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Replacing Worcester oil boiler with an ASHP

JulianC · 2021-03-30T18:15:26Z

I am replacing my 25/32 Worcester oil boiler with an ASHP Had discussions with many suppliers, a lot of whom wouldn't quote because we have 10mm pipe drops to each radiator, from 28mm loft pipes. Anyway: 201m2 bungalow. Built 2001. EPC rating of B after triple glazing, 300mm of loft insulation. We currently use between 1220-1500L of oil per annum. 100A incoming circuit. ASHP approved by DNO (Western Power). 20,500kWh of heating energy required. 3000kWh of hot water demand from the EPC. An energy loss calc and room by room heat demand has been undertaken. This has lead me to select Ecobubl from Winchester to undertake the work. They have proposed a Daikin Altherma 3H HT 18kW ASHP. Also a Mixergy 150L H/W tank - but we are also considering a standard cylinder with a large internal coil, to maximise the ASHP. And a 3kW immersion to use my 4kW of PV and Solic 200 electric diverter. Simple control system, using my current Nest. Had wondered about the Homely Energy control system, but I wonder if this adds complexity. Price is £13,700 for ASHP + Mixergy + buffer tank + installation and support for RHI. I should get back about £10k through RHI. I will take photos before, during and after installation which should be 12 April

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Air Source Heat Pumps (ASHPs)

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JulianC

(@julianc)

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Topic starter 15/10/2021 10:58 am

Good point @jeff. Let me confirm the day to day 2kWh number

Daikin Altherma 3H HT 12kWh ASHP with Mixergy h/w cylinder; 4kW solar PV with Solic 200 electric diverter; Honda e and Volvo EX30 Ultra Twin Performance electric vehicles with Myenergi Zappi mk1 & Ohme chargers

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Derek M

(@derek-m)

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15/10/2021 2:07 pm

Posted by: @julianc

I didn’t think 2kWh was too bad. In the summer my solar PV will be providing the electricity and in the winter it will contribute to heating the home.
Yes the MCS installer, Ecobubl profiled the demand and the estimate was 530kWh. So we are a small amount below 👍

Hi Julian,

Just to clarify, is the 2kWh being used solely by your ASHP, or is it your total import?

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JulianC

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Topic starter 15/10/2021 4:06 pm

I’ve checked back and it is 1 to 2kWh /day for the Daikin system.
@derek-m this is metered for the ASHP, so nothing to do with wider home use. But I don’t know the source of the electricity.
But not an insignificant amount as @jeff points out

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Derek M

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15/10/2021 4:50 pm

@julianc Hi Julian,

If you have a look at your manual it may show the energy consumption to be expected when the ASHP is not actually running. You should find this information in the specification section.

It may pay you to record your daily consumption to see if it is a regular daily amount, or whether your system uses several kWh on one day and then a much lower amount for several days. This could possibly indicate that your ASHP is running to carry out the sanitation cycle.

Now that we are going into the heating season it may not be possible to perform this test just yet.

As you say much of the energy may have been provided by your solar PV system.

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JulianC

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Topic starter 15/10/2021 5:45 pm

@derek-m when you say “sanitise” cycle, do you mean the hot water cylinder? Or is there something for the general pipe work? As I have the cylinder sanitizer off at the moment as the solar PV has been taking care of this.

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Derek M

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15/10/2021 5:51 pm

@julianc Yes, it is for the hot water tank, so obviously that is not the culprit.

👍

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JulianC

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Topic starter 29/10/2021 9:41 pm

Next RHI payment on the way.
Consumed 598.87kWh to date since April

MCS estimate 938kWh by end Oct

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batalto

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30/10/2021 10:04 pm

@julianc consumed, or purchased from the grid? Two very different things

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE

👍

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Mars

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30/10/2021 10:30 pm

@batalto, as far as RHI is concerned there's no distinction between consumed or purchased from the grid.

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JulianC

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Topic starter 30/10/2021 11:59 pm

@batalto I disagree. This is projected (MCS) vs actual. I have no way of telling if solar PV or from grid. And I pay two prices depending on time of day (Octopus Go).

My point is I’m happy thus far with the performance

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Jeff

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31/10/2021 9:21 am

Posted by: @julianc

@batalto I disagree. This is projected (MCS) vs actual. I have no way of telling if solar PV or from grid. And I pay two prices depending on time of day (Octopus Go).

My point is I’m happy thus far with the performance

Excuse my ignorance.

Does the MCS calcs take into account water heating done via an immersion using solar PV so the ashp will use less electricity?

Just wondering what the MCS figure actually includes

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Kev M

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31/10/2021 11:57 am

Posted by: @jeff

Posted by: @julianc

@batalto I disagree. This is projected (MCS) vs actual. I have no way of telling if solar PV or from grid. And I pay two prices depending on time of day (Octopus Go).

My point is I’m happy thus far with the performance

Excuse my ignorance.

Does the MCS calcs take into account water heating done via an immersion using solar PV so the ashp will use less electricity?

Just wondering what the MCS figure actually includes

My MCS calculation has an annual figure for space heating and HW energy consumed and required, based on theoretical annual SPFs for both. I can't see a monthly projection although I suppose could work something out.

@julianc, where did your MCS figures come from?

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