Part L, Interlock?

[Paul Goff]

Good Afternoon Chaps,

Another day another question!

I see from looking in the WIKI section on here, that a room thermostat is still required to meet part L of the regulations, even if there are radiator thermostats.
Is this true even if the rad stats are fitted to all rads, and they are all smart stats, and all of them can therefore provide individual interlock with the boiler?

If so, is it just a case of the legislation being behind the technology?

I assume that the basic interpretation of the regulation is why I was unable to buy a functioning Drayton Wiser system without the room stat included.



Thanks in advance,
Goffy.

 

[Dan Robinson]

The rules are about shutting down the boiler demand completely when the property is up to temperature

 

[Paul Goff]

Thanks for your input Dan,

On my system I have 13 rads, all with Wiser smart stats which are all, via the Wiser Hub, able to start and stop the boiler completely by energising/de energising the switched live (as opposed to the permanent mains connection to the boiler). Thus if all 13 rooms demand, as sensed by the rad stats is satisfied, the boiler demand is shut down completely.
Conversely, as soon as any one of the rad stats opens as a result of that room's temperature falling below setpoint, that one rad stat will put the boiler back on demand.

So my system, without a room thermostat, meets the regulation, which does in fact not specify how it should be met, merely that it must be?

Cheers, Goffy.

 

[Madrab]

It does specify..... A Part L heating interlock is a device(s) that will shut down the boiler and it's pumps when demand is met.

If your wiser hub completely shuts the boiler down - the boiler & pump(s) - then that would be classed as an interlock and satisfies part L. If it doesn't then it isn't.

 

[Dan Robinson]

Indeed.

 

[Paul Goff]

Thank you Gentlemen, that is what I suspected

The WIKI section here strongly implies that the device must be a room thermostat! But in fact a "device(s)" is required, the type of device is not specific.

The controls here were wired incorrectly when I moved in, this resulted in the boiler being enabled/cycling and the separate pump running 24/7, if the system was switched on! Finally corrected when I retired and had time to reconnect all the controls properly. I have idly wondered since, how much this had cost in LPG and electricity from build in 1999 until 2016

Thanks again, Goffy.