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That's not correct. A 4P buffer is to allow hydraulic separation, allowing the emitter circuit to take energy at a different/slower rate than the ASHP adds energy, reducing short cycling. Thermocline/stratification is a robust phenomena that does not require balanced flow rates - it occurs in HWCs that do not have balanced flow rates, and have no baffles or features to promote stratification.

You'll be losing a lot of temp from the uninsulated pipe work. Can you measure the temp on the pipe into the buffer from the ASHP, just at the joint to the tank.

Keep an eye on the temp gauge, there's no circumstance where it should stay at 30°C. At 2/3 up the tank then when the ASHP is on it should mostly be showing a temp around the flow temp, and when the ASHP switches off, if the UFH is still running it will, after a while, drop to return temp, shortly before the ASHP switches back on. Flow temp is water temp coming away from the ASHP. The flow rates either side of the buffer do not need to balance, a 4 port buffer is there to allow the exact opposite, ie, the UFH to take energy from the buffer at a different rate to what the ASHP supplies it, it's what protects the system from short cycling. The biggest improvement you could make is some insulation on those pipes.

It would mean 0.714m³/m².h, rather than ACH, natural ventilation. For total ventilation you'd then need to add the MVHR ventilation (converting your 0.5ACH to m³/h). Or you need to convert the air permeability target units to ACH and add to the 0.5 ACH of the MVHR. Apologies, I shouldn't have included the "@50PA" on the MVHR figure, it would be just the m³/h. The *10% is to account for the 90% heat recovery of a PH certified MVHR. If we're keeping everything in ACH, and the target is 2 ACH, then total house loses from air flow is the 0.2 ACH (from natural ventilation) + (0.5 ACH * 10% (from MVHR)). If the heating engineers don't consider MVHR then then I'd give them this value. [physical air permeability testing (blower door test) in the UK tends to provide results in the m³/m².h@50Pa units, as that's what building regs uses, so you need to work out how to convert between them and ACH for your property] I'd ignore natural ventilation for the MVHR figures. The building regs airflow requirements are a minimum, so base those on MVHR only. I'd only consider natural ventilation figure within the total house losses, when sizing the heating system.

Is it a 4 port buffer? What size is it? What height is the temp sensor? Assuming 4 port (or 3 port) I'd go with flow temp control running off a weather compensation curve.

It's actually 8m³/m².h@50Pa rather than ACH. Each house has a different relationship between the two so you'd need to calculate the ratio for your house. (PH is 0.6 ACH as you say) Supposedly, the Building Regs change due 2025 (if Labour continues with the plan) for the future homes standard will drop to 5m³/m².h@50Pa. 20 is used for an unexposed area, 14 tends to be used for an exposed area. I'd keep it, but use the "rule of 14". But, infiltration losses should be based upon: (air permeability (m³/m².h@50Pa) / 14) + (MVHR flow rate (m³/m².h@50Pa) * 10%) The higher insulation and air permeability you target the greater the proportion of losses due to thermal bridging. Have you attempted to account for thermal bridge losses for your construction type? Most heat loss calculators include a "standard" psi value for typical construction methods, if you are mitigating thermal bridges you should adjust for this.

Hello and welcome, Sounds like your LPA is taking a pragmatic approach, which is as much as you can hope for. Look forward to seeing your plans once you are ready to share. Hopefully keeping the portal frame has not put you off the passive slab, depending on finished floor level versus the height of the pads under the columns there's a bit of extra detailing to do, but it is all "doable". I worked through mine with Advanced Foundation Technology Ltd and came up with a neat solution dove tailing the two together so they have some previous experience which may be useful to you if you've not already settled on a supplier. Have you thought of construction method for the timber frame? While the existing portal frame is quite an open structure, keeping the purlings in place (to keep teh LPA happy that it's a conversion) does make it awkward to crane a panelised system into place. I settled on a stick built solution but went with an I-Joist structure to allow lots of insulation. Good luck with your planning app.

pre-2015 discharges have to abide by the "Rules that apply to all discharges" section of the General Binding Rules. When you say "OK treatment plants", if you mean a (BS EN 12566) small sewage treatment plant or a package treatment plant then they are meeting the requirements of the rules, but if they are still on a septic tank as most "1940 to 1960s" properties would have originally been, then they must upgrade or get a permit (which they are unlikely to get without changes). Under the General Binding Rules the must have a plan to upgrade within 12 months.

Nope, they'll assume you've gone through the rules and worked out you can't discharge under them. Yes, but... pre-2015 still have to follow the rules, which likely means having a plan to upgrade within 12 months. If they don't have a permit, then they are under the rules, if they're not discharging within the pre-2015 rules they're at risk of a prosecution, but in the context of your connection, they are discharging "within the rules". If your discharge would be wihtin 50m of one of your neighbours (that doesn't have a permit) then you can't discharge within the rules. (but you could have done pre-2013) If you can position your discharge 50m away from the closest neighbour's discharge, then you can discharge under the rules.

Does the Culvert have have water in it for most of the year? Do your neighbours have permits or are they using the General Binding Rules? Can you not discharge under the general binding rules or is there a neighbour within 50m of your discharge point already doing so?

So you say. Fridges are typically at or above that level, washing machines and boilers far higher. I assume you have the same issue with those. Added to avoid an additional post: From the NoiseAwareness.org website. Some context for dBA levels

There is. There's a 42 decibel limit at the neighbour's property, legally enforceable. HP noise levels have been taken quite seriously since to some extent its constraining their role out in higher density housing areas. I believe this is the most recent government report should you wish to know more: https://assets.publishing.service.gov.uk/media/659bc3f2614fa2000df3a992/ashp-planning-regulations-review-main-report.pdf It's not going to keep everyone happy, but ASHP rollout can't wait for a 100% thumbs up from the population.

Hi and welcome, I'm not sure there'll be many members with experience of Scottish agricultural PD that can give advice. I'm not one either, but if it were in England I'd suggest that that the LPA are not convinced that your business is "Agricultural". Checking the definition in Scottish planning law: From what you have said you have evidenced, "Agriculture" stops at the rearing. To benefit from Agricultural PD the Use of the land and buildings prior to the PD must be Agricultural as must the use of the land and buildings after the PD has taken place. You may have muddied the waters with the slaughterhouse and food processing content which are not "Agricultural". The land and/or buildings you wish to develop under under Agricultural PD must also be part of an Agricultural Unit. The Scottish Planning definition is: In short, there needs to be an Agricultural business in place. Does your animal "rearing" amount to a business in its own right? and is the rearing taking part on the land and/or buildings you want to benefit from agricultural PD? and will the use of the completed development be in association with the rearing? It's likely that your local council have determined the answer to be "no" to one or more of those questions based on the evidence you provided them.

From what you have said, it's already 1 year in to the 3 year timer for finishing the build, and you are yet to get an offer accepted, let alone buy the site. The problem you have is the Class Q Rules have changed, so you can't submit a new Class Q Application for a 4000 sqr ft unit and reset the clock after May next Year. Going forward, you are restricted to 150m² per unit. This year is a transition phase between old an new rules, where you could submit under either rules until May 2025, but it would mean you acting quickly and carries a risk. From the questions you are asking it doesn't sound like you have experience of a similar build/conversion, so would be relying on professionals to pull everything together (Structural reports, Planning app, building control drawings, contamination survey, drainage survey etc.), and you may find it difficult to motivate those professionals to meet the timing you require. I'd suggest as it stands there is too much risk. However you could make a conditional offer on achieving full planning permission for a change of use conversion, using the Class Q as a fall-back. Although the LPA will be aware that the fall-back evaporates at the point there is insufficient time to theoretically complete the the Class Q conversion.

Our local LPA say they are protecting their Planning Officers who have been subject to abuse. They no longer publish which PO is assigned a case and will not respond to any calls/messages regarding a live application. If/When they come out for a site visit you'll be told there's no officer assigned, they now share duties. If you want to discuss an application you have to do a pre-app. They're gaming the system, increasing the cost of an application and reducing the time from validation to decision.

What were the outside and inside temps? Not sure that ~16°C in a corner is that bad, if it's close to freezing outside. What's under the door threshold? Is it block & beam on a strip foundation, similar, or an insulated raft? A quick calc has the inside face of the door at 16.7°C with an outside temp of 0°C and inside temp of 21°C for a door frame with a 0.86 Uf value. With a little thermal bridging that could easily drop lower.

My LPA has now gone the way of any many others and will now not have any discussion during the at planning application. They won't even tell you who the planning officer is and there's no way to contact them. It's made pre planning advice more or less compulsory. While I'd normally recommend a Planning Consultant, sounds like your position has already resolved the areas that they would help with. If your LPA will talk to you during the application I'd suggest going straight to a full Application, if not then use the pre-app advice service and hold your nose of the extra costs.

The conversation wasn't about your specific installation, I have no doubt a single zone works for you, although not in the way you visualise it. I responded to your point on how a single zone responds to a dynamic change: Which isn't correct for all houses, mine as an example.

Of course. The 28°C -> 22°C gradient in the slab is relatively stable pre-solar gain due to the room losses maintaining a 21°C internal temp and the slab boundary settling at a 1°C ΔT. (It's not really stable, there's a small hysteresis that occurs when the HP compressor switches on and off.) When the solar gain adds an additional 500W into the room, the air temp increases, and reduces the energy coming out of the slab, but until the compressor switches off the rising flow temp continues to push energy into the slab until the flow temp hits 28°C. When the compressor switches off the temp gradient in the slab does not remain fixed, the slab temp equalises through its thickness (2nd law of thermal dynamics), trying to get to a single homogenous temp, say (28°C+22°C)/2 = 25°C. If the internal air temp is lower than this then some slab energy will move to the internal air, if it is higher then some energy from the air will move to the slab. Either way the slab surface temp increases as room over-heats. The HP will be periodically checking the averaged return temp waiting for it to drop the bottom of it hysteresis. The slab warming in the over-heating room increases the averaged flow/return temp of the ASHP and therefore reduces the time the HP will run for and will fall short of the energy needs of room B, so Room B will chill off. Yep, compressor switches off, and the room without solar gain continues to take energy from from the slab, so the slab starts to cool. The over-heating room stops the ASHP coming on for as long as the cooling room needs it to in order to maintain its temperature, so it gets colder. There are no controls in the system to maintain the 22° slab surface temp, this is just a product of the temp gradients and boundary conditions. When the steady state is disturbed by a dynamic change the surface temp in any given area of the slab will change. It is not possible for the UFH to push 28°C water through a slab that averages a lower temperature without energy passing from the UFH to the slab until the air temp in the room is equal to or greater than the flow temp and the slab temp has averaged out at the flow temp. The warmer the over-heating room gets the shorter the compressor will run and teh colder the non solar gain effect room will become. For any given house its a matter of scale of incidental heating (solar, occupancy, cooking) and whether the temp changes away from target are acceptable to the occupant. For my house it would not be possible to run on a single zone and still allow the solar gain in. For days on end I will have no heating on in 50% of the house effected by solar gain, but on in the rooms on the Northern side. Those solar gain effected rooms require 0W from the ASHP and it is not possible to pass flow temp water through the floor in those rooms without a transfer of energy from the UFH into the slab, so those rooms would over-heat.

The output can't be 0W unless the floor temp of the over-heating room is equal to the the WC defined flow temp, while there is a ΔT between flow and floor energy will continue to be exchanged. From your data it appears that @ 11°C OAT your WC is setting the Flow Temp to around 28°C so it will continue to push energy into the 22°C floor, until the ASHP can't modulate down to stop the flow temp over-shooting the WC set target, when it will switch the compressor off. The over-heating room will cause the compressor to switch off before the non-solar gain room's energy requirements are met.

Hopefully that was installed with the ASHP and not a hang-over from a previous system, so is probably a buffer rather than a TS. TS are unsuitable for ASHP. You say the buffer is set to 35°C, do you actually have a thermostat on the buffer or a temp sensor connected to the ASHP controller? It could run a little more efficiently if controlled it via the flow temp or return temp, especially if you add a Weather Compensation curve so in mild weather the flow temp is lower and therefore more efficient, and in cold weather it raises it up. Hopefully your installer gave you a design flow temp - that will be for the coldest day, so gives you a good place to start from when creating the WC curve. That's pretty much how I run mine. I do have rooms set to slightly different temperatures and I leave the ASHP to run when it needs to through most of the day. I do block it from running between 22:00 and 06:00, but that's a personal choice and my HP can comfortable generate in 16 hours all the heat my house would need.

? Not sure how your ASHP is reacting to your floor surface temp, I believe it's reacting to the averaged return temp, but that's not the point. Creating a simple example with a two room house, Room A averages a 600W heat loss and Room B a 400W heat loss. The ASHP pushes 1kW into the house and the flow rate in the loops have been fixed to push 60% of the energy into A and 40% into B, maintaining the temperatures for each at their target. The 60:40 proportion is fixed as they are not zoned. Room A starts to receive 500W of solar gain and starts to over-heat, the warming floor of A starts to take less energy from the UFH and the ASHP, in time, modulates down to 500W. The 60:40 proportions are still fixed, so Room A gets 300W from the ASHP and 500W from solar gain, so with 800W total delivered to the room A it continues to over heat, but Room B is now only getting 200W from the ASHP, so starts to chill. The average temp across the house is fine but neither room is at its target temperature.

Which works fine for the room with solar gain, but your ASHP has just modulated down and the the rooms without solar gain are now not getting enough energy, so will start to chill off. At this point you need to change the proportion of the space heating energy that the non solar gain rooms get compared to the solar gain effected rooms, in order to maintain each at their target temps. It works for you so that's great, you appear to have put many hours into to getting yours to run correctly, changing settings on the ASHP controller that most domestic users wouldn't know where to start with, but for other houses there are better solutions. It is mid-September, so current COP isn't going to tell us much. I typically switch my system over to heating season around mid-November. Thankfully there doesn't need to be a "one size fits all" solution, there are plenty of options.

Thought that was the plan for the Future Homes standard, coming in next year. Not heard Labour commit to it yet though.

Not in my airtight (<0.1 ACH) house with MVHR. I choose to have the bedrooms slightly cooler than living areas, and office slightly warmer. Possibly. If you have a single zone, you can still adjust the flow rate of each loop so that you control what proportion of the total space heating energy is sent to each loop. You can set those proportions so the rooms are roughly the same temperature, or with some generally warmer and some cooler. But, you are then fixing that proportionality. So, whether it's a shoulder month, deepest winter, over-cast or sunny, each room will get the same proportion of the total space heating energy. It doesn't allow the space heating to react to dynamic events that change the proportion of the space heating energy a particular room needs. ie. solar gain, occupancy, cooking the Sunday lunch. Although UFH no matter how it is controlled will struggle to react to short-term dynamic changes. This would not work for my house that makes best use of solar gain (during the heating season), which effects a third to a half of the rooms in the house. The reported benefit of a single zone seems to be the elimination of a buffer, or more specifically a 4 port buffer. That's not necessarily so, you could still zone without a buffer as long as you have sufficient volume of water always open to the ASHP, ie. a loop or loops always open with sufficient flow rate, or a 2 port buffer/volumiser to meet the manufacturers minimum requirement. To me that feels like playing a game with short cycling so that you are just above the minimum requirements from the manufacturer. OK, but not ideal. With my install most rooms are their own zone with modulating actuators all controlled by Loxone and I have a 200l 4 port buffer. In the heating season the ASHP generally runs for not less than an hour and from my rough calcs. achieves a slightly better COP than "advertised". My only involvement with the system is to decide the start and end of heating season, other than that it looks after itself. On days with a few hours of winter sun, the UFH in rooms on the South-East and South-West sides will be off, but those on the North-East and North West will be on, but after a couple of over-cast winter days, all rooms will need their UFH on. If I tried to run it as a single zone then on those sunny winter days I'd either be overheating on the South side or cold on the North. I could of course block out the winter solar gain, but that would increase my heating costs and spoil the views. There is of course an additional capital cost for the buffer and extra pump and additional day-to-day costs for running the extra pump and minor standing losses of the buffer, so you'd need to justify their inclusion. The longer ASHP run times provided by buffer can improve the COP, but others say there is an efficiency hit to the COP due to badly designed buffers that experience "mixing". I can't comment on the latter as I've never seen any evidence of it myself. Personally, I wouldn't put a buffer together with an ASHP that was not a recommended combination from the manufacturer, which would restrict the options. The other benefits the buffer provide me is to circulate the UFH without the ASHP on, to redistribute solar gain, and to also run a wet duct heater/chiller on the MVHR without the UFH on. The energy transfer of the wet duct heater is far below what the ASHP can modulate down to so it couldn't be run directly off the ASHP. Just to add though, the wet duct heater/chiller can only "trim" temperatures, it's seldom used on its own.