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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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JulianC

(@julianc)

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Topic starter 27/01/2025 10:48 am

@judith we probably could have got away with an 8kW ASHP. I have not formally checked.
But given the modern variable scroll compressors, I’m not there would be any savings? Havenwise seems to run the hp for longer at a lower temperature. Thus less compressor starts which is good for longevity.
Similar sized property.
When you do go EV, make sure the charger you choose can be controlled by Octopus so you can benefit from Intelligent Go e.g. Zappi mk2. Many others.
Im enjoying the electric journey.

Daikin Altherma 3H HT 12kWh ASHP with Mixergy h/w cylinder; 4kW solar PV with Solic 200 electric diverter; Honda e and new Hyundai Ioniq 5 N electric vehicles with Myenergi Zappi mk1 charger

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Majordennisbloodnok

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27/01/2025 3:19 pm

Posted by: @julianc

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...

When you do go EV, make sure the charger you choose can be controlled by Octopus so you can benefit from Intelligent Go e.g. Zappi mk2. Many others.

...

I agree with getting a charger that can be controlled by Octopus (since if you want to go down that route then your installation will already allow it) but I'm not entirely convinced that one's charger should be controlled by Octopus. However, that's a very subjective debate going on elsewhere with no obvious right or wrong answer so far.

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

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JulianC

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Topic starter 27/01/2025 3:27 pm

@majordennisbloodnok I’m completely happy with Smart Meter & giving Octopus remote control of my EV charger. I can take back manual control if required.
The dynamic management of the grid will deliver massive benefits.

Daikin Altherma 3H HT 12kWh ASHP with Mixergy h/w cylinder; 4kW solar PV with Solic 200 electric diverter; Honda e and new Hyundai Ioniq 5 N electric vehicles with Myenergi Zappi mk1 charger

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Majordennisbloodnok

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27/01/2025 3:52 pm

Posted by: @julianc

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@majordennisbloodnok I’m completely happy with Smart Meter & giving Octopus remote control of my EV charger. I can take back manual control if required.
The dynamic management of the grid will deliver massive benefits.

And that makes it the right setup for you. It just also happens to be entirely the wrong setup for me.

The important part of your penultimate post, though, is that if you get an Octopus-compatible charger then you're free to exercise that choice whichever way you decide.

"Semper in excretia; sumus solum profundum variat"

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JulianC

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Topic starter 13/04/2025 6:27 pm

The annual update.
so the April 24 to 25 numbers: we used 4316 kWh.
SCOP was 3.91

SCOP since starting 3.83.

So this is ok, but was hoping for better with Havenwise. But switched off since 10th Feb (2months). As they were trialling with Daikin directly. Hopefully they will switch me back in for autumn / winter 2025.
Otherwise running costs are well below the target. And much better than the oil boiler.
Will be switching off over summer as the solar PV heats the water.

Daikin Altherma 3H HT 12kWh ASHP with Mixergy h/w cylinder; 4kW solar PV with Solic 200 electric diverter; Honda e and new Hyundai Ioniq 5 N electric vehicles with Myenergi Zappi mk1 charger

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