Smart heating controls

ThisIsWeird

FreeBear said:

A couple of points here - You do not leave the TRVs to "control the heating". All they do is restrict the flow of water through a radiator as the room temperature rises. When the flow is shut off, the boiler starts to overheat and will throttle back or even shut down (and start to short cycle). Not the most efficient way to run a modern heating system.

Using these smart switches will work with some boilers as long as they can be controlled with a switched live - Some boilers use a "no volt" line, others, a low voltage terminal. Feeding 240V mains voltage in to either type of terminal risks blowing up the PCB which will cost a fortune to repair (and won't be covered under warranty or insurance).

If you do not know what you are doing with electrics and boilers, call in an expert for proper advice.

Two good points. But.

For the first, many basic systems do use just the TRVs to control the heating, and that is exactly what Jenni has in the hall at the moment. All she asked for was a way to remotely manage the timings, and my presumed solution will cost £20 for all three.

As with any system without an interlock, and even those with (such as a room stat), one rad should be left permanently partially open to act a by-pass, but even without this any modern (~15+ years old) boiler will be monitoring its own delivery temp, modulating it down to suit, firing the burner on and off below this to match demand, and have a built-in by-pass for the worst case scenario. They shouldn't be under any stress at all. If they are, it's 'cos they are faulty.

I agree a non-interlocked system wouldn't conform to current regs (for domestic use at least), but it is the current setup in this hall, and it ain't Jenni's job to upgrade this. What she hopes to do will provide immediate benefits and cost savings. Adding a room stat to this setup will make hardly any additional improvement or difference, but will cost £100s more (you'd be able to remotely monitor the room temps - I think that's it.)

The two Hives I fitted in our hall were the easiest solution for me as there were room stats already on the wall and the Hives were a direct replacement. But, there are also TRVs on all the rads... Each Hive has an instruction page pinned up beside it showing how to operate and override the unit, and carries the message; "Leave all TRVs on 'max' - '5'". Do the occupiers follow this? Do they heck. :-)

It doesn't really matter for our, and presumably Jenni's, halls, as they only tend to be used for periods of around 2-3hours each time, and all that really matters is that the halls are adequately warm at those times.

Yes, the wiring would need to be checked and done by someone 'competent', but whether the current Danfoss setup is 'switched live' or 'volt free' is largely moot, as these switches will, I think, handle both (if the switch side is separate).
Should Jenni wish to try this - and I hope she will - the existing wiring would need confirming first, which would involve merely unclipping the Danfoss from its backplate to have a gander. Then transfer 4 wires max for each, which we'll be happy to guide her on.