Vince s
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Leaking boiler pipe
- Thread starter Vince s
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That looks like the pressure relief valve,if your not handy call a professional
Last edited:
Mitchell-DIY-Guy
Well-Known Member
Looks to me like the air purger. Maybe the threads have lost their seal. Happened at my dads and the furnace repair guy fixed the leaking by changing the piece at the top, the vent. Wasn’t difficult or expensive.
Here are the two pieces:
https://www.supplyhouse.com/Amtrol-700-30-1-8-MPS-Float-Air-Vent
https://www.supplyhouse.com/Amtrol-444-1-1-1-4-Air-Purger-1-8-NPT-Vent-125-PSI-Cast-Iron
Here are the two pieces:
https://www.supplyhouse.com/Amtrol-700-30-1-8-MPS-Float-Air-Vent
https://www.supplyhouse.com/Amtrol-444-1-1-1-4-Air-Purger-1-8-NPT-Vent-125-PSI-Cast-Iron
Bird Doo Head
Well-Known Member
Hello Vince S,
From the photos, I could not tell for certain if the dripping pipe is from the pressure relief valve. If that's what is dripping:
First, check the system pressure when it's cold. If it is over the relief valve setting (usually 30 PSI-G), the automatic make up water pressure reducing valve needs adjusting, rebuilding or replacing.
If system pressure is OK cold:
Check the pressure of the diaphragm in the expansion tank. That tank has a rubber diaphragm separating the tank into two compartments. One's air and one is water.
If the air section loses its air charge, the pressure relief valve generally will drip when the boiler heats (and sometimes when not heating).
There is a Schrader fitting on the bottom of the tank. Check the pressure with a tire gauge. A rule-of-thumb is 12 psi-g.
You can pump it up with a bicycle pump.
If water comes out when you put the tire gauge on the fitting, the diaphragm is broken in the tank. Then then tank needs to be replaced. Be Careful- It will be very heavy because it is full of water.
(Note: When you have time, the expansion tank really should be supported by framing or a floor stand, instead of the piping.)
Next Problem: If the relief valve has been dripping for a time, it's seal might be compromised by sediment or lime. You may have to change it, too.
I Hope This Helps!
Paul.
If you want to be really accurate when calculating expansion tank pressure requirements:
Pa = H(dc / 144) + 5
Pa = Tank Air Pressure
H = Height in feet from top of tank to highest item in heating system
Dc = Density of the fluid in t he system in cubic feet. (Water at 70-F is about 62.3 pounds per cubic foot)
5 = Typical PSI-G at highest point in system. (You can change this if yours measures differently.)
144 = The constant conversion factor
From the photos, I could not tell for certain if the dripping pipe is from the pressure relief valve. If that's what is dripping:
First, check the system pressure when it's cold. If it is over the relief valve setting (usually 30 PSI-G), the automatic make up water pressure reducing valve needs adjusting, rebuilding or replacing.
If system pressure is OK cold:
Check the pressure of the diaphragm in the expansion tank. That tank has a rubber diaphragm separating the tank into two compartments. One's air and one is water.
If the air section loses its air charge, the pressure relief valve generally will drip when the boiler heats (and sometimes when not heating).
There is a Schrader fitting on the bottom of the tank. Check the pressure with a tire gauge. A rule-of-thumb is 12 psi-g.
You can pump it up with a bicycle pump.
If water comes out when you put the tire gauge on the fitting, the diaphragm is broken in the tank. Then then tank needs to be replaced. Be Careful- It will be very heavy because it is full of water.
(Note: When you have time, the expansion tank really should be supported by framing or a floor stand, instead of the piping.)
Next Problem: If the relief valve has been dripping for a time, it's seal might be compromised by sediment or lime. You may have to change it, too.
I Hope This Helps!
Paul.
If you want to be really accurate when calculating expansion tank pressure requirements:
Pa = H(dc / 144) + 5
Pa = Tank Air Pressure
H = Height in feet from top of tank to highest item in heating system
Dc = Density of the fluid in t he system in cubic feet. (Water at 70-F is about 62.3 pounds per cubic foot)
5 = Typical PSI-G at highest point in system. (You can change this if yours measures differently.)
144 = The constant conversion factor
Bird Doo Head
Well-Known Member
I apologize Vince for complicating a very easy repair. It's like filling a bike tire.
Check the fitting on the bottom of the tank with a tire gauge.
If water comes out, you need a new tank.
If no water comes fromt he air fitting, pressure should be about 12 pounds per square inch & that pressure should be higher than the boiler's pressure gauge (usually about 6 - 8 pounds cold). Add air with a bike tire pump.
If you get a plumber, try to get a hydronic specialist.
Many times, for friends, I've gone behind honest & well intentioned plumbers who changed a leaking relief valve, thinking it was defective when it was system pressure or a saturated expansion tank. They meant well and the symptoms pointed toward the relief valve, but hydronics present atypical symptoms sometimes.
Paul
Check the fitting on the bottom of the tank with a tire gauge.
If water comes out, you need a new tank.
If no water comes fromt he air fitting, pressure should be about 12 pounds per square inch & that pressure should be higher than the boiler's pressure gauge (usually about 6 - 8 pounds cold). Add air with a bike tire pump.
If you get a plumber, try to get a hydronic specialist.
Many times, for friends, I've gone behind honest & well intentioned plumbers who changed a leaking relief valve, thinking it was defective when it was system pressure or a saturated expansion tank. They meant well and the symptoms pointed toward the relief valve, but hydronics present atypical symptoms sometimes.
Paul
Bird Doo Head
Well-Known Member
If you post your location, perhaps a member here will know someone trustworthy in your area. It might also help to post your inquiry as a separate New Question so more people will notice it. There are lots of knowledgeable and helpful people in this group.
Posting the boiler make & model, plus whatever details you think may help might allow someone here to suggest a repair that you can do yourself. (Details such as if it is spark ignition, water pressure- is it sparking - Indicator lights on the zone control panel, stuff like that.)
If you don't find what you need here, HeatingHelp has lots of hydronic information and a forum for questions called "The Wall".
Last Resort: Your local gas or electric utility might have a service team employed by the utility. They tend to be honest because they have nothing at all to gain by selling you anything. Some require you to have a service contract to use their in-house people, some don't.
Paul
After seeing those pictures I'd have to agree with Mitchell diy guy you can see the leak stains
Bird Doo Head
Well-Known Member
Automatic air vents are famous for leaking after lime coats the float seal.
If you're so inclined, perhaps consider an air scrubber instead. It replaces the scoop tee and the air vent. The expansion tank screws into a tapping at the bottom. They work well and I've never replaced one. Spirotherm's Spirovent is a reliable brand.
Paul
