Boiler pressuring slowly rising and relief valve going off.

[FuzzyWuzzy]

i have hydronic baseboard heating system set up in the basement in a two story house. ill start off by saying someone came and replaced the pressure relief valve and the expansion tank with a amtrol 15 one and we are still having the same issues. with everything shut off the pressure still slowly climbs. someone else suggested it might be a undersized expansion tank and to get a bigger one. at this point im not sure what's going on and ive already wasted money on someone who failed to fix my issue and am just looking for advice to see if its something i can tackle myself. ill post pictures shortly, the system is extremely old. i was thinking maybe the water shut off valve that adds water into the system is faulty? any help would be appreciated as its been slowly getting colder and colder.

some additional information, i have drained the entire system and water still gets added somehow, when the heating is on, ive observed it does stay steadyish at 180 degrees.

 

[Fitter30]

With boiler pumps off and boiler temp down to 100* water pressure should be down to around 12 lbs. If water pressure is much higher drain some water out. Valve makeup water off. With a low pressure tire guage 0 -50 and a bicycle tire pump. The expansion tank is the grey tank attacked to the piping theres a plastic nipple off bottom of tank that unscrews depress valve short burst should be straight air if water comes out tank is bad. No water check air pressure should be 12 lbs. Turn system on.

 

[Sponsor]

 

[Jadnashua]

The air pressure in an expansion tank will generally equal the water pressure pushing back on the other side. TO check the precharge, there cannot be any pressure on the water side of the tank. You don't need to drain the whole system, but you do need to depressurize it to be able to check the precharge. Water doesn't compress, air does, so even if there's not much air volume in the tank, the pressure could look correct when the water is pressurized.

 

[FuzzyWuzzy]

thanks for everyone answering, i was busy and and didnt get a chance to try to tackle this issue until now. so i replaced the expansion tank and taco hyvent(it was leaking). it seems to have done the trick since the pressure seems to be holding steady, but im no longer getting any heat in certain parts of the house which im assuming is because i have air in the system. there are no bleeder valves on any of the baseboards and im sure of that. i tried looking up youtube videoes and other threads with other people with a similar set up to mine but i havent been able to find any. my set up has no automatic feeder valve, how would i go about purging air out of my system?

thank you for reading!

 

[Dana]

thanks for everyone answering, i was busy and and didnt get a chance to try to tackle this issue until now. so i replaced the expansion tank and taco hyvent(it was leaking). it seems to have done the trick since the pressure seems to be holding steady, but im no longer getting any heat in certain parts of the house which im assuming is because i have air in the system. there are no bleeder valves on any of the baseboards and im sure of that. i tried looking up youtube videoes and other threads with other people with a similar set up to mine but i havent been able to find any. my set up has no automatic feeder valve, how would i go about purging air out of my system?

thank you for reading!

To purge air from the zones without bleeders you need to run a TON of water through the zone. Turn the boiler off first and let it cool to something less than instant-scalding temps. Somewhere near the boiler there should be a valve with a hose-compatible thread for purging air. If with multiple zones (is yours a single zone system?) look for valves for isolating the zones you're NOT purging to be able to do them separately. In most systems it will be necessary to close a valves to ensure the water flows in only one direction- usually in the same direction of the loop flow.

Run the purge water into a 5 gallon bucket in a slop-sink (or outdoors if it's warm enough) bucket and let it overflow into the drain/ground. Start by just cracking open the purge valve then opening the system fill valve, keeping an eye on the pressure (keep it under 30psi but over 12psi), eventually opening up the purge valve fully (if you can). By running the purge into a bucket you'll be able to see the air bubbles as it purges, and when the bubbles stop. When no more bubbles are coming out of the purge water, ease off on the fill valve while slowly closing the purge valve to keep th pressure over 15 psi until both are fully closed. Then bleed water from the purge valve to adjust the desired system pressure.

This is a bit easier to do when there is an auto-fill valve in place (most of which also have a "fast fill" lever), but it's not really hard even without the auto-fill- just tedious.