camelot-forum.co.uk

Hi all,

While this has been covered before, I'll start a post to see if a discussion happens.

I've just had a crazy estimate form Octopus for an ASHP. Net of grant funding the quote was £858.55 (they are calling it a quote, I'd probably be more comfortable calling it an estimate, but time will tell) with an extra £250 off if ordered by the 31st of October. I've has an initial call to check their assumptions and they are standing by this price.

This seems like a no brainer, but we shall see... I've paid my £200 refundable deposit and booked in.

I've got the survey booked for next Friday, so will see how much the number changes. I understand that there are some optional extras such as trunking and hidden pipework.

These are my EPC results For information:

Feature Description Rating
Walls Average thermal transmittance 0.26 W/m²K Very good
Roof Average thermal transmittance 0.12 W/m²K Very good
Floor Average thermal transmittance 0.12 W/m²K Very good
Windows High performance glazing Very good
Main heating Boiler and radiators, mains gas Good
Main heating control Time and temperature zone control Very good
Hot water From main system Good
Lighting Low energy lighting in all fixed outlets Very good
Air tightness Air permeability 3.1 m³/h.m² (as tested) Good
Secondary heating None N/A

2017 new build semi, 18 kW system boiler with unvented cylinder.

I guess my questions are:

Are we still in the early adopter phase, or are the kinks getting ironed out? Will this be relatively cost neutral to run compared to a gas boiler?

Our house is plumbed with 10mm plastic, so will be interesting to see how the plumbing and rads works. The 10mm is supplied off 22mm plastic manifolds. Is this a deal breaker, or has this been overcome now? Relatively recently, I've heard claims of rads needing 22mm supplies.

Is there any reason why we shouldn't do this?

Obviously, I'll be doing my own calcs to sense check Octopus.

What are people's thoughts on locating the ASHP? I don't have a very big back garden so am a little limited.

I'm currently digesting this thread https://camelot-forum.co.uk/phpBB3/view ... =17&t=2602

I never went down the ASHP install route despite being a heat engineer for 35 years. One reason was that forcing householders to ditch the boiler to qualify for the grant seems just nuts to me, is that still the case? I never understood the logic of not having a boiler sa a back up for the coldest few weeks of the year. Also too near the end of my working life got better things to play with now, like motorbikes

Your 10mm pipery may be ok, do you know the flow temp you typically need to keep the house warm, and the flow temp the ASHP typically delivers whilst keeping a decent COP? if so you could compare the pump curves and make a pretty good estimate of the ASHP performance.

I have a few customers with great ASHP installs and they are very happy with them, most say running costs are broadly similar, None of them have PV.
Two of them wish it had never been installed, but I think that is basically down to shonky installers over selling what was possible with an existing system, they shiver when the weather is really cold. Hence my feeling about boiler back ups.

If well designed and installed you should be ok, but as a customer you need to be fully clued up to oversee the install, you should be fine on that score, but sadly many are not able or too busy to keep an eye on it.

Desp

Is that for the actual Octopus-branded heat pump? Does it do hot water as well as central heating?

I agree the price seems almost too good to be true. But that would be a great opportunity to ditch the gas...

dan_b wrote: ↑Mon Sep 23, 2024 2:21 pm Is that for the actual Octopus-branded heat pump? Does it do hot water as well as central heating?

I agree the price seems almost too good to be true. But that would be a great opportunity to ditch the gas...

I can't get my head around the price. Others have had much higher (after grant applied). When they called too discuss/book survey they had my EPC certificate (I know it's easy to get hold of) but means they may use some science behind the prices.

They've not (yet) clarified if it's a Cosy 6, but I'd assume so. Inf fact I'd be surprised if it isn't. I guess they're trying to get some units into the wild. I'm more concerned that 6 kW feels a bit under powered, but I've not done the calc.

I think it does hot water too.. (Youtube suggests flow temperature of 50C)

Next Fridays survey outcome will be very very interesting thats for sure, and a great oppertunity to grill whoever appears as to its validity.

Smegal, have you turned down your gas boiler flow temperatures to mimic an ASHP to see how the house and the emitters behave at low flow temperatures ? It certainly sounds like the rest of the house insulation and piping rads etc is ok - the plastic pipe at 10mm is fine, the inserts at the connections would normally be the choke points but they should only take it to 8mm (again fine). I suspect the price will increase when they survey and you ask for the system to do DHW and CH, this will require a much larger coil in the HWT than I expect your current tank has.

If that becomes the case you need to consider what your DHW requirements are in terms of liters and time, they may try to give you a larger HWT than you need which makes the reheat times longer than required at which point they may then try to give you a larger ASHP which will degrade your COP for 4/5ths of the year. Better to have a ASHP thats big enough for the average conditions and a SMART HWT that can add off peak energy to the tank in times of high demand via the immersion or other input.

Theres acres more detail but I have to go and collect the kids - I will be reading this with interest

Moxi

Wondering now whether the Octopus Cosy would be suitable for my flat... Don't have a great demand for heating as it's a recent build and is well insulated, plus not all that large space to heat overall - I've got a gas combi boiler for heat and hot water... I know some of the rad piping is the small bore plastic stuff, but that's not necessarily a deal breaker is it? Hmm.

dan_b wrote: ↑Mon Sep 23, 2024 3:33 pm Wondering now whether the Octopus Cosy would be suitable for my flat...

Last time I checked, Octopus were not installing in flats. I think this is because there are issues with siting the ASHP on the outside - ie. generally, with a leasehold flat, you don't own the outside skin of the building and so gaining permission for the outdoor unit becomes a pain.

I spoke to them on the phone as a freehold mixed-use property - with a flat above a shop - wholly owned would not have the same siting problems. Their response was that they just don't cover any flats at the moment. this was about 4/5 months ago.

Just had a look on Heatpumpmonitor.org and there are 14 monitored heat pumps installed by Octopus, all Daiken Altherma 3 units varying from 4-11kW.
The COP range is 2.1-4.0 with an average COP of 3.23.
There are only another 6 Daiken Altherma 3 units on there and all have COP's within that range.