Central heating wiring with ufh plus rads

[an203888]

Hi all, I'm not quite sure what the neatest, simplest solution to my central heating wiring. I have 4 zones. Two radiator zones, a hot water and an underfloor heating zone.

My understanding is that when the radiator zones are turned on, the ufh pump should not come on so should be isolated from the main pumps live supply, presumably through a relay.

I see there are specific wiring centers such as heatmiser which offer this but only offer one radiator zone and I need two.

I could override the stat imput on the wiring center to always be on and then add a second simple wiring center to operate the two rad zones with two seperate stats. This isnt the best solution I'm sure though.

Any suggestions please?

 

[CBW]

My understanding is that when the radiator zones are turned on, the ufh pump should not come on so should be isolated from the main pumps live supply, presumably through a relay.

Would have thought through the zone valve switch live? Not entirely sure what you’re after - a thermostat arrangement, wiring center solution or both? What do you have currently?

 

[an203888]

I'm after a wiring center. If one of the radiator zone valves is opened a live (orange) is sent to pump/boiler however this will also turn the ufh circulation pump on. How do I stop this?

 

[CBW]

I'm after a wiring center. If one of the radiator zone valves is opened a live (orange) is sent to pump/boiler however this will also turn the ufh circulation pump on. How do I stop this?

I could be wrong (I’m not fantastic with wiring),but if your ufh is a separate zone with a separate pump, then surely it would work from ufh stat switched out from zone valve to pump live?

 

[an203888]

I could be wrong (I’m not fantastic with wiring),but if your ufh is a separate zone with a separate pump, then surely it would work from ufh stat switched out from zone valve to pump live?

The underfloor heating has a seperate pump for circulation but also uses the main pump to add hot water to the circuit so both need to be switched on... Easy no problems.... So the live from the zone valve goes to both pumps and the boiler to turn them all on. However the zone valve for the rads still needs to turn on the boiler and the main pump so the live needs to go to boiler and pump.... BUT not to the ufh circulating pump. I am presuming a relay is needed and that's what the likes of the Heatmiser has...?

 

[CBW]

A bit beyond my skill set, sorry, but I’m sure someone will answer it, usually flameport. I thought they’d have worked independently from the room stats?

 

[EFLImpudence]

Don't buy a specific wiring centre; just get a box with connectors in it.

I don't understand why you need two pumps and both pumps to be on to work the UFH.
Why not just have another valve for the UFH and just the one pump?

 

[an203888]

Don't buy a specific wiring centre; just get a box with connectors in it.

I don't understand why you need two pumps and both pumps to be on to work the UFH.
Why not just have another valve for the UFH and just the one pump?

Underfloor heating works at lower temps than the 70 degrees that the boiler spits out. So a manifold with a blending valve is used to keep the temperature to the ufh at whatever its set to. So the main pump is used to circulate the 70 degree water to the manifold/blender. The second pump mounted on the ufh system is used to circulate the ufh water.

Maybe I have this wrong. Even if I do... Still need one pump for rads and one for ufh. So my previous pumps still stand..... Unless someone tells me otherwise..

 

[EFLImpudence]

Well electrically you can obviously do whatever you want with relays.

However, it still sounds odd but perhaps you would be better in the plumbing forum.


I'll ask for the thread to be moved.

 

[an203888]

Well electrically you can obviously do whatever you want with relays.

However, it still sounds odd but perhaps you would be better in the plumbing forum.


I'll ask for the thread to be moved.

I would have thought it's an electrical question. A plumber wouldn't wire this would they?

 

[oldbutnotdead]

1x 240v 2 pole NO relay will do it.

Your normal zones connect direct to the main circ pump as now (via the internal microswitches).

The UFH zone valve switch fires the coil on your 2 pole NO relay.
Pole 1 has live to the circulating pump (effectively in parallel with the heating zone microswitches).

Pole 2 has live to the UFH pump.
Easy life. The attached link will work, there are plenty of others https://www.amazon.co.uk/sourcing-m...ocphy=1006669&hvtargid=pla-357842209603&psc=1

 

[EFLImpudence]

I would have thought it's an electrical question. A plumber wouldn't wire this would they?

They would. They call themselves heating engineers.

However, I think someone more used to the plumbing to sort out what you have is required.

I am not familiar with the manifolds.


While you are still here - Just interested.

If only the UFH and boiler are on (none of the radiators) would not the UFH pump manage on its own? I don't see why the other pump has to be on. The manifold will close when UFH water is at the set temperature whether the incoming water is at that temperature or 70°.
If any of the radiators are on then it makes no difference.

 

[an203888]

They would. They call themselves heating engineers.

However, I think someone more used to the plumbing to sort out what you have is required.

I am not familiar with the manifolds.


While you are still here - Just interested.

If only the UFH and boiler are on (none of the radiators) would not the UFH pump manage on its own? I don't see why the other pump has to be on. The manifold will close when UFH water is at the set temperature whether the incoming water is at that temperature or 70°.
If any of the radiators are on then it makes no difference.

I don't think it works like that but I am not 100% sure tbh

 

[an203888]

1x 240v 2 pole NO relay will do it.

Your normal zones connect direct to the main circ pump as now (via the internal microswitches).

The UFH zone valve switch fires the coil on your 2 pole NO relay.
Pole 1 has live to the circulating pump (effectively in parallel with the heating zone microswitches).

Pole 2 has live to the UFH pump.
Easy life. The attached link will work, there are plenty of others https://www.amazon.co.uk/sourcing-m...ocphy=1006669&hvtargid=pla-357842209603&psc=1

This is what I was expecting but was hoping not to have to get so involved with the relay mounting/wiring! Was hoping for somthing a bit more off the shelf. Presumably what I'm doing is fairly normal.

 

[oldbutnotdead]

Well its not common but not unheard of, problem with too many zones can be the boiler running (less efficiently) in a derated mode. No need to be scared of a relay, v straightforward