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Hot water scheduling

Air Source Heat Pumps (ASHPs)

Last Post by glpinxit 2 years ago

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glpinxit

(@glpinxit)

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Joined: 3 years ago

Posts: 31

Topic starter 08/11/2023 10:07 am

Although we are happy with how our system is running I thought I'd check that none of you has come up with a better schedule for heating DHW. I do recognise that I may be overthinking this given that we're only consuming about 30kWh per month!

Our domestic hot water is heated exclusively by our Ecodan 11.2 (apart from the legionella routine). Ideally I'd like it to do this when the outside air temperature is highest leading to optimum efficiency. And not at all before 10:00 on cold mornings when heating DHW means the house cools, noticeably.

So far I've tried two basic strategies- neither entirely successful:

a) allow the programmer to decide when to heat the water- which it does whenever it feels like it. In the last 24 hours this was at 00:40 for 30 minutes (raising the temperature by 6C) when the outside air temperature here was also at its lowest and hearing the machinery running might have disturbed our sleep.

b) set the DHW programme to run between 13:30 and 15:30. We tend to use hot water first thing in the morning and this approach left the water around 41C with the potential to run out if we had people staying.

In the absence of a better approach I'm minded to stick with a) as it means we don't run out of hot water and even a 10% efficiency improvement would save less than £1 per month.

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Harry987

(@harry987)

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Joined: 2 years ago

Posts: 2

09/11/2023 8:12 am

Hello,

I'm also trying to get my ecodan to schedule the hot water when I want it to but am struggling.

I've set the schedule to be 11.30pm-5.30am when our octopus tariff is 1/4 the standard price.

Set the temp to 50 degrees and maximum temp drop to 10 degrees, however it still often reheats when it wants, despite not getting near the 10 degree max drop.

Quite frustrating!

This is the last 24 hours for example

Screenshot 2023 11 09 08 11 37 41 399e0effe8b0148198e727db3f2fa3b1

Any ideas?

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Dunlorn

(@dunlorn)

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Joined: 3 years ago

Posts: 79

09/11/2023 8:12 am

@glpinxit

I have a similar thought process but you're right, the DHW consumption is tiny in comparison to heating so I don't worry unduly.

I set two schedules per day, 1300-1400 and 2300-000. In summer the first is generally peak PV production and with batteries full. In winter it's generally the warmest time of the day so it doesn't interfere with heating too much, which I found can be a problem. The second is timed for after heating goes off late evening and before we (generally) reach night time minimums outside so hopefully a tiny bit more efficient. This has given us all day hot water for 2 of us but if we have people staying then I put it back on auto or it can leave us short.

I've just this week changed to Octopus Cosy so I've amended the two schedules slightly to reflect the off-peak pricing times.

2 x 12kW Samsung Gen6 ASHP, 5.6kW solar PV ground mounted c/w 10kWh Puredrive battery & Solis inverter.

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newhouse87

(@newhouse87)

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Joined: 3 years ago

Posts: 231

09/11/2023 12:03 pm

I changed mine a while back to just heat from 2-3pm, have no lower set point so sometimes its heating 300l tank from below 30, would it be wise to put in reheat set point. I use over 2kwh to heat from low temp alot of days.

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Harry987

(@harry987)

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Joined: 2 years ago

Posts: 2

09/11/2023 3:33 pm

Has anyone actually managed to get the ecodan to heat hot water according to when you schedule it to?

This post was modified 2 years ago by Derek M

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Dunlorn

(@dunlorn)

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Posts: 79

09/11/2023 5:36 pm

@newhouse87 I reckon so, although more for convenience rather than power saving. Mine is set to come on when temp drops 5°C below set point (50°).

2 x 12kW Samsung Gen6 ASHP, 5.6kW solar PV ground mounted c/w 10kWh Puredrive battery & Solis inverter.

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glpinxit

(@glpinxit)

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Joined: 3 years ago

Posts: 31

Topic starter 10/11/2023 11:19 am

Posted by: @harry987

↑

Has anyone actually managed to get the ecodan to heat hot water according to when you schedule it to?

As well as setting the time you want it to run you also need to ask it to do that for DHW in the 'home' screen (at which point it will then change to a circle with a diagonal line across it (from run or pause symbols, previously).

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