contactor to run boiler and 2 water pumps

[pspec]

Hi all



I have a nest thermostat that will turn 2 things on and off.

Current setup is

Oil Boiler and radiator pump are linked so it counts as one thing

To heat the hot water it turns boiler on but the hot water pump is turned on with a timer switch.

Which isn’t the best....



I’ve been told I need to fit 1 or 2 contactors. So the nest will turn the radiators on and the contactor will then turn both radiators pump and boiler on.
when the nest turns the hot water on the contactor then turns the water pump and boiler on..

It all runs off a 5A fuse ..

Does anyone know what contactor i would need ?

How many ?

Is there a special enclosure for them ?



Thank

 

[Hugh Jaleak]

Sounds like you might be better converting the system to a S or Y plan.

 

[BlueLoo]

Dunno, but logically, I'd just treat the nest as a smart switch and use it to actuate the CH or HW circuit as required. I'd be wiring and plumbing the system so that it does that.

Perhaps go back to basics, look at what kit you have, draw out your circuits and then upgrade, redo the systems properly.

I wouldn't look to make a bad job just "do", I'd look to have it right.

 

[Exedon]

You could convert system to standard S or Y plan. But if you want to leave things as they are with 2 pumps you need 2 relays
so that the pumps are electrical separated.
Typical you need 2 relays and box to mount them in, permanent live & neutral switch wires from your nest one to each relay then a feeds from relays to boiler and associated pump.
Any decent electrical wholesalers will stock what you need last ones I bought less than £30.

 

[stem]

Oil Boiler and radiator pump are linked so it counts as one thing

To heat the hot water it turns boiler on but the hot water pump is turned on with a timer switch.

If the "boiler and heating pump are linked" that would mean that you can only have the central heating 'on' on it's own. And when you put the hot water 'on' the central heating would have to be on also.

Is that correct? I would expect it to be the other way around:

Oil Boiler and hot water pump linked & central heating pump turned on with a timer switch.

This way, you can have the hot water 'on' on it's own. And when you put the central heating 'on' the hot water would have to be on also.