Underfloor Heating Manifold - normal setup?

Civil Eng

Hi all,

I’ve been trying to figure out the UFH in a house Ive recently purchased. I have a suspicion that it mightn’t be installed to the best standards based on some water hammer that I hear when the heat pump kicks in.

Some basic facts - two storey house, UFH downstairs, rads upstairs, GSHW heatpump

So, please help me out here. A couple of questions:

Is it normal to tap off the flow and return pipes into the manifold for upstairs rad or should they come directly off the manifold like each of the ground floor zones? The tap of the flow has a 2 port zone valve installed.

Is there any reason a 2 port zone call would be installed with the arrow facing into the flow???

Doolittle51

The underfloor circuits run at a lower temperature to radiators, so you should have a mixing valve & pump at the manifold? Taping off the flow & return to the manifold is fine, if it's done correctly. It does sound like the radiator zone valve is installed backwards though.

Civil Eng

Doolittle51 wrote: »

The underfloor circuits run at a lower temperature to radiators, so you should have a mixing valve & pump at the manifold? Taping off the flow & return to the manifold is fine, if it's done correctly. It does sound like the radiator zone valve is installed backwards though.

Thanks Doolittle,

No sign of a mixing valve or pump I’m afraid. I believe there is a pump nearer heat pump.

Will get the rad valve turned around. It makes an all merciful bang when it closes.

I think there is something else causing water hammer too tho. I’m not sure whether the Heat pump is possibly being engaged too early

corkgsxr

No bypass is cause banging

Calahonda52

Are we taping or tapping off here?
In any event the same temp is used on poor installs when the UFH pipe spacing is pushed out and the same flow temp used across the rads and UF.
The rads may be sized correctly for the UFH temp flow rate design.

Doolittle51

Sorry, just noticed you have a Heat Pump. Temperature output is low enough for underfloor so no mixing valve would be required at the UF manifold. As corkgsxr said, lack of a bypass would cause issues. Does your rad zone valve have a manual override? (usually a small lever that you open and a catch to keep it open) You could try leaving it open for now & it should solve the banging problem, but your thermostat for that zone will be ineffective.
Throw up some pictures if you can, might give us a better idea of your setup.

Dtp1979

I’ve seen it a few times where a motorised valve facing the wrong way caused banging.