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Postby Freddy42 » Thu May 06, 2021 5:01 pm

1972 built 5 bedroom house. A new central heating boiler is to be fitted and the installer tells me that it is mandatory to now fit trvs on all but bathroom rads and the one next to the room stat. Is this correct? There are 13 eligible rads so that is considerable expense.
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Postby stoneyboy » Fri May 07, 2021 9:26 pm

Hi freddy42
The cost of supplying and fitting TRVs will be minimal compared to the whole job - get it done and you will benefit from having control over individual room temperatures.
Regards S
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Postby ericmark » Mon May 10, 2021 12:05 am

The modern gas boiler is controlled either by a modulating thermostat or the TRV's the latter through the return water temperature.

Depending on type of wall thermostat it may need a TRV in the same room, there is no hard and fast rule any more, it is now possible to control every room independently.

The TRV cost around £6.50 plus, I say plus as with a wifi head can be looking at £80 each, and yes one really does need to work out what stage to stop. But a lockshield valve is around £2.70 so since the TRV replaces the lockshield valve in real terms start at £3.80 extra to fit them, so it would be daft not to fit them.

But as to when to stop, that is another question, the programmable TRV head did start at around £10 for the Eqiva eQ-3 also there is the Terrier i30 but since leaving the EU it seems the price has gone up, I got 5 bluetooth eQ-3 for £15 each, but today more like £25.

I made a mistake getting Energenie TRV heads, was told they worked with Nest but they don't, but even with Drayton Wiser system with smart TRV heads clearly it does not reduce gas bill to zero, and there has to be a balance, if the control system costs £750 and the fuel saving is £100 per year then it will take 8 years to break even, and so yes it may well be the system only saves £10 a year over a basic set up, it is near impossible to tell.

But down to how it is used, by over sizing radiators and setting a sequence so not all radiators start heating together you can speed up the reheating of critical rooms, so say kitchen, then dinning room, then living room, then finally bed rooms, but that will not help me when retired.

So a lot down to your life style as to how much the smart controls can save.
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Postby Freddy42 » Mon May 10, 2021 9:08 pm

Thanks for your replies
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