Room Stat

Go for an electronic one like a Honeywell CM67

These are far better than any of the bimetallic mechanical types and will work without a neutral, or indeed an earth. There is a small battery to run the thermostat and timer function

.andy

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Hello BIC

Got any solvent left over from waste pipes?

Dab of that on the spindle, refit the knob and leave for five minutes, jobsa.

Randal TP5 (or similar) should do the trick. On offer at £30

You could go for a three wire option. This is supposed to be more economical, on certain makes of boilers. If you buy a double-insulated room-stat ( Drayton Combi-Stat, for instance, £12 ), then you can use the earth connection as the neutral; best to sleeve it with something to show it's not an actual earth anymore. I assume the other end of the earth wire emerges at or near your boiler/timer, and can be patched in to your boiler's neutral connection ( if it has one ).

Andy

Nooooooo!!!! Most definitely not acceptable. Either use a 'stat which doesn't need a neutral, or replace the cable with triple + earth.

I was given the advice to reuse the earth by H____________l !!!!!!

Jeez, that's bad (and probably highly negligent on their part)! Apart from it being likely to confuse anyone else who works on it, I'm pretty sure that the Regs require all cables carrying mains voltage to contain an earth conductor. I'm sure I've even seen an insulated & sheathed red 'single' which contained an ECC used in a lighting circuit on a new build a few years back...

My combi instructions specifies flexible wire for all connections to it ( the wires go to a drop down panel which causes the wires to flex a little when opened ). Attempts to find a flexible triple cored wire in the DIY places failed, and three core plus earth is not in the flexible category. I considered it dangerous to use non-flexible cable in a flexible situation. I used flexible three core and sleeved the earth wires to indicate their change of use ( in the same way that a neutral line can become a switched live and thus requires a red sleeve ). One recognises an earth core by the colour of its insulation. By placing a sleeve on it you change its identity, hence its function. I suppose that someone will say that this is against the law; so, don't do it then!

How to square this circle?

Two wire roomstats have the disadvantage ( I understand ) of large over-and undershoots of the temperature, +/- 3 degrees C being cited. This can be noticeable, and is not as economical as the three wire roomstat ( which contains an anticipator ), and can offer +/- 0.5 degree C stability, allegedly. I don't therefore wish to use a two wire connection.

Short of ordering specialist cable the only option I can see is to use TWO three core cables, i.e. six cores where only three are required; seems daft to me, slavishly following regs and doubling the amount of cable needed, especially for domestic use, where the change of use is signalled by sleeving. I know the regs are intended to prevent accidents, but common sense should be a guide as well. Otherwise we should all be writing out hazard assessments and doing COSHH inventories in our kitchens etc.

I should mention that the combi/roomstat are both on an RCD protected spur.

This message should in no way be taken as advice to ignore the electrical regulations..................

Andy.

Any half decent wholesaler should have various types of multi-core for just this purpose and sell it by the metre.

TLC prices:-

"andrewpreece" wrote | My combi instructions specifies flexible wire for all connections to it | (the wires go to a drop down panel which causes the wires to flex a | little when opened ). | Attempts to find a flexible triple cored wire in the DIY places failed, | and three core plus earth is not in the flexible category.

Maplin XR48C / MW62S 4-core mains flex 0.75mm 6A per m or per reel GF71N / MW63T ditto 1.25mm 13A

Brown / blue / black / green-yellow in a black rubber sheath.

Bl**dy one pound forty-nine a metre through.

Owain

Replace with a digital thermostat. Much more accurate than analogue types. Almost all digital thermostats only require the timer live (in) and demand for heat (out) connections. Earth, neutral and permanent live are not usually required.

The earth may be a neutral for an old analogue thermostat, naughtily using the green/yellow or bare conductor. In any case, the digital thermostat won't need it, so it can be ignored, provided it is tucked away safely insulated.

Christian.

Use a digital thermostat. These operate on two wires and frequently have complex microprocessor based control theory implementations that antipate better than any analogue contraption. If you install a programmable one, you can vary the temperature at different times of day, and they are often installed in convenient locations for programming, rather than at the back of a dark cupboard full of cr*p.

Christian.