Posted by: @cathoderay

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It's definitely worth getting the rad sizing right, or at least ensuring none are too small, rather, all are matched to the loss and a bit, and ideally none are too large

Thanks, I like the chart, very helpful and this will definitely help my discussion with the possible installer this week. It will be interesting to see how the debate goes with HG AI!

Posted by: @baroquebank

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I'm embarking on the ASHP road, hopefully with care, to replace the gas boiler on our 4 bed detached property. Initially had a HeatGeek survey which seemed to go well, liked the installer, all made sense and price seemed OK. But in the spirit of being cautious decided to have Octopus do a survey as well.

There are some differences between their heat loss assessments (HeatGeek 7.1kW (I feel probably better) vs approx 6kW), HeatGeek proposed 7kW Vaillant @ 45 degrees flow vs Octopus 9kW Cosy @ 50 degrees, the Octopus cost is noticeable lower than the HeatGeek but both tolerable.

The thing which is really puzzling me though is a discrepancy in their radiator replacement requirements:

HeatGeek - we must upgrade 2 upstairs bedroom radiators, both in rooms where the calculation shows existing radiators exceed heat loss

Octopus - we must replace 2 downstairs radiators, both in rooms where I do feel current radiators are marginal. Indeed one of these, in the kitchen, Octopus are saying must be significantly upgraded (or I must provide an additional heat source) in order to qualify for the government grant.

I am bemused by such a discrepancy for what should be similar heat pump solutions and am concerned that one of them might be wrong in a way that could be significant.

So I'm turning here to ask whether anyone with knowledge can provide an explanation for this discrepancy. Thanks in anticipation!

Hi I am a Heat Geek installer so thought it worth sharing some light as it may help others, as far as I am aware Octopus are using manual design meaning that the designer is translating the information taken on the heat loss and then manually choosing which radiators to upgrade to meet the required SCOP or flow temperature.

The Heat Geek software is doing this all for us using machine learning, this uses lots of data to not only provide the best SCOP and running costs but striking the balance between what will cause the least disruption to your home but provide the biggest impact to SCOP. It is likely that replacing the 2 radiators suggested by HG will offer a greater overall positive impact to the system than the 2 suggested by our eight legged friends.

Either way definitely reach out to your installer, I am yet to meet a Heat Geek installer who isn't super passionate about heat pumps and they will gladly answer any questions you have.

Hope that helps!

Posted by: @tomtheheatingengineer

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…

It is likely that replacing the 2 radiators suggested by HG will offer a greater overall positive impact to the system than the 2 suggested by our eight legged friends.

…

Thanks for your insider view, @tomtheheatingengineer.

I’ve left your post as is precisely because the information about approach is really helpful, but do please also be careful about accidentally wandering into the territory of self promotion. I’m happy that human choice vs machine learning may well give differing results, but whether one is “better” or not is more difficult to claim - at least without more data and by someone who necessarily is not independent. That’s not to suggest you’re wrong, but just that Octopus may be just as sure their process has the edge.

It is, though, a very interesting and relevant point. Done well, I’ve seen machine learning produce some amazing results in many fields. I’ve also seen it done poorly and produce abysmal results. The same is true of human choice; an experienced and competent person in the right place at the right time can be amazingly effective but we see plenty of evidence even in the news that not all human choices are good ones.

@majordennisbloodnok  @tomtheheatingengineer 

For my money both Heat Geek and Octopus have the advantage of volume.  This provides them with real data on a relatively large number of real installations which, if they use it well, is potentially enormously valuable.  They are not alone in this and of course a good, intelligent, installer with a sound understanding can almost certainly work out much of what the volume installers can discover in the field.  Nevertheless the fact that both seem to achieve relatively low levels of complaint (if what we see here is anything to go by) suggests that they have both done something useful with the data they have collected which gives me hope for the future.

What would be really good is if they could share the 'lessons learned' and use the information to improve the practice across the industry, by using their doubtless significant influence with MCS to embed the key elements in the 'processes'.  There is, surely, enough business to go round that they could do this without materially damaging their competitive position and to do so would be a service to us all.

Whilst the industry remains reliant on universal installer excellence across a wide range of skills it will inevitably fail to deliver consistent quality at volume.  The process must be redesigned so that, at least for the vast majority of installs, installers don't need to be excellent.  Of course there will always be some particularly difficult cases where out of the box thinking is required, but these are surely a minority.

Heat Geek and Octopus appear to have approached the volume challenge differently, with Octopus rejecting many installs as (outside our scope) and Heat Geek relying more on installer training and now machine learning.  Both approaches are valid and they are complementary and for the avoidance of doubt Im not saying that Octopus installers aren't also well trained..  Both organisations deserve recognition for this, if only they would share their key learnings in a way that the rest of the industry could adfopt.

Hi, sorry that I have been absent for a while. I'd like to say thanks for all the constructive comments that have been provided here and thought I should let you know what I'm doing.

I decided to go with Heat Geek even though it was the more expensive option, for a few reasons:

• I felt more comfortable with the personal Heat Geek approach and the particular installer I was dealing with. He was always very responsive, informative and constructive.
• By contrast the Octopus solution separated surveyor, design discussion contact and installer.
• The Heat Geek approach enabled consideration of options which were not possible for Octopus: they could only do whatever fitted within their standard offer (see kitchen radiator comment below).
• The Heat Geek Vaillant solution enables the heat pump to be wall mounted close to the current boiler providing a very straightforward installation whereas the Octopus solution must be floor mounted which would require it to be some distance away with a more disruptive piping run.
• My wife and I both find the Octopus heat pump really ugly!

Octopus identified the kitchen as a particular area of concern, which I could understand because I have always felt the  radiator there to be marginal in our current system. Heat Geek put no requirement on the kitchen whereas Octopus mandated an upgrade, but were unable to provide a suitable radiator that would fit in the available space. I had to find a solution (which they advised) which had to be carried out prior to their installation.

I discussed this with Heat Geek, he provided me with the option to go for an enhanced radiator that does fit and reran the calculations with this in place. It reduced the upstairs changes required and slightly increased overall efficiency (at the cost to me of having it added to the installation, of course).

This is how we agreed to proceed, installation is scheduled for late September.

Thanks for the update. Vaillant is a good choice, their technical team is very responsive, helped to understand the controls that we wanted.
With HG, they handle all the comms anyway. Just curious if you went for an arotherm pro or a plus? 

@majordennisbloodnok Apologies, it wasn’t an attempt to self promote. I only mentioned it to give context to my post.

Noted for future.

Posted by: @tomtheheatingengineer

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@majordennisbloodnok Apologies, it wasn’t an attempt to self promote. I only mentioned it to give context to my post.

Noted for future.

Not a problem; that’s why I left it as it was. The perspective you’ve provided is not immediately obvious to many of us and so is particularly useful as a result.

@batpred They offered both, I went with Pro. As an amateur very difficult to understand the differences. Longer warranty on Plus was appealing, as was slightly lower price for me, but recommendation was Pro with benefit of being smaller and also a 400% guarantee vs 390% for the Plus.

Posted by: @baroquebank

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@batpred They offered both, I went with Pro. As an amateur very difficult to understand the differences. Longer warranty on Plus was appealing, as was slightly lower price for me, but recommendation was Pro with benefit of being smaller and also a 400% guarantee vs 390% for the Plus.

The Pro is supposed to be cheaper, but we also saw this changing round with the various quotes 🤔. Not much difference in features, just easier to place near opening windows (perhaps also not a consideration for you, ours is disabled..) and 25% smaller. 

Posted by: @tomtheheatingengineer

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The Heat Geek software is doing this all for us using machine learning, this uses lots of data to not only provide the best SCOP and running costs but striking the balance between what will cause the least disruption to your home but provide the biggest impact to SCOP. It is likely that replacing the 2 radiators suggested by HG will offer a greater overall positive impact to the system than the 2 suggested by our eight legged friends.

Agree with Major. 

And even if I was very happy with HG, I have not seen any solid approach to optimise the rads, etc. 

The basis for the optimisation cannot be "AI working on data all the houses except the one the system us being design for"! As I also saw my HG heat loss survey was questionable and not even the best AI can sort that. It is a simple method to follow anyway (to even out the rad output per room and allow the pump to operate at lower temp)..

If I was HG´s CEO, I would either get the heat loss survey issues sorted or stop talking up AI. Specially the HG approach and network has a lot of great things going for. Namely HG sorts all the paperwork smoothly with all the regs, etc. 

I have just had 3 heat loss surveys, one by heat geek one by octopus and one that I did myself.

The octopus surveyor arrived and asked to be shown where the heat pump would go, he looked at the consumer unit and then the airing cupboard where my recently fitted unvented cylinder is. There’s not much room in here he said, I asked him why and he said that they had to install a new, bigger unvented cylinder and a buffer tank. I asked him if he meant a volumizer but he said no, octopus would be installing a buffer tank. This was before he had done his survey. He also said it was not an option to keep my cylinder.

Having lived in my house for 40 years and been present whilst any building works were carried out, I know the details of the fabric very well, so I offered to accompany the surveyor and tell him which walls were dry lined etc. He then asked me when the house was built and what was the date of the extension and explained that the way octopus worked was they imported those dates into their system and then scanned the room and the system worked out the U values based on those dates.

 I told him that they that the house was originally built in 1924, but we had just spent a lot of money renovating upstairs, a lot of which went on improving the insulation. We had dry lined walls, removed the plaster from the ceiling, fitted 70 mm of celotex between the rafters and 70 mm across under them, and so on. He asked me if I had any certification, I said I had the  architects plans for the extension which specified the insulation  and the certificate of completion from the council building control. He said that was not sufficient.

I had taken photographs of the insulation being fitted, but the surveyor said that he couldn’t accept those as they could have been taken anywhere. I pointed out that you could see out of the window in the photographs and see that it was the same room, but he wouldn’t accept that .

When he was finished, he said that he had calculated the heat loss at 17.5 kW and he was very sorry that octopus didn’t have a heat pump big enough.

When the surveyor came from Heat Geek . I went round the house with him and told him which walls were dry lined, which were solid, 9 inch brick, which were insulated cavity and so on.

He calculated the heat loss as 10 kW, which was quite close to my calculated heat loss of 9.5 kw.