Water moving noises in one zone and expansion noises

Larry Chappa

Have a 3 zone system with one circulator pump.Two zones on the upper level and one on the lower level.I always hear moving water on one of the upper level zones when the heat is on and I also hear expansion noises when the system is on.I have a Crown cast iron boiler which is about five years old.The expansion tank is almost new and holding pressure 12-15 pounds.I dont know how to bleed the system properly.The auto feed valve is new.Pressure on the gauge is 15 pounds and about 20 pounds when running. Water temp is 180 running.Any clues on what to do?

Jim Eastman_2

Noises

If the "water noise" is just the upper zone, there is, probaby, some trapped air in this zone. A proper purge of this zone and the system will, most likely, solve this problem. Call a hydronics professional and ask if he/she can purge your system and show you how to do it, yourself, if it requires purging in the future. As far as the expansion noises, this will be a continued problem due to how the system was installed. One solution would be to install an outdoor reset control for the boiler so that the water temperature in the system will be only high enough to emit enough heat through your baseboard fin tube convectors to meet the heat loss of the room. That way, you will approach constant circulation and avoid the "bang bang" of 180 degree water surging through the piping that has cooled to 70 degrees during the time that the thermostat is in the "satisfied" or "off" mode.

You should ask the same professional that you have showing you the purging procedures to evaluate your system to see if the reset option is viable!

Good luck,
Jim Eastman
Marmot Heating
Niwot, CO

Unknown

Jim is correct

but I'd like to expand on what Jim is saying about the expansion noise. It is indeed caused by installation issues. More than likely there are pipes that are locked into a space where they can not expand or grow in length as they want to do when 180°F water flows through them. This usually occurs when they protrude through the floor to feed the baseboard. Either too tight a fit through the floor or they are locked into a space under the floor where they can't expand. By running with cooler water such as what a reset control accomplishes, this creaking goes away due to longer running cycles with much cooler water.

Glenn Stanton

Manager of Training

Burnham Hydronics

U.S. Boiler Co., Inc.