New Vaillant boiler fitted, problems with underfloor heating.

[moonlight]

I fitted a vaillant eco tecplus 630 in July. Underfloor heating now required. It will only come on when the towel rails are calling for heat and zone valve open. I know this is a wiring problem. I didn't wire the boiler a colleague did. Live, neutral earth ok. But I can see only one of the wires on a separate wire is connected to the 240v rt. Any suggestions before I hire a sparky? Thanks

 

[ShaunCorbs]

You have a separate port valve on the under floor correct?

 

[moonlight]

There is only zone valves on the towel rails and hot water. No zone valves on either underfloor manifolds

 

[ShaunCorbs]

There is only zone valves on the towel rails and hot water. No zone valves on either underfloor manifolds

There’s your problem need them on and that’s why it’s only running with the towel rads

 

[Harvest Fields]

As above, each area (water/heating/ugh) should have its own valve. That’s why it is working with the towel rails. Who did the spec for the UFH?

Please like this post if you have found it helpful.

 

[moonlight]

Update electrician been, needed one extra live than normal. Wiring from underfloor has an electronic switch on the rails that switches the boiler on that, also has all the other heads wired to it. That's why I am not a sparky, even he found it wasn't straightforward.

 

[ShaunCorbs]

Update electrician been, needed one extra live than normal. Wiring from underfloor has an electronic switch on the rails that switches the boiler on that, also has all the other heads wired to it. That's why I am not a sparky, even he found it wasn't straightforward.

That means your going to get the slab warning on it’s own with other circuits on eg like reverse circulation

 

[moonlight]

That means your going to get the slab warning on it’s own with other circuits on eg like reverse circulation

There is no reverse circulation, tested all, valve on towel rails and hot water. The underfloor was fitted 12 years ago no problem till new boiler went in. Now working perfectly.