I cant comment on Grant HPs specifically, but its quite common to do what you are suggesting. Just be aware there will be some catch up to make once the expensive period stops. You could overheat in the period preceding as one strategy.

Most heat pump programmes allow you to set up a ‘set back’ so you may be able to use that expensive time as set back. I know the installers will likely tell you low and slow is best - but they aren’t paying your energy bill! The alternative would be to set up a schedule if your system allows you to; with a daily programme whereby the pump is off for that time slot ought to be possible. If you are unsure, I feel sure another reader will be familiar with the programmer / controller you are using who can guide you. Regards, Toodles.

We have a Grant Aerona3 as well. We are not on Octopus Cosy as I am still learning the system and am not sure if it is better to warm the house on the cheap periods and drop the temperature in the expensive slots or to have a low constant heat the whole day. If we had solar PV and batteries, the Octopus Cosy would be very attractive. But you don't have to switch the ASHP off in the expensive slots but could drop the target temperature in those periods. We have a EPH CP4 controller ( https://www.ephcontrols.com/section/cp4/) which would allow us to set up to 6 different target temperatures at different times if we wanted. You could ask your installer what the recommended set back temperature is for the expensive slots. I'd be interested as I can't get an answer off our installer!! 

I must admit I have not been impressed with the installer and it is worth checking your climatic curve settings that you have been given. Ours were utterly bizarre and resulted in piping hot radiators and a huge electricity bill.....

Hi all,

I am in the same boat, new install of Aerona3 13kw on cosy tariff (although we have rads only), I have just had the installers chief heating engineer around to make a final QC check of the install and he suggested the following settings as a start point: Weather compensation on, 45c max - 30c min @0c with a hysteresis set point of 2c. From there tinker with the 45c (Tm1) setting (he did suggest keeping the set water temp and WC max temp the same value, not sure why). I have placed the remote therm in my office one of the coldest rooms in the house set to 21c, he did suggest we could put a setback a few degrees lower for the 1600-1900 expensive time, but not too aggressive maybe 19c.

This tracks with info I have gleaned from other posts that I have read on here. I am trialling 42c Tm1 at the moment to see if it delivers the comfortable temps we want. 

(installer mode registers - 2100 = 1(WC on), 2101 = 45 (Fixed temp set point), 2102 = 45 (WC Max flow temp Tm1), 2103 = 30 (WC Min flow temp Tm2), 2104 = 0 (Min outdoor Temp for max flow temp Te1), 2105 = 20 (Temp when heating no longer comes on Te2), 2141 = 2 Water Hysteresis). 2101 and 2102 are the ones I am tweaking.

Regards Si.

@davidm06 

I have the same controllers and added the GW04 gateway which gives us access to the system via the Ember app way better than the finger cramp inducing RF controller. Why installers don’t use the CP04i and include the gateway I have no idea!

Regards

Si.

@grantmethestrength One thing I will say in praise of the EPH controllers - I've had my HP for almost 2 years now, and still on the original set of batteries. Can't knock the efficiency of low-power RF signals.

@grantmethestrength 2101 is irrelevant is it not if the WC is on (2100)?

On an aside, it sounds like you had a better installer. Have you been told what to do about Legionella? Did you have the extra unit that switches the immersion on or have you been told to do it manually?

Posted by: @ashp-aerona

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Grant Aerona3 13kW HPID 13R32

I have a Grant Aerona3 ASHP and I am on Octopus Cosy tariff, with underfloor heating and room thermostats plus Grant HPIDTM4 programmer.

As you probably know the Cosy tariff gives 3 periods of cheaper energy and one of more expensive energy.
I would like to reduce my energy costs by turning off the ASPH from 16:00 to 19:00 when energy is more expensive.
My installer insists that I should have the ASPH on constantly, so the programmer is doing nothing as it is set to Constant.
Does this make any sense?

It all depends on your house and how long it take to lose heat.

If you can turn your HP at 16.00 and it only loses say 1/2 ° by 19.00 hrs then that will be fine. If it loses 1° or more then you are better off leaving it running.

Posted by: @davidm06

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But you don't have to switch the ASHP off in the expensive slots but could drop the target temperature in those periods.

You have to take into account what the actual house temp is. 

If at 16.00 your house is at set temp, then any setback by 1° will turn off the HP. The only way to do real setback is to adjust the flow temp itself and then increase it later on

Posted by: @grantmethestrength

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I have placed the remote therm in my office one of the coldest rooms in the house set to 21c,

Why have you put it in here?

If its used all the time then fine, that's where it should be. But its the coldest room then the rest of the house will over heat.

@davidm06 We still have no idea, the guy who came around the other day meant to tell us about it but got distracted and left without telling us. In the documentation it says it was enabled but on checking the installer settings 31-40 - Anti-legionella function 0=disable 1=enable ours was set to 0 so I have set it to 1. No idea what this will do but as a belts and braces approach I have set the manual immersion timer to come on after the DHW cycle on Monday, I figure if the tank is already up to temp then the boost wont need to run as long.

I will have to put out a post about our install, it was atrocious, the reason the head heating engineer came out was due to our repeated refusal to give a review until all snagging had been done, fair play to the company they seem to want to resolve all the issues, unfortunately the clowns they subbed out the work to were absolute cowboys.

Regards

Si.