help - honeywell product

[Marco1976]

http://www.google.co.uk/products/ca...uhLZSQwQWAnYzpDA&sa=title&ved=0CAwQ8wIwATgA#p

Hi,

Does this product have both thermostat and on / off options?

I was thinkinh of using on / off during the week when i am at work and the thermostat option for the weekend. Is this feasible with this product?

thanks

 

[MJN]

I think you might need to elaborate on what your question. What do you mean 'on/off'? You want the boiler just to run flat out for periods during the week, rergardless of what temperature the house might reach...?

If so that stat could be made to function like that, but you'd be nuts for doing so.

Mathew

 

[Aunsh]

I suggest you run a web search for the user guide, which will show you what this device is capable of, which is quite a lot more than you think you want.

Essentially, you can set the target temperature for up to six different periods each day, with different times and temperatures for each day.

For example, you could set each weekday to have a target temperature of 20C from 7:00am to 8:00am, then 16C until 5:00pm, then 20C until 11:00pm, then overnight 15C until next breakfast change. You could set Saturday and Sunday individually with similar periods, with times/temperatures to suit your lifestyle.

Don't be put off by the apparent complexity of the device, and expect to tweak the times/temperatures over the first few weeks of use to match your needs. Once set up, you will probably only change it a few times each year for days off, illness, etc.

Hope this helps

 

[MJN]

[...] you will probably only change it a few times each year for days off [...]

Not even that given that the CM-series has a very handy 'day off' button! For those that aren't familiar, it runs the Sunday programme for those days you tell it you're off.

Mathew

 

[Marco1976]

In response to one of the posts, I need a thermostat / timer that I can set on a temperature basis for sat and sunday but for the weekdays when i am at work i want it off no matter what the temp is, hence the need for the timer on off stat. I would let it come on an hour before my return.

 

[MJN]

You can achieve that with the type of programmable stat described - just set the target temperature for your 'off' periods to something very low e.g. 10C or whatever. Given that the temperature will not drop that low the stat will not tell the boiler to fire.

The CM907 you've been looking is generally held in high regard - good functionality and easy to use (at first you might not agree but get to know it a bit and you should find it is quite intuitive).

I would let it come on an hour before my return.

That too is possible, however an alternative with this stat (and some others) is that you can tell it you want it to be, say, 21C at 6pm when you get home. It will then decide when to come on to achieve this. One caveat however - it sounds perfect but some people have found it to be somewhat over-cautious and actually reaching target temperature too early. This is fine for getting back to a warm house but not so good from an energy conservation perspective.

Mathew

 

[Marco1976]

You can achieve that with the type of programmable stat described - just set the target temperature for the 'off' periods to something very low e.g. 10C or whatever. Given that the temperature will not drop that low the stat will not tell the boiler to fire.

The CM907 you've been looking is generally held in high regard - good functionality and easy to use (at first you might not agree but get to know it a bit and you should find it is quite intuitive).

Mathew

ok, who would i get to install it? Gas Safe engineer or electrician?
Boiler is an old Worcester 28si.

 

[MJN]

It's a relatively trivial job, particularly if it is just replacing an existing room thermostat. Thus, it's either a job for a DIYer or any tradesman with familiarity in this area - plumber[1]/electrician/whoever.

If you want to describe your current setup (i.e. the boiler and rest of the system, is there a clock/programmer on the boiler itself, or elsewhere, is there a room thermostat and what does it look like etc) I'm sure the friendly folk on here will be able to walk you through. You can then decide if it is something you or a friend would be confident in tackling yourself.

Mathew

[1] I am using the term plumber to encompass all grandiose titles in this areas - boiler technician, heating engineer, etc. The titles are abused so much they are for all intents and purposes meaningless. Basically, you want someone who understands how a boiler is controlled via a simple external stat/programmer.

 

[Marco1976]

MJN,

The current setup is a Worcester 28si and a on / off timer.
I have tried to find a wiring diagram for this boiler but there does not seem to be any.

At the moment a wire runs from the 3a fuse to the timer and from there to the boiler. There are four cores connecting to the boiler which is what threw me, I thought there would only be three ie L N and Earth. Would the fourth be something to do with hot water?

I would be happier if I had a wiring diagram for my boiler before commencing this task, would not want to bust the PCB....

 

[mikely]

28Si manual here:
http://www.worcester-bosch.co.uk/installer/products/gas-boilers/28si-february-2000-march-2002

To wire up a CM907, you simply connect boiler terminal Ls to thermostat terminal A and boiler Lr to thermostat B. See manual Figs 12 and 14.

 

[MJN]

As you haven't mentioned a room stat this may be an issue as positioning the CM907 next to the boiler will likely not give good results. Your options here are to use a longer cable and locate it in a better place (e.g. lounge or hall - wherever it ends up remove the TRV head on the radiator if fitted) or go for its wireless brother, the CM927, so you can locate the receiver by the boiler and the transmitter (programmer/stat) elsewhere.

Mathew

 

[Marco1976]

thanks for the replies.

mikely, at the moment the mains cable from the 3a switch fuse runs into the timer and then from there there is a wire that links back the timer to the boiler.

In the figure shown on the instructions the mains lead comes in separately from the timer/thermostat. Is my understanding of the figure correct?

I am wondering if the 3a switch fuse should feed the boiler mains AND new programmer sepaarately or should they both run through the new programmer as they appear to be doing now?

btw The boiler is in the garage attached through the house. The current timer is in the hall.

 

[D_Hailsham]

mikely, at the moment the mains cable from the 3a switch fuse runs into the timer and then from there there is a wire that links back the timer to the boiler.

In the figure shown on the instructions the mains lead comes in separately from the timer/thermostat. Is my understanding of the figure correct?

Yes, the boiler needs a permanent electricity supply. If it doesn't have one, you can only have hot water when the timer is ON, The Honeywell is a programmable Heating stat.

I am wondering if the 3a switch fuse should feed the boiler mains AND new programmer sepaarately or should they both run through the new programmer as they appear to be doing now?

The 3amp fuse should feed only the boiler. The new programmer is battery powered and just acts as a switch between the Ls (A) and Lr (B) terminals of the boiler.

The boiler is in the garage attached through the house. The current timer is in the hall.

I would definitely consider a wireless thermostat, i.e the CM927. The receiver, which can be in the garage, does need a permanent 240Vac supply but this can come from the boiler's Mains terminals.

 

[Marco1976]

mikely, at the moment the mains cable from the 3a switch fuse runs into the timer and then from there there is a wire that links back the timer to the boiler.

In the figure shown on the instructions the mains lead comes in separately from the timer/thermostat. Is my understanding of the figure correct?

Yes, the boiler needs a permanent electricity supply. If it doesn't have one, you can only have hot water when the timer is ON, The Honeywell is a programmable Heating stat.

I am wondering if the 3a switch fuse should feed the boiler mains AND new programmer sepaarately or should they both run through the new programmer as they appear to be doing now?

The 3amp fuse should feed only the boiler. The new programmer is battery powered and just acts as a switch between the Ls (A) and Lr (B) terminals of the boiler.

The boiler is in the garage attached through the house. The current timer is in the hall.

I would definitely consider a wireless thermostat, i.e the CM927. The receiver, which can be in the garage, does need a permanent 240Vac supply but this can come from the boiler's Mains terminals.

I can only assume then that the current setup is a bit of a bodge since the mains wire runs from the 3amp fuse in the garage through the wall and then there is another wire that comes out of the wall feeding the boiler. I can only assume this is because the current timer works of mains electricity. Maybe there is some sort of connector block behind the timer in the house feeding both the timer and the boiler mains.....

Is the CM907 discussed previously only battery operated?

 

[MJN]

I wouldn't go that far - there could be very good reasons why it is wired as such, particularly if you're not sure of the history i.e. what boiler was in place before and what options it had for external controls. Besides which, it makes just as much sense to use the programmer as the wiring distribution point for the boiler, particularly if it cuts down on cable length or otherwise made installation easier.

Is the CM907 discussed previously only battery operated?

Yes.

Mathew