Help Please Honeywell 703010000b replacement

[atatum]

Hi, I should start by saying I am totally DIY inept, but I have Honeywell 703010000b that seems to have stopped working, it will briefly for a mil second click into life if you press the rest button and I think I need to replace it.

I am trying to establish if it has a standard back plate and therefore if I can buy any programmer with a standard back plate as I do not really fancy the job of rewiring. Can anyone help me please?

Also I would like a 7 day programmer which controls the on off for hot water separately from heating and also has a internal battery backup as we live in an area with frequent power spikes and cuts can anyone suggest what I should be buying please?

It is quite urgent as I have not hot water or heating today.

Any help much appreciated.

 

[robin7]

Your current programmer seems to be a Honeywell ST712, which has an industry standard backplate. I would suggest you replace with a Honeywell ST9400C, a 7 day programmer with fully independent control of CH & DHW - which also has a standard backplate - so should require no rewiring. Try ebay - I bought one for less than £30 earlier this year.

 

[D_Hailsham]

Also I would like a 7 day programmer which controls the on off for hot water separately from heating

I take it that you can have HW by itself in the summer but, in the winter. the HW always comes on at the same time as the heating. This may not be a fault of the timer but due to the type of system you have - a pumped heating/gravity hot water system. If that is the case, a new programmer would not overcome this.

Do you have any valves looking like one of these? They will normally be near your hot water cylinder.

View media item 5946 View media item 11762

 

[atatum]

Thanks for the responses

D Hailsham I do not appear to have any motirised valves just a pump.

Does this make a difference

 

[atatum]

yes we can have the hotwater coming without the heating in the winter, but what we can do is have the hot water timings set indepedantly tot he water times, so for example we want our heating on to 11pm but the hot water could go off at 7pm if we could set it.

Not sure if this is due to the valves/ type of system?

 

[D_Hailsham]

D Hailsham I do not appear to have any motirised valves just a pump.

If that's the case, then you most likely have a pumped heating/gravity HW system. If your boiler is easily visible, how many water pipes are directly connected? (A connection which immediately branches is still one connection.) If there are more than two, then you definitely have a pumped heating/gravity HW system.

yes we can have the hot water coming without the heating in the winter,

As you would in the summer.

but what we can(not?)do is have the hot water timings set independently to the water times, so for example we want our heating on to 11pm but the hot water could go off at 7pm if we could set it.

I presume you mean cannot. You won't be able to do what you want if it is a gravity HW/pumped heating system. You would either have to change it to a fully pumped system or convert it to a C Plan system, which puts a valve into the HW circuit, so it can be separately controlled. The fully pumped solution will cost more, but give you a more efficient system.

 

[atatum]

I have a tank stats on the hot water tank which goes to the programmer.

It is an oil fired boiler with two pipes going to it as far as I can see.

If it is as I supect pums what are the rough likely costs of the two options you suggest?

Thanks for you help

 

[D_Hailsham]

I have a tank stat on the hot water tank which goes to the programmer.

Do you mean something like this?

View media item 10596
,If so. it's probably there to stop the cylinder overheating in the summer. Would need to know how it was connected in the programmer.

It is an oil fired boiler with two pipes going to it as far as I can see.

Very unusual for a GHW/PCH system. Can you post a pic of the hot water cylinder and surrounding pipe work etc.

what are the rough likely costs of the two options you suggest?

Impossible to say without viewing. Best to ask three independent installers for quotations.

 

[atatum]

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• atatum
• 3 Oct 2010
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• atatum
• 3 Oct 2010
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• atatum
• 3 Oct 2010
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Thanks for your help here are the pictures. If we have a pumped system and replace the programmer then decide to upgrade later by adding a motorised valvle will we need to replace the programmer again, as I have an urgent need to get the thing up and running. so a quick fix then an upgrade I think might be the best option.

 

[D_Hailsham]

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• atatum
• 3 Oct 2010
• 1

There is a grey box visible at the bottom of this pic, below the Myson pump and behind the 22mm pipe. What is it?

 

[atatum]

on off power switch fused

 

[D_Hailsham]

on off power switch fused

OK

Presumably the connector at the top is the backplate for the existing timer.

On the back of the timer, there should be a switch. Can you say what it is set to?

 

[atatum]

Yes the connection at the top is the back plate for the existing timer.

There is no switch on the back of the timer or the bas plate.

There is the wring diagram that just says for fixed wiring

 

[D_Hailsham]

I would need to have more details of how your system was plumbed together to be able to make sensible suggestions. So all I can suggest, at this stage, is that you get a local plumber/heating engineer in to see the system and advise what you should do. You can then talk through the options and costs with him.

 

[atatum]

Thanks for your help, After looking again I found a motorised valve down the back of the pump, after speaking with honeywell they said the ST9400c would be a 7 day replacement for the st712 so I went out and got one this morning and fitted it.

It looks lovely, it goes on and off when it should but does not fire the boiler so I am not further forward. I have called a plumber who is going to take a look this evening abd I am just hoping it is a programming issue I ahve not seen or a problem with the motorised valve and not that I now need a new oil fired boiler?

Here is hoping, thanks agin for you help and time