Residential Knocking

JR

We just moved into a new home with a gas-fired baseboard hot water system. The house is pretty airtight, a small cape with three zones, so I think its easy for the system to bring the home up to temperature. However, through the night, we are subject to a fair bit of intermittant knocking and banging; I assume it is a result of the system firing back up.

The problem with this is that the heating system now scares my 3-year old daughter. Is this just the way it is with this type of system or is there something we could try to reduce the noise?

Mike T., Swampeast MO

Expansion and contraction are most likely causing the noises.

Look for poorly or loosely secured tubes. If you can tell that it's coming from particular baseboard units remove the cover(s) and see if the piping seems in a bind where it comes through the floor/wall. You might be able to slide something firm but slippery between the tube and framing. You might be able to enlarge the holes slightly but BE EXTREMELY CAREFUL not to damage the tubing!!!

hr

What type of boiler?

Copper tube boilers piped wrong, or with inadequate flow will make wild noises.

Otherwise I would also guess expansion noise. A reset control may help minimize the noise allowing a less extreme temperasture difference and near constant circulation.

If it is air, it could be the installation of the purger or it's operation. Boosting the fill pressure will often help by reducing the bubble size and allowing it to move to the purger easier. A simple first step, becareful not to run too close to the relief setting, grnerally 30 psi.


Hard to tell without actually hearing the noise firsthand.

hot rod

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Dale

Expansion noise

Best guess is expansion noise, you didn't say but if you zone with zone valves one in backwards makes a really loud bang. You could try all the usual expansion restriction checks and if that doesn't fix things lower your water temp with and indoor/outdoor reset and go to constant circulation. Many zone systems have isolation purge valves at the end of each zone which can be closed one at a time to test for the noise location.

No Sleep!

King Kong Walking

Hey! I had the same problem in one of my rooms! We put a 1" wood board under the radiator and the noise went away! The wood board doesn't go with my decor! But I am sleeping well at night. Good Luck!

Bob Flanagan_3

Also look for..

wire hangers in the basement used to support the main. Sliding a piece of foam pipe insulation between the tubing and the hanger will make the noise go away.

I agree with the others that this is most likely the cause of your noise.

Good luck!!

Noel Kelly

Bypass

Your second floor piping is most likely touching wood and unless it is accessible, there's not much you can do to repair it. However, I had a similar problem in my own home and the following fix was effective.
Have your heating professional run a bypass from the supply to the return of the offending zone. At what point you do this is dependent on your setup - circulators or zone valves - and their location. Install a ball valve on the bypass for balancing. The idea being that you temper the hot supply water with cooler return water. You will find that you will get a more gradual increase in temperature at the offending zone thus reducing the expansion noise level considerably.
This is a relatively inexpensive fix for a very annoying problem that should never have been allowed to happen in the first place.

J.C.A._3

Dumb ....but effective for,

Pipes being too tight to holes cut. I found through lots of trial and error that waxed milk cartons were a help. I put them between the offending pipe and the wood and it seemed to give some "lubricity and forgiveness" as opposed to the rubbing.

I cut squares of about 1" , so they fit above and below the floor board, and put them between the pipe and the boards. My Mom was pretty impressed, so I think it's worth a shot.Chris.

Unknown

Funny, Chris,

I was using PLASTIC milk jugs for the same thing. I'm going to try the wax paper ones, now.

Noel

Tom M.

My dad used to

wrap a plastic coated playing card around the pipe and slide it in.

Tom M.