Underfloor Heating And Radiators On A Combi Boiler Wiring?

[pistenbroke]

Just trying to put my mind at ease, plumbers put in new combi boiler, and a new underfloor heating loop in a small extension.

Customer would like two programmable stats, to operate ufh and rads separately,

I'm I right in thinking that the plumber will have installed two 2 port valves. Or a 3 port valve?

On the wiring will this just be alittle custom S plan?

When the rad stat calls for heat Fires 1st port valve then fires combi boiler,

when the ufh stat calls for heat fires ufh pump then the 2nd valve then fires combi boiler.

Any inputs/experiences with this systems welcome as haven't done a ufh with a combi for awhile.

Thanks

 

[steptoe]

yep,

plumber could have done either of the above,

or, as he is a plumber,

something completely different.

 

[ProDave]

Ideally two 2 port valves, it's a lot simpler.

Then you really want them on different programmers. Under floor heating takes a lot longer to warm up (and cool down) compared to radiators, so you want the UFH to come on earlier than the radiators.

You want radiator programmer (and any room stats) to fire radiator 2 port valve.

UFH controller to fire UFH 2 port valve.

Then the feedback contacts from either valve fires the boiler

 

[kme]

Concur with my colleagues above.

 

[spidersparks]

As its a small ufh loop its possible that it doesn't have any actuators, thus ufh control unit would be not doing a lot, if you run the rads on a programable stat and the ufh on a separate one that would be fine, what I will say is put the live to the pump on the brown of the valve (powers the valve) not the orange ( switch live to the boiler) other wise if you where to put it on the orange when the rad circuit calls for heat it will also fire up the ufh pump, hope this helps

David

 

[Theorysparky]

Interesting I have a customer with such a problem that I am trying to sort out

combi boiler 2 chan programmer but only one chan works

so when the downstairs ufh comes on so do the rads upstairs

muppets who put that in should be shot

so this new plumber has put in a 2 port valve which will be controlled via the second chan on the programmer from the wireless stat receiver wired to the valve

 

[pistenbroke]

The ufh manifold board had an actuator fitted before the ufh pump, but the actuator takes sub six minutes to open, this in turn when the stat calls to fire the boiler, the boiler pump would be pumping into the actuator which takes sub six minutes to open.

so came to the conclusion that an two port valve was a better method as opens in sub 20secs closes by spring sub 6 seconds,

Are my thoughts right or I'm I missing something of the purpose of the actuator over a two port valve, on a small two loop ufh manifold.

Thank the help

 

[ProDave]

The actuators commonly used on UFH manifolds are a hot wax mechanism so they do take some minutes to open.

BUT it is not an issue, because as soon as the UFH manifold pump starts, it has it's own thermostatic bypass circuit, so it's not in fact pumping into a dead end.

Besides, a well designed system using just two port valves, will have an automatic bypass valve somewhere in the system.

 

[spidersparks]

If you only have one loop off the ufh piston, then I would just use the two port the only thing the actuator does is isolate different circuits on a system that has multiple zones if you are going to use the actuator make sure its 230v some are 24v or 12v if your not going to use it take it off as they shut

Sorry didn't manage to finish (fat thumbs on an iPhone) yes in their relaxed state they are in the off position

D

 

[utterlyfab]

This advice helped me cheers guys!