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Issue with a Grant Air Source Heat Pump & Tado Smart Thermostat

Air Source Heat Pumps (ASHPs)

Last Post by JamesPa 7 months ago

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Renewables345

(@renewables345)

Eminent Member Member

Joined: 1 year ago

Posts: 14

Topic starter 04/03/2026 1:58 pm [#2864]

Hi all

I'm having some trouble with a Grant ASHP and Tado Smart Stat.

The heating has been temperamental for the last few days after we replaced the old heat pump. The hot water is currently on a timer and is working as expected, although we would like to have it set up on hysteresis, if you can do this on a Grant. It's a 17kW Grant R32, with a standard cylinder, and 3 port with just rads.

Thanks in advance for any help.

This topic was modified 7 months ago by Mars

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GrahamF

(@grahamf)

Estimable Member Member

Joined: 1 year ago

Posts: 131

04/03/2026 4:12 pm

Out of interest, why did you buy the Aerona 3 R32, rather than the Aerona R290?

You would probably be better off with the Aerona Smart Controller, rather than the Tado Also, if you have not set up weather compensation, then I would definitely advise you to do so. People on here can advise you how to do it.

Grant Aerona 290 15.5kW, Grant Smart Controller, 2 x 200l cylinders, hot water plate heat exchanger, Single zone open loop system with TRVs for bedrooms & one sunny living room, Weather compensation with set back by room thermostat based load compensation

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Renewables345

(@renewables345)

Eminent Member Member

Joined: 1 year ago

Posts: 14

Topic starter 04/03/2026 4:47 pm

@grahamf It was due to the clearances, would have preferred to have had R290.

Weather compensation is set up, but just struggling with getting hysteresis set up.

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JamesPa

(@jamespa)

Illustrious Member Moderator

Joined: 4 years ago

Posts: 5520

04/03/2026 5:49 pm

Posted by: @renewables345

↑

Weather compensation is set up, but just struggling with getting hysteresis set up.

Im assuming from your original post that hysterisis refers to the DHW and you want it to reheat immediately the water temperature falls below some particular value as opposed to only on timer.

I wouldn't recommend this TBH, I would instead suggest having 2 timed periods, but if you are determined then this would be called something like 'constant' or 'dhw priority' or similar in the grant controller menu. Probably in the installer menu only not the user menu. Maybe a Grant expert will pop up who knows, otherwise it will be a trawl through the manual.

Like @grahamf I would consider dropping the TADO. External controllers are usually not good for the efficiency of heat pumps, or indeed the level of comfort, unless they have been specifically designed to integrate with them and control flow temperature not just operate as an on/off signal. To do this they have to be adapted to the particular heat pump model and I cant find any evidence that the TADO is, nor did the salesman claim that it was when I quizzed him at last year's installer show.

This post was modified 7 months ago 3 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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