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Two possible heat pump routes - how to evaluate them?

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(@johnmo)
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Posted by: @lucia

Clearly, the closer to the mythical 'accurate' I can get my heat loss figures, the better

My heat demand is around 3kW but I have a 6kW heat pumps, you make it work just a bit of fiddling and reading the installer manual back to front several times


   
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Toodles
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@lucia I too wonder what the 3V3 model might be - as in the case of your proposed one, mine is the EDLA08E2V3. I did once see a table that set out what the elements in the nomenclature stand for; of course I cannot locate that now, SORRY! As mentioned the B rather than D means that there is a fitted back-up heater (booooo-not the best use of kW’s!) and of course the 08 indicates mine is the 8 kW version. In some places I see that the 8kW version is rated at 7.1 kW so we may have to compare oranges with drain pipes or summat! For all that, I am very pleased with the performance of our unit that is controlled by a Homely smart controller. Regards, Toodles.

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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(@derek-m)
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@toodles

Page 20 of the attached manual provides a detailed breakdown of the model number.


   
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Toodles
(@toodles)
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@derek-m Ah! Thank you Derek - and as usual, I had it all wrong! Toodles.

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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(@lucia)
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Posted by: @derek-m

@toodles

Page 20 of the attached manual provides a detailed breakdown of the model number.

-- Attachment is not available --

Thank you. 

 


   
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(@lucia)
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Posted by: @lucia

Today I have a visit that I've waited 9 months for under the Great British Insulation Scheme. However, I now understand these tick box projects (despite the 'rules' saying otherwise) work on being able to show big EPC jumps to make the fitter's £s... so despite everything it probably won't succeed. 

Forgive me quoting myself but it's because I have to say I was wrong. The GBIS guy was extremely thorough including drilling holes in my walls to take borescopic pictures.

So... this will be a test of how joined up Octopus are because they will get a copy of my report and it backs up my thermal camera images. Instead of ticking a heat loss assessment box that says 'cavity wall insulation' they need to add 'which is only half filled in places' .... 😏

The GBIS scheme guy showed me the images. He reckons that when they were filling the cavities they ran out of the filler and were too lazy/in a hurry to bother fitting another cartridge (or whatever they are) and finishing the job. You can clearly see the spaces. He worked as an apprentice for the company that did the insulation many years ago and saw this happen.

It looks like my heat loss assessment is probably correct and I need the 6kw not the 4kw.  Oh. my. days. 🙈


   
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(@derek-m)
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@lucia

The better option would be to get the cavity filled correctly.


   
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(@lucia)
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@derek-m  I agree, but unfortunately, that's not an option. I can't afford the approx £3,000 it would cost to extract and replace. 

I have to buy some kind of new heating as my gas boiler is 20 years old and can't do hot water any more - hence ASHP.  I also have to get work done on one side of my roof. These are my 2 priorities. 

But today's investigation confirms why my thermal images look the way they do and why my 'de Podesta' calc came up with a higher number than the Octopus heat loss assessment. 

 

This post was modified 5 days ago 2 times by Lucia

   
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(@derek-m)
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Posted by: @lucia

Posted by: @lucia

Today I have a visit that I've waited 9 months for under the Great British Insulation Scheme. However, I now understand these tick box projects (despite the 'rules' saying otherwise) work on being able to show big EPC jumps to make the fitter's £s... so despite everything it probably won't succeed. 

Forgive me quoting myself but it's because I have to say I was wrong. The GBIS guy was extremely thorough including drilling holes in my walls to take borescopic pictures.

So... this will be a test of how joined up Octopus are because they will get a copy of my report and it backs up my thermal camera images. Instead of ticking a heat loss assessment box that says 'cavity wall insulation' they need to add 'which is only half filled in places' .... 😏

The GBIS scheme guy showed me the images. He reckons that when they were filling the cavities they ran out of the filler and were too lazy/in a hurry to bother fitting another cartridge (or whatever they are) and finishing the job. You can clearly see the spaces. He worked as an apprentice for the company that did the insulation many years ago and saw this happen.

It looks like my heat loss assessment is probably correct and I need the 6kw not the 4kw.  Oh. my. days. 🙈

This is what is so annoying about the present society in which we live, in that one cannot always trust people to do what you have paid them to do.

 


   
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(@judith)
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@lucia 

I’ve been having a think about your choice. Which magazine says the ovo tarrif is the best followed by octopus agile then octopus cosy. I think some pages back you said you didn’t want to choose based on tariffs but the ovo one is only possible with a Vaillant heat pump.

Does the installation contract withBG tie you into them, and for how long? Do they fit Vaillant? Since future options are good to have.

OVO is 15p for the heat pump part of your bill only and the rest is at normal prices. That’s why they need it to be a Vaillant because the consumption can be measured separately

6kW PV south-facing roof 9.5kWh Givenergy battery. MVHR. Investigating ASHP


   
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(@judith)
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@lucia another thought is flow temp. I played around with our house on heat punk to address this question. If I adjust our radiators to those needed for Flow temp 50C then 4 needed to be replaced but at 42c flow (at our design temp, and is the lowest sensible) we needed 6 changed (and to larger ones). That changed the SCOP and for our house the annual bill increase for 50C would be £200.

But that is the simplest penalty for higher temperature flow. If the volume of  the smaller radiators needed for 50C means a volumiser (aka 2 port buffer) is needed then there is a further temperature increase and SCOP fall and hence bill increase.

I’m glad you have supporting evidence of your cold spots and need for a higher power pump. But shame that it exists.

6kW PV south-facing roof 9.5kWh Givenergy battery. MVHR. Investigating ASHP


   
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(@ivanopinion)
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Posted by: @judith
OVO is 15p for the heat pump part of your bill only and the rest is at normal prices.
I'm guessing that the Which? figures don't take into account this factor, which could tip the balance towards Agile, as it applies to all your electric.

I don't yet have a heat pump and I pay about 18p per kWh on average on Agile. If I did have a heat pump and I switched to the OVO tariff I'd be paying about 22.4p (and more from October) for this non-heat pump electric. I currently use about 2500 kWh of annual electric and surveys suggest the ASHP will use about 4500 kWh, so even if my ASHP was cheaper on OVO for two thirds of my usage I'd be paying a lot more for the other third of my usage. 

Also, I'm guessing that the Which? calculation just assumes the ASHP is operating 24 hours a day. If you programme a set back temperature for your ASHP from 4-7pm, you avoid the peak rates on Agile and you bring down the average cost considerably. (The house shouldn't lose much temperature in 3 hours.)

 


   
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