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British Gas versus Octopus: Two possible heat pump routes - how to evaluate them?

Lucia · 2024-06-23T11:05:01Z

Hello , after lurking & reading the knowledgeable folk here + researching all over the web inc Heat Geek, YouTube etc, I've organised 2 possible heat pump heat/loss surveys. 1: British Gas 2: Octopus I'm what is known in the trade as a 'distress purchase' with a gas boiler on its last legs. Funds are limited so obviously installation costs matter but so do running costs. My home is a '70s 2/3 bedroom bungalow, 72sqm, sw facing in the south west of England with very old cavity wall & loft insulation. I'm aiming to top up the loft insulation but can't afford to replace the cavity insulation. It's an easy install, I think, with good outside space, a ground floor level cellar which also has cavity wall insulation (the gas combi is in there) (the bungalow is built into a hill) so no floors need lifting for pipework etc. The garage adjoins the house & has electric, water & the CU. But may be too far from pump unit for the boiler. The rads deffo need replacing for K2s at least but fairly sure pipes are ok. The 3rd bedroom is now minus a (floating) wall & is part of a (24sq m) open living/dining room with ceiling to floor sliding glass doors & window at one end. And a wood burner. BG are coming to do the heat loss survey in 2 weeks. I understand they often fit Vaillant but don't include rads etc so will be the 'expensive option'. I reckon 5/6 new K2 rads are about a £1000 on top of the boiler/pump installation costs if they have same widths & pipework as the current P11s have . Octopus have my £500 but have not given me a HL survey date yet. They fit Daikins - as an all-in deal are obviously cheaper. One reason why I'm going for it now is I don't want their own home-grown Octopus Cosy HP + I'm concerned that once that is launched they will stop fitting Daikins. I've read people's woes with over sized pumps or bad installations, I'm shoe-string productions, a wee bit geeky, so controllability, efficiency, scop/cop (cheapest possible running costs) matter. Oh, I work from home & hate being cold. Qs.... What do I need to consider? What Qs should I ask BGas & Octopus? What about the Daikin v Vaillant (I hope that's not like iPhone/Android or Apple/Microsfoft 🫣). Will either of them share their HL reports? What would you do if you were me? Forgive my long 1st post but figured it was best to spell it out. Some of the previous posts here really helped me to toe dip & learn a wee bit. Thank you.

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Anonymous 5011

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12/07/2024 12:31 pm

Posted by: @lucia

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Reality - half insulated cavity wall

Half insulation is as bad as no insulation. Bit like a hole in a bucket. It may be a bucket but it's not holding the water.

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Anonymous 5011

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12/07/2024 12:34 pm

Posted by: @lucia

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Question:What would you do?

BG and get all the rads changed out for bigger. Allows you run cooler for better running costs. If it's too big you can sort out the cycling. Mine is a 6kW on a 3kW max duty and not much modulation. Works fine.

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Lucia

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Topic starter 12/07/2024 1:10 pm

@johnmo You have a 6kw Daikin?

Good point about the bucket...

My preference if going for the 6kw is to try and convince Octopus to accept it. I prefer their whole approach. Plus BG want a lot more money for the 6kw set up.

This problem is caused by MCS regs and EPC ridiculousness. Neither account for problems with the insulation - it's either insulated or not. The EPC says insulated - the borescope (which was done for a different purpose says it's not insulated everywhere....) - 🤦🏻‍♀️

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Toodles

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12/07/2024 1:23 pm

@johnmo That might depend how high up the hole is in the bucket! 😉 Toodles

Toodles, heats his home with cold draughts and cooks food with magnets.

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Jancold

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12/07/2024 1:25 pm

BG have been and quoted at about 1/3 off the original website estimate.

They would change 3 Emitters (as they are now called!) and add one on the landing and came up with 4Kw heat loss which agrees with Ultimate Renewables. My foray into Heatpunk gave 4.9Kw . It would be a Daikin HP.

He appeared to accept my 'no buffer' request but slipped it into the quote!

I would also have to prepare the site for the ASHP with buried pipework for my preferred position which is the other side of a path around the house, about 1 meter away from the house. Where can I find information on a suitable pipe system and fittings?

This was only the quote survey so I look forward to getting the detail later.

Daikin 6Kw ASHP.
MG4 EV
1926 Semi with loft and wall cavity insulation, all radiator.

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Toodles

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12/07/2024 1:29 pm

@jancold Mars may be able to help you with the insulated pipe runs I think. Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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Anonymous 5011

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12/07/2024 1:31 pm

Posted by: @toodles

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@johnmo That might depend how high up the hole is in the bucket! 😉 Toodles

I know what your saying but - Not really, heat will take the path of least resistance, that's why it's so important to get no gaps in insulation. If the cavity is incomplete don't take any credit for it, that is the correct thing to do.

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Anonymous 5011

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12/07/2024 1:39 pm

Posted by: @jancold

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Where can I find information on a suitable pipe system and fittings?

I made my own.

110mm flexible underground conduit I had black left over from the build. Inside 28mm Hep2O pipe, and closed cell (armour flex 25mm wall thickness insulation. Wrapped the insulation in aluminium tape. Where the conduit and pipe came out the ground used stainless steel mesh on the end of the assembly to keep wildlife out, foamed into place. Once out of the ground used UV resistant insulation and a 90 Deg fitting to take through the wall.

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Toodles

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12/07/2024 1:40 pm

@johnmo Can such partial insulation jobs be ‘topped up’ or is there a practical method of removal so that a ‘proper job’ could be carried out subsequently? Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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Anonymous 5011

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12/07/2024 1:46 pm

Posted by: @toodles

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Can such partial insulation jobs be ‘topped up’ or is there a practical method of removal so that a ‘proper job’ could be carried out subsequently

You can normally get mineral wool blown in or use EPS beads they should make their way to fill everything up fully. Beads are less likely to settle later and don't hang on to water if you did get days (or weeks) of rain like we just have.

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Lucia

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Topic starter 12/07/2024 1:56 pm

@toodles No, it can't be topped up.

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Lucia

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Topic starter 12/07/2024 1:58 pm

@johnmo You have to extract everything first and only then can you refill it. Even for a small bungalow like mine it's £3,000 at least. I can't afford to do that.

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