Help please with thermostat swap...

[Robin D]

Hi all

I would really appreciate any help with a problem i'm having changing my thermostat.

The old thermostat is a Towerstat RS [DLMURL]http://www.tfc-group.co.uk/assets/graphics/static/RS%20RCS%20RFS%20User%20instructions.pdf[/DLMURL], and I've been trying to change it to a Honeywell DT90e. But so far, I've blown 4 fuses when turning it all back on!

I've put back the old one, but i think it's wired wrong as it seems to turn on the heating when you turn it down.

I wish i had taken a note of the wires before removing them, but i think the cabling was:
red - pin 1
yellow - pin 3
blue - pin 4

Using a multimeter on the towerstat, gives me the following:

call for heat [ON]
PINS
1+3 0v
1+4 240v
3+4 240v

no call for heat [OFF]
PINS
1+3 240v
1+4 240v
3+4 0v


I connected the DT90e with:

red - pin A
blue -pin B
yell - pin C


I've must've got it wrong somewhere as this blows the main fuse every time.
Anyway, I'm totally at a loss and was gonna phone the plumber, but i really think it must be a simple thing i've got wrong.

I've uploaded some pictures to make it easier to explain what i'm talking about:
Flickr: Robin-D's Photostream

many thanks in advance
Robin

 

[doitmyself]

Red to A
Yellow to B

Blue is not used; make it safe.

I hope you haven't damaged the new stat.

 

[Robin D]

i think the stat is fine as i can see & hear it call for heat each time just before the fuse goes.

many thanks

it worked!!

thanks a lot for your help, i feel silly cos i should know better

cheers

Thanks again with the help earlier, this forum is excellent.

Slight problem since yesterday though is I've noticed that the boiler kept on coming on every now and then throughout the night, even though the Danfoss 102e7 programmer (http://www.plumbnation.co.uk/site/d...gp-mini-programmer-087n653400/102E7 Guide.pdf) was set to off.

I guess it could be damaged after I blew the fuses so often.
Luckily I have a tempus six programmer handy, so i'm thinking of swapping it.
Trouble is that I'm stuck at the first hurdle, i can't remove the Danfoss unit...! I've unscrewed the the holding screw underneath but it won't lift off. Any ideas?

A bit of background to my heating system...
The plumber tells me it's gravity fed. There's a pump next to the boiler and another in the cupboard above. I don't think there is a valve to seperate HW and CH, and the HW cylinder doesn't have a thermostat on it. It's an inefficient system that just seems to regularly heat up my hot water (and indirectly the rads) whether the house needs heating or not.

I hope I've made sense. I uploaded a few more pics to aid my description (Flickr: Robin-D's Photostream). Again, any help is really appreciated.

thanks
Robin

 

[Billy Bob Bob]

why dont you get some one in who knows what they are doing before you destroy it your self,or worst your self!