Porgrammable Room Thermostat

[ollie3686]

Hi, I havn't really posted on here much before but I use I reguarly use it for solutions, however i'm now struggling on specific information about my new Programmable Thermostat.

We've got a Potterton Suprema 40 boiler (i think thats the name) with a Danfoss CP725 programmer, and up until now, a Danfoss RMT230 room thermostat. Our RMT230 wasn't working correctly so i decided to replace it and wanted something more advanced, i was advised a Timeguard Programastat TRT035. After a load of hassle yesterday we finally got it working. Not 100% sure it's correct but it turns the heating off below the temperature and on about the set temperature.

Anyway, the problem is that I set the heating and water times on my programmer which I assumed was correct. Apparently not. When the programmer is set to 'off', then the thermostat will start the boiler when the temperature falls below the set temperature, but when the programmer is 'on', then the radiators are heating up regardless of the air temperature around the thermostat.

I appreciate I probably don't have a full understanding of the system, but it seems that one scenario is contradicting the other. Could someone please shed some light on how the system should work, and what what I should set my programmer too so it works properly.

(NOTE: I can't set the heating and water times separately on the programmer however I can set them to on/off/auto/allday separately)

Thanks in advance

 

[Fluffster]

You require a 2 channell programmer for independent heat and hot water. It sounds like you have a single channell which means you can only control the heat with hot water on at the same time.
Do you have a mid position 3 port valve or 2-2 port valves on your system?
Pete

 

[picasso]

I cant find a cp725 do you mean a cp75 ?

 

[ollie3686]

I cant find a cp725 do you mean a cp75 ?

No i mean CP715 - sorry, must have hit wrong key.

With regards to Pete's reply, i don't have no idea about the valves - any ideas on how I can find this out?

It doesn't really bother me that I can't control the water and heating separately, I'm really trying to get the programmable thermostat working. Should i turn the heating off completely at the programmer and let the thermostat take over?

 

[picasso]

The output from 4 on your danfoss programmer should be connected to "com" on the stat and "on" is connected to the boiler, the danfoss programmer central heating setting is then left on constant, look next to the hot water cylinder for the valves.

 

[ollie3686]

So basically i should leave my programmer on 'on' (contstant) all the time?

 

[picasso]

So basically i should leave my programmer on 'on' (contstant) all the time?

Yes thats right, the old programmer is just supplying the voltage to the new programmer/stat which you then set for time and temp.

 

[ollie3686]

Oh ok. Just a couple more things:

1) does it sound strange that even when i've set the heating to off on the programmer, the thermostat will still turn it on and off as necessary? If so is there a solution as i've got no way of completely turning the heating off.
2) Will the water still turn on and off as directed by the programmer?

 

[picasso]

you need to find out what valves you have, your old programmer might be set for gravity or its been wired wrong from the start.

 

[ollie3686]

Ok, how do i find out the valves? I know they're in the airing cupboard but there are several in there, how do i know what each one does?

 

[picasso]

honeywell 3 port

• picasso
• 18 Oct 2010
• 26

honeywell 2 port

• picasso
• 18 Oct 2010
• 31

which and how many of these do you have?

 

[ollie3686]

i cant see any exactly like it but there is an actuator, Danfoss HSA3. It's on a 3 way junction like the first photo. Is this what you mean?

 

[picasso]

yep thats the one, what you have do now is switch off the power to the danfoss programmer, take the front off and see if the dil switch is set to pumped and that there is a wire in number 1 (hw off) 3 (hw on) and 4 (ch on) the last one should be connected directly to your new stat.

 

[ollie3686]

ok

 

[ollie3686]

Right, the Dil switch is set to pumped and not gravity. The wires are as follows:
Neutral: Black
Live: Red
1 (HW Off): Red
2 (CH Off): (Blank)
3 (HW On): Yellow
4 (CH On): Blue

Assuming the colour of the cables are correct, when wiring the thermostat, we connected red to live, yellow to on and isolated blue. Does all sound correct?