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suemahoney
banging pipes

We had a new gas boiler installed about 5 years ago and since then we have had problems with the pipes banging and it keeps getting worse. The furnace kicks on runs for a minute or two shuts down for a minute then kicks back on again two or three more times in a short time. I think the water going thru the pipes is getting too hot shutting down the furnace but the thermostat is calling for heat still, so it starts back up and it continues.

tylersway
Re: banging pipes

where is all the banging located ,near the furnace .in the bathroom ,at the sinks, in between the wall or floors .if you have access to any of your pipes where the knocking is coming from ,what you can do is go to any home depot or plumbing supplier and ask them for a water hammer or there might be another name for it as well (water arrester). this is a copper pipe maybe 6 to 10 iches long it would actually be rounded at the top of it.what this is suppose to do is prevent water from making noise within the pipes.if you are handy and can sweat copper pipes than its easy.what you do is cut the pipe about 3/4 to a inch from each other add a tee connector between the space of the pipes and sodder the coupling/connector make sure the bottom of the tee is facing upward then insert water hammer in to that part of the tee and sweat that. make sure you have no leaks. before you cut any pipes close the main valve from your water meter located in your home. then open up all faucets to drain the rest of the water out then you can start cutting pipes

NashuaTech
Re: banging pipes

suemahoney:

This condition is known as "short-cycling".

I think you will have to have a heating technician come in to find out exactly what is causing this condition--it could be any one of 10 different causes.

The previous post relates to airbound pipes in a hot water supply system & IMHO is not applicable in this case.

Since you are not getting results from your current service person, try to find someone who is familiar with hot water heating systems--check the Yellow Pages under "Burner Service", etc.

Short cycling can occur due to relatively simple problems like a misadjusted aquastat setting, worn or dirty aquastat relay contacts, a faulty circulator (pump), a defective ignition module on a gas boiler, air blockage in piping, dirty or defective flame sensor, improper differential setting, oversized boiler, undersized zones on a zone system, poor near-boiler piping arrangement, wrong burner nozzle size, wrong size circulator (pump), considerable load variation on various zones, etc.

The noise you're hearing can come from the pipes overheating & expanding due to poor circulation, and/or air-bound pipes in parts of the system.

Google "boiler short cycling" for numerous articles on this problem.

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