CM907 and outdoor sensor

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plumbarius

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• 22 Feb 2013

• #1

Hello All I have just ordered a CM907 and see they do a outdoor sensor to tell you the temperature outside, is the sensor low voltage (from Batteries) if so I could use spare N & E going to existing Room Stat at side of wiring centre.
I like gadgets.
Thanks Alex.

 

A

ALEC1

• 22 Feb 2013

• #2

then you should go one step further and get a weather compensator..what boiler is it?

 

achrn

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• 22 Feb 2013

• #3

Since the CM907 runs off batteries, the sensor isn't going to be at a high voltage (though the relay obviously might be if your boiler is 240V switching)

The sensor is just a weatherproofed temperature-dependant resistor. I used (low spec) speaker wire to connect one to my CM67 (it doesn't look like the CM907 outdoor sensor is any different to the CM67 outdoor sensor).

Be aware that it is just a report of the temperature - it's no more functional than an independent outdoor thermometer with an indoor display (at least, that was the case on CM67, and it looks like it's so on the CM907). That is, it doesn't do any weather compensating, it just tells you what the temperature outside is when you press the button on the thermostat.

 

A

ALEC1

• 22 Feb 2013

• #4

and thats because we use on-off controls in the UK...my bet is that it does do weather compensating with the opentherm connection...witheld from the UK market by honeywell

 

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plumbarius

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• 22 Feb 2013

• #5

Thanks for that lads I realise it will just tell me the temp outside, The boiler is a Ideal Logic+ heat only with weather compensation fitted Dec.2012 It works very well, I bought a clip on thermometer (brannan)
I dont know how accurate it is, the return temp I have never seen above 55c so the boiler is condensing most of the time I have it on the flow at the moment the highest I have seen that is 63c the boiler is set on "e" We are quiet comfortable with the temp. in the bungalow.
I thought I would improve it further with the CM907 I dont go out much when it is cold to much dust, soot, asbestos etc from 50 years plumbing.Sorry to go on I thought people might be interested in the set up I will let you know if my gas bills drop.
Thanks Alex

 

A

ALEC1

• 22 Feb 2013

• #6

thats a neat idea, but the honeywell is simple on-off, and the boiler more advanced looking at the outside temperature to optimise the flow temp.

You need something that influences the flow temp, not turn things on and off.

The two comtrol logics will fight each other, with you the looser!


I am sure Ideal have something...

 

Dan Robinson

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• 22 Feb 2013

• #7

Alec, TPi works fine. Not perfect I know, but there is such a thing as over thinking things (I should know ).

 

A

ALEC1

• 22 Feb 2013

• #8

Dan there have been whole threads about TPI and condensing boilers... never mind weather compensated ones...

you need to vary a parameter on the honeywell..to make it work..

I still thin its a mismatch though WC being vaguely predicitve (due to thermal lag) and TPI being reactive...

 

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plumbarius

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• 22 Feb 2013

• #9

Thanks for all your comments, to me it is getting the most comfortable temperature at the least cost it must be better than my old Ideal W2000 24 Years old.
I am still not sure about my original post is the sensor low voltage? I am a bit lost with Electronics.
Thanks to every body Alex.

 

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mikely

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• 23 Feb 2013

• #10

plumbarius said:

I am still not sure about my original post is the sensor low voltage? .

Click to expand...

Yes, it's low voltage.

 

achrn

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• 23 Feb 2013

• #11

plumbarius said:

I am still not sure about my original post is the sensor low voltage? I am a bit lost with Electronics.

Click to expand...

Yes, very low voltage, two wires, negligible current.

Pretty much any old wire will work - speaker wire is fine, or doorbell wire if you only need a short piece. Anything suitable for mains voltages is overkill but will work. If you use a very long piece of thin wire (say, 50 yards of doorbell wire) it will slightly reduce the accuracy - it might report accurate to within 2 degrees rather than accurate to within 1 degree.

Don't go as fine as telephone, burglar alarm sensor or computer network wire.

If you get the sensor and need a longer wire, best bet is probably to then take it along to your local DIY shed or hardware shop and buy some wire that's similar conductor size (ie, the actual wires inside the plastic insulation are similar size) to what the sensor comes with. Or if you have a Maplin shop near you take it in there - they'll have a rake of 2-core wire for speakers and doorbells and will have something similar, and assistants in Maplin are normally fairly helpful, in my experience. Tell them it's very low voltage.