Room Thermostat Problem....Any Ideas???

[retrosimon]

Hi!
I hope you make be able to help me with a problem with the central heating in a house that we moved into a few months ago. This problem has only just come to my attention, and I believe that it has been like this since we moved in.
The problem is that the Room Thermostat will enable water to be pumped around the radiators whatever the Programmer's setting is. This means that by turning up the Thermostat the circulating pump cuts in, even if the 'Hot Water' & 'Central Heating' are off. The Thermostat seems to react to temperature exactly as it should. I have traced the wires up to the Backplate from the Thermostat and they are connected to the section marked "Roomstat". The programmer works as it should i.e the timer controls for the boiler etc apart from this problem. I have looked around on the internet for info about this Backplate-Programmer combination but have had no success.

The Thermostat is a "Honeywell T40"
The Backplate is a "Wirerite Octopus" (which has a 'Pump-Overun')
The Programmer is a "LP241"

I do have electrical experience in the automotive trade and feel confident enough to tackle this if I could have some advice. If anyone has any ideas or information it would be very much appreciated.

Thanks

Regards.

Simon

 

[newbie1]

what boiler are you running is it combi or a 3 port or 2 two port system
with regular boiler

 

[retrosimon]

The Boiler is a 'Baxi Solo 2"
I'm not sure how to identify a 2 or 3 port system.

 

[stevetheplumber]

possibly the programmer isnt switching of its a case of working your way through the wiring to see
two or three port refefers to the typr of motorised valve/s you have controlling your system identifiable by the number of pipes going in and out

i would start from the clock see if there is power coming out to the stat even when of

 

[retrosimon]

Yes, there is power going to the stat from the programmer even when programmes are off. I have suspicions that one of the links in the backplate may be in the wrong place? Nothing would surprise me in this house!

 

[Rox]

Might be best to install a new thermostat which will come with all wiring instructions etc. And if it's wireless (see the new DT92E) then you can forget about the signal wiring, you just wire the receiver unit to the boiler. It'll be more energy efficient too!

 

[Bernie2]

If it is wired from a two channel source, you would expect the stat supply to be off when the programmer is switched to off.

But it could be so many things, its hard to say.

 

[Rox]

Might be best to install a new thermostat which will come with all wiring instructions etc. And if it's wireless (see the new DT92E) then you can forget about the signal wiring, you just wire the receiver unit to the boiler. It'll be more energy efficient too!

Oh, I forgot, you need a timer of course.

 

[Jason.S]

I am thinking its probably incorrectly wired in the centre, as there should be no power at all at either stat until the programmer lets it have some.