frontier system 2000

mongonad

my system is 10 yrs old for heating & hot water. over the last 3 winters the pipes will bang loudly as soon as the circulator starts. one bang & then it's normal operation. this only happens for about 3 days ; & the banging stops completely. this happens just once per winter. the banging sound seems to be coming from the main circulating pipes. it also seems to come from different sections of the circuit. I can see different sections of the piping moving at the sound of the bang. after 3 days of banging the banging completely stops & runs for the rest of the winter. I tried bleeding the air from the radiator bleeder valve & got little or no air. should I just accept this condition or is there some sort of remedy for this??

SuperTech

It sure sounds like air in the circuit. Maybe try to purge the zone. You should have a purge station on the return. Either one valve and drain below a manifold or a valve and drain on each return. Both setups will get the job done. First shut off the boiler at the switch on the manager. Next, your going to want to hook up a hose to the drain on the return and close the valve below it. Then you open up the fill valve and open the drain valve. I usually close the drain valve for a few seconds while purging to keep the pressure up, but watch the gauge and make sure the pressure stays below 30 PSI.
If you give the zone a good long purge and bleed the radiators you should be able to keep the system free of air. Also make sure the air vents on the boiler are in good condition. If they are original they probably should be replaced.

Sometimes you can get noise when the system first comes on after a setback period on a programmable thermostat. When the zone valve opens and sends hot water through a cold pipe you get some expansion noise until everything warms up, but not necessarily a bang. What kind of piping do you have? I imagine copper or iron if you have radiatiors. Can you post any pictures of the boiler and near boiler piping?

mongonad

thank you for the suggestions!! how long is a good long purge?? I am not going to mess with it now as it is 6 degrees outside & my experience with heating system is minimal. ( don't want to make anything worse) I will try thu. or fri. thanks very much

mongonad

I have copper pipes. I cannot post pics ; no phone! it's not expansion noise. it's immediately as the circulator starts.

SuperTech

The length of the purge depends on the size of the zone and length of the piping. Sometimes you can tell when the water stars purging out hot and then fresh cold water starts coming out you know that you have forced water through the entire zone. Usually most zones only take a couple of minutes. If you get sputters of water coming out you know that you are purging the air out. If the water comes out in a nice steady stream you are good to go.

Immediately after the circulator starts does sound like air, or possibly a pipe not secured correctly and banging against another pipe when the circulator starts.

As long as it functions I wouldn't touch it now either. Below zero today where I live. Later this week sounds much better. Keep us posted on the results, I hope this helps!