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Boiler: Water coming out of pressure relief pipe

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John Vlahos

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Hi,

I purchased a house last year, it has a really old American standard boiler gas (1950s). It's still working but I keep noticing water coming out of the pressure relief pipe/valve.

I had someone come to look at it end of last winter (I have one of those service plans), and he said the pressure set was kind of high so he reduced it. It is starting to get cold here and I noticed again, it is letting water out.

When the boiler is not running the PSI gauge shows about 10-15 PSI, but when it runs, I guess for awhile, it shoots upto 30psi, and then shuts off for safety reasons (I assume it shouldn't get that high in PSI, or is it normal for it to be that high when RUNNING?)

I made an appointment for another service call - I have one of those plans by the power company, but the appointment is not until October 13 (almost a month away!).

Is this something I could do on my own (reduce set pressure) - I'm a complete beginner or should I leave it to a professional? It is letting out about 4 oz of water a day. My concern is obvious boiler expolision, but also new water coming into the system and adding further minerals - the system already makes knocking sounds (like someone is kicking the pipes). I know the boiler should be replaced soon, but trying to recover from house purchase costs.

Also, when I bought the house a had a licensed plumber come and split the heat so each floor has its own zone, I suspect he may have made the pressure high to ensure upstairs got strong heat.
 

Matt30

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Sounds like your expansion tank. If it’s a bladder type, replace it. If it’s an air/water type, drain it
 

John Vlahos

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Thanks - I think they replaced the expansion tank last year when they split the heat though, is it possible it could have been bad or defective in a years time?

They also installed all those air bleeders on each baseboard - I know some people think they are useless. Not sure if that has any relation
 
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Geofd

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if it from the 50s there would be a tank in the ceiling with a pipe going to it and a drain,if it was replaced you would see a smaller tank, connected to the piping on the boiler is there a temp gauge/pressure gauge so you know what the water temp is when the boiler is running ???? should be down around 180 or so those bleeders take air out of the system,so water can continuously flow
 

Riickk

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Are the bleeders "automatic", or do you need to open them (to bleed air out)
with a small key, shaped somewhat like mickey-mouse's ears?
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johnjh2o

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Thanks - I think they replaced the expansion tank last year when they split the heat though, is it possible it could have been bad or defective in a years time?

They also installed all those air bleeders on each baseboard - I know some people think they are useless. Not sure if that has any relation
Matt 30 gave you the correct answer to your problem. The vents have nothing to do with the T&P leaking.
 

John Vlahos

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OK, I can have the expansion tank checked. Here are photos of my setup.

I am very concerned because I am noticing that the temperature of the boiler (according to the thermostat in the boiler itself registered 270F and the PSI was almost 30. The unit then shut off and released a bit of water out of the pressure relief pipe. I read online that normal operating temperature should be 180F! Should I shut the boiler off completely?

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John Vlahos

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thanks for asking, I mentioned it above, but it is running very hot when operating it hit 270F! I could hear water boiling outside! I'm getting very concerned. I'll have the expansion tank checked ASAP, of course Id like to squeeze a bit more time out of this boiler - we have a 1yo baby and the wallets are still bleeding from buying the house. :steamed:

if it from the 50s there would be a tank in the ceiling with a pipe going to it and a drain,if it was replaced you would see a smaller tank, connected to the piping on the boiler is there a temp gauge/pressure gauge so you know what the water temp is when the boiler is running ???? should be down around 180 or so those bleeders take air out of the system,so water can continuously flow
 

wood4d

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Is your circulating pump working? Hitting 270 is dangerous. Do you have heat? The knocking sound could be air in the lines or if its coming from the boiler... boiling water with no where to go. does it work if you manually open the zone valves?
 

John Vlahos

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Yes, the heat is working and the pump is working, the cirulcattor pump is quite loud (humming sound) and was replaced last year. I think the noise is air or lines, or mineral build up. I assume if water is leaving the system, new water is being added contribuitng to more minerals?
 

wood4d

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dont worry about minerals...If your temp is too high you need to get your boiler serviced soonedr than a month from now the valve thats leaking is a pressure temp valve and its the safety on your system. but your temp control on your boiler is malfunctioning which results in high temp and pressure.
 

John Vlahos

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I called the plumber who did the work, he says it sounds like the aquastat. Then he said he needs about a week., I got the local utility company to come and look at it sooner so they are on the way, will let you all know what they say. I appreciate everyone trying to help me diagnose.

I need to take a class on this stuff once everything opens up, it drives me nuts not to be able to fix some of this stuff on my own.
 

Riickk

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Aquastat - Yes; It should be shutting off the burner much sooner.
 

Matt30

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Definately the aquastat. You didn’t mention the temperature spike in the original post. Get that addressed ASAP, that’s a dangerous temperature. If you don’t need the heat, then the power off
 

FishScreener

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The high heat could be causing reduced pressure in the pump inlet, resulting boiling/cavitation. Thus the continuous noise.

And, the Temperature Pressure valve is kind of working. It should be opening perttty much full bore at the temps you‘re describing.
 

John Vlahos

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The uility company came by to check the boiler this morning (I have one of those service contracts).

He changed the aquastat and then checked everything and that appears to have been the problem.

The only thing is that he noticed the draft hood was cracked (the previous owners taped it - they were quite frugal), so he gave me a violation and cut the gas off at the branch line! I usually tip these guys and forgot to do so this time - I dont think thats why he shut down the gas line but thought that was extreme for a small crack. maybe he was a by the books kind of guy

Anyway is that really serious, if its just cracked? Any idea of costs for that and if a chimney specialist is qualified to replace it? I thought to have them clean the chimney as well.
 

John Vlahos

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Also to replace the draft hood on the boiler, is that a job for a plumber or can a chimmney specialist do that?
 

John Vlahos

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Here are photos of the draft hood- The last owners just put tape around it. They were very very frugal people.

Could this also be affecting boiler performance?

The utility rep just shut off the gas to the boiler but I can switch it back on

Do you all think it needs to be replaced urgently, I definitely see some rust? If yes, what types of professionals are best to replace this? I called the local plumbing shop and they dont sell hoods for these old boilers, they recommend a sheet metal shop. I was thinking of calling a HVAC professional or plumber.
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