Water Hammer

heatguy

if you have honeywell zone valves they tend to close quick and can give you a good bang,if honeys you can remove one of the return springs and this quiets them up

klaus

Water Hammer

I have asked about this before and we had solved it with my old system but now I have the issue again with my new system and the old solution won’t work so I’m asking for help again.

I have a 5 zone system with two pump circuits. One of the zones hammers when it shuts off if another zone on the opposite pump circuit is running and the water temperature is up above 160 or so.

I was thinking of lowering the system pressure. (Currently 9 static and 20 when up and running) I have a 5 gallon expansion tank. If I put a 10, is there a way
to calculate how much of a drop I might see? I’d like to get it down to 15 when running. Perhaps a 30? Do you think this would be effective against hammer?

What about differential bypass valves? I don’t have a lot of room but I could fit them in if they would solve the problem. Do I need one for each circuit? Will they solve the problem by themselves?

DC Pumps with variable speed, I am thinking they will react as the valve is closing but will they solve a hammer issue by themselves?

Timco

Near boiler piping pictures will help. Water hammer is what steam systems do, in hot water systems it is usually a pipe not properly secured, or a ratteling swing check valve. Hate to say it, but rattle or hammer are results of poor design near the boiler.

Tim

ChasMan

Thanks

Thankyou for the response. The Check valves are noisy. They are all brand new, came with the pumps. The two pumps are on the supply pumping away and the zone valves are on the returns. It is 1" copper to the pumps and then 3/4" takeoffs to the zones. The return manifold is 1" copper as well. We have like zero space and had to do a fair number of 3/4" 90's to line up the pipes. The hammer is fairly minor. I'll try and take a picture. Do you think I should reduce the size of the check valves? They are Grundfoss pumps. The Zone Valves are caleffi. Some of them close faster than others.

Timco

Well, swing check valves need 3-4 pipe diameters of straight pipe before & after to ensure they swing open nice & smooth, as turbulence from 90's makes them chatter. A slower pump speed may also help. Post those pics...

Tim

Jamie Hall

If it only happens

on one zone, and then only when the other one is pumping, one possibility which occurs to me is that the zone valve on the problem zone may be closing rather slowly. This would allow water to be pushed back (the pump now being off) by the other zone, perhaps, and slamming the check valve on the pump.

Just a thought...

klaus

Honeywell's

I had them at first and removing the spring solved the issue. I replaced them with EBV's at one point and they did not hammer. Now I have Caleffis. Only one out of the five hammers.