DIY Doctor UK DIY Forums

My current roomstat is an old Honewell type dial model with connections 1,2,3. etc.

I,ve bought a digital type Honeywell DT200, T6620B 1008, which has a,b,c connections.

The instructions indicate I should use connections a and b, on the digital, but not sure whether 2 or 3 should be connected to b?

I have a Y Plan system, Oil boiler with a 3 Port Valve.

Can anyone advse off wiring connection?

Thanks
Alan

Can't find any reference to a Honeywell D200 thermostat is that the right number?

Can't give exact instructions as every stat is slightly different.

The three wires on your old thermostat would be live, switched live to the boiler, and neutral. When wiring to a digital thermostat the neutral is unused. The neutral would have been connected to the ballast resistor on the old stat.

Wire it the right way or it will go bang, and you will probably be buying another stat.

Hi,

Not sure why I posted that model? Any way, the correct new digi stat is:
T6620B 1008.

Thanks
Alan

Connect wires from con 1 to con A and con 3 to con B. Leave the third wire from connection 2 unused.