@jamespa 

Also, check the noise spec given its going to be indoors. 

They say it's 56db, which is apparently similar to a modern boiler? And much lower than our tumble dryer (64db), both of which we have on at night currently. So I'm hoping it's ok!

they are (presumably) drawing heated air from the house so they should be factoring in the COP to produce that heated air - which I dont think they are doing.

Aye I clocked that too. But, if we'll have spare capacity on the heating front anyway, I suspect it won't be an issue in practice?

albeit that they falsely claim that 'conventional' systems do [use LLHs]

Tbh in my experience it does seem like most installers still want to install buffer tanks by default! 😣 And some refuse to install without one, regardless of the property (3 of the installers I spoke to: Aira, BOXT, and one local guy).

It might be worth finding out about the control unit

So they have a simple wall-mounted controller which allows WC changes, DHW schedules, etc (for folks who don't wanna do anything too fancy). Then the kit can also be connected to a 3rd party app called "Smart Life", to set some automations. So for example you could use that to tone down cycling frequency if needed, set up various rules around hot water reheating, or to divert excess solar to that. I've spoken to one homeowner with this system who says that stuff is useful and easy to use at least. 🙂
And there's also apparently some AI component which can monitor usage and suggest settings adjustments to improve efficiency. I don't have any details on that though! But in theory it sounds a bit like having Home Assistant and Homely running out of the box?

As to more conventional brands a quick search shows:

Thank you for the research! It looks like Panasonic does a claimed 3kW as well? But I think that could well be the 5kW derated too..

One issue I found when speaking to other installers was the location. We don't have any good place to stick the outside unit other than wall-mounting it, and some installers (eg those working with Vaillant kit) won't wall mount. We've had a lot of issues working around R290 requirements as well, since there's various electronics directly below the obvious spot to wall mount it. This Adlar heat pump is still R32, so we can be more flexible.

I found the Aurora/AdlerCastra user Manual. Page 4 concerns me, the WC curves are stepped as a function of OAT not smooth and the steps are, in some cases, quite large. 

I also found a user manual, which looks different and might be a newer version perhaps? 

I think the WC "curves"/steps are the same in each doc, though the graphs/scales make them look different. Either way it looks like the steps are 1 degree each. Is that unusual? Could it be just the way they've chosen to display it? I haven't actually seen how any other WC curves look!

I might also be concerned about long term support.

This is 100% my primary concern with these guys. Yep it's a UK branch of a much bigger company operating in a few different European countries, but the UK branch is very new.. And their system is so different from "the norm", that if the UK branch closed up shop it would probably be quite hard to find anyone willing to service their units. :/ It's a risk for sure, and one that keeps me questioning whether the low upfront cost is worth it. 😰 

Posted by: @morganr

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Also, check the noise spec given its going to be indoors. 

They say it's 56db, which is apparently similar to a modern boiler? And much lower than our tumble dryer (64db), both of which we have on at night currently. So I'm hoping it's ok!

I definitely wouldn't want that near my bedroom (which is where my DHW tank is) but as you say in a kitchen area is OK

Posted by: @morganr

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Tbh in my experience it does seem like most installers still want to install buffer tanks by default! 😣 And some refuse to install without one, regardless of the property (3 of the installers I spoke to: Aira, BOXT, and one local guy).

Lots of installers certainly do, and those installers are equally certainly to be avoided.  (note that a 2 port volumiser, fitted in either the flow or return, is OK)

Posted by: @morganr

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Thank you for the research! It looks like Panasonic does a claimed 3kW as well? But I think that could well be the 5kW derated too..

The give-away is physical dimension and refrigerant charge (given usually in kg).  If both are the same then its almost certainly software limited.   Confirmation, if you can find the data, is in the capacity data tables if these contain minimum output as well as maximum, which only some publish.

I cant actually find the Panasonic specs, but here is a snip from the Riello showing  that the 4kW unit and the 6kW unit are very likely the same hardware

Posted by: @morganr

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One issue I found when speaking to other installers was the location. We don't have any good place to stick the outside unit other than wall-mounting it, and some installers (eg those working with Vaillant kit) won't wall mount. We've had a lot of issues working around R290 requirements as well, since there's various electronics directly below the obvious spot to wall mount it. This Adlar heat pump is still R32, so we can be more flexible.

Vaillant heat pumps are very heavy on one side, which is why many installers wont wall mount.  There is a very common misconception that R290 cannot be mounted under a window.  As long as openings are above the top of the heat pump its OK (propane is heavier than air).  

Posted by: @morganr

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I think the WC "curves"/steps are the same in each doc, though the graphs/scales make them look different. Either way it looks like the steps are 1 degree each. Is that unusual? Could it be just the way they've chosen to display it? I haven't actually seen how any other WC curves look!

Yes as you say 1 degree per step, so probably OK.  I don't however understand why the 'floor' temperature is so high, normally you would start off with the floor being perhaps 27-30C at OAT20, this seems a bit half-hearted.   

There are two principal 'types' of WC curve - those with a set of fixed curves which you can switch between with a single parameter - eg Vaillant

and those where you have to program two OAT-FT pairs on a straight line (or sometimes even more than 2 pairs)

Both are normally represented as continuous, but of course they may in fact be discreet.  

Having looked again at the Aurora manual my main concern is now the high 'floor' temperature for the curves that are likely to apply to radiators, which does not appear to be adjustable.   

Posted by: @morganr

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... one that keeps me questioning whether the low upfront cost is worth it.

What are you being quoted for Aurora and alternatives?

@jamespa

Posted by: @jamespa

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I definitely wouldn't want that near my bedroom (which is where my DHW tank is) but as you say in a kitchen area is OK

Hmm, ours would be on an adjoining wall to one bedroom (our current bedroom), and directly below another bedroom (which will be our future bedroom when we move up there). But that's the same location our boiler currently is, and it's never disturbed our sleep when its on at night. 😮 I gather the pattern of noise might be different and could have an impact maybe? It's something I'm a bit worried about, but I'm not sure realistically how worried I should be. I wish this was something you could try before you buy/install!

Posted by: @jamespa

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Vaillant heat pumps are very heavy on one side, which is why many installers wont wall mount.  There is a very common misconception that R290 cannot be mounted under a window.  As long as openings are above the top of the heat pump its OK (propane is heavier than air).  

I was told by the Vaillant installers it's because official Vaillant service engineers can refuse to service if they have to use a ladder to reach it. A normal ladder, that is. We're only talking about having it 1.7-2m up!

We don't have any windows on that side of the house, but people seem very wary of having an R290 unit above anything that could potentially cause a spark, like our EV charger and electric meter box. 

Posted by: @jamespa

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I don't however understand why the 'floor' temperature is so high, normally you would start off with the floor being perhaps 27-30C at OAT20, this seems a bit half-hearted.   

If I understand what you mean by floor temp, and if I'm reading this correctly, it looks like the lowest the Aurora can go is 26C on the lowest two curves? The app can be used to automate switching between different curves btw, if it's a concern that the other curves don't go that low? 😮

Posted by: @jamespa

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What are you being quoted for Aurora and alternatives?

All including the BUS grant:

My Adlar quote is £2,300 for the 6kW Aurora & 300L cylinder, 2 new rads and 2 swapped rads (based on my request), and fittings for the air cooling. We'd need to do a bit of boxing in after, though.

My closest quote is Octopus, which would be £637 + around £1000 for the trench they'd need to get it into the garden. This is for the Cosy 6, 210 slimline cylinder, and 5 new rads (which I think is overkill). We'd also need to relocate a large bush, and probably erect some trellis to the side of the HP.

The alternatives that all use well-known brands start at £4700 for installers I'm not sure about, and increase to £6700 for installers I definitely trust (but I'm not sure if that includes any rad upgrades).

An additional factor is that we're eligible for Barclays' Green Home Reward, which is a grant of £2000 that they give on any heat pump install costing at least £2000. So for all of the installs above, except Octopus, we should be able to get that, which makes a huge difference! So Adlar would be £350-450, Octopus maybe £1700, and everyone else £2700-4700+.

Posted by: @morganr

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Hmm, ours would be on an adjoining wall to one bedroom (our current bedroom), and directly below another bedroom (which will be our future bedroom when we move up there). But that's the same location our boiler currently is, and it's never disturbed our sleep when its on at night. 😮 I gather the pattern of noise might be different and could have an impact maybe? It's something I'm a bit worried about, but I'm not sure realistically how worried I should be. I wish this was something you could try before you buy/install

tricky that, I cant say I have a solution.

Posted by: @morganr

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We don't have any windows on that side of the house, but people seem very wary of having an R290 unit above anything that could potentially cause a spark, like our EV charger and electric meter box. 

Fair enough. 

Its all a bit crazy IMHO.  You can have a 13kg bottle of propane in a garage or on a boat, and you can pipe unlimited amounts of methane directly into your house, but 3kg of propane in a heat pump is apparently super dangerous.  The latest Vaillant press release says that they are incorporating 'safety features' so that these restrictions aren't necessary - we will see.  Presumably neither the meter box nor the EV point are at ground level so most of any leaking propane will simply drop past them!

Posted by: @morganr

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If I understand what you mean by floor temp, and if I'm reading this correctly, it looks like the lowest the Aurora can go is 26C on the lowest two curves? The app can be used to switch between different curves btw, if it's a concern that the other curves don't go that low? 😮

Yes, but the need to switch will happen on most days in the shoulder season and a fair number in the high season, so in practice you will almost certainly end up controlling on thermostat unless you automate it.  That might not be so bad but will impact efficiency. 

Goodness only knows why they have done this - I suppose its to ensure that radiators always feel hot (and thus avoid call outs) - but its a silly thing to do really!

Posted by: @jamespa

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Posted by: @jamespa

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What are you being quoted for Aurora and alternatives?

 

All including the BUS grant:

My Adlar quote is £2,300 for the 6kW Aurora & 300L cylinder, 2 new rads and 2 swapped rads (based on my request), and fittings for the air cooling. We'd need to do a bit of boxing in after, though.

My closest quote is Octopus, which would be £637 + around £1000 for the trench they'd need to get it into the garden. This is for the Cosy 6, 210 slimline cylinder, and 5 new rads (which I think is overkill). We'd also need to relocate a large bush, and probably erect some trellis to the side of the HP.

The alternatives that all use well-known brands start at £4700 for installers I'm not sure about, and increase to £6700 for installers I definitely trust.

An additional factor is that we're eligible for Barclays' Green Home Reward, which is a grant of £2000 that they give on any heat pump install costing at least £2000. So for all of the installs above, except Octopus, we should be able to get that, which makes a huge difference!

In general you want to design (and thus size radiators for) for the lowest flow temp possible, the saving is about 3% per degree which soon mounts up.  So if the Aurora quote if changing fewer radiators are they also designing for higher FT?  Its worth bearing in mind that, in reality, FT is determined by the radiators and the house not the design, so whichever is quoting larger radiators will in fact end up with the lower FT.

The price differences with the Barclays grant are indeed quite large.  Perhaps you can persuade Octopus to increase their quote to £2001?  Presumably the trench is required because of R290 forcing you to site the product away from the house.

I am happy to answer any questions but in the end this is obviously a set of trade offs (with a fair few unknowns) that only you can make.

Posted by: @jamespa

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Presumably neither the meter box nor the EV point are at ground level so most of any leaking propane will simply drop past them!

Yep! And I agree.. the R290 placement restrictions are crazy prohibitive atm. 🙁 If R32 continues being phased out (and manufacturers don't add more 'safety feature' updates to reduce the leak risks) people are going to have an even harder time finding anywhere to install heat pumps on their properties! Ours is a semi-detached house with a big windowless & doorless gable end with no other properties anywhere near that side, and it's been incredibly hard to get people to agree to put a pump on it!

Posted by: @jamespa

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in practice you will almost certainly end up controlling on thermostat unless you automate it.

Ah, yes sorry I edited that bit to make it clearer you can automate the switching between curves in the app, which I think should be a simple one? Something like If OAT => 20, Then switch to one of the lower 2 curves I guess..? But yeah, I dunno why the other curves don't go as low!

Posted by: @jamespa

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In general you want to design (and thus size radiators for) for the lowest flow temp possible, the saving is about 3% per degree which soon mounts up.  So if the Aurora quote if changing fewer radiators are they also designing for higher FT?  Its worth bearing in mind that, in reality, FT is determined by the radiators and the house not the design, so whichever is quoting larger radiators will in fact end up with the lower FT.

So, this is a bit complicated, and where a lot of my Heat Punk time went. 😀
Octopus are basing their 5 radiator updates on their own room-by-room heat loss calcs, but I didn't like the fact that they didn't really attempt to balance the outputs to get consistent temps. Their planned coverage for each room ranges between 98% and 169% at their design FT of 50C, which would leave some rooms with pretty big shortfalls if we start trying to drop the FT down into the 30s. They're also only updating 3 out of 4 bedrooms, but doing 2 bathroom towel rails.

I really wanted to avoid fiddling with TRVs if possible (to keep things as open as possible), and I wanted to aim for a lower FT than 50 of course, so with my own room-by-room and radiator plan (which Adlar accepted), I attempted to get everything very close to 100%, at the exact room temperatures we find comfortable, at a FT of 35-37C. So the 2 new rads I requested are larger than Octopus was planning, and, because our current rads aren't that old, it seemed wasteful to replace ALL of them for new, when actually just moving existing large radiators into smaller rooms would upgrade that room, and should get things better balanced than Octopus's plan.

So all 4 bedrooms would be upgraded on the Adlar system. With the bathrooms, I'm happy to take a "wait and see" approach, since it's a bit more complicated to predict. We currently don't have the towel rails on in the summer so we don't really use them for drying towels/the room.

Existing hallway rads are already overspecced and could apparently handle 35C FT.

One thing I'm not really sure about is the ground floor UFH! I've got the original design specs from the UFH installer (from before our time), but the doc does make some assumptions (such as "a heating output of 50 w/m2 has been assumed". That sounds like something they should know..?), and it seems heat pump installers can only make assumptions when retrofitting to UFH too. Is UFH generally just... fine & happy? Any issues commonly found when trying to go for 35-37C FTs? I do find that the smallest circuit feels unheated more often since I reduced the boiler temp. 🤔 

Posted by: @jamespa

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Perhaps you can persuade Octopus to increase their quote to £2001?  Presumably the trench is required because of R290 forcing you to site the product away from the house.

I did try, and unfortunately not. 🙁 Octopus is very adamant that a 3rd party needs to do the trench, and Barclays will only count the invoice from the actual renewable tech installers, not other general contractors (even though they're ONLY digging the trench specifically for the HP). And Octopus won't inflate their quote either (no free money for them I guess)..

I would happily commission Octopus regardless of the price difference though (due to a higher likelyhood of long-term support and integration with potential new Intelligent tariffs).. IF they could put it anywhere other than in the middle of our tiny, silent, very nature-y, very actively-used garden. With the pump location being far worse for us, and their system probably being less efficient, and more expensive.. It just doesn't make a load of sense in my mind.

Posted by: @jamespa

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I am happy to answer any questions but in the end this is obviously a set of trade offs (with a fair few unknowns) that only you can make.

I definitely appreciate this, and am aware I've done a lot of waffling haha. It seems like at this point most things of concern have been sanity checked by you guys, which was my main hope and is very much appreciated!

As you suggest, at the end of the day the fact that Adlar is a less proven option is just down to our appetite for risk. Which I don't have much of tbh! And is why these decisions have been agonising, and why I've gone a bit overboard with my own research! 🤣 But, they do have good reviews, and the homeowners I've spoken to that live with their systems are happy, and.. I figure, if the kit started breaking down in <7 years, and the UK Adlar branch is no longer in the picture, I'd hope the much more well-established European component would still honour the warranty in some way. If it happens in 7+ years, I assume HP tech (and prices) will have improved by then and we might be glad to swap it out for something new anyway. Switching to a big hot water tank isn't something we're looking forward to, and maybe heat batteries or something else will be a better option for us in future!

It sounds like you have thought about this a lot and everything you are saying looks sensible.  A windowless, doorless gable with no properties nearby sounds absolutely perfect for a heat pump - its bizarre that this is causing a problem.  Its equally bizarre that heat pump maintainers wont go up ladders, how many commercial AC units do you see mounted on office/factory walls?

I cant really comment on UFH, I dont have it, others will need to comment here.

As you say fiddling with TRVs is the wrong way to go, you want as much open as possible.  I've got mine down to just one 'active' TRV in a guest room (out of 16 in total) and one fancoil, which modulates its fan speed according to its own temperature sensor but never shuts down.  Everything else is just pure WC and a one-time balancing on the LSVs.  Of course to do this and have it work when its 15+C outside means that the FT must go down pretty low  -  I have mine set to bottom out at an FT of 27 (FT is 42 at the design temp of -2).  You do, IMHO, need to be happy with how you are going to manage that with their prima facie crazy curves (which might also have the wrong slope given that they have been truncated at the lower end).

I think that a part of the problem with R290 is that there are (so far as I can tell) no rules (as in no nationally/internationally set rules).  So HP manufacturers have taken the easy way out, specified something quite extreme, and left it to installers to deal with the fall out - its the liability culture we live in.  At least Vaillant has recognised the problem in their press releases, it remains to be seen whether they actually do anything.