"Clever" controller for central heating?

"Clever" controller for central heating?

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Discussion

skilly1

2,169 posts

156 months

Monday 3rd January 2011
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skilly1 said:
So Can I replace this for a Honeywell CM927 - if so is it easy? Are there just two wires I need to connect to the new controller?

Any one know how to remove the cover on this? Can't see any screws or holes to push clips in...

Ferg

15,242 posts

218 months

Monday 3rd January 2011
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Push a small screwdriver into 'slots' around the edge close to the wall. They used to have one screw top right which needed releasing before pushing that clip in.

NiceCupOfTea

25,006 posts

212 months

Monday 3rd January 2011
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Mine had a small screw top right in the side. Remove it and you can just unclip the housing by squeezing slightly top and bottom IIRC.

Be careful if you start poking a screwdriver through holes, it's mains voltage!

Hobzy

1,270 posts

172 months

Monday 3rd January 2011
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Minor hijack, but if your condenser was fitted without a room thermostat, how simple is it to add one of these wireless jobbies?

Ferg

15,242 posts

218 months

Monday 3rd January 2011
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Hobzy said:
Minor hijack, but if your condenser was fitted without a room thermostat, how simple is it to add one of these wireless jobbies?
Very easy, but if a condensing boiler is fitted without a room thermostat it contravenes regulations.

Fort Jefferson

8,231 posts

183 months

Monday 3rd January 2011
quotequote all
skilly1 said:
So Can I replace this for a Honeywell CM927 - if so is it easy? Are there just two wires I need to connect to the new controller?

I replaced ours with one of these years ago. It turns the temp up and down, and not just on or off.

Hobzy

1,270 posts

172 months

Monday 3rd January 2011
quotequote all
Ferg said:
Hobzy said:
Minor hijack, but if your condenser was fitted without a room thermostat, how simple is it to add one of these wireless jobbies?
Very easy, but if a condensing boiler is fitted without a room thermostat it contravenes regulations.
Hmmm. Its a vaillant, and I can control the temp of the rads from the boiler but there is no sensor/thermostat anywhere else. No way of contacting the original fitter - any chance (pretty please) you could give me some brief advice on how to proceed? I've got to get a plumber in to sort the gas out for the new kitchen - best to get him to sort it?

Ferg

15,242 posts

218 months

Monday 3rd January 2011
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Is it a combination boiler? If not how many motorized valves do you have?

Roger645

1,683 posts

208 months

Monday 3rd January 2011
quotequote all
skilly1 said:
skilly1 said:
So Can I replace this for a Honeywell CM927 - if so is it easy? Are there just two wires I need to connect to the new controller?

Any one know how to remove the cover on this? Can't see any screws or holes to push clips in...
Be careful when you do remove the stat as mine was connected to 240v.

oldcynic

2,165 posts

122 months

Monday 3rd January 2011
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Ferg said:
oldcynic said:
So is there a controller that allows variable temperature settings through the day, is capable of optimisation, and will also manage the water heating including the holiday programming?
Not that I've seen for a while, I have to admit. Normally just a programmer set to constant on the heating side and a programmable room thermostat on the wall.
Thanks. I suspect I'll split CH and HW between 2 controllers, as the current timer is very simple and won't allow them to be on different cycles.

Hobzy

1,270 posts

172 months

Monday 3rd January 2011
quotequote all
Ferg said:
Is it a combination boiler? If not how many motorized valves do you have?
Yes combi - ecotec plus 824. Thermostatic valves on all the rads bar two upstairs I haven't got round to doing yet.

Ferg

15,242 posts

218 months

Monday 3rd January 2011
quotequote all
Hobzy said:
Ferg said:
Is it a combination boiler? If not how many motorized valves do you have?
Yes combi - ecotec plus 824. Thermostatic valves on all the rads bar two upstairs I haven't got round to doing yet.
I can't remember off hand, but it will have a link in the boiler which should be removed and switched with a room thermostat. The wireless base station will require LIVE and NEUTRAL and will switch the other two conductors.

smn159

7,664 posts

178 months

Friday 14th January 2011
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Tempted by this thread, I've bought a CM927, and I'm trying to work out how to wire it up and then how the controller should be set to make best use of it. I currently have the controller and thermostat below. The controller needs the hot water to be set to come on at the same time as the heating - otherwise it just pumps cold water around the radiators.

Presumably I'll need to set both the heating and hot water to 'Continuous' and let the CM927 control the temperature?

The current thermostat, which I'm going to replace with the CM927 relay box, has three wires - the red appears to be live, the blue neutral, but what about the yellow?

Actually I think that I've worked it out - the Red goes to L in the relay box, the blue to N and the yellow to B (boiler presumably), with a link added between L and A. Can anyone confirm?

I won't be popular tomorrow if I mess the heating up spin








oldcynic

2,165 posts

122 months

Friday 14th January 2011
quotequote all
smn159 said:
The controller needs the hot water to be set to come on at the same time as the heating - otherwise it just pumps cold water around the radiators.
Sounds like your system isn't wired correctly at the moment. I had similar problems and ended up tracing all the wiring and writing up a circuit diagram with the help/motivation of a friend. We then googled central heating circuits, although I later found these were in the boiler installation manual as well, worked out it was a Y-plan in my house, and worked out two seperate wiring mistakes. It would seem that not all plumbers are good with electrics. I'd hazard a guess that your 3-way valve and/or pump is wired wrong, but it's not my line of work so don't take my word for it.

The biggest clue as to whether you've got a Y-plan or S-plan is the number of 3-way valves (ie 1 or 2)

Until you work out what's wrong at the moment you'll not get anywhere with making your system efficient and making best use of your new controller.

smn159

7,664 posts

178 months

Saturday 15th January 2011
quotequote all
oldcynic said:
smn159 said:
The controller needs the hot water to be set to come on at the same time as the heating - otherwise it just pumps cold water around the radiators.
Sounds like your system isn't wired correctly at the moment. I had similar problems and ended up tracing all the wiring and writing up a circuit diagram with the help/motivation of a friend. We then googled central heating circuits, although I later found these were in the boiler installation manual as well, worked out it was a Y-plan in my house, and worked out two seperate wiring mistakes. It would seem that not all plumbers are good with electrics. I'd hazard a guess that your 3-way valve and/or pump is wired wrong, but it's not my line of work so don't take my word for it.

The biggest clue as to whether you've got a Y-plan or S-plan is the number of 3-way valves (ie 1 or 2)

Until you work out what's wrong at the moment you'll not get anywhere with making your system efficient and making best use of your new controller.
Unfortunately I think that the number of 3-way valves is zero - i.e. it's a semi-gravity system with a 2 channel controller fitted.

Ferg

15,242 posts

218 months

Saturday 15th January 2011
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If it's a gravity hot water system the programmer should be set to always heat the water when the central heating comes on. It sounds like the programmer is the wrong type.

smn159

7,664 posts

178 months

Saturday 15th January 2011
quotequote all
Ferg said:
If it's a gravity hot water system the programmer should be set to always heat the water when the central heating comes on. It sounds like the programmer is the wrong type.
Thanks - what would the rough cost be of converting to fully pumped? Is it a worthwhile change?

Ferg

15,242 posts

218 months

Saturday 15th January 2011
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Regarding the CM927 wiring. I don't fit them myself, but I would imagine the base station requires a permanent live to keep it in contact with the wall unit so the red wire from your old thermostat may not be suitable since it's switched from the time clock. You could make it permanent at the boiler/junction box end, but there are issues with running the boiler for hot water then, I think.. (it's a bit early for gravity systems today!)

Ferg

15,242 posts

218 months

Saturday 15th January 2011
quotequote all
smn159 said:
Ferg said:
If it's a gravity hot water system the programmer should be set to always heat the water when the central heating comes on. It sounds like the programmer is the wrong type.
Thanks - what would the rough cost be of converting to fully pumped? Is it a worthwhile change?
Fully pumped systems are infinitely more efficient than gravity hot water. How easy to change is often the issue since you have to avoid obstructing the vent with a pump or valve.


Edited to add.....

What a cracking 2a! I had one in the dim and distant... before Land Rovers became rebodied Range Rovers.

Edited by Ferg on Saturday 15th January 09:59

smn159

7,664 posts

178 months

Saturday 15th January 2011
quotequote all
OK, thanks for that - time for a bit of head scratching I think...

The 2a has been great the last couple of winters especially - have had it for about three years now and always makes me smile when I drive it!