ISAR HE30 + CM907

B

Bohumil

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Hi.
I have purchased /NEW boxed/ CM907 over amazon and need a help.

From my boiler ISAR HE30 are comeing out 5 wires :
* brown / blue / gree-yellow -- main power for old Danfos
and
* from L1 in boiler is RED which is LIVE wire / from L2 in boiler is BLACK which is SWITCH wire
ISAR HE30.png


Here is how was connected old Danfoss TS715-Si + Honeywell T40 / they are working excellent.
Danfos + HoneyWell.JPG


So, I have connected : RED to A connector / BLACK to B connector
I would like my CM907 will work with my Combi boiler.
Hope I connect it correctly.

- I now find that it keeeps starting the boiler even when the main programmer is in the off position.
- When room temperature is above target temperature it still keeps starting up
even though the little flame signal is not showing.
- It keeps starting up even when batteries are not in.
- I can hear a click inside while changing target temperature under room temperature.

I have got multimeter at home, so I can meassure anything if needed.

Please help
 
Last edited:
Disconnect the Honeywell stat, disconnect all wires in terminals 1 3 and 4 of the Danfoss plate.

Connect L2 from boiler to 1 on Danfoss plate
Connect 4 from Danfoss plate to a on new Honeywell
Connect L1 from boiler to b on new Honeywell

Wiring must be suitable insulated and sheathed cable.

Just out of interest, if you have just bought a programmable room stat why are you keeping the old programmer?

You should disconnect Danfoss programmer and it's wiring entirely and connect
L2 to a
L1 to b

If you have blown any fuses with this thermostat the contacts will be welded together and it will not switch off and will need to be replaced.
 
Thanks for interrest everybody. And sorry for my terminology /I'm not an installer/. It looks like I did not explain what I want clearly. My fault.
I would like to have only CM907 working with my Combi boiler.
Yesterday I check continuity on CM907. I disconnect all wires from it, put batteries inside. Room temperature was 23*C. Once required teperature was above that and flame was shown on display I had some readings on my multimeter. As required temperature was under room temperature I still had some readings on multimeter. And when changing required temperature on Manual mode from above to under room teperature I can hear click inside of CM907.

Thanks
 
Wire like this then:
You should disconnect Danfoss programmer and it's wiring entirely and connect
L2 to a
L1 to b

This still applies:
If you have blown any fuses with this thermostat the contacts will be welded together and it will not switch off and will need to be replaced. These still 'click' even with the contacts welded together.

Before you wire it in check:
When flame icon lit you have continuity between a and b only
When flame icon is not lit you have continuity between a and c only.
 
Thank you very much. I have tryied continuity as you descibre and I have allways continuity between A and B. No continuity between A and C. Looks like it needs to be replaced.

Just to be sure. As this is diagram for wiring. It looks like there should be LIVE in A and switch live in B.
honeywell.jpg




My LIVE is L1 red wire and switch live is L2 black wire.
 
Yes it is good practice to put the permanent live into the common terminal, a in this case, though it makes no difference what way around it is connected, as joining L1 to L2 will start the boiler. As long as you use terminals a and b it will switch on the boiler when it is cold.

If there is continuity from a-b all the time then the thermostat has been connected to live and neutral at some point and has been blown. If not by you by a previous customer who has returned it and it has ended up back on the shelf in the shop. It will need to be replaced with a new one.
 
I have ordered new one in screwfix for Tuesday collection. And this one I have got I need to send back to Amazon, where I bought it.

Thank you very much for all help.
 
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