Ommm

Having done a lot of reading of the service material, I'm actually reasonably impressed with Chofu. Grant claim to offer a 7 year warranty which is nice too. I think installers like them because they're just like a system or oil boiler install - all the controls are on the outdoor unit, with just a small control cable to a wall mounted keypad inside. I do have some wonders about support though: it looks like Grant would be the only source of parts, and otherwise you're left dealing with Japan. In theory Grant should provide all you need, but sometimes things don't turn out like that...

Thanks, I've been posting to that thread I thought I'd start a new one as that thread has rather got into the specifics of sourcing and installing fan coils, whereas I'm more interested in performance of ASHPs against air conditioning. What are you using for emitters for your ASHP in cooling mode? (We're east-facing with no shading which has lots of solar gain problems, but when you want to cool below night time air temp no amount of shading will help)

I'm speccing out an ASHP system with radiators at the moment. One of my requirements is cooling in the summer for a couple of rooms (ideally want temps <20C which no amount of passive measures are going to help with). While it's not advertised or supported by the installer I think I know how to put the ASHPs being offered into cooling mode, so I seem to have two options: Fan coil radiators on a separate ASHP zone, insulated pipework, condensate drains. Going to cost about £300-400 for each radiator plus associated electrics/plumbing works Separate multisplit air conditioning unit with refrigerant pipework to each room, wall mounted fan evaporator unit. Maybe £800-1200 for the A/C unit plus installation (perhaps some DIY but need F-gas for the refrigerant side), let's say another £600. ASHP is cheaper but not enormously so. The ASHP is easier to expand to other rooms by fitting more FCUs, although insulating all the internal pipework and running condensate drains would be annoying it wouldn't be impossible. ASHP is potentially quieter than a typical A/C wall unit. But I'm wondering about the relative effectiveness of each approach. With an ASHP in cooling mode you're pushing around cold water at 7C, and your temperature change is dependent on how much air you can blow past the heat exchanger in the FCU. With a refrigerant system the heat is being absorbed by the refrigerant evaporating. I can't help but think that the phase change of evaporation is going to be more effective than just shipping around cold water. So I'm wondering if anyone who uses an ASHP in cooling mode has any advice as to how it compares to 'proper' A/C?

On an iPhone 8 Plus I have the app NIOSH SLM (sound level meter) which has been calibrated against real sound level meters on specific Apple hardware, and I've been using this to measure various noise sources like our portable a/c unit. I'd be very interested to know what kind of noise figures people are getting. Not sure what a comparable app would be with Android - since there are so many phones it's hard to calibrate.

My installer has quoted for a Mira Element EV, which is pretty bog standard thermostatic. If I happened to want to play with this, can this or other thermostatic showers be swapped to a non-thermostatic mode? For example by tweaking a lever or swapping cartridges? I would still want temperature control, of course.

I had a look through the sites and most are Italy-only. I did find: https://www.promoclima.it/ who will quote for delivery to the UK (for 1x large-ish radiator fan coil about EUR60, which sounds about right, for 3x is EUR215, which is a bit steep but probably what it costs for 3 parcels to go UPS. Their list prices are probably ex-VAT, plus customs fees). They list shipping for most of the EU but not Ireland for some reason - worth asking, or presumably UK includes NI and maybe you have a friend across the border... (whether they will actually go through with a transaction to the UK is another question, but they let me get as far as payment) For the FCU that was EUR215 plus EUR60 delivery, Sabiana UK quoted £324+VAT plus delivery (which for 3 FCUs was £70+VAT). So not a huge deal in it if buying multiples. The alternative is one of the 'parcel forwarding' companies intended for online shopping that can consolidate onto a pallet. I asked SourcingItaly for a quote but they said they're out of warehouse space at present. I might try others, but not sure it'll be much improvement on EUR215, and probably pallets are a bit too big for many of them. Might make sense for more units though.

This is a bit clearer (my bold): https://www.ofgem.gov.uk/sites/default/files/docs/2021/03/drhi_essentialguide_forapplicants_mar2021_v7.pdf

I've had no end of problems switching supplier where they got the night and day readings mixed up (in different properties too). I'm waiting for Octopus to line me up with a smart meter so that they can push an E7 tariff to my meter if they want to, but will probably stay on the regular tariff. Although you could do something funky by switching tariff mid-year: E7 for the summer, regular tariff for the winter? Even more interesting if you have solar PV where you can offset the expensive day rate with your own generation. Still probably makes more sense to be on Octopus Agile or one of the EV tariffs though.

It is mentioned under a strange heading: https://www.ofgem.gov.uk/sites/default/files/docs/2021/03/drhi_essentialguideforinstallers_mar2021_v6.pdf It's unclear if that's solely about MVHR heat pumps or applies to heat pumps generally. If it was about MVHR the third sentence doesn't really make sense (MVHR forbidden, MVHR with cooling still forbidden, non-MVHR ASHP allowed?)

What size cylinder would you recommend for a 3/4 bedroom house (1 bath+shower room, possibility of another shower in the distant future) out of interest? Bearing in mind sizing for the property rather than the current occupants if you ever plan to sell it, and not assuming those future occupants having any particular usage pattern.

I don't have any experience in this area, but just to note that this setup is common in the US where it's called 'central air conditioning'. They use it for both cooling and heating - although some units eg in Texas only have resistive heating because they don't use it very much, they use heat pumps in places like Missouri where it gets cold and hot in different seasons: https://www.consumerreports.org/cro/central-air-conditioning/buying-guide/index.htm I can't recommend UK suppliers but I would imagine that it's more in the skillset of commercial A/C installers, where you might already have ducted air in say a hotel or office building. I would talk to people who do commercial HVAC and see what they say.

While I have it open, this is the info for Grant. It's why I'm not entirely happy going with a Grant system:

Thanks. Looks like Horne only have hospital-style enclosed shower units, or mixer valves that are designed to be hidden away. But good to know low-difference mixers exist.

Look up 'ventilconvettore' - there are quite a number of suppliers in Italy, where they seem to be popular. Here's a price comparison for example: https://www.trovaprezzi.it/prezzo_climatizzazione_ventilconvettore.aspx (for examples of suppliers that list prices, rather than the specific models they have there) As to who will ship to the UK post-Brexit, that's another question... (perhaps need a freight consolidator in Italy? Or drive to Calais...?)

At present we have washing up water come from the hot water cylinder which is only run when someone wants a bath. The dishwasher does 90% of the washing up, and other times there's usually a recently-boiled kettle next to the sink. So lack of hot water doesn't bother me - if it did, instant-heat taps aren't that expensive and running costs relatively minimal given the sink doesn't use a lot of hot water. If you run your cylinder at 48C, how hot can the shower water go?

Now I understand that if you have an unvented cylinder it's a regular hot water system and you can drive pretty much any shower. But I wondered... an ASHP runs more efficiently at a lower temperature. Yet thermostatic mixer showers tend not to work if they can't mix in some cold. One I looked at said it expected a 12C difference between hot in and outlet out. So you heat the water up to 50C and then mix it back down to 38C again. This seems crazy to me. Obviously, you need a thermostatic control because sometimes you're on the legionella cycle and the water temp really is 60C. And having cooler tank water means you get less runtime compared with mixing in some cold. But is there a mixer that requires less temperature 'headroom', and so if the input is 38C it would output something like 38C and not 26C?

I'm familiar with Carrier - they and the Japanese/Korean big brands are the air con units that we install in the middle east when it's 50C outside, and they keep going for decades. Many others can't handle it. Which is why I'm biased towards brands that sell lots of A/C units because they've been in this game a long time. That's why Chofu puzzles me: I've not come across them (they don't appear to sell a lot internationally) which isn't encouraging, but on the other hand they're not Chinese (which fall apart in middle east conditions). Lack of volume makes me worry about spares though...

I'm not sure if anyone makes vented cylinders with ASHP-suitable coils? So I suppose that reduces the choices down to how to boost the mains pressure...

My installer has recommended a Grant ASHP over a Mitsubishi 'because it's the better product'. I've never considered traditional boiler manufacturers for ASHPs - much prefer to go with a known air conditioning vendor who has been doing this for years. Anyway, I did some digging around and I think the Grant heat pumps are made by Chofu of Japan. Compare the diagrams from the Grant installation manual: https://www.grantuk.com/media/3710/grant-aerona-r32-installer-uk-doc-0136-rev-2-0-september-2020.pdf to those of the Chofu: https://www.centralheating.co.nz/assets/resources/Chofu-Operating-Installation-Manual-R32.pdf - they're identical in many cases. I've not come across Chofu before. Anyone have any experiences? Or with Grant themselves, for that matter? So I'm wondering how much to push for a Mitsubishi. What would you do?

Currently looking at an ASHP to replace an oil boiler and electric shower. One thing that's arisen is we have quite low mains pressure - 2 bar and 10 litres/min flow. What would be a sensible way to address this? It's a bungalow with a loft conversion, so there's not a lot of space for a header tank (~150 litre cold tank at present) nor much headroom, and access to the remaining loft is awkward. The hot cylinder is currently level with the shower so there's no head of hot water. So we won't have a lot of head for a vented cylinder or much mains pressure for an unvented cylinder. I see there's various accumulators that can be added as a reservoir, but how big an accumulator should I expect to need? I was looking at the Stuart Turner Flomate range - they have an accumulator (for increased flow) and pump (for increased pressure). We only have the one shower so how much runtime would you get before the accumulator is exhausted? Are there any other ways to make this work? Are all ASHP cylinders unvented?

I'd definitely be up for a shared order. I was talking to these folks: https://yuexinlengnuan.en.alibaba.com/ as they have a radiator-replacement FCU for ~$150: https://yuexinlengnuan.en.alibaba.com/productgrouplist-823836568/ultra_thin_fcu_radiator.html They do ceiling ones too - do any of these match what you need? (see also the other categories) https://yuexinlengnuan.en.alibaba.com/productgrouplist-823312868/ultra_thin_concealed_horizontal_fcu.html They quoted ~$320 for UK shipping. That's likely air freight. It'll cost roughly the same for a pallet to go by sea (~40 days) but multiple units could fit on a pallet. Do PM me for further plotting ?

Having done some digging around, I find there are plenty of fan coil units on Alibaba in the $100-200 range: https://www.alibaba.com/trade/search?IndexArea=product_en&CatId=&fsb=y&viewtype=&tab=&SearchScene=&SearchText=fan+coil+ They appear to be imported into the EU and rebranded as various local brands (found some in Greece, Bulgaria). Of course the suppliers are in China so you need to pay shipping and import taxes (but shipping from Italy might not be a lot different - how much does a FCU weigh?), and the unit price for small volumes may be higher. The main thing that's hard to judge is the quality. But a fan coil isn't that complicated, just a motor and some metalwork, so I wonder if it would be worth the risk?

We have a loft conversion with a long strip of east-facing glazing. It gets very hot in the morning and the windows are small so it's slow to cool down afterwards. I've fitted 50% window film which helps, but the heat has still got in by then. The existing uPVC windows also have perished gaskets so the wind comes through. I've been thinking of installing roller shutters on the outside to block the heat. The problem is that the existing windows are outside-opening casement, which will foul the shutters. Inside-opening casement won't work either. Which leaves me looking into sliding windows (openings roughly 700mm high x 1800/3000mm). It seems there are few suppliers of these, mostly in aluminium. Anyone have any experience? There are some more suppliers of sliding doors - is there a good reason why you can't make a short door into a window? There are also suppliers of uPVC sash windows - I wonder if those could be used in a horizontal fashion?

Do you reckon the fan coil units would make sense over a separate air-to-air split unit? I've been looking at an ASHP for heating, but we have a loft conversion which gets hot for about 6 months of the year. Window gain and lack of thermal mass are issues (it's lightweight wood/plasterboard construction, and we can't really add masonry for structural reasons), but it just has a lot of external area and in summer the temperature can sit at 20+ all night so there's nowhere to drain the heat out to. Being lightweight should hopefully mean it's quick to flush out with active cooling, and then added insulation (my current WiP) should help keep it cool, and more should reduce energy requirements. The advantage of ASHP cooling is only a single external box, and not having a separate radiator and indoor A/C unit (space is a bit limited for both in the rooms). I'd be looking at the radiator style fan coil units. Plumbing into a separate ASHP zone would be feasible, and a condensate drain could be tapped through the loft into the existing soil stack (although I'd be worried about it freezing and backflow of sewer gases) or out of the soffit (backdrafts of cold air from outside?). The single-panel radiators will likely need replacement for an ASHP anyway. On the merit of the split unit, it's simple, ubiquitous in other countries, easy to fit, and the failure modes are well-known. I also can't work out how it plays with using the ASHP for hot water - supposing somebody has a shower and the tank needs refilling, does the ASHP cycle between pumping cold for the rooms and hot for the water? Does that kill performance? I suppose it's not a big problem when it's that hot - people might like a cold shower! If you have an ASHP sized for heating a whole house (say 5-10kW) then would it be feasible to cool say 30m2 (obviously that rather depends on heat flux, but as a rule of thumb)? But I'm also curious how well the air to water ASHP compares for cooling with an air to air A/C unit. Is the A/C unit more efficient?

Thanks, lots of food for thought. My questions were made up as I thought of them so definitely a bit stream-of-consciousness ? A few clarifications... I've been looking at the RHI and the Green Homes Grant. We're eligible (I think) for 10K of GHG, which must be spent before end March 2021. Needless to say, all the installers are going to be very busy over the next 6 months (the GHG is a bit of a poorly thought out scheme where there's no time to train up any more staff). The GHG is paid upfront but deducted from the RHI payments, meaning you get the same money as the RHI but don't have to wait for it. That means there's a perverse incentive to spend more on eligible items, since it'll mean once you've expended your GHG you get the remainder as RHI (but you have to wait for that part). The RHI has been extended to March 2022, so slightly less pressure on that front. The boiler looks like it'll run inefficiently but is still operating - unless something else happens. The tank is almost full (got some at 19p/litre and used little over the summer). The main urgency is the GHG deadline and contractors' busy order books. I agree with fabric first approach. although there's a limit in a place you're living in. Loft access is horrible (no parts of the lofts are more than a metre tall, really awkward hatches), so I'm pondering about doing that insulation myself to avoid builders traipsing around the place. It would need to be carefully designed due to the construction - plain old fibreglass would be problematic (due to height restrictions). I've been in touch with a local company but they look like basic fibreglass-stuffers, as it seems is the insulation under the Energy Company Obligation (who want to tick boxes as fast as possible). The windows aren't anything to write home about but I'm not sure replacement would be covered under the schemes, nor make a huge difference (eg double to triple - since the existing panels look in good order). Low-E film may help a bit. Floor insulation and UFH would have been something we could have done before moving in, but we already had our hands full with redecorating, and there was a pandemic on so even basic supplies were difficult to get. We didn't forsee the boiler replacement being that imminent and we can't really tear up the floors at this point. I'd really like to do the flat roof but there are few approved contractors who will cover flat roofs, and the need for scaffolding means I reckon a non-approved contractor will be about 3K... and it doesn't leak at this point so doesn't seem urgent (I'd actually like to use the opportunity of having scaffolding up to add PV too - but that would be too much right now). Good idea about getting a new EPC. Is there a way to find someone who isn't just doing the estate-agent tickbox thing, but will do a proper assessment? (I have a Flir thermal camera and have been taking pictures of things - gives me some ideas, although we haven't had cold enough days yet). Some of the ASHP vendors say the next step is an assessment for about £300, which they'll deduct if we choose to go ahead with them - but that would mean picking a supplier which we're not quite ready for yet. I suppose that's roughly what you might pay for a decent EPC. Maybe a plan might be to get the assessment and see what difference loft insulation is going to make, before going ahead and doing it. Then we can assess what impact it would have on the ASHP sizing. We probably want to do the insulation anyway for cost reasons, but would be good to find out what to do first.