IanR

If you are targeting a high level of air-tightness, self adhesive gaskets for small wiring penetrations and gaskets + tape for large penetrations such as ducting. Sealing to your air-tightness layer. Mine was the external t&g DHF egger board, so all gaskets and tape went to the outside sheathing layer (under the cladding):

So it does...should be a doddle then! But (c) is for the Change of Use of existing structures, (e) is for (isolated) green-field sites.

I think you should run 2 UVC's of around 350l each, but have some control that only brings the 2nd one into to play when you need the capacity, ie. a "party" mode. It will save quite a lot of standing losses on the system when there are only 2 people in the house. You would need to include the unused cylinder in the Legionella cycle every two weeks. There doesn't seem to be a lot of ASHP cooling experience with the installers. Probably due to it being disallowed on RHI up to a couple of years ago. It is "relatively" simple, as long as you pick an ASHP that can do this out the box (There's an add on for the Nibe and you need to use the SMO40 controller I believe) But, I don't believe standard UFH controllers can handle cooling (they couldn't when I specced in 2017), and not all installers will know how to get the UFH actuators opening for cooling. (assuming you'll have multi-zones with potentially different temp requirements) I'd assume on the build you mention you are considering some home automation. If so make sure it can control UFH actuators for cooling as well as heating and don't bother with a dedicated controller for the UFH manifolds. Edited to add: The Nibe's mentioned need 100l each of buffer (or permanently open UFH/Radiators) so a 500l buffer seems overkill

If you are running a split system ASHP rather than a mono block, then this discussion regarding energy losses via the pipes run between the ASHP and the UVC (and buffer) are not relevant to you, at least not the calcs. and losses discussed here. There are much lower losses with the small bore pipes that run between the 2 units of a split system, hence they are recommended for installs where the ASHP is up to 50m from the indoor unit. You can achieve that through the UFH and a single buffer that is either heating or cooling at anyone time. But I assume you plan to provide heating and cooling simultaneously, via large bore ducting.

Larger pipes for same duct size means less insulation = higher U Value = higher energy losses. Correct, the notional extra 44W is when the ASHP is heating the DHW Cylinder. So not for very long each day ie. 1 - 2 hours perhaps. A lower wattage, depending on flow temperature, for when the ASHP is supplying heat for Space heating, which may run for more hours per day depending on your property heat losses. 8°C is the ground temperature, which is fairly constant all year at 8°C - 10°C Not without knowing you DHW usage and Space Heating demand, and doing a long calculation. But, for every hour the ASHP is running the loss is around 0.5 pence. PV will contribute, but you can't run an ASHP solely on PV. (unless the array is very large and supported by battery backup) It is a long run, you need to insulate well, or perhaps choose a split system ASHP, where the losses are less due to small bore pipe, however this brings a part of the ASHP in to the house, which while it is quieter than a Gas-combi boiler, is not as quiet as having the whole unit outside. Bring the UVC and UFH buffer as close to the ASHP as you can Hot & cold buffers and chiller coils, sounds complicated, are you installing offices and heating/cooling via air?

Hi & Welcome... and good luck, Para 80 has got to be the hardest way of getting planning. Fingers-crossed and you get positive feedback so that we hear more about your "truly outstanding and/or innovative" plans.

+1 to this. Recognise the risk you are taking on. If you are installing, then you are likely receiving a kerb side delivery, so responsible for handing and any damage from that point on. I had around 96m² of glazing and doors Installed for about £8K iirc, with 16 man days for the install, delivery costs, consumables, hiring lift equipment, contingency to cover corrections and repairs - it's a premium, but removes the majority of risk and arguments about where damage was caused.

I was told by the Installers the recommended Max distance from (a mono block) ASHP to UVC (not just the distance outside the house) is 10m. I assume the manufacturers' COPs and SCOPs etc. are based on that Max. I put my UVC quite central in the house so had a 20m pipe run, 15m of which is under the slab to the ASHP. To mitigate the extra length I used a pre-Insulated twin-pipe duct from Rehau - the Rauvitherm SDR DUO 32+32/150 with a claimed U Value of 0.26 W/m-K A quick hand calc suggests that with a flow temp of around 50°C and a ground temp of 8°C (I've used the twin-pipe duct for the underground portion of the run) the energy loss is around 11W/m (7.25W/m for a 35°C flow temp) For your 10m run that suggests quite a small 110W loss when heating the cylinder, and less when space heating (assuming lower flow temp). So with a worst case COP of 2.5 that shouldn't be costing you more than 44W extra electricity into your ASHP. A small loss, but with you for the entire life of the installation.

That's the unit I have. It's subjective, but It's quiet when running normally, makes a bit more noise when defrosting. I have mine positioned adjacent to a bedroom wall, close to an opening window. With the window closed I can't hear it. We're very rural, and my light-sleeping wife can hear it at night if we use that bedroom, when there is no other background noise. Compared to the modern gas combi-boiler I had in my last house the ASHP is significantly quieter within the house. Inside the house I would not know whether or not the ASHP was on. When outside, during the day and with a little background noise (we have a dual-carriageway around 1km away), you'd need to be within 3m or 4m of it to notice it is on. When it first switches to defrost there is a louder noise that is audible from further away. It defrosts only occasionally in spring, summer or autumn. Outside of the heating season the ASHP runs two or three times a day for 30min to 60 min. A. Not ideal, you can avoid being that close to a neighbour. B. Yes, positioned as close as possible to the UVC location and at least the Minimum distance from the wall. I think Nibe recommend 150mm, but I went to about 500mm C. Not ideal, the longer pipe runs will reduce efficiency as you will have to run a higher flow temp to get the same heating and cylinder temp. D. Not when you have Option B. Risk of vibration noise transfer to inside the house that could be difficult to resolve. Edited to add: I'd not install any noise shielding at the start. Retrofit if you are sensitive to the noise it produces and can't move the run time to a time that doesn't effect you.

With a 500l tank that would be a flow rate well above mine to deplete all the hot water in 20 mins. However, that's neither here nor there. Leaving the hot tap on full for 20 minutes is not a use case I've ever done, so even though my system could do it, it's not something its designed to do. Needing multiple 15 minute showers at 38°C is a use case used regularly, so the system is designed to cover that. And for times we have guests and there's a higher DHW demand the Hot Water is switched over to "Lux", so the tank is lifted to 55°C. I'm glad we've moved the needle, even if it is only a little. You were previously stating ASHP are for "niche" builds, and a dead technology.

Not sure what "20 mins full bore" would prove or dis-prove. What matters is if the heating and DHW system is designed for the worst case use in the house it's installed in. Unless our winter temps drop to -20°C for long periods, winter has no effect on the ability to produce hot water, just the efficiency it can do it at.

Really? you'll have to explain how you worked that out. Your bias is making you jump to incorrect conclusions. What you are seeing is an ASHP reacting to DHW usage.

I know you don't want to hear it, but an ASHP works perfectly for a family of 5, and as the tank temp seldom drops below 47°C, I'm turning mine down a bit to push the COP up further. Please offer some data/figures to show how it doesn't work, rather than conjecture.

The Government are backing Heat Pumps, and are changing the landscape to enable their mass use, so I have to disagree. Why not? works fine for my family of 5.

Dave, you need to look in to how Hydrogen is going to be produced in sufficient volume to heat homes. That's after it has satisfied the need for long distance HGVs, Ships and planes for which there is not an electric alternative. In short, it's not going to happen. Hydrogen will be the niche when it comes to heating homes, where using electricity is just not possible. And for those houses that have to rely on Hydrogen the costs will unfortunately be higher than electricity. No need to come around, just work it out for yourself. In my case there's 500l of water at 50°C. Nobody needs endless/limitless hot water, they just require enough to suit their needs.

The issue I have with Dave's statements is that we don't actually know what his issue is as he won't provide any detail of his experience. If he'd provide some detail for a discussion we might be able to help drag his head out of the sand.

Not sure what you are expecting the passage of time to do. He's provably incorrect now.

Not really, just makes a lot of ignorant statements about a subject he appears to know nothing about.

Welcome to the forum. Are you after Planning pitfalls with Class Q or design & engineering pitfalls for the conversion? What are you trying to achieve? Long-term home for yourself? Do you have aspirations for a Passiv Haus type build? Is there a mezzanine or are you trying to introduce one? Have you got any pictures? Is it a portal frame, with shallow pitch roof?

The DV1100 I mentioned is PH Certified and designed to the same standards as their domestic units, so noise levels are comparable. When the house is occupied I run it at 20% with no discernible noise and switch it down to the minimum 12% when unoccupied. I have the boost set at 55%, which is about the limit for hearing "wind" noise from the outlets, and still no noticeable noise from the unit which is in a 1st floor storage area - all my habitable space is on the ground floor. Boosting at this level clears the bathrooms relatively quickly after a shower, and stops kitchen odours travelling anywhere else in the house while cooking. I also have a purge setting that I use to help purge heat at the end of a warm day, if I can't open up the roof vents due to rain. That runs at 80%. Sound from the outlets are noticeable if you are within 2m of them and there is a light hum from the unit. I wouldn't describe it as intrusive, but I don't tend to run it for too long on this setting. Since mine is a converted cow-shed, with a 6.5m ridge height, my volume is particularly large in relation to the floor area. From memory it's about 1650m³ within the thermal envelope.

You could consider a small commercial unit. I have an Airflow DV1100. I understand balancing is more difficult with 2 units. I got Airflow to design my system and they were against two smaller units, plus it was cheaper to go with one slightly larger unit.

I may back away from that statement a little... The installation instructions show the horizontal tube having to be assembled to the vertical, but no wiring connections being made, so they have a trick coupling for making that joint, which includes the electrical connection, and on theirs it rotates. Really quite clever. Unless those couplings can be found as an "off-the-shelf" item, then it's likely the joint would need to be up-sized a little so that the wiring can be carried through it and into a slot in the horizontal tube.

They kindly supply some "basic" 3D CAD, which is helpful The drop is 2300mm. If you can find similar glass spheres on another product or available as a shade then the rest of it is easy. You do need the supporting wires, if you want it in the thin tube they are using.

No it won't. Heating Oil is 42p per litre and 10kWh per litre so at 90% efficiency of an Oil Boiler = 4.67p per kWh A heat pump has only got to get to an average COP 3 to be cheaper - that's pretty easy. The OP is actually using LPG, which is more expensive than Oil. That's rubbish. I've never run short of hot water with a family of 5 and a 12kW ASHP. DWH efficiency is unrelated to insulation and air-tightness, so the same for everyone.

It's not really as simple as that. At current pricing electricity is around 3.5 or 4 times the kWh cost of Gas. Gas boilers are up to 90% efficient, so if you are going to use (renewable) electricity to heat your home, you need an electric heater that is 350% to 450% efficient (averaged throughout the year), for it to have the same day-to-day running costs. With a heat pump, it is possible to achieve and exceed this. If you don't have access to gas, then the comparison to electricity is much more favourable, as you have to spend much more on every kWh of energy you purchase in the form of oil or LPG A heat pump is more efficient with a low flow temp, so larger heat emitters (UFH and large rads) and a large water cylinder, allow flow temperatures to be reduced. The lower SAP score suggests a higher energy loss due lower levels of insulation and/or poorer air-tightness. This means that proportionally larger heat emitters would be required to achieve the same low flow temperature. For UFH that would mean closer spacing of the loops, or for radiators, even larger ones. Undoubtedly a heating system can be more easily designed for low flow temperatures with a house that has a better EPC score, but that doesn't mean they can't work in a house that doesn't. The capital cost is a different matter. If you are not already planning a renovation then the cost of changing heat emitters to UFH and/or large radiators to accommodate a heat pump has to be considered. And if you are planning a renovation, insulation and air-tightness should be high on your list, so however you are heating your home you need to buy less kWh of the energy required.