Hi everyone, This is my first posting and I hope someone here can help. I have a home that use hot water, baseboard heat. It has an Ack-O-Matic boiler, it looks very old but not sure how old. I couldn't find a model number on it. My problems with the system started last fall. The Armstrong S-25 BF motor was making a lot of noise so I bought a spare to keep handy in case it went out on a cold night. This February I was out of town and my wife called to tell me that the heat on the 2nd floor would not shut off (90 degrees in the bedroom!!). Also the pressure relief valve had blown and dumped water all over. So I had a friend of mine replace the pump until I could get home. When I got home I found that the zone valve to the bedroom was stuck open and would only shut manually. 2 different valve would only open manually. So I had my HVAC guy replace all the zone valve since I figured they were all the same age and would all be going (Erie Controls V8043 replaced with new Honeywells). That was the end of the heating season so I assumed everything was OK. It's a 5 zone system 3 zones on the 1st floor, 1 on the 2nd, 1 on the 3rd. This year when I fired everything up all worked well except that now when a zone valve shuts off there is a loud BANG shortly after the thermostat would kick off and the zone valve would close. The BANG is associated with the valve going off but the BANG comes from further down the line. I placed a towel on the hot valve and held it while my wife turned off the thermostat, I placed one hand on the valve and the other a couple of feet further down the line. It sure felt like the BANG came from further down the line and not at the valve. The pressure tank is an Xtol SX30. There is always a bit of air in the tank (smells REALLY bad). I put a tire pressure gauge on the pressure tank and when heat is not called for my pressure gauge will not move. When hot water is circulating the pressure reads 16 psi on the tire gauge. I cleaned out the water regulator and also replaced the blow off valve. The pressure in the boiler runs from 18 to 22 psi and the temp runs between 140 and 160. I can't get it to go hotter. Is my Aquastat bad? We have bled the air out of the lines until my fingers bled (not literally) and at my HVAC guys advice emptied and refilled the boiler twice. He also says he has double checked the flow valves and they are all OK. My HVAC guy says he has talked to a dozen of his peers and everyone is stumped. It's getting awfully expensive as he keeps coming out to try and figure out what the problem is. I am a super light sleeper and this BANGING is keeping me up all night. I thought that if I could raise the temp to 180 the BANGING might stop but I can't do that unless I drop another $150 plus labor on the new Aquastat. Does anybody here have a thought as to what the problem might be? :wall: Thanks Martin

I have a 3 Zone Hotwater Baseboard heating system that has worked fine for years. Last winter, one of the motors failed on one of the Honeywell zone valves. Since [B][B]that[/B][/B] motor was replaced when [B]that[/B] particular zone valve shut off, the pipes clanged. Last summer I replaced all 3 zone valves, the expansion tank, (checked the tank air pressure with a digital guage), then flushed & purged the system. Now my pipe(s) clanging has increased when any zone valve shuts off. If I manually "Slow Down" a zone valve with my finger when it is closing, the pipes are quite. The pipes that are making the noise are not just in the wall but in the baseboards as well. My guess is that the old zone valve motors may have had some extra drag and when the new motors were installed, the drag decreased and the valves now close faster making the pipes clang. It there a particular Zone Valve that I can install that is made for systems with loose pipes, or is there some way that I can adjust the return spring on these valves to slow down the closing speed? Thanks, Bob D