Horstmann DRT2 Room Thermostat query

Hi NDRT.

First, don't buy the Horstmann. Why? 'Cos I have one and regret it...

It runs on tiny AAA batteries which last no more than a year, and the programmed settings WILL be lost when you replace them despite what the instructions say. Also, it has limited on/off settings, and finally it is not completely self-explanatory in use (not exactly complicated, but you do have to 'pause for thought...')

If, however, it's a fait accompli, then you wire it as follows:

The RED wire (which is your live 'supply') currently going to terminal 1, goes to term 'COM' on the Horstmann.

The YELLOW wire (which is the 'switched' live - ie: becomes 'live' when your 'stat calls for heat) goes to NC (which means 'normally closed')

The BLUE wire (which is your 'neutral') is no longer required (the new 'stat is battery operated), and should be terminated safely inside the backbox ideally with a single screw terminal block which is then wrapped in blue tape.

The Earth is not required to the new 'stat, and should be terminated to the earth screw in the back box.

Have a look on eBay for a 'Heatmiser' programmable room stat. I've seen them for around £37 delivered which is a good price for a cracking unit. If you go for one of these, you WILL be using the neutral wire as it's mains powered. But it won;t need batteries, has a nice blue backlight, and it very nice to use.

 

I have a query to, I have the diabolicial Siemens Wireless Thermostat which has finally given up after a tumultuous three years!!

I bought a Horstmann DRT2 and obviously the wiring is totally different. In the Siemens I have the following cables:

White connected to LX
Black connected to L1
Brown connected to L
Blue connected to N

On the Horstmann DRT2, I only have COM, NO and NC

Any help of advice is most appreciated.

Thanks.