Archer

As an aside to my post above... We got our smart meter home energy display fitted today - so I can start to have a play about with the SAHP to see what real world efficiencies it is achieving with our hot water. There seems to be scant information online about this so I guess it might be useful for others. Will put something up when I have a chance.

Working through ideas for our retrofit and looking for advice on whether there are any benefits in keeping the heat source for the heating and hot water separate...? Here's my thinking - we currently have an old gas fired warm air heating system which is coming out; we have a newer vented hot water cylinder heated by a solar assisted heat pump ("thermodynamic panel"). The question is whether we leave this in when we update the system - because it's only 6 years old and cost the old owner c.£7k to install - or whether we just put everything through the new ASHP we are planning on installing. In my mind, if we left it then it should mean a cheaper/ simpler install for the heating system, needing a smaller ASHP. Also, are some of the installation problem people experience due to the added complexity of running heat and hot water concurrently - with different flow temperatures etc? Maybe I've got this wrong...? The downside with leaving it are that the SAHP "Magic Box" we have was installed by a company that are no longer trading. There's very little uk information about these systems generally and my concern is what we do to get it serviced or when it breaks completely. If it costs another £7k to replace it would be ridiculous. Sort of leaning towards leaving it in with the option of fitting a combined hot water cylinder/heat pump in the future. I didn't even know these existed until stumbling across them on this forum! Any advice or thoughts welcomed. Cheers.

This is really useful thanks @DamonHD. It's always worth asking a question on Buildhub. Awesome forum... The rabbit hole that I'm now exploring is whether spending money on PV to offset increased energy use will actually be more cost efficient than significant extra insulation. I'm sure others have been on this journey, will share any interesting findings.

I know absolutely nothing about VIP's but my instinct is that they would be incredibly hard to DIY install and probably not suitable in walls where they could be accidentally punctured over time? PUR board with a conductivity as low as 0.018 sounds very interesting though, do you know who supplies this?

Proctor list the Lambda value for Spacetherm as 0.015 W/m2 so considerably better than PIR but you're right, it's actually not as good as I thought. The literature online seems to suggest that you can use about half the thickness of Aerogel for the same insulating performance in PIR - that value suggests that it's somewhat worse than that - and costs around £250/m2 (for c.15mm)

Cheers, hoping Damon responds with some words of wisdom. On airtightness, yes I heard that for detached houses (ie. with a relatively poor form factor) that airtightness starts to become more significant than insulation. It also feels like it will be harder to sort out though. We've got what looks like a pretty well installed and maintained polythene VCL between the plasterboard and the studs. The loft is well insulated but very drafty so planning to tackle that as as relatively easy win. Other than that though I worry that airtightness might be difficult to drastically improve. Ideas welcome though

Hi All, Embarking on a home retrofit and considering options. Our house is 1970s timber frame with 75mm mineral wool insulation in the (90mm) studs. We might be able to fit external wall insulation to the 1st floor which is cedar shingles but the ground floor has brick cladding and a cavity... So... Looking at options for IWI, will probably do it room by room rather than a big bang and I like the idea of Aerogel because it wouldn't need a huge amount of extra space to make a big improvement. The cost though is hideous. This is a long shot, but wondering whether anyone here managed to find an importer from China or elsewhere that makes this product more affordable?

Exactly! We are mulling over whether to rip out the warm air system though and potentially getting a new ASHP system for ufh or fan assisted radiators... So there is a secondary question in my mind about whether this SAHP is worth retaining when we modernise or whether we would be best off having everything off a single reputable heat pump manufacturer. It feels a bit hard to know without any performance data, or certified test data.

I'm going to "re-ressurect" this thread because I've just moved into a new house which has one of these systems installed, about 6 years old now and cost the last owner nearly £8k by the look of it... It appears to run our DHW - a 160l cylinder, and just ticks away in the background with a single LED showing the tank temperature. The blurb says that it will heat up to 55 degrees and shuts off, then starts again after a 5 degree drop. So far it seems to work but the temp has hovered between 45-51 degrees. The blurb says that it runs a weekly legionella cycle using an immersion - although I've not seen this yet, so no idea. The manufacturer (Magic Box) seems to have gone out of business but the British SAHP company sells boxes that look identical so I'm assuming it's the same outfit. On the plus side, the system looks very straightforward, they offered a 10 year warranty on the panel and 5 year on the main unit / compressor. From @Jeremy Harris post above, it would seem that this is at least a legitimate technology. We have gas fired warm air as our heating so I'm dubious that this is saving money, but it may at least be reducing carbon emissions. I would also like to know if anyone else has one of these systems, how they get them serviced or repaired and if there is a simple way to calculate what COP they provide in use. I'm a bit wary that the immersion is doing most of the work.

Thanks, that was my (limited) understanding as well, presuming that I was missing some technical wizardry though... Because in heatwave conditions surely you would have air with higher humidity potentially and even at higher temperatures you'd likely see condensation and moisture with a flow temp between 16-18 degrees in some conditions. Maybe the risk of serious drips is low or mitigated somehow... Everyone 'real world' experience is incredibly useful.

Thanks, that would be awesome. I'm trying to get my head around the "light cooling" idea, and how meaningful this would be in practice. From reading the Jaga literature they output significantly less in cooling than heating mode anyway, which means you'd probably need to oversize the rad's to really benefit. This could be worth doing anyway, because the fan at max "boost" speed is really noisy - nearly 50db - so avoiding the need to use this setting for long would be beneficial. Jaga seem to think you can get (up to) around 3 or 4 degrees of cooling from the light cooling function, running water chilled to 16 degrees without it condensing. I haven't spoken to them yet but it's not entirely clear what's special about the system that couldn't be replicated in a DIY route as others have posted above. I did read somewhere about an optional temperature/humidity sensor that you can purchase as an add-on, but the rad's with the DBH module (ie computer fans) are already seriously expensive. It might be cheaper to get a unit with a condensate pipe and tray but it's hard to know how often you would need to empty them

Hello, sorry to jump on this thread, but interested in the Jaga radiators and wondered if you can provide a quick update now that they are installed? It seems that you can size them similar to conventional rads if replacing a gas boiler system with a low temp ashp... The "light cooling" function is also very interesting. Any advice on what Jaga are like to deal with, UK suppliers and product warranties, how noisy / effective they are in use and also whether the cooling works in a meaningful way? It looks like a very good product, any feedback appreciated. Cheers

Thanks Steamy Tea. By a thermal model, do you mean with certain modeling software, or in more general terms? I would like to do both of those approaches (ie. some upgrade of the fabric + some "tech" to update the heating and energy systems). Depending how far the money stretches, my instinct is fabric first but the govt £5k grant seems a good thing to grab while it is still available if possible. Could it work to use a thermal store or heat battery charged on off peak electricity from the ASHP? In which case a COP of 2.5 - 3 might be acceptable and basically equivalent to running off gas. Or an actual battery I suppose and run everything in the house off the E7 rates but the battery cost for this might be prohibitive.

Yes that's what I am trying to work out... Naturally cautious but also naturally supportive of a solution that could be rolled out to millions of hard to heat homes. Looks like they have successfully completed 1000's of social housing retrofits already + have a degree of government interest. The science seems pretty solid, the company doesn't seem like a cowboy outfit with very thorough sub-floor inspections prior to spraying. They also have instructions for access hatches etc. The "un-mortgageable" scandals tend to come about when you have cowboy operators flooding the market which this firm doesn't look to be at all, but it's always a risk when doing work that can't easily be "undone". They seem to have a BBA cert though and this recent govt report refers to them by name when covering "spray foam" as a method. Would be interesting to see if you can get an insurance backed warranty for the work.

Has anyone come across this system/supplier before or have any general wisdom to share? It's a prop-tech company using a robot under the timber sub-floor void to map and then spray a closed cell foam insulation to encapsulate the joists from below. Always wary of this sort of work but this looks well thought out at least, they have building physics research base from a university partnership and conduct a survey first to check the moisture content of sub-floor timber + number and position of wall vents. The blurb says that they avoid electrical cables and in our case there will be minimal pipes (looking at a warm air ducted property) What do you think? https://q-bot.co/

Hello all. Been following this thread with interest. We are in the process of buying a 1970's house with a warm air ducted heating system in place. We don't have much info yet because this is pre-survey etc but there is loads of useful information in this thread. Hadn't even considered the possibility of asbestos paper in the ducting. The house appears to be timber framed and we want to (over time) renew the first floor shingle cladding and add EWI. The ground floor looks trickier because it has a brick skin but we will probably add a thinner layer of IWI. If the suspended ground is uninsulated we are considering using a spray foam system like Q-Bot which would also encapsulate any heating ducts. It would seem that upgrading a warm air system, theoretically at least, gives us the option of introducing whole house cooling via an Aquair HIU with an ASHP as the primary heat input. It's also quite attractive that these seem to allow for summer night time ventilation without heating or cooling as a way of purging built up heat. @Gooman (or anyone else) - it seems like it should be possible to run the system with lower warm air temperatures if the house has higher levels of insulation. 80 degrees rules out heat pumps & even high temp models run inefficiently with a COP of 2 or less. Hybrid systems are not permissable under the govt Boiler Upgrade Scheme which rules them out unfortunately. It looks like there are models now that do reasonably well in mild weather generating up to 55 degrees (ie. The Hitachi Yutaki S80 HT, COP 3.63 @ 55 degrees). Cutting to the chase, my question is whether there is any accurate way or working out how the insulation level could affect the required warm air temperature to avoid a situation where you specify an expensive system and then have to run the heat pump at an expensive and inefficient setting rather than sticking with gas which could be half the price? Obviously the alternative for us would be to do the insulation work and address the heat pump down the line when electricity pricing is more competitive with gas. It just seems crazy from a policy and climate change perspective though...

Well... we got on, eventually and finished the extension! Really pleased now all that the work is done, but it was a stressful year. We had big problems with our builder, also with leaks into the flat below and various other things. So pleased with the end result though and we learned a lot by doing lots ourself and commissioning trades after the builder disappeared. For your questions, I can't say too much more than my original post on the 45 degree rule. I don't think the extension ever complied with it because it projects 3m out, less than a metre from a bedroom window. But the neighbours didn't mind and it ultimately didn't change much in reality because the wall matched the fence height before pitching upwards. The planners visited the property and ok'd it after our architect wrote to them. I think it really helps if you're neighbours are onboard with proposals so definitely consult with them early. We learned that there are usually solutions to the issues you come across. Our kitchen shared the open plan fire issue that you've described above. There are various possible solutions to this - auto misting systems; fire doors on magnetic closers or hidden fire curtains for larger areas. Several maisonettes in our area have the same layout and BCO wasn't that concerned about the issue (or dedicated escape windows for that matter either). We stressed about it lots and even followed up with emails but in the end it just got waived through. Good luck if you move forward with it all

If you've got decent water pressure and a smallish house or flat then combi's are great because they only heat the water you use so no storage losses and they never run out of hot water, plus you save tank space. Oversize the lps to avoid issues with pressure dropping when you turn on the hot tap... We never had issues with a decent shower but they take much longer to run a bath. Bigger houses, then a system boiler is better

I installed a Vent-Axia HR100R in a bedroom that was suffering from condensation and mould in the winter. It worked wonders and was quiet enough to run at night with the windows shut. Would recommend for that sort of use. I can't comment on models with a summer bypass, but as above it's not really the same as active cooling. They work slowly and continuously so no substitute for opening windows. You can get acoustic wall vents but I imagine that would be expense.

Not used this, but interested in any experiences you have if you go for it. Looks like an alternative to stick built timber frame that might be more straightforward for an amateur if you can get a decent saving against a factory built pre-assembled panel system. Be interested in whether they have any British accreditation (LABC type approvals) and whether it works out cost effective against other options. Why was Glavlock of interest to you compared to all the other options out there?

Because there is less scope for neighbours and planners to object if you stick to PD rules? That's my understanding of it, worth checking with the duty planner though or even the Building Control team once you know what you want to do.

Speak to this guy who beat you to it! Built a roundhouse with his son as a lockdown project. https://www.google.com/amp/s/www.bbc.co.uk/news/amp/uk-england-norfolk-52737762 I'm aware of the CAT and Lammas in Wales. Incidentally, for anyone in here who hasn't yet visited the Centre for Alternative Technology, it is a great day out (obviously not at the moment). They have a water powered funicular railway. I think you need to be realistic about what you are trying to do. It this is a place that you will live and bring up a family; potentially wanting to sell on in the future, then all of the health, safety and property laws will apply to you, same as they do to everyone else for the same reasons. Other alternative communities still have regulations applied to them (for example traveller communities). As said above, you can always try doing this with a temporary building first (or just try to get away with it). Depends whether you are aiming to do this in using an authentic, traditional technique or because you fancy the lifestyle. If it's the latter them it shouldn't be too difficult to build something which complies with the regulations - will also be a bit easier to live in long term as well. Good luck, please post your progress up here if you move ahead!

Could you use shuttering to raise the slab depth? Agree with others, you probably want at least another 2 inches concrete and depending on what it will be used for possibly more insulation

Agreed, we got a good price and the material cost for silicone render is significant. I was most impressed by the basecoat, it's a waterproof fibre reinforced cement product that you also use as an adhesive with external insulation. Pretty bullet proof stuff and looks good when finished.

We had a thin coat silicone render on polystyrene though and it looks great. They are about 7mm thickness when complete so it may be that the weight of other render systems is not appropriate for direct render to ICF/Poly? Used a system from EWI Pro and it sounds similar to what you've been quoted. The basecoat went onto jablite graphite eps boards which have some texture and there was no roughing up required. Other than that the method was identical to what you've been quoted except there was a primer applied between the 2nd base cost and the top coat silicone render and we didn't need a spray on top. Price for ours in London was about /£60m2 for a small extension job 25m2, but no spray pump needed.