28 day CH Controller

[alex_sh]

All of the central heating controllers I have seen are programmable over 7 days but I could do with one with a 28 day programmer to suit my shift pattern. Any ideas please?

Alex.

[John W]

If your shift pattern consists of 7 day chunks repeating over 28 days (as opposed to 3 days here, 5 days there etc) then you could consider the quite costly option of having two timers that you swap at the weekend one programmed for one type of 7 days and one for another. As long as you choose a type thats easy to unplug from the backplate (which I think is most of them) then the you should have no problem.

[Roger Mills]

That *sounds* ok - except most of them run on batteries which are kept charged by being connected to the mains via the backplate. The battery will maintain the memory contents for a limited period when removed from the mains. This period may not be long enough!

[Having said that, I've just looked at the spec of my Danfoss Set5 programmer - and that claims to hold the time of day and programmed on/off times for 16 days when disconnected from the mains - so you may be ok].

Roger

[alex_sh]

I have considered 4 x 7 day timers in parallel with appropriate switching that would not be difficult but its expensive and not a very elegant solution

Alex.

[Bob Eager]

Funny, I was thinking about this kind of problem and was going to post to the NG tonight in any case...then this thread came up...

We occupy the house at irregular (but predictable) times each day. I wondered if one can get any kind of box that plugs in, in place of a normal CH controller, that allows one to program a 'calendar' of times via a PC...indefinitely into the future. Clearly one needs a manual override and failsafe, but the savings are potentially a lot greater than the cost of leaving a PC on (especially if it's going to be on anyway...)

[stefek.zaba]

Two places to start suggest themselves to me. One is to look at X.10 home automation controllers: I'm pretty sure the range of stuff includes the kind of donwloadable programmer/sequencer you suggest. The other is the user-friendly version of programmable logic controllers, like the Mitsubishi Alpha and the Siemens Logo! (yup, the bang is part of the name ;-) which cost about 80quid and have calendar functions as well as all the ANDs, ORs, timed-delay, and other automation building blocks you could want for a small setup - allowing you to program your very own flavours of control suited to you particular "predictable" patterns. See rswww.com for (full) prices, or the suppliers websites for detailed downloadable programming manuals.

HTH, Stefek

[Toby]

From an earlier reply to the spookily similar thread Re: Thermostat Control

Say really want to go the whole hog and have a fully programmable heating system you could change your current heating controls to the Honeywell smartfit system, then connect these via this interface

to the Comfort home control system. This will give you the control you seek plus the option to override programs by phone or optional web interface. (check this - quite cool really ) If you are really curious, it will phone you up if it gets frosty. The interface is about £160, the Smartfit around £125, and the complete system should leave change from £1k.

Toby.

[James Hart]

Presumably X10 can be set up with an incoming phone line and a programmable thermostat so you could knock off early one day and still come home to a toasty warm home and a tank full of hot water for the bath, I think I'll have to look at this a bit more.

[Bob Eager]

Thanks - I thought of X10 but understood that it's not so satisfactory this side of the 'pond'. But I'll look around...

[Bob Eager]

Thanks...must have missed that on a day when I was speed reading the NG!

[David]

So he could hang on to the backplate which comes with the second timer, and install it as a 'dummy' alongside the 'real' timer so that the second backplate also receives power, but doesn't do any controlling - that way he just swaps the timers over as needed, and both receive power 24/7.

David

[Ian Clowes]

Hi Alex

What sort of shift pattern are you trying to accomodate, and are you looking to control HW and CH?

If you work one of 3 shifts for a few days, then move to the next (days, afters, nights type pattern) then you might be able to make something workable using just a single 3-channel programmer. Horstmann do one, and maybe others. Honeywell didn't last time I looked.

Use channel 1 for days, channel 2 for afters and channel 3 for nights. When you're on days manually turn off channels 2 and 3, and turn channel

1 on. Then do similar for the other shifts.

There are other variants on this theme where you might use channel 1 for 'middle of the day' and 2 and 3 for morning and evening, say. You might then leave channel 1 on all the time, and simply turn 2 and 3 on at the right time depending on whether you're in the house in the am or evening.

You should be OK commoning up the three outputs, since although this will present 240V to the 'off' channels this shouldn't be a problem electrically for the components.

You could then drive just the CH from the output and control HW via different means, or drive both HW and CH from the output. In the latter case you'd want an additional switch (a light switch would be fine) in the line from the contoller to the CH part of your circuit so you can turn it off in summer.

I realise that isn't as automated as you might like, but it might just get the job done. Let us know if you have other things that need to be taken into consideration to make something workable for you.

HTH IanC

PS: Sorry if anyone sees this teo or three times. I seem to be having posting trouble.