Hot water heating system problem - Question

[DaveNH]

I think this is going to be costly.

Here's the setup:
Hot water to heat the house comes out of the furnace
goes to an air separator valve. It's a one way valve with 4 ports.
One input and one output (1"), a port on top (1/2") and another on the bottom (3/4-1"?).

On the bottom port of the air separator is connected to the expansion tank.
On top port of the air separator valve is connected to the air relief value.

I discovered that water is coming out of the air relief valve.
There is a small valve on top that looks just like a tire stem valve.

I am assuming that the bladder in the expansion tank is shot.
I am also assuming that the air relief valve falls into the same category.

So the question is:
Are my assumptions correct?

 

[beenthere]

Dave
I apparently have a different system, as my air separator has only the air outlet above (one below is plugged) that goes to an air/expansion tank that I can drain if it gets water logged (rare) and it sets above the air separator valve.
Can you drain your expansion tank?

If your expansion tank has a bladder, can you add air? to test the bladder?

 

[leaddog]

The air release valve my be corroded and need replacing. Not a real expensive deal. You can do it your self. The expanstion tank should be ok unless the water pressure is going up to high. You can look at that by checking the temp-pressure guage. Even a new expantion tank is only 50-75 bucks and you can change that yourself also.
leaddog

 

[Mark_in_NH]

I agree with leaddog.
It is most likely just the relief valve that needs to be replaced. In all the houses that I take care of with FHW, this appears to be a common item to get repaired. Once replaced it won't or shouldn't bother you again for several years.

 

[Bob999]

The air relief valve you show sells for about $10. Replacement is very simple--it just screws in. The only time consuming part of the job is draining the system down and then refilling the system and getting the air purged.

The expansion tank is separate--the replacement process is the same. From my experience there is no reason to believe that a leak in the air valve means that the expansion tank is bad. Assuming that you have a pressure gauge on the system and that it is showing a normal pressure (usually 12 lbs unless you have more than 2 floors above the boiler), a quick test for the expansion tank is to shut off the auto fill valve and then open the drain valve for the system. If you get a pressurized flow for several seconds it indicates that the expansion tank is probably good. If pressure drops immediately the pressure tank is probably bad.

 

[tawilson]

Before you drain the system, check for isolation valves. You should be able to isolate the air separator from the zones in your house so you won't have to completely drain the system.