Honeywell CMT921 Operation?

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I have just bought a Honeywell CMT921 wireless thermostat on Ebay.

I have just installed it in place of my BG one which was intermittently failing to switch motorized valve even though green receiver light was on.

My question is, there seems to be a lot of "tolerance" as to when the receiver light illuminates to start valve/boiler.

It even fires up after target temp reached although not always for long, is the thermostat designed to do this, ie keep house at the target temperature even if it means turning on after target reached, I read in the instructions something about flame indicator showing and boiler not on as signal is 0-100%?

The reasons I am asking is that I suspect the Thermostat I bought may not be brand new and am wondering if it was swapped out from somewhere as faulty... :cry:[/b]
 
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Yes it is an Intelligent Stat, designed to maintain a very comfortable environment with little Hysteresis it may be set to Optimiser mode, which is designed to allow the room to reach the required temperature at the time selected ;)
 
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Yes it is an Intelligent Stat, designed to maintain a very comfortable environment with little Hysteresis it may be set to Optimiser mode, which is designed to allow the room to reach the required temperature at the time selected ;)

Ah, thanks Boilerman2, so it is in effect a sort of lag otherwise would be switching boiler on/off all the time, didn't notice it with the BG wireless one though, perhaps the Honeywell one is a bit more intelligent...
 
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I use the same Control on my own system, you will find that it switches on and off at frequent intervals, and the radiators will be warm rather than hot, in this way it is smoothing out the peaks caused by more traditional thermostats ;)
 
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I use the same Control on my own system, you will find that it switches on and off at frequent intervals, and the radiators will be warm rather than hot, in this way it is smoothing out the peaks caused by more traditional thermostats ;)

Thanks for the reassurance, so may not be a duff one after all, will see how it goes for a while, I do have an nPower service contract but wasn't sure what type of wireless thermostats they fit and found this one on Ebay.

So fingers crossed it may be okay...
 

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