New C/H room thermostat
- Thread starter mr_chaela
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I interpreted it as him having a live, but lacking a neutral - that had a possible implication of him borrowing the neutral from another circuit, which is a really bad idea on several fronts. As someone suggested above, the best solution is a stat which doesn't need a neutral.
What he said in full (which doesn't really allow your interpretation).
Yes, the second power source is not ideal as it may confuse a future electrician.
I just thought that we should respond to the actual suggestion, rather than everyone piling in and going on about borrowed neutrals.
Or worse, confuse a future plumber. An electrician should understand the risk because he(she) will carry out safe isolation procedures.
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When trying to sort out my central heating step one was test and record?
Although a three core and earth was in the utility room, and seemed to go to the flat where the boiler is, only 2 cores had continuity and also colours changed, so seems likely some where there is a junction where either one core never connected or it has become disconnected.
So I looked at how I could control CH + DHW with two wires (plus earth) and if possible keep the thermostat running without the need to replace batteries.
I also already had Energenie TRV heads which claimed would work with Nest.
So using Nest Gen 3 allows two wires working with very low current, and extra low voltage, to maintain the thermostat back up batteries, and send information down same two wires.
Not saying Nest Gen 3 was best option, but I selected a thermostat which would do the job required. Should the cable joint not be good, there is no undue strain on it, and should it fail I have option of using USB, I have designed the new system to allow for lack of wires between utility room and flat, also found cable utility room to hall so thermostat mounted in hall.
Yes I made errors, but not due to lack of research, it was due to incorrect information being published.
I balanced the cost of Nest Gen 3 to cost of running new wires, and Nest Gen 3 won.
I am sure there are other thermostats which can also be hard wired, I stopped looking once I found a way to do what I wanted. Having used wireless in past did not want to use it again.
Although a three core and earth was in the utility room, and seemed to go to the flat where the boiler is, only 2 cores had continuity and also colours changed, so seems likely some where there is a junction where either one core never connected or it has become disconnected.
So I looked at how I could control CH + DHW with two wires (plus earth) and if possible keep the thermostat running without the need to replace batteries.
I also already had Energenie TRV heads which claimed would work with Nest.
So using Nest Gen 3 allows two wires working with very low current, and extra low voltage, to maintain the thermostat back up batteries, and send information down same two wires.
Not saying Nest Gen 3 was best option, but I selected a thermostat which would do the job required. Should the cable joint not be good, there is no undue strain on it, and should it fail I have option of using USB, I have designed the new system to allow for lack of wires between utility room and flat, also found cable utility room to hall so thermostat mounted in hall.
Yes I made errors, but not due to lack of research, it was due to incorrect information being published.
I balanced the cost of Nest Gen 3 to cost of running new wires, and Nest Gen 3 won.
I am sure there are other thermostats which can also be hard wired, I stopped looking once I found a way to do what I wanted. Having used wireless in past did not want to use it again.
Thanks for all the advice and info. From my point of view borrowing a neutral just seems a messy way of doing things and as has been suggested powering the stat (with a volt free switch) from the lighting circuit is no more dangerous than the original battery operated stat (again with a volt free switch), when the system is isolated so is the circuit to the volt free switch.
However, being a bit pernickety at doing things right, I spent the day cutting holes in ceilings (luckily I am decorating at the moment) and have managed to get a supply from the load side of the isolator switch to the stat, so all is good and I can keep the new stat. Tomorrow I'll patch the holes and carry on decorating.
However, being a bit pernickety at doing things right, I spent the day cutting holes in ceilings (luckily I am decorating at the moment) and have managed to get a supply from the load side of the isolator switch to the stat, so all is good and I can keep the new stat. Tomorrow I'll patch the holes and carry on decorating.
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