same problem after new relief valve/expansion tank

[knix333]

Hi all,

Gas boiler. I'm not an expert, just a wannabe DIYer.

woke up saturday to a bucket full of water off the relief valve. not sure if that was the problem so i replaced both that and the expansion tank (which was waterlogged) the day after.

anyway, everything was fine after install. bled the lines. started the boiler up and inspected for leaks every 30 minutes. 5 hours later...woooosh! about a quarter of a bucket of water from the PRV as I was watching it turn on. I'm assuming my gauge is shot because the pressure is stuck at 15, but temp on the gauge goes up and down when boiler calls for heat. drained it again and no leaking for the next hour

woke up today and you guessed it, another 1/2 bucket of water. what else could it be. gonna try and get a new gauge and new PRV again, but would like to hear your thoughts....

thanks

 

[maple1]

More info needed. Exact type of expansion tank & size, system size, complete range of temperatures, exact procedure you used, and maybe pictures. You will also need a new pressure guage to try to figure out what's happening - that is the first order of business. And if you can plumb in two pressure guages while you are at it (preferably at different spots in the system), even better - they can go wonky & it's good to have more than one. I think I have 8 guages in total at different places on my system, overkill but that's what I ended up with.

 

[knix333]

thank you very much. ok, let me try....and yes, planning to get another gauge.

Amstrol 30 (like the old one)
90k BTU
3 Zone (1400 sq ft)

Procedure:

1. shut off boiler and let cool down below 100 deg
2. shut water off from main
3. drained whatever I could to relieve some pressure
4. unscrewed PRV and replaced
5. unscrewed tank, splatter myself with water, and replaced
6. turned water back on and waited 10 minutes
7. bled the zones.
8. 10 minutes later turned the boiler on

note on No. 3, height of the boiler is about knee high and the drain is about 2 inches from the top and not at the bottom. I could only drain about 3 buckets. even tried unscrewing the hy-vent above the air scoop. is there something I'm missing

 

[maple1]

By system size, I meant how much water is in it.

Pictures would help. And a working pressure guage is a necessity. Could be more than one issue. Could be something in the way you did it - could also be a malfunctioning or dirty pressure regulator thingie on your feed line.

Also still don't know exactly what kind of tank that is - does it have a bladder?

 

[knix333]

sorry, not sure how much water is in it.



yes, my next guess was the reducing valve....

 

[maple1]

I think I won't have much more to offer, until you get a new pressure guage & install it.

But - that is a bladder expansion tank. Did you check the air pressure (precharge) in it before you hooked it up? Should be an air valve (like on your car tires) under the cap on what is now the bottom of the tank. The cap should screw off. But you will need to get all the pressure off the water side of the tank now before you can check it. I don't see a really easy way to do that with what I can see in the pic. You can isolate it by closing all the valves on either side of it, but don't see a drain to drain the water pressure off while isolated. You'd likely have to close that valve that the tank is screwed into, and remove the tank. Which I guess isn't that hard but you'll likely get wet again. You could do that when you put your new guage in. Or, remove the tank & check the air in it, then before you reinstall it, put a new T in there (bottom of valve) with the new air guage on the other branch of the new T.

 

[knix333]

I think I won't have much more to offer, until you get a new pressure guage & install it.

But - that is a bladder expansion tank. Did you check the air pressure (precharge) in it before you hooked it up? Should be an air valve (like on your car tires) under the cap on what is now the bottom of the tank. The cap should screw off. But you will need to get all the pressure off the water side of the tank now before you can check it. I don't see a really easy way to do that with what I can see in the pic. You can isolate it by closing all the valves on either side of it, but don't see a drain to drain the water pressure off while isolated. You'd likely have to close that valve that the tank is screwed into, and remove the tank. Which I guess isn't that hard but you'll likely get wet again. You could do that when you put your new guage in. Or, remove the tank & check the air in it, then before you reinstall it, put a new T in there (bottom of valve) with the new air guage on the other branch of the new T.

thanks for all the help. appreciate it. I know, till I get a new gauge we can't go further. and yes, I checked the pressure on the tank before installing it was at 8 so added to make it 12 psi.....

 

[JMac23]

After you get it all purged shut off the valve at the PRV, if it doesn't blow off anymore you've got a bad PRV.

 

[maple1]

After you get it all purged shut off the valve at the PRV, if it doesn't blow off anymore you've got a bad PRV.

That doesn't sound right. Or I'm not reading right.