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Hot water. Baseboard leak

8K views 13 replies 4 participants last post by  Mark Potter 
#1 ·
I'm having a issue with my hot water baseboard heater leaking.

The water is coming from what I believe is a automatic air purge valve, slowly leaking from the top side where the black cap is.
I took the cap off and pushed a small piece of metal rod in the hole.. Which released some water and seemed to stop the leak. But it returned after a couple hours..

This is the only baseboard in the house that has that style valve, the others have a manual air bleed on them.. Could I replace this with a manual one?
 

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#2 ·
So far as I know you can replace that bleed valve with a small manually operated or automatic coin valve. I have small Watts coin valves throughout my house (I have a similar heating system), once in while they will leak, and I replace them. A few of my valves claim to be automatic, but they never seem to purge the air automatically, so I wind up manually bleeding the air from the system at the start of heating season, and usually at least one more time during heating season.
 
#5 ·
I haven't checked all the registers yet, but so far this is the only one I've found with a automatic bleed on it. The rest are all manual.

This one does thread into the 90. But it's offset and looks like it will impact the wall if I try to remove it. I'm going to try shutting the valves off tonight and clean it. The top cap unscrews from the body.

Should the system be under pressure? The heat was shut off for the summer and it hasn't gotten cold enough to turn it back on yet. So I know the water is going to be cold.
 
#6 ·
Even in the summer, there should be pressure in the system.

The large top brass piece turns off, and then you can clean the float and valve assembly.
 
#7 ·
Ok well doesn't hurt to clean it if it still leaks and I take it it's leaking from the top were it spits the air and the heat is off so there for will be worse once you have pressor when system is running so if u don't want to go through the trouble of soldering ect I would see if you can get the same type air vent and just swap out the top of it.
 
#8 ·
If the heat is off no circulators are going then there wouldn't be pressor just what ever water is sitting there in the pipe hot water creates pressor. Also if the air vent is a threaded male at the bottom then at the 90 should have female at the T can get a threaded male adapter plug or cap 3/4".
I'm only saying cuz I think cleaning it would stop it from leaking I wish it would be that easy although I'd be out of work lol
 
#9 ·
Thee is pressure there. If there wasn't any pressure then no water would leak out.

The OP can check, by simply looking at the gauge on his boiler. If it works, it will show 10 or more pounds of pressure.

The fitting that that air vent is screwed into is called a radiator ell.
 
#10 ·
The pressure in your hydronic system is created by the house water pressure. Typically the makeup boiler water feed line is run through a pressure reducer next to the boiler that reduces the pressure from house pressure (typically 60 psi or so) to boiler pressure, which can vary, but is usually around 15 psi. When the circulator is off, this is static pressure, meaning that the measured pressure in the line will be 1 psi lower for each 2.3 feet of pipe rise above boiler level. So a first floor radiator will read about 12 psi.

When the circulator turns on, it increases the pressure slightly at the outlet from the boiler, which causes water to flow through the loop. The water returns at static pressure. The circulator actually adds a relatively small amount of pressure, just enough to get the water to flow at an appropriate rate.
 
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