 06:59 PM
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I think it is unlikely that your work caused the problem. It's the sole job of the expansion tank to regulate pressure over the range in temperatures. As I said before you can let some air out while the boiler is hot. I would predict that you'll see an immediate drop in pressure. Let enough out to drop the pressure at temperature to 15 psi and then watch it for a couple of cycles.
Scott
 
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Old 03-10-05, 07:15 PM
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Yeah thats the thing I can get it down aroung 15 during a few cycles but for some reason it will surge to over 30 early in the morning after being cool all night???
 
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Old 03-10-05, 08:08 PM
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Turn off the supply then let it heat up then bleed air from the tank to bring it down to 15 psi. If the pressure still rises after a few cycles I would be at a loss.
Scott
 
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Old 03-13-05, 04:04 PM
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Okay I turned off the feed and the pressure seems to be holding steady at 12-15 so what now? Bad auto feed? The one that is on there is brand new.
 
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Old 03-13-05, 05:02 PM
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JohnJohn

If you turned off the feed valve & the pressure is holding steady, 99.99% probability the feed valve is bad. If the pipes have any rust or other crud in them, there might be some stuck under the seat of the valve. Would not be the first time a new feed valve got trashed by junk in the pipes. A small filter just ahead of the valve helps. This something I do all the time on steam boilers.
 
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Old 03-14-05, 04:49 AM
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Well I think I have figured this thing out. With the feed turned off I still was getting too much pressure so I checked the expansion tank and it was full of water so I removed it from the system and drained it.

After the tank was empty I re-filled it with 12 psi of air and then wondered why the tank was full of water before. I filled my sink and held the tank under water and as it turns out the schrader valve was leaking air so now I have to fix that but at least with the feed turned off it went overnight and no high pressure.

The crappy thing is that tank which was new from Lowes was on clearance so now I have to settle for a et-30 or get a new valve and the tool to remove/replace it.
 
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Old 03-14-05, 08:14 AM
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most auto feed valves are adjustable. You can loosen the lock nut on the manual feed lever and turn the shaft out or in to increase and decrease the pressure for the auto feed. It just might need calibrating rather then being bad. Sometimes dirt will get in the seats. By using the manual fill lever a few time will often clear the dirt and the spring valve will seat properly. This should be done once a year.

Can you put a cap on the expansion tank valve to stop the leak??
 
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Old 03-14-05, 04:18 PM
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Thanks for the reply. Yes a cap might have worked but Advanced Auto had a tire kit with 4 valves the Schrader 4 way valve tool, and a dial type gauge for $4.99 I replaced the valve when I got home and everything is good to go now.
 
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Old 03-15-05, 06:24 AM
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Good to hear you fixed your problem! Did you go back to the auto feed, or do you still have that shut off?

to adjust the pressure on the valve, your boiler wants to be cold and not running, then you use the boilers pressure gauge to adjust the auto inlet valve pressure to 12#s. if you go over just put a can under the pressure relief valve piping and relieve a little pressure (10#s on gauge) until you get the auto feed valve to shut off exactly at 12#s.
 
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Old 03-15-05, 08:50 AM
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No I turned it back on and it seems to have equalized itself so it should be all set.
 
 

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