Talk to me about CH timers/stats!

[NiceCupOfTea]

OK,

I have thermostat waiting to go on.

Old thermostat has the following terminals connected

1 - red wire
2 - black wire
3 - blue wire

According to the doc on this page:

http://www.diyfaq.org.uk/docs/Sundial-Wiring-Rev1d...

(which is a more modern Honeywell electromechanical stat but seems similar to my ancient Honeywell stat, those terminals are:

1 - switched live from the timer/programmer
2 - neutral
3 - call for heat to boiler/zone valve

The new Honeywell CM927 has the following: N, L, L, A, B, C

According to the manual, for a zone valve setup N & L should be connected as expected to the switched lived and neutral, then you should bridge L to A, and the B wire is the call for heat wire to boiler/zone valve.

See here:

http://europe.hbc.honeywell.com/products/pdf/en0h8...

So - is this right? Should I bridge L to A?

[Ferg]

Yes.
The A and B switch connections are volt free for switching low voltages, so Livening A with 230v will give 230v out on B.

[Ricky_M]

Seems you have it sussed. Connect a 230v permanent supply to L+N on the reciever, bridge a L to A.

Trace your old stat wires back to the wiring centre and connect the call for heat to B on your reciever. It should be connected to the brown wire of the heating zone valve or the white wire if its a three port valve.

[NiceCupOfTea]

Thanks for all the help guys.

CM927 wired up to the stat - L, N, B is call for heat, and L to A bridged

Replaced the Randall 4033 with a ST9400, L, N, HW on, CH on. That seems to be OK too!

Only slight annoyance is the "holiday mode" on the ST9400 holidays both the heating and hot water - would like it to holiday only the hot water and leave the heating to be controlled by the CM927.

I suppose I could just wire the CH on wire in the junction box to L and bypass the CH side of the programmer completely...

Replace the Immersion switch with that timer too, well chuffed.

The power of PH

[John Wheater]

Is this the right way to access the heating expertise so kindly offered?

Hoping so, here is my problem:

I've encountered an ancient Honeywell programmer that looks very like the ST699, but shows no model number and has no reset buttons.

My daft problem is that I can't get into it! I don't want to wreck it, but it hasn't got that slot in the bottom that you push up to let the assembly come forward off the backplate.

I feel dumb not being able to suss it out, but can you help? I should think it's over 10 years old.

With best wishes,

John

[Ferg]

The 699 has always come off in the same way. It has tabs that lock into the backplate which need to be 'depressed' with a small screwdriver. Earlier ones were Beige and Brown rather than the White they are now.

[John Wheater]

Thanks, Ferg. Yes, this one's beige. The ST699 instructions mention a tab. they say "Remove the programmer front from the sub-base by pushing tab in bottom slot A with a small screwdriver...". Or, in another version, "Remove the subbase from the timer by depressing the securing clip A and pulling the two halves apart."

And there is a picture with an arrow showing 'A' at the bottom right of the base.

The trouble is, I can't see any slot to get a screwdriver in. I wonder if you could go into a little more detail of what you do?

[John Wheater]

I must pay tribute to Honeywell support. I sent an email and got a phone call, and pictures, which showed the hole in the base as *very* small. And, in my case, the superstructure was old and stuck. But all was well.

Thanks for the help fellows!:-)

[The Wolfhound]

Hi - sorry to 'hijack' the post but I have a question, if I may? I've been mooching around trying to find the correct wiring sequence for the Sunvic 207 XLS.

I live in France and have a Chauff Eau (Elecric Water Heater) that takes a 230V supply direct fm the mains. I bought a 207 to allow on/off timing of the chauff. The connections on the 207 are N L 1 2 3 4. No1 is HW Off No2 is CH Off, No3 is HW On, & No4 is CH On. I've wired the 207 with N & L and tested it with a MMeter, I have 230V showing. The chauff simply requires has a 230V L & N feed.

Can anyone tell/explain where I would connect the L & N fm the chauff to the 207 to allow the 207 to act as the timing device as planned pse? I've wired a simply lightbulb and connected it to the all the feeds to try and establish a current out to the 207 to the chauff, but alas to no avail, there's no current flowing (also checked all the connections with a MMeter). I've set the 207 DIP switches to allow independant CH & HW so it shld work, sadly it doesn't.....can anyone help pse?

Thanks VM in anticipation. Regards.

Wolfhound

[Ferg]

If it's a water heater I suspect the programmer won't have the current carrying ability.
It's probably rated at 5amp and the water heater is probably nearer 13amp.


If it CAN take the current you need Live and Neutral to the timer and then a Live to the heater from the 'hot water on' terminal and a Neutral from the supply.

Edited by Ferg on Saturday 29th May 17:42

[The Wolfhound]

Ferg Hi

Thanks for that. Am I being a bit thick here or am I missing something? The 207 has a HW Programme so should it not be able to support the Chauff Eau requirements? When you say a Neutral from the supply, do you mean a direct connection fm the supply ie the Consumer Unit, to the Chauff Eau, missing out the 207 completely? If so. what function does the HW Off terminal on the 207 have, and what should it be wired to then pse?

Thanks once again.

[Ferg]

The Wolfhound said:

Ferg Hi

Thanks for that. Am I being a bit thick here or am I missing something? The 207 has a HW Programme so should it not be able to support the Chauff Eau requirements? When you say a Neutral from the supply, do you mean a direct connection fm the supply ie the Consumer Unit, to the Chauff Eau, missing out the 207 completely? If so. what function does the HW Off terminal on the 207 have, and what should it be wired to then pse?

Thanks once again.

Hello.
The programmer is designed to switch less than 3 amps to activate a control system for a boiler, heating a cylinder through an indirect coil. IF you are intending to switch a SOLELY electric immersion heater i.e. no other fuel involved then you'll blow that programmer.

If the current requirements are OK then you need a neutral (which doesn't require switching) direct from the mains, and the live is switched via the 'HW On' terminal.

Look at the rating plate on the water heater. 3kW??, that's 3000watts divided by 230 volts = 13 amps. Too much for the switches in that timer.

Or is it a gas fired heater.

Sorry if this isn't clear, I've been in the pub.

[The Wolfhound]

Ferg Hi

You enjoy the results of your visit fella.....I can wait!!! I'll look at the Chauff tomorrow and see what the numbers are.....can I come back to you then pse?

Take care.

[Ferg]

Of course, I have another mission now involving my wife.

[Simpo Two]

Ferg said:

Of course, I have another mission now involving my wife.

You mean the central heating in her house has broken as well?

[The Wolfhound]

Ferg said:

Of course, I have another mission now involving my wife.

Hope you had a successful mission Ferg.....???

Just checked the Chauff and yup its 3000W and 230V, so I guess thats that idea down the swany? Is there anything I can buy to put inbetween the 207 & the Chauff, or do I bite the bullet accept its the wrong item and buy the correct item to do the job? If so, what would you suggest pse?

Thanks......

Wolfhound

[Ferg]

You COULD put a relay in to take the high current, but it might be easier to get one of these....

http://www.screwfix.com/prods/89388/Electrical-Sup...


..or the digital equivalent.

[The Wolfhound]

Would this do? http://www.screwfix.com/prods/92265/Electrical-Sup...

[Ferg]

Looks good to me.

[The Wolfhound]

Any complications/issues with the wiring that I would need to be aware of pse?

TVM