Hot water undefloor heating

[aberdeen]

I'm in the process of having underfloor heating installed as an add-on to a conventional combi (Alpha CD35C) + zoned radiators. The plumber has installed the underfloor pipework and the manifold but no pump (yet). Am I correct in thinking that there should be a separate pump that circulates the water around the loop that is separate from the pump that circulates the water around the radiators (that in my case is integral to the boiler), or is one pump sufficient ?

[Brew]

Hepworth have a new system for SMALL (15 sqm) areas that does not use a pump or manifold. I've not seen it (only an advert) so can't comment on it. All others I know of use a pump.

Jb

[Charles Fearnley]

I've used the Hep system in a new bathroom, with some success - it warms the floor nicely and the room. It uses a lever valve at one end of the floor pipework, and a thermostatic radiator valve in a special wall mounted enclosure at the other. With these two it can be regarded as just another radiator on the system, and does not need a separate pump. It does not use manifolds, and is just a double spiral of pipe.

I think this simple system works because the pipe resistance is relatively low. A large UFH system will have much more pipe resistance, and hence the need for an extra pump.

Charles F

[The Natural Philosopher]

No: the need for an extra pump is because you need to circulate warm water *independently* from hot CH water. Because you want it timed differently, or because your CH water is too hot, and needs temp reduction. Partial recirculation is the way to achieve that.