CH heating programmer

They nearly all do this, so long as they have "independent" mode:

two channel is the term I should have been looking for Do you know if these come with a decent wiring diagram? I will be replacing a Honeywall st772 timer

One way of achieving what you want to do is to use a programmable thermostat on the heating side. Then set set your original timer with HW on 'Timed' and CH on 'Constant'. The *actual* timing for the heating is done by the programmable stat - and can be completely different from the HW times. It also means that you can have different room temperatures at different times of the day should you so wish.

I haven't seen a new programmer not capable of this in the last 20 years, apart from the mechanical ones.

Christian.

Are you *sure*? Most programmers I have come across have only got *one* timer. Whilst they provide independent *control* for HW and CH - such that each can be either Off, Timed, or On constantly - if both are set to Timed, they both come on at the *same* time. The OP wants one with independent

I don't doubt that such timers exist. I just haven't seen one on my travels.

Christian.

The Horstmann CentaurPlus C27 will do what the OP wants. You can set separate times for CH and HW.

Pity I can't get it to work as a replacement for my Landis & Gyr RWB2 - see the 'Horstmann CentaurPlus C27 replacement for Landis & Gyr RWB2: wiring problem' thread below if you can help.

I have had one of these for 3 or 4 years:

HTH, Steve S

I haven't fully researched this, but every timer I considered was able to control the HW and CH independently, but are often shipped with them locked together for those whose system requires the HW to be on for the CH to work.

But there's a world of difference between *switching* independently and

Locking together only really applies to gravity HW systems, thus ensuring that the boiler fires when you select just CH. But even when not locked together, most programmers don't provide independent timing programmes for CH and HW. A few do, as has been reported here, but it's not too common.

The Grasslin TOWERCHRON QE1/QE2 I mentioned earlier can be set up for either gravity of fully pumped and, as I said, offers fully independent timing.

Steve S

Thanks Set square I was really looking for a 24H timer to achieve this, as due to my work shift patterns I have to reprogram the timer settings every 4 days. so that I have hot water to shower when I get up, im not in the house long enough at the getting up time to warrant running the CH. and a warm house to come home to. As you correctly say there are lots of programmers such as

Thanks that one looks the job, as it will also programme in 24H mode.

I fitted a Honeywell ST6400C....does just that. Here's the user manual...

Please explain?

That's because they are single channel!

What I mean is this. If they've only got one timer, you can still have independent control of CH and HW to the extent that you can have (say) HW Timed and CH Off, or HW on continuously and CH Timed (or any other combination of Off/Timed/Continuous.

What you *can't* have is CH and HW *both* timed but coming on at *different* times from each other. For that, you need the programmer to have *two* independent timers - as indeed some - but by no means all - do.

Then you *obviously* can't do what the OP wanted.

Which is why I replied to you earlier "Thanks two channel is the term I should have been looking for"