Replacing a programmer

[the_mouse]

Hi
I've been asked to replace an old mechanical programmer for a new digital one, I've not done any central heating work before and can't find much info on net( I've only got limited web access). Are they a straight swap or do I need to get a compatible unit, the only info I've been given is the boiler is an Ideal Mexico.


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[Marvo]

Is there a digital programmer available specifically for this make and model or are you going to use a generic replacement?

 

[Marvo]

Is there a digital programmer available specifically for this make and model or are you going to use a generic replacement?

You could try here but there's about 30 different models of the Ideal Mexico.

 

[topquark]

No simple answer to this one I'm afraid. Most of the modern programmers will come with a standard 5 terminal back plate. It will be then a question of working out how to configure the wiring panel. Have a look at the old unit. You may find it only has a mains feed, pump, valve and two stat connections (tank (if there is one) and room stat). There may not be any boiler connections if it's a really old unit (it will fire up when the pump starts and water flows through it). There is info on standard Y Plan and S Plan in the sticky's at the top of the forum.

 

[truckster]

Boiler is irrelevant, you will have a L/N at the programmer and up to three other cores. A HW on, HW off and a CH on. If you are just changing the prog, take notes of which cores are connected to which and put them in the right terminals on the new clock.

NB The old clock may have links in to take the live to the other switches HW/CH You may or not need these on the new programmer depending on whether it has volt free terminals.

 

[topquark]

Boiler is irrelevant, you will have a L/N at the programmer and up to three other cores. A HW on, HW off and a CH on. If you are just changing the prog, take notes of which cores are connected to which and put them in the right terminals on the new clock.

No the boiler is not irrelevant. Some require a feed as they are pumped and some don't.

Edit: and some have built in logic that requires power as well.

 

[truckster]

Topquark

For a simple clock change the boiler is pretty irrelevant, it is only a case of duplicating the original switching. If he were changing the wiring centre for instance then he would need to know the details of the boiler.

 

[topquark]

The wiring centre will probably need to be changed as well, it is often built in to old mechanical timers. Ony pretty irrelevant now eh? I'm out of here.

 

[truckster]

Good book.......Central Heating: Fault Finding and Repair

 

[ratpig]

Have you had any joy with this yet? I work as an electrician for a central heating installer fitting 90+ boilers a week. Could probably help you out if you need it.

 

[the_mouse]

Thanks to all that replied, still not got broadband access! I'm still waiting for customer to get back to me with more info and arrange a visit to see what's what.


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[the_mouse]

Hi a little more info, the prgrammer is SMC which after some digging, may mean fitting an external relay if switching to modern programmer, does anyone know of a direct replacement?? or where to purchase the relay.

 

[truckster]

Hi mouse

Have a look at this one Centaur Plus

Wiring diagrams