Making underfloor heating control smart

[thr32]

Morning all,

The house is heated by Air Source driving UFH. Because the underfloor acts on a very thick concrete slab, it takes time to respond, which is fine, but it always feels like it is behind the curve: when the temperature suddenly drops outside, the house takes a day to get itself back to temperature. The electricity tariff is also based on time-bucketed wholesale prices, so think I could be smarter about using energy when it's cheap rather than when the roomstats call for it.

The controls are HomeKit-enabled, so it should be simple enough to make them internet-enabled and consume electricity cost data and weather forecasts. Does anyone have experience of doing this, and what platform did you use to bring it all together?

Thanks all

TH

[thr32]

Thanks both - useful input so far.

I'm hearing clearly that trying to save by switching zones out based on room temperatures is not the way to go, so thank you for that steer.

The heat pump doesn't have weather compensation, and is operating quite dumb at the moment - UFH manifold calls for heat, and the ASHP supplies it at the preset temperature. That's what I would like to improve on.

cazique's point is clear - heat when it's cheap and stop when you're warm enough - but how does that work given the lag? By stopping only when the air temperature is comfortable, you will always overshoot, won't you?

The other question is about the coefficient of performance of the ASHP itself... Is it better to flog the pump when energy is cheap, or have it working more efficiently when it's warm outside? If it's 15deg during the day and 0deg at night, the pump will be significantly more efficient during the day, but the unit price will probably be considerably higher.

Appreciate the inputs guys

TH

[thr32]

Thanks both for more food for thought.

jymmm said:

Which heatpump do you have and what cheap tariff do you have?

It's a Daikin Altherma. I'm currently on Octopus Agile, but not wedded to it.

jymmm said:

Cheap rate lower efficiency Vs. expensive rate higher efficiency …. I’ve not experimented and probably never will but the way to think about it is in terms of average pence/Kwh – Octopus for example lists this on the bill.

That's true, but it's only half of the equation I was thinking of: when air temperature is higher (or the air is wetter, or both), the CoP of the pump will be higher, so each Kwh of electricity consumed would put more heat into the system - I think it's the difference between Kwh-in and Kwh-out that I was asking about.

Best

TH

[thr32]

Good shout - thank you

TH