Thermostat won't activate boiler for central heating

[steven239]

Hi all

I would greatly appreciate any advice on the following problem.

I have just moved into a new home, which has had a newly installed Ferroli Optimax HE Plus 31C combi and a Timeguard TRT035 Battery Powered Programmable Room Thermostat.

The problem seems to be that the thermostat won't activate the boiler. When the room thermostat is manually adjusted to the maximum room temperature it doesn't activate the central heating and on the automatic settings it likewise has no effect.

I contacted the seller of the house who told me that the central heating definitely works as when the boiler was installed the engineer fired it all up so that he could balance the radiators. However, they said the thermostat was fitted a week later and as it was the middle of summer they never checked that it worked. I think they got a family friend to wire it up, so my assumption is that it's wired wrong.

Does this sound like the right conclusion and should a boiler engineer or an electrician be the most sensible choice to call out? Or is it something I could have a go at myself? I have looked at the wiring diagrams in the boiler manual but they look very complicated to me and I'm worried about potentially damaging the boiler irreversibly if I was to fiddle around myself.

Many thanks

Steve

 

[Whitespirit66]

Do you have the instructions for the stat?

When you turned the temp up on the stat, did you make sure that the programmer part of the stat is also set for heating to be on?

Also, does the boiler have it's own built in timer/clock? If it does, you will have to set this to heating on 'constant'. Leave it on constant, permanently. You will then use the room stat/programmer to run your heating, bypassing any timer that the boiler may have.

Hope this makes sense!

 

[steven239]

Thanks for your reply.

Yes, I have the instructions and used them to ensure the jumper on the back of the unit was in the correct 'On' position. Is this what you mean?

The boiler doesn't have an in built timer/ clock.

 

[Whitespirit66]

Ok, so presumably you have set the programmer part of the Timeguard to 'heating on', and turned up the stat part of the Timeguard.

After doing this, did you get the small flame symbol in the bottom left of the Timeguard's display?

I'm not referring to the jumpers.

 

[steven239]

As far as I can work out from the instructions, there is no off period as such using this thermostat. It allows for a 7 day function or 5/2 day function, which then allows within those days to match times with required temperatures. An off time effectively being when you set the required temperature at 10degrees, which it would only ever drop under in a harsh winter.

With all my experimenting I haven't once been able to get the heat symbol to come up. But the instructions say that as soon as the +/- is used to adjusted temperature from the main screen then it automatically goes into manual mode and won't alter temperature until the next programmed sequence. So if I crank the temperature up, it should call for the boiler to fire up immediately.

 

[Whitespirit66]

Ok, which connectors on the stat are the 2 wires going to? Should be one to COM, and one to ON.

Have a look on this boiler PDF, page 17. Each end of the two wires should go to connector 72 - bottom right of page. The link between the connectors on 72 should be removed.

http://www.wickes.co.uk/content/ebiz/wickes/resources/images/pdf/OPTIMAX HE PLUS 31C 3540I882[2].pdf

 

[steven239]

This is a great help thanks. I'm not home until tomorrow midday but I'm pretty sure there is a wire going to On, Off and Com. If my memory serves me correct the grey to On, the brown to Off and Black to Com. I'll double check this and the boiler wiring tomorrow and update this thread.

 

[steven239]

Right the stat has Brown going to Com, Black to Off and Grey to On.

The boiler has the Grey and Black going into the 2 connectors at 72.

Is this wrong?

Cheers

 

[steven239]

Ps. At the boiler the Brown is taped at the end.

 

[flameport]

Right the stat has Brown going to Com, Black to Off and Grey to On.
The boiler has the Grey and Black going into the 2 connectors at 72.
Is this wrong?

It's wrong - the system could never have worked with that wiring.

At the stat, swap the brown and black wires.

 

[steven239]

Great stuff! Works a dream now. The help was very much appreciated.