Boiler controls replacement

[jstallan]

Hi,

Just moved into a house and discovered the Switchmaster 900 is not working correctly. The timer part just does not work, so for HW we have to flip the switch to 'Continous' and then remember to flip it back.

Did consider changing it myself, then thought again. Got a quote for £210 (by a company we used to replace the Heating system in our old house) to replace with a Honeywell ST9400c and Digital Room Stat (we had same model in the old place). But after 3 days they have yet to call to arrange a date. So, I'm thinking about doing it myself.

Is it straightforward ? Is there a better programmer more suited to the wiring of the Switchmaster 900 ? The boiler is a Glow Worm Space Saver (wall hung) and looks pretty old...

Advice please. thanks

 

[D_Hailsham]

The Switchmaster 900 has a non-standard backplate; so you will have to replace that in any case.

Switchmaster terminals are:

1 = CH ON (Call)
2 = CH OFF (Sat)
3 = HW ON (Call)
4 = HW OFF (Sat)
L
N

It also has four other terminals marked A-D which can be used as junction points.

The programmer and thermostat suggested are suitable. The only problem will be if the A-D terminals of the Switchmaster have been used as there are no equivalent terminals on the Honeywell; you would have to use a separate junction box with a strip of connectors inside.

Post info about the wires connected to the Switchmaster. If you can also trace the other end of the wires, post what they connect to.

 

[jstallan]

thanks for the quick response. sorry for the delay in mine

Unable to look at the programmer until Monday and then the electritian arrives at the door with a new programmer and room stat. As he fitted it (10 mins) noticed there were only 4 wires attached to term1-4 ... gutted I didn't sort this out earlier as it would have saved me £100+

Oh well, it's done now.