Talk to me about CH timers/stats!

[Duke Thrust]

My system is ancient (20 years +) and I also have a mechanical timer system.

Come the summer I'm planning a big upgrade with a new boiler, a back burner on the Clearview and a heat bank.

In the mean time, is it work fitting a decent timer? (interesting reading the post re the boiler not being on so much). All the rads have TRV's but if the system has a room thermostat I'm yet to find it.

Interestingly enough, the stat for the hot water appears to be gaffer taped to the H/W pipe just as it exits the boiler, no idea why.

Anything I can do to make it more efficient would be good, using a lot of gas at the moment...

[Ferg]

philmots said:

Thanks Ferg. I might graft in a bit of external help just to keep it all safe!

It really is simple, Phil. You'll walk it.

[NiceCupOfTea]

andy43 said:

Something like this would do for the hot water.

So could I just replace the timer in the airing cupboard with that? Presumably I'd leave the old timer there as Ferg says it is a junction box. So how do I wire in a new 1 channel timer? In some way I need to bypass the other channel and allow to to be controlled by the stat...

[doolie]

I must be the 5th or 6th to say on this thread, but the CM927 is amazing. I installed a WB CDi boilder a couple of years ago with the front panel timer and no thermostat. Pain in the arse it was to maintain constant temp

Fitted the CM927 around 6 months ago, idiot proof to use. Took a bit of dwelling over the wiring diag but turns out dead easy to install to our boiler.

Party mode gets used a lot. Holiday also very useful

Highly recommended and we got ours off fleabay, from memory it was £70 to £80

[K50 DEL]

I think I may be the lone voice of dissent on this thread.

I've just moved into a house with a Honeywell CM61 cordless timer thing in the hall.
I thought it was broken as no matter what I did with the times, the moment I clicked the system on to auto, the heating came on.

A thread I posted on PH lead to some of the Heating gurus here telling me that it's supposed to behave like that.

So, the next time I'm back in the UK I'll be having it ripped out and a normal, manual control system put in.
The Worcester Bosch system in my old house had a dial on the front of the boiler with each hour split into 4 little flick switches, flick them in and the heating came on at the set time, leave them out and everything was off.

I see these automated things as another example of the dumbing down of Britain, I'm quite capable of deciding when I want my heating on... what's the point of having the temperature maintained at a certain level if I'm not in...... you don't leave the climate control on in your car when it's sat in the garage do you???

[Simpo Two]

K50 DEL said:

I see these automated things as another example of the dumbing down of Britain, I'm quite capable of deciding when I want my heating on... what's the point of having the temperature maintained at a certain level if I'm not in...... you don't leave the climate control on in your car when it's sat in the garage do you???

Cheap software tweaks allow companies to sell you things you don't really want and charge you extra for it. How many times do we find that the 'new improved' version is actaully not as good as the one before?

[andy43]

NiceCupOfTea said:

andy43 said:

Something like this would do for the hot water.

So could I just replace the timer in the airing cupboard with that? Presumably I'd leave the old timer there as Ferg says it is a junction box. So how do I wire in a new 1 channel timer? In some way I need to bypass the other channel and allow to to be controlled by the stat...

Provided you're not going to switch on the 3kw immersion element with it.

We have a Honeywell CM907 downstairs, and a cheaper Danfoss stat upstairs, and they're ace. Well worth it, but I'd recommend Honeywell over Danfoss, as it works in half-degree increments, looks nicer and has a bigger screen with a clock and a backlight and stuff. Wooooo shiney. And more buttons.

K50 DEL said:

I think I may be the lone voice of dissent on this thread.

I've just moved into a house with a Honeywell CM61 cordless timer thing in the hall.
I thought it was broken as no matter what I did with the times, the moment I clicked the system on to auto, the heating came on.

A thread I posted on PH lead to some of the Heating gurus here telling me that it's supposed to behave like that.

So, the next time I'm back in the UK I'll be having it ripped out and a normal, manual control system put in.
The Worcester Bosch system in my old house had a dial on the front of the boiler with each hour split into 4 little flick switches, flick them in and the heating came on at the set time, leave them out and everything was off.

I see these automated things as another example of the dumbing down of Britain, I'm quite capable of deciding when I want my heating on... what's the point of having the temperature maintained at a certain level if I'm not in...... you don't leave the climate control on in your car when it's sat in the garage do you???

I reckon that's not wired up right. If you set it to 14 degrees with the house already toasty warm and the heating still comes on, it broke.
And personally, far from dumbing down, I think they're labour-saving. My mum gets up every morning, goes downstairs, and clicks the roomstat dial up 1/32456th of a turn. Then turns it down when they to bed. If you're there at fixed times each day, it's a no-brainer. You did read the instructions didn't you?
Statheads - temperature matters.

[K50 DEL]

andy43 said:

I reckon that's not wired up right. If you set it to 14 degrees with the house already toasty warm and the heating still comes on, it broke.
And personally, far from dumbing down, I think they're labour-saving. My mum gets up every morning, goes downstairs, and clicks the roomstat dial up 1/32456th of a turn. Then turns it down when they to bed. If you're there at fixed times each day, it's a no-brainer. You did read the instructions didn't you?
Statheads - temperature matters.

This was back during the real cold snap just before Christmas, but that shouldn't matter....

IE: I want the heating to come on for 1hr in the morning and 2hrs at night, the rest of the time I want it off, irrelevant of what the temperature in the house is, if I'm cold I'll put on a jumper, but modern houses are so warm anyway.
The system I now have seems to think that I want the house to permanently be 16c or so, and then up to 18c (the temp I've set) for the 3hrs I've told it I want heat.

I eventually managed to get round it by running the system in holiday mode permanently (keeps house above 9c) and simply flicking the controller to ON for those 3hrs a day.
That's a bit of a faff though, so I'm just going to junk the wireless thing and get a proper controller installed.

[Ferg]

doolie said:

I installed a WB CDi boilder a couple of years ago with the front panel timer and no thermostat.

Since Part 'L' became part of the Building Regs!!?? Good Lord!!

[Rollin]

I'm getting one. It really pisses me off going to the cellar to turn the temp up or off.

[Ricky_M]

NiceCupOfTea said:

andy43 said:

Something like this would do for the hot water.

So could I just replace the timer in the airing cupboard with that? Presumably I'd leave the old timer there as Ferg says it is a junction box. So how do I wire in a new 1 channel timer? In some way I need to bypass the other channel and allow to to be controlled by the stat...

Right, if you have an ancient timer, chances are, all the lives and neutrals for the heating wiring are probably linked inside the timer and the live supplies for the CH and DHW side of the clock are probably wired externally within the timer also, if that makes any sense!

So in short, you'll probably find a lot of wires when you open up the timer!

Take your time and figure out which wire does what, I'm guessing you have a fully pumped heating system? Can you run the heating without the hot water? Or do you have to have the hot water on to run the heating? If its the latter, it'll be difficult to make the programmable stat work as you need the hot water timer to come on at the same time.

Back to the wiring, you need a permanent 230v live supply and a neutral to the single channel timer for your hot water. In the old timer you should have a diagram on the inside of the timer, you need to find the wire that is connected to "HW ON", make sure you mark that one out before you remove the old timer, also find "CH ON" and make note of that.

On the new timer, you should have a backplate which is layed out something like this......... N L 1 2 3 4..... N + L are your Live and Neutral supply. Havn't wired up a single channel programmer in a while, but out of 1, 2, 3 and 4, one will be a common, which you will need to be be livened up, ussually from the Live terminal of the timer (be careful if its a modern boiler, as they have low voltage switching and don't like 230v!!)

Once you have the common livened, another terminal will be the "on" side of the switch, which will be livened up when the channel is turned on, this need connecting to the "HW ON" wire that was in the old timer, if you have a three port valve, you'll need to find a "HW OFF" wire in the old timer and connect it to the "Off" side of the switch on the new timer.

As for the heating side of the wiring, if you connect the "CH ON" wire from the old timer to the live supply of the new timer, this will override any switching of the timer, you can then remove your old stat, which should have two wires, one will be the common, which is your live supply you just linked up, the other will be the demand for heat, the Honeywell CM907 wires up the same and will be a doddle to fit.

Hope this makes sense, it sounds daunting, but is very simple once you gain an understanding of how it works. Don't attempt it if you are not competent, can get yourself in a right mess with wiring! I hold no responsibilty for any damage you may cause on undertaking this task! This is advice only not instructions!

Good luck!

Edited by Ricky_M on Friday 12th February 23:15

[NiceCupOfTea]

Had a look at the system yesterday. In the airing cupboard there is the CH pump and two zoning valves. There's what looks like a junction box and some wires coming out to the CH/HW timer (by the way, the 2 systems work independently of each other), so I am hoping it should be "relatively" simple to change the timer as hopefully most connections are made in the junction box. However, if it's not immediately obvious I'll leave it be.

Don't want any bells and whistles, the old Randall timer would be fine if I could take 2 of the pins out - I just don't want the hot water on in the evening, only use it for showers in the morning!

The old Honeywell electromechanical thermostat has 5 connections numbered 1,4,3,2,5 from the bottom upwards. 1, 3, & 2 are connected. Don't know any more without taking it off the wall. Does that give any clues as to how wasy it should be to hook up the new thermostat?

[Ferg]

Not difficult at all. Timer needs a live and neutral and two 'on' wires. One for heating, one for hot water. The thermostat simply needs the neutral disconnecting and the other two wires switched by the new the new thermostat.

[NiceCupOfTea]

Ferg, in theory how easy is it to identify the wires given they are just numbered? Multimeter whilst live or an easier way?

[Ferg]

Very.
I could give you my number for a chat if you like. I'll find a wiring diagram.

[NiceCupOfTea]

Very kind offer Ferg - haven't ordered the stat yet but will do in the next few days and give you a shout when it turns up if that's OK?

[NiceCupOfTea]

OK, got the stat (CM927) and the immersion timer, going to do them in the next couple of days.

It looks from the installation diagram with the CM927 that it needs all 3 wires - L (from timer), N, and the call for heat wire that goes to the boiler or zone valve, not sure which. The wires in the current stat (1,2,3,4,5 - 1,2,3 are connected) seem to correspond with here: - this would imply that:

1 - Live (from timer)
2 - Neutral
3 - Call for heat

I'll see how it looks when I get it off the wall...

In the meantime I've been looking at replacement timers. I think a 2 channel one may be easier to fit as there is already a 2 channel one there - even though the "heating" channel will be permanently on and controlled by the thermostat.

What I *do* want is:
- digital timer
- variable (1-3) on/off settings per day
- boost & advance settings

The Honeywell ones look good as always, but expensive. Somebody linked to a cheaper single channel ebay one (ST6100C) but with a long delivery lead time - really want to get it done in the next couple of days though.

Have happened across a Sunvic which seems to do what I want (207 XLS) http://www.heatingcontrolsonline.co.uk/sunvic-sele...
Any experience? Or would it be better spending more (double!) money on the Honeywell ST9400C http://www.heatingcontrolsonline.co.uk/honeywell-s...

[Ferg]

I like the ACL Lifestyle timers. They rarely give me problems although not as nice looking as the Honeywell ones.
I don't think Honeywell's stuff is anything like as good as it used to be.
Their 'Smartfit' cost me a packet in teething problems.

[NiceCupOfTea]

Ferg, just had a look at the ACL Lifestyle stuff - I see an "advance" setting but not a "boost" - want to be able to push a button and have an hour of hot water and then switch off, rather than it stay on until the next "off" event in the timer IYSWIM!

Sunvic seems to be the best featured at a mini price. Some cheaper Honeywells on ebay but slow delivery...

[Ferg]

Oh, yeah, good point.