Integrating UFH to current system. Components required

[ado]

Im trying do install a DIY Wet UFH kit in my new extension and want to integrate it into my existing rads, but having it controlled independently of Rads. The instructions with the UFH kit has it linked to Rads so it comes on when the rads are on.

I'd appreciate it if someone can have a look at my set up and recommend any missing components.

So far I have the pipes laid and screened over, pipes connected to a manifold. The manifold has 3 circuits each controlled by electronic actuators.

From the combi boiler the flow is split with one pipe going to service rads and the other to the UFH manifold via a blending valve and a UFH pump.

The return goes back via the blending value to link up with the flow returning from the rads back to the boiler. The boiler is a vaillant ecotec 937 with VRC 430 weather compensator.

None of the electronics have been wired up yet. What do I need to complete the installation, eg wiring centres, VR61, motorised Zone values, thermostats etc.

Questions I am thinking of are Would I need a 2 port value prior to the blending valve, so have the UFH on a separate Zone Or would I need a motorised 2 port value else where to zone of the rads? Do I need an bypass value to control preasure when a zone is off?

Do I need a pipe overheat thermostat on ufh circuit to shut off pump incase of the blending valve failure?

And finally how would I wire all these up (the 3 acturators on the Manifold, UFH theromstat, pumps, any zone valves, VRC430 ) and connect back to the boiler. I read of an VR61 mixer unit, but would that handle every thing? Do I need additional wiring centres. I have also read a simple relay VR40 would do like wise!!

Just trying to figure out how this all hangs together before I call the experts in. I have a electrician who will wire it altogether if I can tell him how it all hangs together.

Thanks for any help Adrian

[The Natural Philosopher]

Ok.

1/. For fully independent timed operation, you need a separate timer.

2/. You heed some room stats radio or otherwise, to act as 'TRV's. You had better make one the master that shuts the whole thing off when warm enough.

3/. You will need a mains relay, so that operation of the normal CH pump and boiler does not result in the UGH pump running. 4/. You need to wire it all up. I bought plastic box and some DIN rails and a relay to fit, and a load of connector blocks and simply wired it myself. 5/. you will need a LOT of three core cable and some T&E. And some sleeving.

- you need to start with a takeoff from the CH switched fused spur. This is your master power feed.

- run that through a timer and your master stat, in series, to provide the main signal. Connect that to the motorised valve motor part.

- run the main live to one side of the motorised valve contacts. The other side goes to the UFH pump AND the relay coil. And any room stats you have as well.

- connect the main live to one side of the relay contacts, and the other contact to the 'call for heat' part of the boiler circuitry. If you like, the relay contacts are across whatever normally switches the boiler on, as an extra way to fire it up when UFH alone is running.

- connect all earths to a common busbar

- connect all neutrals to an insulated common busbar.

The above is now running the UFH as one master stated zone: to use the individual room stats, connect those between the switched live on the switched side of the motorised valve contacts, and the individual valves on the manifolds.

yes.

No. As with RRVS have one zone on master settings, that takes the residual flow.

No.

I looked at what wiring centers I could find, none were what I needed. I made my own.

If you need a wiring diagram, I can probably draw one.

[David Hansen]

On Tue, 28 Sep 2010 06:35:04 -0700 (PDT) someone who may be ado wrote this:-

That is a silly idea. Underfloor heating has different characteristics to radiators and should be controlled separately. As it warms the floor up, which then warms the room up it will need to be started earlier than the radiators and can be turned off earlier.

Assuming the boiler doesn't have a built in pump and time clock, which are only a good idea for installers seeking to minimise installation time. I suggest that you need two pumps, one on the branch to the radiators and one on the branch to the underfloor heating. When one or both of them is running the boiler is activated.

The one for the radiators is controlled by a time clock and thermostat, or programmable thermostat or optimum start controller. Ideally this will be a variable speed pump, assuming that some of the radiators have thermostatic valves.

The one for the underfloor heating is probably best controlled with something reasonably sophisticated. Optimum start and optimum off ideally, together with proportional and integral control.

If the boiler has pump overrun that gives an interesting conundrum. I would experiment with driving both pumps and work out which is best for this.

I might turn weather compensation off. I would certainly wonder how well it would work with the other controls.