Furnace making a banging noise?

Question

When my furnce is on it seems to make alot of noise, not unberrable but noise. It seems when it kicks on after a few moments when it is circulating it makes like a banging noise none of the pipes move or anything. It almost sounds like air pockets getting forced around. It had it's last service on November of last year and the blow off valve and expansion tank replaced and the furnace is only about 6 years old.... Any thoughts about this would be helpful before i have to have some one come back to look at it
Thanks alot, Tom

Answer 1

It sounds like you either have trapped air circulating in the system and/or your near boiler piping may be incorrect. The expansion tank should be in the proper location to work correctly and remove entrained air (if it is a standard compression tank and not a bladder style).
The expansion tank and pump need to be piped correctly. The circulator should be on the supply, pumping away from the compression tank.
See this link - http://www.hotwater.com/lit/piping/E1070.pdf
You probably don't have all the components this drawing shows, but it shows basic circulator and tank piping.
When you pump away from the compression tank, the circulator adds its pressure to the system's static fill pressure. That drives air bubbles into solution and makes it much easier for you get rid of the air that appears when you start the burner. Usually, you'll find you won't have to bleed the radiators when you pump away.

And MiKe, by the way, you have a forced air furnace, not a boiler.
Your noise is ductwork which is poping open when the fan comes on. The ductwork is either too light a gauge, and/or is not crossbroken properly (the familiar X you see on the side of a piece of duct. The duct needs to be externally braced at the point of collapse (or expansion) to fix the noise.

Answer 2

Well tom I have a small miller furnace. I run forced hot air off of straight kerosene. After my furnace's burn chamber reaches the temp where the blower kicks on it will stay on for a few minutes then the furnace will shut down but the blower will run for a few more minutes. After the blower shuts down for a few minutes it will kick back on and run for 3 or 4 minutes. After that it sounds like someone gave the side panel of the furnace a nice swift kick. BAAAPPP. It has been doing that for nearly three years. Never had a single problem with it. If you are concerned with it call the service man. I mention it to him but he never seems to be concerned.

Answer 3

I had this comparable factor ensue at my pastime very final week. i'm a upkeep guy at a retirement village. besides they concept it replaced into something to do with the heater besides. grew to become out it replaced into their refrigerator. on a similar time as the compressor might cycle off it made an undesirable bang somewhat such as you're describing. It ability that the compressor is approximately to pass out and additionally you like a sparkling refrigerator. a superb thank you to purpose it somewhat is to open the door to it until eventually ultimately the fan indoors and compressor come on. on a similar time because it does close the door back. on a similar time because it builds the temperature back off the compressor will close down and if thats whats makeing the noise, will make an undesirable, slamming a dumpster style of a valid. wish I helped......