Wiring a relay to protect a programmer help.

[Lee Edwards]

You can install it anywhere convenient, where you can intercept the necessary wires. I.e. the wires to the TADO receiver and the wires to the pump (and a mains supply)

This is good to know. Wiring isn't really my favourite thing to do.

So let me just make sure i get this correct for a y plan.

So I have my N L from the fused spur in the Wiring centre which i can take to the relay, then as the CH common is linked from live in the receiver can I link this at the relay? Then the CO which goes to the white wire on the zone valve and so connect into that before the zone valve.

I hope that makes sense.

 

[Lee Edwards]

If the TADO contacts are rated 6A and they fail so frequently, I’d use a 30A relay.

You should also consider whether the pump is on its way out. Maybe this will save the TADO, but then the pump will fail completely in 6 months time, and the replacement pump will not need it.

So, do I just change the pump and see if that works? Or is it too risky.

 

[Lee Edwards]

Could anyone explain how this only happens to the central heating contact and not the hot water?

 

[Harry Bloomfield]

Snubbed circuit, will need to look that one up.

Snubber circuit.

 

[Harry Bloomfield]

Could anyone explain how this only happens to the central heating contact and not the hot water?

It will be both, it's just that at the moment, your CH will be switching on and off, more frequently, than your HW demand. Each time, the pump will be started, which ever i creating a demand. Really, the relay needs to be connected to the output of the valve(s), so that either demand for heat, switches the relay on, and subsequently the pump.

Modern boilers, themselves turn the pump on and off, rather than the old system, of it being powered via the valve.

 

[mattylad]

Can you move the Tado from the kitchen to in the airing cupboard too? Will it still work in there? (worth a test).

 

[Lee Edwards]

Can you move the Tado from the kitchen to in the airing cupboard too? Will it still work in there? (worth a test).

Can I ask why? It was just replaced with an old potterton ep p2000 programmer or something like that.

 

[ericmark]

I had a problem with two pumps and stopping back feed and I used one of these

which was no longer required, with a relay like this

which I had in stock.

 

[Harry Bloomfield]

The pump is in the airing cupboard with the wiring centre.

If I could do this, that would make life a lot easier.

Even better...

Connect the relay coil, across the wires which at present, power the pump.

Find, and connect an unswitched live, to one relay contact, then the output, to the pump + a neutral.

 

[Lee Edwards]

Even better...

Connect the relay coil, across the wires which at present, power the pump.

Find, and connect an unswitched live, to one relay contact, then the output, to the pump + a neutral.

Like this...

 

[mattylad]

Can I ask why? It was just replaced with an old potterton ep p2000 programmer or something like that.

It might make the wiring easier.

You need a permanent live to the relay, if you currently only have a 2 core + earth cable from the Tado to the pump, you will need to replace all of this with a 3 core + earth cable - taking a permanent live from another circuit in the wiring center could cause problems if it is not on the same circuit as the Tado supply (I assume the kitchen ring).

If it's in the airing cupboard, you can use the same L supply to the Tado to provide the permanent live for the relay.

Permanent live source: L & N.
L to Tado L
N to Tado N.
L to relay common.
N to relay A2
N to pump N

Tado output switched live to relay A1
Relay N/O to pump L

When the tado turns on via wifi/app etc. then the output turns on the relay that then supplies power to the pump.

(all earths connected to relevant earth terminals).

The 3A fused spur supplying power in the wiring center may (or may not) blow if the pump draws 10 amp, being instantaneous and reduced almost immediately then it may not.

Got a picture of the view of the inside of the airing cupboard showing the wiring center and surrounding area?

 

[Harry Bloomfield]

Like this...

I cannot see much in that drawing..

 

[Lee Edwards]

It might make the wiring easier.

You need a permanent live to the relay, if you currently only have a 2 core + earth cable from the Tado to the pump, you will need to replace all of this with a 3 core + earth cable - taking a permanent live from another circuit in the wiring center could cause problems if it is not on the same circuit as the Tado supply (I assume the kitchen ring).

If it's in the airing cupboard, you can use the same L supply to the Tado to provide the permanent live for the relay.

Permanent live source: L & N.
L to Tado L
N to Tado N.
L to relay common.
N to relay A2
N to pump N

Tado output switched live to relay A1
Relay N/O to pump L

When the tado turns on via wifi/app etc. then the output turns on the relay that then supplies power to the pump.

(all earths connected to relevant earth terminals).

The 3A fused spur supplying power in the wiring center may (or may not) blow if the pump draws 10 amp, being instantaneous and reduced almost immediately then it may not.

Got a picture of the view of the inside of the airing cupboard showing the wiring center and surrounding area?

Thanks for this.

I believe a 3a fused spur supplies the wiring centre and then goes from the wiring centre to the tado receiver.

 

[Lee Edwards]

I cannot see much in that drawing..

Oh, If I click on it it becomes enlarged.

 

[mattylad]

I think he means it becomes enlarged but is not clear enough to read the terminal markings.