Fitting honeywell BDR91 with only common and N/O wires possible?

[stem]

Good, halfway there! last task is to make the unused blue wire a neutral.

 

[ianmcd]

Good, halfway there! last task is to make the unused blue wire a neutral.

What could possibly go wrong

 

[Drogen24]

Good, halfway there! last task is to make the unused blue wire a neutral.

Now you've confused me again, isn't the blue sleeve indicative of it already being neutral?

 

[stem]

It can only be used as a neutral, if it's physically connected to a neutral at the other end. Usually I find that the far end isn't connected to anything the same as at the thermostat end. Hence:

2. Find the other end of the blue wire and attach it to a neutral associated with the boilers electrical supply.

But you might be lucky, get the multimeter out again and measure between brown and blue. If you get 230V it's connected.

 

[Drogen24]

But you might be lucky, get the multimeter out again and measure between brown and blue. If you get 230V it's connected.

No such luck, I'll see if I can find where the wires come out to the boiler, obviously being careful of opening up something I shouldn't as per your previous post about a gas safe engineer

 

[ericmark]

The Gas Safe guy is likely safe with gas, unfortunately that does not mean he is safe with electricity, I have found many an installation where the person installing the central heating has used a green/yellow wire for line without any over sleeving, so specially with central heating you need to test every wire to find what it really is.

Clearly there are good and bad with all trades, there was an attempt to clean up the way electrics were installed with Part P, but it has failed, and in the main in England it is back as a free for all.

However what you want does not need the TRV heads linked to the wall thermostat, clearly better if they are, but I made a mistake, and fitted Nest Gen 3 then found it will no longer link to TRV heads. Nest e does not need mains power by the way.

But I have 9 electronic TRV heads this is now the second house to use electronic TRV heads, and still tweaking this house, but got mother old house nearly spot on before leaving.

So basic idea, you want a lower floor room, normally kept cool, so when we get warm weather the wall thermostat in that room will switch off system earlier than if installed in a warm room, then you set the lock shield and TRV so that room takes long enough to warm up, so other rooms in the house have time to reach set point.

So lock shield controls speed, too fast and not enough time for the TRV to act, the TRV sets a range of room temperature, the old mechanical has quite a large range at around 2.5 often 18 - 21°C the colder it is out side the closer to bottom of range, the warmer closer to top of range. So a wall thermostat set to 20°C will only switch off when warm outside.

Whole idea of wall thermostat is to stop the boiler cycling, the boiler normally can modulate say between 6 kW and 26 kW, but it can't switch off completely, so the wall thermostats job is on warm days to turn off boiler, it is not designed to control room temperature.

The big problem is non electronic TRV heads have *123456 which to most means nothing, the heating guy has a differential thermometer and can set the lock shield spot on, the user does not have a clue if lock shield or TRV needs tweaking, once electronic heads are fitted, then the user can see what the settings are, so if room over shoots close the lock shield a tad and if never hits target open lock shield a tad, using EvoHome is clearly better, but if you can't work out electrics there are other ways.

 

[ericmark]

post about a gas safe engineer

In a perfect world the electrical connections should not be where an electrical inspector can't inspect them, or he would need to award a code FI which is a fail with an EICR, it is not a perfect world, and it seems some manufacturers do put electrical connections in sealed compartments, but one would hope at least they would affix a large sticker to warn electrical inspectors not to remove.

 

[denso13]

there was an attempt to clean up the way electrics were installed with Part P

If you mean notification, it has nothing to do with Part P.

 

[ericmark]

If you mean notification, it has nothing to do with Part P.

In this case no, Part P was introduced mainly due to kitchen fitters who would ignore the rule book, but it removed the need to show some one was working in the home, in the main the electricity at work act and others covered the home as some one at some time was working in the home. But Part P made it easier to show a law had been broken.

It does not matter if it required notifying or not, Part P still applies. But not in Scotland.

 

[denso13]

In this case no

Not in any case. Part P has nothing to do with notification, ever.

 

[Drogen24]

Sorry, me again.
Just for confirmation/a second opinion, this is next to the boiler. Looks like the thin black wire not connected is the one that terminates behind the tp5000. I just need to hook that up to the middle connector on the block (with the mains turned off as this isn't on its own circuit from what I can tell) and then I can re-test at the thermostat to confirm neutral is now connected on this circuit?

 

[stem]

If:

1. The black wire you refer to is the unused wire with the blue sleeve that goes to the thermostat, and
2. The middle terminal is a genuine neutral that forms part of the heating circuit wiring [test with the multimeter to confirm]

Then yes.