air in pipes - well or heating system?

[Alleycat]

We have new home with a drilled well (over 450 ft deep) and a forced hot water heating system. There is a knocking in the bedroom pipes. The plumber has bled the pipes three or four times already. It is much better but the knocking keeps coming back. The plumber says he has done all he can and the fact that the air keeps returning means there is a crack in the well lining or the line running from the well to the house. The well company is skeptical (husband is calling them back today but it sounds like they are pointing the finger back at the plumber.) Anyone have any experience with this?
thanks much

 

[RioHyde]

I dont see how a crack in a well lining could make your pipes rattle. I'm not saying its NOT the case, but I think I'd look at something else first. It sounds like a water hammer issue to me...that is your pipes are banging in the wall when water runs then is shut off suddenly. I'd bet the lines in the wall aren't anchored very well, however this isnt always the case. You may need to install water hammer arrestors, open the walls to anchor the lines or even a combination of the two. Like I said, I'm not saying it couldnt be something the plumber has stated. I'm not there and he is....but if it sounds like a horse, smells like a horse and walks like a horse, I wouldnt immediately start looking for zebras.

Good luck!

 

[Sponsor]

 

[Alleycat]

thanks for the reply Riohyde - by "water hammer" do you mean the noise would occur when we call for water? If so, my post was not clear - we all seem to agree that the noise is air in the heating pipes rather than the water pipes. (we unfortunately have lots of experience with this - our last house had the copper heating pipes resting on nails and they made an emormous racket - we fixed the exposed pipes but we didn't open the walls.) In this case, we saw the rough plumbing (to make sure we wouldn't have to live with that again!!) and I don't think the pipes are moving. So if it's air in the heating pipes, the plumber says the blow off valves on the heating system eventually purge any small amount of air that comes in from the well line, but this excessive noise suggests that there is more than the normal small amount of air getting into the pipes... The well company says if we had a crack in the line, we would see all kinds of air coming through the faucets too - we were away last week and when we returned, i did notice that the laundry sink faucet had lots of air in the water when I first turned it on, but other than that, we haven't noticed anything unusual.

 

[Jadnashua]

You could have a bleed valve that is a little leaky, need a recharge to the expansion tank, or other things. I'm not a pro, but first thing I'd do is check all of the bleed valves and make sure they are closed tight. Then, I'd check the expansion tank and make sure that it is not full of water. Another thing, a device like a Sprirovent to extract disolved air in the system isn't a bad idea. You should find the air leak, since air in the system leads to corrosion. My unprofessional opinion. You probably have an air valve in your system - they tend to get corroded, and stop working. They allow air to be expelled. The Spirovent (there are other brands), works by "combing" air out of the liquid as the water is pumped through the system. The air valve requires air to pool in the area it is installed. The pump tends to cause the air to disolve in the water, and the air valve (I don't remember the "correct" name for these) doesn't have any vapor to allow to escape. Works well when filling the system, but not as effective during normal operation.