Brilliant subject and something I have been thinking about for a while, I am quite certain of 2 things right now.

1, there are some new 3rd party control options coming to market soon (I am hoping at installer show) that will enable us to better control and temporary control undersized emitters and start designing whole house heating rather than room by room, hear me out! So we have been whole house designing as well as room by room for over a year now, what we find is where say 3 emitters are undersized in the home 3 others maybe correct or slightly over. We look at all of the emitters in the whole house how they sit next to each other and if they will effect the areas short, lets call this keep the doors open design, I think you follow me lead.

2, Adia is a very good solution (so far in my testing) for exactly this, it can be manipulated safely to stretch the DT to maybe 7 for short periods but not cause the ASHP stress, this gives us a bit more usable energy transfer and allows the undersized rads to use more of the heat moved, its also runs the ASHP between 20 and 60 DegC Flow, it just works it out and hunts for a SCOP of 4, imagine like boosting a room and then relaxing.

I think from an AC point of view V ASHP point of view they are not faster installs as such and the biggest issues is the lack of skilled labour, the risk of getting the install right for your heating engineer to change the boiler for an ASHP V a new boiler is all in the capability and confidence of the installer, Adia looks like it may largely address this, I genuinely did not commission or balance the installation we did (which made me feel uncomfortable) I turned it on and let it sort it all out for itself, it works, the DT was perfect, every rad ran at capacity and the ASHP bolted to the side of it ran like a dream so far. To add but this is a story for another day, I have not paid 1p for any heating or hot water for 6 week so far, the Adia has been further tweaked (I asked for and they game me a very special permission) I tweaked the perimeters to make sure the ASHP cannot draw more than 2.5kW of my 3.6kW solar inverter and Batt set up so I truly only use batteries and solar 1st and leave my home a spare 1.1kw for other items. My energy for April and May 2025 was around 30KW per month from grid and everything else form solar set up, this year I used 26 and 29 respectively. The ASHP has done 870kW of heating so far, the years before were powered by gas, so for all the heating now by electricity but no more electricity use from the grid than last year or the year before, its effectively free so far. This systems has 2 heat meters and a shelly monitor on it so its quite accurate.     

@ashp-bobba thanks for those comments, I was going to name check you in the hope of a response but now I don't have to!

My perception, rightly or wrongly, of Adia is that it is too expensive (and perhaps should be designed to be installed temporarily and then retrieved) rather than being cheap enough to leave in place permanently.  However perhaps I am wrong here and things have moved on.  

In the ideal situation to the 'distress purchase failed boiler in a house definitely under 6kW', the cost to the end customer would be < say 1500 after BUS IE less than a replacement gas boiler.  With the right kit and subject to some conditions (but accepting that 'MCS lite' has got to be a lot simpler and a lot cheaper and that it may be a product for some instailers but not others), is this even remotely achievable?  It feels like it might just be but I'm not the one doing it!  

Posted by: @jamespa

↑

In the ideal situation to the 'distress purchase failed boiler in a house definitely under 6kW', the cost to the end customer would be < say 1500 after BUS IE less than a replacement gas boiler. 

It does not sound impossible to me (if it is replacing a system boiler), but the barriers to that MCS lite would have to be lowered.. Like if it could be NAPIT-HPlite or NICEIC-HPlite. Will be a bit too late for us to wait for it..

@batpred I was more thinking about doing it in advance and getting rid of the whole "oops it's failed panic" mindset. It's a transitional process which also means it's much more consumer friendly even if it's not perfect.

Otherwise I think it's much like an A2W retrofit in most respects except that the costs are usually a bit lower, the problems change and the houses that are hard or easy differ.

The more fundamental problems like "why do I have to do all this paperwork when I can put in awful electric heaters that use twice the power without any" need fixing in both cases.

Posted by: @etchedpixels

↑

@batpred I was more thinking about doing it in advance and getting rid of the whole "oops it's failed panic" mindset. It's a transitional process which also means it's much more consumer friendly even if it's not perfect.

Otherwise I think it's much like an A2W retrofit in most respects except that the costs are usually a bit lower, the problems change and the houses that are hard or easy differ.

The more fundamental problems like "why do I have to do all this paperwork when I can put in awful electric heaters that use twice the power without any" need fixing in both cases.

 

Thanks for the comments.  Are you suggesting 'awful electric heater's as an interim measure or permanently and who are you thinking about when you say 'why do I' - installer or customer.

I think the answer to both from a customer standpoint is running cost.  That of course is not an answer to the paperwork question which lies with others who also have to step up to the plate IMHO, but one step at a time!

@jamespa Sorry - in the abstract - why can I install one electricity sucking heat device yet another that uses less power is treated with all sorts of bogus complexity.

Posted by: @jamespa

↑

@ashp-bobba thanks for those comments, I was going to name check you in the hope of a response but now I don't have to!

My perception, rightly or wrongly, of Adia is that it is too expensive (and perhaps should be designed to be installed temporarily and then retrieved) rather than being cheap enough to leave in place permanently.  However perhaps I am wrong here and things have moved on.  

In the ideal situation to the 'distress purchase failed boiler in a house definitely under 6kW', the cost to the end customer would be < say 1500 after BUS IE less than a replacement gas boiler.  With the right kit and subject to some conditions (but accepting that 'MCS lite' has got to be a lot simpler and a lot cheaper and that it may be a product for some instailers but not others), is this even remotely achievable?  It feels like it might just be but I'm not the one doing it!  

The Adia Thermal is about £1500 so if you have an existing cylinder that is in good condition then you can off set it against this, equally if you have a lrage number of rads that are say 80% correct the Adia will allow you to not have to change these as well so you could offset it this way. That said, it is another cost if you do have to change some of these items later. My 210ltr cylinder with a 0.75m/3 coil heats up in 48mins from 35-55, I must admit I did not trust it until I have seen it more than 20 times, the 1st few times I just assumed its a fluke but nope, always less than an hr for 30 deg lift. What it does is it pushes the ASHP up to 62-68 Deg Flow and than runs the system gentle to top up that last couple degc, just above the set point.

We unfortunately did not install it all faster than the 5 days standard, perhaps we were being cautious as it was our 1st and we may get quicker but it has been said it saves a day on the job compared to a standard installation, if it does then that would also off set some cost towards it. TBH I am going to look to install a few more so I may just discount them by a bit and offset it further so its cheaper than a conventional system.

I think you are onto something and we just need to find that way that it works in stages or we have the control to make use of existing system structures and we programme the system to operate closer to a boiler for a short period of time.

I would just offer the customer a single rented ASHP A2A (which would be free of charge) in one central room of the house, tell them to place their water on electric and allow them to rent that from us for 10 weeks FOC until we could complete the works for them, chuck in some 1kW oil heaters for the bedroom and they would be covered with some heat and some water, no one would freeze it would just cost perhaps £10 a day.

I also think I could design and develop a fast connect ASHP A2W system that could be fast clamped to the existing heating systems and rented to the home owner until we all had the stuff ready to install a permanent system. Something like this exists in the boiler world for plant rooms and district heating systems when they have major breakdowns as you cannot leave multiple homes with no heating. I would even design and biuld a trolly to pull the ASHP around with. Why manufacturers are not coming up with this stuff I do not know, I have about 10 ideas a week.

Provided the rig is rented no renewable tech is installed for the heating at the property, grant still applies, provided its temporary then noise rules would be not breached even if in the wrong place just for a short while and provided it covers most or some of the heat it would be a temp solution, even a small 4kW system would do on 32mm rubber lines fast clamped to the existing circuits. (would also be a good way to see how it performs)

Posted by: @etchedpixels

↑

@batpred I was more thinking about doing it in advance and getting rid of the whole "oops it's failed panic" mindset. It's a transitional process which also means it's much more consumer friendly even if it's not perfect.

@etchedpixels

Doing the a2w in advance of panic is what I managed to get to. 

We had a few boiler failures and plumbers advising to get a new boiler. But we are lucky that we have no safety issues. 

Weather not being too cold, we managed to get it going again for the hot water.

We are over 1 month just in the estimates stage for a pump. I cannot see it taking less than another month to have the pump working..

We are also not typical in the sense we even knew what the process would be like.. 

I also doubt many people would take this long to be able to choose a pump, if their boiler was having constant failures. 

Posted by: @ashp-bobba

↑

My 210ltr cylinder with a 0.75m/3 coil heats up in 48mins from 35-55, I must admit I did not trust it until I have seen it more than 20 times, the 1st few times I just assumed its a fluke but nope, always less than an hr for 30 deg lift. What it does is it pushes the ASHP up to 62-68 Deg Flow and than runs the system gentle to top up that last couple degc, just above the set point.

That's really good info and presumably could in principle be achieved without adia.

I have for some time questioned the business case for a cylinder replacement, but of course get push back.  You have shown it's doable and I would be willing to bet without doing the maths that if you are heating dhw on a night time tariff the business case to swap the cylinder makes no sense at all.  I like your rented rig on flexible pipe ideaa too although from a customer point of view the 'packaged solution' which the supplier can cost up front still matters, because if they have got a rented rig from supplier x they are tied into supplier x and this needs the firm quote to be secure.  However if the supplier can quote the rig buys time for the actual install.

Having had a brief read through some of the comments, it seems very clear to me that swapping to a HP as a distressed purchase if your gas boiler breaks down will almost never happen, even if it would be the better solution!

Posted by: @jamespa

↑

I have for some time questioned the business case for a cylinder replacement, but of course get push back.  You have shown it's doable and I would be willing to bet without doing the maths that if you are heating dhw on a night time tariff the business case to swap the cylinder makes no sense at all.  I like your rented rig on flexible pipe ideaa too …

Are you suggesting heating dhw using the immersion heaters? 

Regarding flexible pipe around the cylinder, I am curious as to what is the reason for having copper in a permanent installation?