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You can pick up an UVC for £1k incl VAT. Doubt they would need 12k ASHP, something very wrong if they need that. I would if buying again just go Panasonic monobloc R32, they seem easy to tune and run well out the box just about silent - they are around £2.5 to £3k. May cost a little more than £5k, but you will have a heat pump of the correct size instead of some monster. UFH on 200mm centres, on ground floor and upstairs wet rooms (100mm centres). Provide provision for fan coils later if you want them for cooling, run at same temp as UFH. You need two zones at least, so use electrical towel rads in bathrooms to do this. Heat pump system simple wins the day, less cost to install, more efficient - no buffers or volumisers, no manifold pumps or mixers, no actuators or zone valves, just a diverter. If you end up at around 6kW and the pipe runs are short you only need 22mm or if you really want 28mm piping.

By way of comparison, below is a table of yield in litres of the mini store (with reheat at the rate shown), according to the Newark data, and a conventional cylinder of the same size (no real time reheat). I am assuming 10l/min draw off, the figures for the mini store improve at lower draw off rate and get worse at higher draw off rate. For the conventional cylinder I am assuming that the flow temperature is 5C higher than the cylinder temperature and that there is 10l of dead space at the top which cant be drained at the charge temperature. Bear in mind that the product is aimed principally at smaller properties which would previously have a combi, so the maximum yield is relatively modest compared to that for a more demanding property/family. If I take the example of an 8kW heat pump then the mini store yield is poorer, but this can be compensated in quite a few cases by raising the flow temperature by about 10C. That will incur a performance penalty of perhaps 30%, but the cost of the extra electricity would be significantly less than the cost of an annual inspection for a UVC. My own case (if my LPA ever gives me permission) would be an 8kW pump. My current cylinder is 140l and I run the current boiler at FT55 or FT50. I get enough DHW. Obviously efficiency (with a heat pump) would be better if I fitted a bigger cylinder than I have at present so I can run at a lower temperature, but there is only so much space in the airing cupboard, which is used for airing. With a 130l mini store and an 8kW heat pump I could get the same amount of DHW as I currently get by running at an FT of 65. The mini store clearly doesn't give the most efficient heat pump performance, but the running cost taking into account the annual inspection may be less or similar. The main attraction is circumventing G3. I could install it myself, wouldn't gave to get a plumber to certify and wouldn't have to get an annual inspection. Of course I could alternatively get the G3 qualification myself, but not requiring G3 also means that I wouldn't have to feed a 28mm pipe that will probably never get used in earnest through an awkward route in the house. I must say Im tempted, perhaps more so once they launch one with an immersion boss (which they say is coming in V2). In circumstances of relatively modest demand I don't think the trade-off is crystal clear. Obviously if you want to run showers at 20l/min or several showers in quick succession, then a large UVC is the only practical choice. But in this case you quite possibly aren't replacing a combi, which is one of the use cases at which the product is aimed. My feeling based on this analysis is that it has a place amongst the range of DHW solutions that is needed. It will be interesting to see how the market reacts. Draw off (l/min) 10 Inlet water temp 10 10l/min/10C Mini Cylinder + Conventional Store Temperature 4 kW 6 kW 8 KW 10 kW 12 kW 14 kW Cylinder Mini Store XS - 60 L Yield @40C (l) 45°C - - - - - - 50 50°C - - - - - - 58 55°C - - - - - - 67 60°C - - - - - 50 75 65°C 50 50 55 60 70 80 83 70°C 60 65 70 80 90 110 92 Mini Store - 80L Yield @40C (l) 45°C - - - - - - 70 50°C - - - - - - 82 55°C - - 50 55 60 65 93 60°C 60 65 70 80 90 105 105 65°C 75 85 90 105 120 150 117 70°C 95 100 115 130 150 190 128 Mini Store Fat / Tall - 110L Yield @40C (l) 45°C - - - - - - 100 50°C - - - - 50 55 117 55°C 60 65 70 80 90 110 133 60°C 85 90 100 115 135 165 150 65°C 105 120 130 150 180 220 167 70°C 130 145 160 185 220 275 183 Mini Store XL 130L Yield @40C (l) 45°C - - - - - - 120 50°C 50 55 60 65 75 85 140 55°C 80 85 95 105 125 150 160 60°C 105 115 130 150 175 215 180 65°C 130 145 165 190 225 285 200 70°C 160 175 200 230 275 350 220

Good news. Just be aware the cupboard it is in may well be lined with Asbestos cement board, so get that checked if you plan to modify the cupboard when it has gone.

I used Google as well, but didn’t quite define my search as well as you obviously did. Thanks also for the ‘how to search’ lesson - I shall endeavour to remember that👍🏻👍🏻

Ours is 1750mm x 2000mm and has the MHVR kit, hot water cylinder, buffer cylinder, two pressure vessels, the CU and the internet hub. There's enough room to swing the door inwards with enough spare to be shelved for overflow stuff like toilet rolls, washing powder and cat food etc etc.... No batteries but like others - not so keen to have them indoors.

Our plant room was designed to be in the middle of the house so shortest runs for everything.

My parents have a similar sized house 0.14 U-Value, less than 1x air changes, MVHR, triple glazing and get by just fine with an 8kW heat pump. We actually upsized the heat pump to heat the hot eater faster, 5kW was good enough for the heat loss calculations. However, they have a double height hall with a glass wall. It accounts for a very high percentage of the heat loss in the whole house (I think around 1/3 from memory). Even with the UFH flow at 50C it struggles to heat the hall to 21C when it is below 0 outside. The flow could be much lower for all other spaces in the house, I turned it up on the weather compensation curve for this reason. When I calculated the output from the floor area, I discovered it was not enough relative to the heat loss of a double height room. We have asked for an extra radiator to be attached to the manifold and put on the half landing. That seems to be what they are getting at, but that would be fixed by adding a radiator, a larger ASHP would have no impact on this issue at all.

Congratulations! It's been quite a long journey for you I'm pleased that you have reached this milestone.

Because the purpose of the MCS calculation and the MCS standards is to protect installers, not consumers. Simples!

Not sure that is a good analogy as wheel rims, once fitted to a vehicle, hang from spokes, while a solid cast wheel distributes the loads through all the 'spokes' (loads vary with the angle, but they can cope with tension, compression and shear forces, traditional spokes can only handle tension).

This one?

Actually despite me quoting my plant room it does not have the DHW tank (as this is better centrally to the house) also the UFH manifold is under the stairs, better for distribution and the MVHR is in the loft for easier pipe distribution. The plant room has fuse board, heating buffer tank, expansion tank and pumps etc, and a washing machine. Oh and a cupboard for all those bits and pieces you can never find 🤣

Bizarre, what happens if the ASHP malfunctions? Maybe they should factor installing 2 for this scenario.

I agree with everything above. We have a sort of plant room, but also stuff elsewhere. I never heard of plant rooms before this build, and really convinced they make much sense Ours Consumer unit, cat5 distribution and battery diverter box in hall cupboard by front door UFH and hot and cold water manifolds in utility cupboard. 2x MVHR units, one in another hall cupboard Second MVHR, old gas boiler and UVC, one PV inverter and battery in roof loft space (inside insulation envelope) MVHR expansion vessel and a few other bits in an insulated shed, that houses the borehole pump filters and second PV invertery.

I have a contrary view on plant rooms. There is a trend to put everything together in one plant room. But is that the best thing? Not always. It was brought home to me when I wired a friends house, a plumber, and his plant room contained all the usual things, the mvhr unit, the manifolds for the UFH. the consumer unit and the hot water tank. Shame was, this put the hot water tank at the diametric opposite corner of the house to the kitchen and main bathroom. I similarly had a "plant room" designated in the room above the adjoined garage. But as it evolved, the only thing in there is the mvhr unit, and a few of the heating controls and a pump. The rest of that room is now my workshop / office. The HW tank is in an airing cupboard in the corner of the spare bedroom, giving it the shortest hot water route to all the taps. The UFH manifold is in the utility room putting it central to all the UFH loops. The plumbing manifolds are under the floor under the bathroom with access through a ceiling hatch in the utility room below, optimised for shortest hot water pipe routes. Consumer unit is on the wall in the utility room for convenience. All network and AV gear is in the cupboard under the stairs optimum position for short AV cable runs to the 2 main televisions. It just made no sense whatsoever to try and put all this in one place.

I’m another that wouldn’t put batteries inside a dwelling, likewise an electric car in a garage attached to a dwelling. The fear of batteries combusting have got to me I’m afraid. For what it’s worth, my plant room is a cupboard… 1.2m * 1.5m. Just houses a cylinder, plumbing distribution manifolds and controllers for poo tank, Ashp and solar on a wall, it’s a compromise on size, but works. MVHR is in the loft as that was the best location logistically for routing the pipe work to where it needed to be, with the supply and extract at each corner of a gable. UFH manifolds are under stairs in a pretty central location.

I am so glad NOT to be a landlord any more.

One option might be perimeter lighting using LED strips pointing up towards the opposite ceiling pitch. Make the whole ceiling glow.

There are some adjustable LED downlights designed for small voids but you will have to search and check the void depth required. The specified void depth normally includes the plasterboard layer but check. Just one example Google found.. https://www.nationallighting.co.uk/nitropro-tri-wattage-360-recessed-fire-rated-4cct-8w-led-downlight-dimmable-ip44-matt-white?vat=1&gad_source=1&gclid=EAIaIQobChMI-I2y5sDghwMVJZdQBh0AIwcCEAQYAiABEgIHK_D_BwE Min void for that one is 45mm so would need 33mm battens and 12mm plasterboard. Get RGB colour controllable will be harder but.. https://www.lightingstyles.co.uk/adjustable-cct-fire-rated-led-downlight---bathroom-suitable but colour not fully adjustable. Just cool to warm. again 45mm void. If already battened can you add another layer of battens?

+1.

3.1m x 1.3m. Feels generous. One end has MVHR. The other end has cylinder and heat-pump internal bits. Will use some of the space for storage with wheeled shelving units which I will push around as needed and even remove if I need to access something big. A flexible space. (Personally I wouldn't put any type of house battery inside the house. Precautionary principle.)

While LiFePO4 battery chemistry is considered safe I still put it in the garage. I don’t have the room anyway. My garage is relatively big at 65m2 so have split the plant room equipment between it and the house.

Probably? I would perhaps paving slab or gravel over it, so that it is accessible.

So called specialist installers can be surprisingly ignorant technically. What if the mvhr breaks down? We don't design for that. A serious talk with the plumber or a change of.

if your soil pipes run perpendicular to the joists work out the maximum length of soil pipe into your equation as you’ll need to account for fall.

Definitely something odd here. But we don't know the details of your "well insulated" house. For another comparison my 150 square metre house has a worst case heat loss of just over 2kW for the whole house when it's +20 inside and -10 outside (a realistic winter temperature here) and is heated fine with a 5kW ASHP. There is a spreadsheet available on this forum that if you care to try it and input all the details of the house will give a very accurate idea of heat loss. I found even the detailed full SAP with all those same details over estimated the heat loss by some margin. Also if you do have a heat loss of say 7kW, then you will need more than a 7kW ASHP otherwise it would have to spend all it's time 24/7 heating the house and would have no off time and no time to heat your hot water.

Just another point for reference, we have a not very well built or insulated 190sqm house from 2003, heat loss was calculated at 7kw and have an 8.5kw Ecodan and it was fine at -6C last winter.

sounds massive, we are 210sqm, only difference is Rads passive std insulation and airtightness. We have a 5Kw Ecodan. We also have a large open plan diner, kitchen, living room but no vaulted ceiling. It’s an MCS install in our self build, his calcs matched my own.

Electric towel rads, I would fit those anyway. Do as many on here have done Do your calcs first Buy and install the heat pump yourself. Forget to mention in first post Our living room is 6m tall, has one wall is all glass, all other room circa 3 to 3.5m all with 5m² of glass except wet rooms.

Hi welcome Number of people make no real difference to heat loss calcs. Do you own heat loss calculations. All those numbers sound plain stupid. Our house from your description is similar to ours and our heat loss is 3kW. So sometimes well off. Are you a new build? What does you SAP report state?

We have an upside down house and it runs along the part of the back of the house (leading from a utility room) where we have no windows as we have a three meter high retaining wall. A good size plant room for ease of maintenance was something we planned at the beginning.

seperate stack pipe through the slab, and a dry drain to avoid smells. it was this or very similar. https://www.google.com/aclk?sa=L&ai=DChcSEwjMutqT3N-HAxWtnFAGHQthLqUYABAxGgJkZw&co=1&gclid=Cj0KCQjw8MG1BhCoARIsAHxSiQmdv4yA0pdq41GGWYQo0K-zzKZwfH4OHH1cJVCu_c6iAjAdt1xzaZcaAjicEALw_wcB&sph=&sig=AOD64_07J-Xz9knQqzSX1DoDgr3Rr--apQ&ctype=46&q=&ved=2ahUKEwjmlNaT3N-HAxW-UEEAHUukIrUQzzkoAHoECAcQJw&adurl=

Eeeek scream. Your house looks like it has been built to, or close to, Passive house standard so something odd is going on somewhere, I don't get why the double height space needs special attention and MVHR must have an impact as it recovers 80%+ of the heat normally lost in air changes.

Sorry, does not pass muster. Way too much maintenance polishing that bell. I presume that’s one of these modern ‘Ring’ doorbells everyone is talking about. 😉

Sorry to lower the tone but down at our end of town we won’t have a plant room, we will have a rather forward thinking plant encapsulation system (a.k.a. a little cupboard at the end of the garage). We’ve streamlined our data centre, patch panel and comms distribution system, it’s now called a Wi-Fi router. We’ve also recalibrated our multi functional audio-visual experience system and using the latest 2018 technologies we’ve managed to cover all the current state of the art functions with a smart tv and sound bar. Oh and we’ll have one of those new fangled DAB radios too. We’ve pushed the home automation system boat out massively in that we will have a couple of hive bulbs so some lights come on when we are away in our campervan. Through dedicated use of exactly what we do already we won’t have any cat anything cables or PoE either so we will save a few bob too. We will however, most importantly, have a whizzy coffee maker. But not in the plant suite.

Used my Heupar S04CG-5RG to do a basic (very) survey of my site. It worked very well once I got the hang of using the receiver. Seems to have a reliable range in sunlight of at least 30m.

Can I just mention that there are no economic benefits of having a mixture of underfloor heating and radiators, particularly in a small property when there is little point in having multiple zones. If you like underfloor heating and don't mind digging up your floors to install it then all well and good. But the heat pump will need to make the water hot enough to meet the requirements of the radiators and it is how hot that heating water needs to be that determines how economical your heat pump will be to run. Unless you have really large area radiators they will probably want hotter water then your UFH could get away with but if so then you need that water hotter.

Also go on renewable heating hub, tat where the book comes from

I don’t have the words to ease the wallet pain, however you’ve now got a really good excuse for the house not finished thread…. Someone else will need to bring the biscuits and cakes for now though.