new heating system with underfloor heating

5 Sep 2007
Reaction score
United Kingdom

My heating engineer has installed a new heating system with underfloor heating, it basically consists of:

grant condensing outdoor oil bolier.
range unvented tank
underfloor heating
gundfos UPS pump

existing Radiators in all rooms except kitchen.

new kitchen has UFH, this is an LK system with mini manifold and its own pump. This is connected to the boiler primaries

There are three 2-way valves - one for heating(radiators) , one for water and one for the UFH.

There are 3 controllers, one for UFH, one for heating, one for water, each is totally independent, each will turn on the associated 2-way valve and also turn on BOTH the boiler and the pump.

What I am concerned about is if the UFH is on while both water and rads are off...
There is no bypass loop, so when they are off the outlet from the main pump is effectively shut off. The pump makes a slightly odd noise because it can't pump anywhere.

My heating engineer says this is O.K and that the pump will not burn out.

I am dubious, I think it needs a bypass loop or a system using relays so that the UFH controller is able to just turn on the boiler and not the main pump.

Any advice would be most appreciated.
Sponsored Links
Sounds like it is wired up wrong to me.

Even with UFH includede the main pump should be isolated when no call for heat is asked for anywhere I would have thought.
Sounds like the system is wired correctly. It is the way uponor systems work.

An automatic bypass valve is required in this set up or the main pump will burn out prematurely.

I would get the installer back to fit one. Most underfloor systems state that a bypass valve or similiar is fitted. If the installer refuses then ask him to put in writing that the installation does not require one.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links