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Re: Running water sound in hot water heating pipes

System is a propane fired boiler two loop system (1st and 2nd floor) Noise mostly occurs on the second floor loop especially when it is first heating up. Once system haas attained heat, it seems to stop. I have not ruled out air in the pipes yet.

Re: Running water sound in hot water heating pipes


Thanks for your post.

I would also need to know:

1) Are the upstairs and downstairs heating pipes connected by a single series pipe loop, or do you have zone valves and separate loops.
2) Do you have copper pipe, PEX, other.
3) How far have you gotten on this problem; have you had any service techs over, and if so, what did they recommend.
4) What is the total square footage of the house being heated.
5) What is the btu rating of the boiler (usually listed somewhere on the boiler).
6) What is the brand and model of the circulator pump and its horsepower rating
7) Do you have bleed valves on the convectors, and have you tried several times to get the air out this way.
8) Do you have any "AIR SEPARATORS" on the main supply pipe or manifold (Spirovent, Air Scoop, hydronic air vent, etc).
9) Do you have an Extrol-type pressurized expansion tank, or the older type steel tank nestled up in the joists.
10) Does the boiler temp max out at ~200 degrees when it's hot, or closer to 180 degrees.
11) Is the piping throughout the distribution system mostly 3/4" copper, series loop, or Split Loop, or Diverter valve.
12) Is there any 1/2" piping going to and from the convectors in your system.

There are examples of heating pipe arrangements at the site below.

Scroll down the page and click onto the different pipe configurations.
13)Is your boiler pump located on the return side of the boiler, or the supply side; is it "pumping away" from the expansion tank (does the output of the pump flow right into the expansion tank intake).

You should be able to eliminate the air out of the system if you have bleed valves on the convectors, especially on the 2nd floor convectors, which is where the air will collect.

If you've had to bleed the convectors continuously & still keep getting air in the piping, please advise.

If you've used the "purge" method of bleeding the system instead, please advise.


Re: Running water sound in hot water heating pipes

Yes it sounds like you have air bubbles in the circulating water. I can only speak of my expirence since every instilation has its own quarks. I have three heat zones and one monster 1-1/2 inch pump feeding a manifold where the 3 zones come off. I have two valves on each zone one to close off the zone the other to blead the zone. I open the fresh water feed to the boiler and close one of the zone valves and open the blead valve into a short hose to a bucket. the water pressure into the water jacket will push the water and air out of the zone piping, when the bubbles stop coming out of the hose in the bucket -- the air has been flushed out of the pipe. then repeat the process on the other zones. the tanks that were talked about in some of the other answers are to take up the pressure of the expanding hot water so that you do not blow water out of the pressure releaf valve.

good luck on venting the air out of your system


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