Room stat problem.

[Turpin]

Hi,

We've been having a few problems with the Veismann Vitodens 100 over the last year or so where occasionally it wont fire. I've had the Veismann engineer out (the plumber who fitted it is no longer around) - he checked it out and pointed the finger at the controls rather than the boiler itself.

It seems to me that the room stat is probably the culprit as it clicks off at the same point no matter what the temp is and wont fire the boiler. I can fire the boiler if I set the cylinder change the cylinder stat up and down and can run with heating and hot water that way.

The room stat is an old Switchmaster, as is the cylinder stat - so for a few pennys I thought lets change the Switchmaster mechanical roomstat for a digital one, checked the wiring on it - 2 wires & earth I think. (brown (term1), blue (Term3) & yellow/green (Term 5)). I got a Honeywell DT200 (T6620B1008) and fitted that.

The issue I have is that the new DT200 wont show any sort of display at all - I have followed the supplied wiring diagram and taken Brown to TermA, Blue to TermB and theres no connection for Earth. The TermC connection on the DT200 is capped off.

Any suggestions ?

 

[D_Hailsham]

The issue I have is that the new DT200 wont show any sort of display at all - I have followed the supplied wiring diagram and taken Brown to TermA, Blue to TermB and theres no connection for Earth. The TermC connection on the DT200 is capped off.

You have put the batteries into the DT200 - 2 x AA?

Your wiring is correct.

 

[Turpin]

The issue I have is that the new DT200 wont show any sort of display at all - I have followed the supplied wiring diagram and taken Brown to TermA, Blue to TermB and theres no connection for Earth. The TermC connection on the DT200 is capped off.

You have put the batteries into the DT200 - 2 x AA?

Your wiring is correct.

Cheers for the reply, yep, Batteries are installed - sounds like a duff one then. Should it still show a display just with batteries in ?

 

[D_Hailsham]

Cheers for the reply, yep, Batteries are installed - sounds like a duff one then. Should it still show a display just with batteries in ?

Yes it should show the current temperature. Hope you didn't buy it second hand from Ebay.

The DT200 has now been replaced by the DT90E or DT92E, if you want a wireless version.

 

[Turpin]

Cheers, yep following your post I just double-checked the supplied batteries were actually working - I popped the set in from the Sky remote and bingo, DT200 started working. So, duff batts it was then.

I've swapped that and the cylinder stat over today (another old Switchmaster thing) and now seem to have working CH again. Perfect timing for the snow. Got the temp probe out on the HW and ambient CH (near the roomstat) and seems spot on now.

Cheers for info.