Copper pipe expansion causes loud bangs

Brad White_9

1) Outdoor reset will ease the rate of expansion quite a bit (rather than all at once!) and save you energy. Yes, it is a temperature problem.

2) With constant circulation, your "higher temperature zones" may not suffer as much as you think, even if getting a temperature cooler than they are used to.

2a) Is it possible to use OD reset on the offending zones if you need to keep the higher temperatures intact?

3) The banging (versus creaking) is somewhat concerning in that it indicates higher stress on the pipe than should occur. May shorten the life. Any deficient joints will make themselves apparent....

4) If you can isolate an area of particular expansion, say at an elbow or major offset, might you be able to cut in a bend of Pex-Al-Pex as an expansion absorber? This may allow the straight runs to "float" a bit, given that they had a season or two to loosen their grip a bit. I hope.

My $0.02

Brad

Phil Reeves

Copper Pipe expansion causes loud bangs

This is keeping me up at night for the second season. In 2005 I did a complete renovation and added two hot water zones to a new bedroom and bathroom. They are both two-pipe reverse return systems using three Myson steel panel radiators per zone. Wall thermostats opens the control valves in the basement. No thermostatic valves. No reset controller. Lots of pipe under the floor.

The installer was a moonlighting sprinkler fitter, so all the 3/4" copper is tied down with clamps to the floor joists. Several notches were cut in the joists for the pipes to pass across the joists.

When the thermostat calls for heat, the pipes begin to expand and strain against the clamps and the joists. I then hear several loud bangs that wake me up at night.

The Myson radiators are completely silent and wonderfully efficient. I love them. It is the copper under the floor that is driving me crazy.

The system is overdesigned. The rooms heat up very quickly and often overshoot the thermostat temperature.

I think I have two choices: 1. open up the floor (or the ceiling downstairs) and correct the problem. 2. Change something about the flow (pressure) or temperature of the hot water in these two zones that bang.

Four hot water heating zones in the rest of the house use old cast iron radiators with some fin tube mixed in. I don't want to lower the water temperature of the other zones in the house.

What should I do? Is it a pressure or temperature problem? What can I do to correct it?

Thanks in advance for your help.

Uni R_2

Outdoor reset?

Have you thought about adding an outdoor temperature reset controller? They aren't that expensive. It'll minimize the expansion, make your home more comfortable and save you money. I would do that before ripping open the floors.


*edited now that I see Brad's post*

or what he said...

mtfallsmikey

Notching joists

Is a no no! violates building code, weakens joists

Brad White_9

Tell that to

a lot of plumbers in my area... Nothing against plumbers mind you, but it is amazing the faith some tradespeople have in the remaining inch of wood they were so kind to leave behind...

Dave_4

No joke. At some point, a plumber notched a 5"x9" (actual dimensions) joist down to 5"x3" in my house. You could fit the novels War and Peace and the LOTR trilogy side-by-side in notch w/ room to spare. Needless to say, the floor sagged and the plaster cracked.

Phil Reeves

The notches are fine.

My joists are fine. Notches are well within limits. I only mentioned the notches because I think they might be a little snug and grabbing the 3/4" copper pipe.