Efficiency. Is the Wiser system doing its best for me?

SamJ · ‎2022-12-09

I'll start by saying I've only had the Wiser system installed for just over 1 month, and only been in this house for 6 or so months (so no baseline to compare a Winter against). Pleased with the system on the whole, what with being able to schedule heating according to our routines.

My heat reports are currently estimating a heating time of approx 5-6 hours per day. 3 bed semi detached, 2 of us working from home. November usage for gas was 916kWh.

Something I'm wondering about is the frequent firing up of the boiler as a room calls for heat, only to stop minutes later, and then another room to call for heat causing the boiler to fire up again. Repeat throughout the day and night (no room set to fall below 15c). Whilst this feels inefficient to me (repeated demand on boiler to start up?), I'm trusting that the system is performing correctly and this way of operation is better than having fewer, longer 'blasts'?

Oh and just to say please excuse the language and lack of knowledge on my part - I'm very much a plug and play, let it do its thing standard!

With multiple rooms calling for heat at different times during the day and night, I'd have thought my bathroom (the 1 zone without Wiser as directed, towel radiator) would be constantly toasty as it would be heating along with any other room. The opposite is true (down to 11c this morning), and I wondered whether others have the same issue?

Is this to be expected, and perhaps more of an issue with the bathroom itself? i.e. inadequate radiator size, losing heat via extraction vent etc?

I guess a solution would be to force a longer heat period for other rooms in the morning, to try and heat the bathroom up more, but that's of course wasting energy elsewhere and not exactly on brand for this product!

SAtewart · ‎2022-12-09

Frequent boiler firing (potentially six time per hour) and an on time so short that barely any heat goes to the rads strikes me as iffy functionality. Note you can adjust the number of firings down to three if you select your heat source as oil or heat pump

PhilHornby · ‎2022-12-09

@SamJ wrote:

The opposite is true (down to 11c this morning)...
Is this to be expected, and perhaps more of an issue with the bathroom itself? i.e. inadequate radiator size, losing heat via extraction vent etc?

I guess a solution would be to force a longer heat period for other rooms in the morning, to try and heat the bathroom up more, but that's of course wasting energy elsewhere

In an ideal world, you'd put an iTRV on the bathroom radiator - so it could call for heat when necessary. However, that's probably not recommended (because of the humidity). I have one in downstairs shower room/toilet - but that shower is never used.

Otherwise, you're stuck with it only getting heat when one of the other rooms is cold. You could double-check that it's fully turned up (check the lockshield end!) - or - turn the lockshield valve down on some/all of the others. That way, they'll be on for longer and give the bathroom chance to warm up.

Alternatively, there's a boost button on the Hubᴿ, that will turn the boiler and motorised valve on for 2 hours. This will warm up any rooms that are not restricted by TRVs - but it would be on-demand.

(In the 80's, I once went to work two hours early, so I could go round the building and turn everyone's radiator down. That finally fixed the problem of my office being so cold 😉 )

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3 Channel Hubᴿ, 13xiTRVs, 8xRoomstats and 2xSmartplug/Repeaters. (UK)

SamJ · ‎2022-12-15

Thanks both - appreciate the useful info.

So, first (and easiest) thing to try sounds like changing heat source in app from gas to oil. Have just seen this in another thread also, and have asked if there are any potential risks in selecting a different source to what you actually have.

If this doesn't make much of a difference then altering the lockshield valve/lockshield valves on other radiators. Out of interest, would turning down the flow temperature on the boiler have the same effect or is the idea not to blanket 'throttle' the entire system, just all radiators apart from the bathroom rail?

PhilHornby · ‎2022-12-15

Have you checked that the lockshield on the Bathroom rad. is fully open?

Turning down the flow temperature would just reduce the heat output of all the radiators proportionately. They would all be colder or take longer to bring their rooms up to temperature - but that would include the bathroom. The idea is turn down everything but the bathroom, so that it gets more of a share.

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3 Channel Hubᴿ, 13xiTRVs, 8xRoomstats and 2xSmartplug/Repeaters. (UK)

SamJ · ‎2022-12-16

I haven't Phil - I will investigate, thanks. I haven't touched the bathroom rail except to bleed it, what with my heating engineer having told me not to touch the valves after he'd drained the system (few radiators needed TRVs adding) and installed the Wiser kit!

SAtewart · ‎2022-12-16

I think you should experiment if you are 1) minded and 2) systematic about your method and note what you have to do to restore the system to your engineer's config. Right now I think I am saving up to £200/winter month and I think a good bit of that is by playing with the system and the locksheilds and observing the effect subjectively and using the graph traces in the insights section of the app.