Hi I have this really old honeywell thermostat and I'm pretty sure it doesn't work. Even if I set it quite low the boiler never turns off, if I turn it completely off the boiler does turn off. See Pic below, it says 4200 3879-001 on inside cover.
View media item 60624
It has 3 wires connected to pins 1, 2, and 3. pins 4 and 5 are unused.
My question is can I upgrade to a more modern one like the 2 below?
http://www.ebay.co.uk/itm/Honeywell...DIY_Materials_Plumbing_MJ&hash=item231bf5f8a9
http://www.ebay.co.uk/itm/Honeywell...DIY_Materials_Plumbing_MJ&hash=item460ce8f963
Which would be easiest to fit and accurate on temperature?
View media item 60624
It has 3 wires connected to pins 1, 2, and 3. pins 4 and 5 are unused.
My question is can I upgrade to a more modern one like the 2 below?
http://www.ebay.co.uk/itm/Honeywell...DIY_Materials_Plumbing_MJ&hash=item231bf5f8a9
http://www.ebay.co.uk/itm/Honeywell...DIY_Materials_Plumbing_MJ&hash=item460ce8f963
Which would be easiest to fit and accurate on temperature?
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