Boiler weather comp being controlled with a optimising room stat

[alisdisco]

Evening chaps. As the title says, can a boiler with weather comp run with an optimising room stat? I have a Glowworm Flexicom 35cx that can accept an external (outside) sensor, and the main controls is a Honeywell CMT927 optimising room stat. Reason I ask is I think they will fight each other as the thermostat optimises without knowing what the outside temp is? Its a wireless model that doesn't have an input like the wired models.

Thank you

Al

 

[ShaunCorbs]

No you will be fine the room stat just stops overshoot temps eg learns how fast the house heats up and cools down egc

 

[alisdisco]

No you will be fine the room stat just stops overshoot temps eg learns how fast the house heats up and cools down egc

Hi ShaunCorbs, thanks for getting back. I did think that, but the bit I'm kind of struggling with is the fact that if the stat has optimised, and if its colder outside (so its colder inside too) how does it react to the ever changing external temps vs optimised time? I take it I'm worrying over nothing then ?

 

[ShaunCorbs]

Your Heatloss is constant just the temp difference

 

[Oli-jj]

Your Heatloss is constant just the temp difference

The rate of heatless is factor of the temperature gradient (between inside and out) and a coefficient of the material's insulating properties (walls etc).

 

[Chuck]

The CM927's optimisation feature just notes how long it's taken recently for the room to come up to the set point in the morning and then advances or retards the time it turns on it the morning accordingly.

In my experience, it doesn't work well in practice because it use an air (i.e. white bulb) temperature sensor but how warm a room 'feels' depends largely on the radiant (black bulb) temperature. As long as the radiators are on, the room will probably feel okay even if the thermostat in not yet satisfied. So, there is little point in having the heating come on artificially early in the morning before anybody is using the room.

Anyway, I suggest you start by leaving 'optimisation' off on the CM927 and see how you get on with just weather compensation. Then try optimisation on and see if you can feel enough difference.

 

[alisdisco]

Hi Chuck, that was why I was asking if it would work as all the boiler would be seeing is a command to switch on (heat up) and a external temp input, and the two never come together because they are two separate signals. I cannot find any info on the internet about a Flexicom 35cx and external sensor. There is a connection for it on the installer interface (OTC1 & OTC2) - and I rang Valiant this morning to confirm that it does have weather comp, and it will connect to the ext sensor. He wanted to sell me a ClimaPro2 which I don't really want. On the installation instructions for the ext sensor, it shows I have to pick a heating curve, it also shows this being done on a Glowworm boiler that isn't a Flexicom. Would I be correct in saying I would adjust the heating curve in d.0 in the Diagnostic Codes to achieve this?

Al

 

[ShaunCorbs]

The rate of heatless is factor of the temperature gradient (between inside and out) and a coefficient of the material's insulating properties (walls etc).

yes thats where weather comp comes into play but the dumb effiency stat doesnt know any of this all it knows its its take lets say 32 mins to heat up the house to 21dc / rise of 13dc from cold