Replacement room thermostat

elmes30 · Posted: Tue Nov 03, 2009 11:06 pm Post Subject: Replacement room thermostat

I have an elderly central heating system consisting of a Potterton Netaheat 16-22 boiler, with room and cylinder thermostats which give independent control of heating & hw by means of a 3 position motorised valve (Honeywell Sundial Y wiring). The Potterton room thermostat is now wildly inaccurate and i would like to replace it with a digital display. The Honeywell DT200 seemed a likely candidate, but I now understand that it has been replaced by the DT90E model which has TPI control. It sounds good, but will my old boiler cope with this new fangled technology?? If so, as it is a 2 wire model, do I just leave the neutral from my 3 wire system disconected?

namsag · Posted: Wed Nov 04, 2009 12:30 am Post Subject:

DT200 Still available . Yes just use 2 wires and safely isolate the neutral preferably back at wiring centre

elmes30 · Posted: Wed Nov 04, 2009 9:17 am Post Subject: Replacement room thermostat

Thanks.
The DT90E model is said to be more efficient due to the TPI control and is roughly the same price as the DT200, but can my old boiler cope with it or am I just tinkering around the edges with an old and very inefficient system and it won't make much difference either way!

D_Hailsham · Posted: Wed Nov 04, 2009 5:25 pm Post Subject:

Yes, your old boiler will work OK with the DT90E. I have the CM927 (wireless programmable version with TPI) connected to a 20 year old Apollo boiler and it works just fine.

stevecritchlow · Posted: Wed Nov 04, 2009 5:42 pm Post Subject:

the room thermostat doesn't nothing more then tell the boiler to come on and go off, the new one will just replace your old one, no problem I too have the wireless honeywell and its excellent