New House/Strange System

[josswallace]

We have just moved into a new house which has a Wocester Boiler in the utility with a Honeywell ST6100A timer with two time zone options but no option for dealing with cental heating and hot water separately,ich I am quite capable of programming. The boiler provides hot water to the central heating system and to a Heathea Sadia unvented megaflow cylinder. In the main hall of the house there is aHoneywell CM907 room temerature 6 stage thermostat which I am also conversant with setting.

What I don't understand is how these two systems interact.

If any one can point me in the direction of some informed explanations as to how such a system would work I would be very much obliged.

Ian Wallace

 

[muggles]

I suspect the ST6100 controls the hot water times, and the CM907 controls the heating time and temperature. They'll both fire the boiler via two-port zone valves

 

[josswallace]

I suspect the ST6100 controls the hot water times, and the CM907 controls the heating time and temperature. They'll both fire the boiler via two-port zone valves

So it really like having 2 boilers one for heating and another for water.......Is thgat right.

 

[muggles]

One boiler, one hot water cylinder, two programmers. Not a conventional way of doing things but acceptable.

 

[D_Hailsham]

The previous owner has probably replaced an old thermostat with the CM907 programmable thermostat. You will probably find that one channel on the ST6100 is set to permanently on - this will be the CH channel - and the other channel is 'timed' as it's the HW channel.

Leave the CH channel of the St6100 permanently on as all CH timing is now controlled by the CM907.

 

[josswallace]

That's the point I don't really understand. The ST6100 controlling the boiler has two start stop times but unlike the controller in my old house it does not appear to allow the user to set the central heating and water separately.

 

[Boilerman2]

The ST6100 Is a SINGLE channel time clock this will be controlling the production of Hot Water
Your Heating is controlled by the CM907 This is the way I would have installed the equipment sometimes there are several heating zones such as ground floor, 1st floor & Conservatory each of these could have it's own CM controller with the ST 6100 just looking after the Hot Water it really is that simple!

 

[D_Hailsham]

The ST6100 Is a SINGLE channel time clock this will be controlling the production of Hot Water

I really should have remembered that; then I wouldn't have talked about the HW and CH channels.

Boilerman is quite correct. The ST6100 controls HW times only. The CM907 controls CH times and temperatures.

 

[josswallace]

Thanks a lot, I think that's resolved my problems.

 

[drgl]

The ST6100 Is a SINGLE channel time clock this will be controlling the production of Hot Water
Your Heating is controlled by the CM907 This is the way I would have installed the equipment sometimes there are several heating zones such as ground floor, 1st floor & Conservatory each of these could have it's own CM controller with the ST 6100 just looking after the Hot Water it really is that simple!

Indeed, building regs for larger houses require split zone (normally ground & 1st floor). Set the programmer to heat the water when you want it & the CM907's have various set temps/times.