JohnMo

Also note what @Seren161 say about timings. We were similar also, but house had no water, heating, kitchen bathrooms etc. So was not habitable. We managed to finish it within the year so started paying full tax at end of year 1. You should only be due the extra tax from June 22. So 6 month worth. I Would 'move in' so to speak, either, you wife or kids, so as not to pay the surcharge.

I have an Atag, super quite, especially when doing central heating. I think Viesmann boilers lets you you do two zones at different temps with different compensation curves as well a different temp for the cylinder. I think the way to have a fall back is to have tcvs on the rads, but set them a couple of degrees over your normal room temp. Then balance the system to get the room temps correct. Worst case, you stop weather comp, set up as normal and away you go. An X plan still gives you the ability to run the cylinder at a different or the same temp as CH.

There a few things to get your head around. No need for geofencing or remote control, the basis is the heating runs all the time at as low a practical temp it can. The longer the heating runs the cooler the flow temps can be. You are trying to match heat loss with the amount of heat given from the heating system. What's the point, efficiency - less gas used, due to gas to heat conversion rates above 100%, I am currently running at around 110% efficiency. That means my DHW effectively comes free compared to running mid 90% efficiency. Most heating system run in the high 70s to 80s% efficiency. Solar gain etc. The closer the heat emitter is to the room temperature the more self modulation that occurs. An UFH or radiator system, works by being hotter than the air around it. The bigger the difference in temp the more heat it transfers. The closer the temp the less heat it transfers. The boiler output modulates based on return temperature. So using the above. Room at 20 degs. Sun comes out, room warms up to 23, radiator gives less heat to the room as the delta between to room and radiator has reduced, return temp to boiler doesn't drop as much, as less heat is given to the room, so boiler ramps down its output, because it tries to maintain a set DT between flow and return temp. Radiator is then cooled. Sun goes away room starts to cool, the reverse occurs. It's taken me a year to get to here. But I took all the actuators off the UFH manifold the other day. There were doing nothing, just powered for no good reason.

X plan, just run weather compensation/ load compensation from the units controller, why do you need a T6 controller at all?

The only thing I would add, your fan power usage is defined by the Specific fan power, measured in (W/l/s). System pressure drop adds to fan power as the fan runs higher up its curve for a given l/s flow rate. So really introspective of how many MVHR units the same power is used for a given flow rate. In fact if two units reduce the duct length it could be argued a low fan speed is required due to lower system pumping losses. So less watts are used for the same flow rate.

I toyed with the idea for our build. Looked and came to conclusion if you want them to last you need to pay attention to a possible cold bridge between the SIP and foundations. A lot of the plans I saw had a good cold bridge at that location, which could lead to moisture being developed due to condensation, then rot etc. The same would be true for timber frames in general. Other than that as long as the wood is kept dry it should last.

Re reading this, they have given permission to install with a noise clause. Have they actually asked you to demonstrate that you comply with the clause, or is it accepted, if you install you comply? If you don't have to demonstrate or prove anything, and really they need to ask for that explicitly, just install. Then take it the clause is the council just playing, let's cover our arse, just in case there are complaints.

The other tack would be go direct to your MP, if that fails direct to the press and social media. State the clauses are impossible to reach and effectively your local council is banning ASHPs, then state all the environmental reason why the government says we must all install heat pumps to save the planet. Name and shame the council.

Still wouldn't bother

Our bath has been used once in the last year, I wouldn't bother. Plenty of other stuff to get on with.

Unless you are a commercial or industrial application, then the BS standard it not applicable to a domestic situation. It clearly states 'Scope 1.1 This British Standard describes methods for rating and assessing sound of an industrial and/or commercial nature, which includes: a) sound from industrial and manufacturing processes; b) sound from fixed installations which comprise mechanical and electrical plant and equipment; c) sound from the loading and unloading of goods and materials at industrial and/or commercial premises; and d) sound from mobile plant and vehicles that is an intrinsic part of the overall sound emanating from premises or processes, such as that from fork-lift trucks, or that from train or ship movements on or around an industrial and/or commercial site.' I would revert to the council, and ask them to define the correct standard to use, as that one is not appropriate to a domestic situation. And also state that MCS-020 is the appropriate standard, copy the wording directly from the introduction. MCS-020.pdf

Fans basically work on a watt per m3 basis, so 2 or 1 unit will use the same amount of watts for a given m3/h. Downside is really 2x the amount of filters.

No - it's easy, each unit looks after its self, as long as the air going in and out of each unit is balanced, they are happy (even if it's not they are still happy). They don't care where the air comes from, it's just air it's compressible and it moves about easily, it's not the same as a hydraulic system. One of my units supplies air in to the bedroom and the other sucks it out from the ensuite.

Once the heat pump has got water circulation around the buffer it's not interested in any other part of the system, except when the 3 port valve opens the flow path to the hot water tank is open. So things that affect flow, Flow restrictions - filter blockage - really the most likely. Flow restrictions - pipe size and length. Assume your piping size is ok, how long are your pipe runs, after about 20m on 28mm pipe the 7 or 8m pump could be running out of capacity.

It actually says no more than 3 starts per hour. So 10 mins run time, 10 on, 10 off - X3 cycles. Also saying 10 to 20 could be desirable, but in a general context not specific to heat pumps. So if you need 32L in your system - so yours is big enough not to need a buffer, at 69L. Just run as a single or two zone system and make sure your open system is always big enough. Questions Do you need Trvs on the radiators? Could you balance the system instead? Do you need more than one thermostat?

I also installed a horizontal batten at the bottom, make attaching skirting boards easy. Did the same at top of wall also. But all my wires ran around the house at the top of the wall.

Still confused as they only control a single loop, not sure how they would be a benefit or be attached, so one can control lots of loops

That's a low loss header not a heat exchanger, the auto vent on top is the give away. I would be tempted to disable any immersion until you figure things out. I would wind the trvs to max, and bring flow temp down 10 degrees. If rooms are not getting up to temp add a few degrees. When most the house is the correct temp, balance the rest, to get them where you need room temp wise. Night setback should be on the HP flow temp not the trvs, otherwise you gain little or no benefit. Treat the trvs as limit stops for room temp rather than controllers. Reducing flow temp is key to good a CoP

Little confused what the 2 Salus auto balancers will do, when you have 23 loops? That will only control DT on 2 loops. What happens to the rest? Common theme today, making thing way more complicated that they need to be for no good reason. People must be on holiday, plenty of time to over think and make as complicated as possibly. Conversely I took all my actuators off today, so now running everything as a single zone, one central thermostat only set a couple of degrees higher than target, running WC. Even the Salus actuators were never moving because all loops were alway open.

Really you need a u value better than 0.15, under the house (ground) will never be warmer than about 6 deg. Ventilated area will be at outside temp. So heat will travel down rather than up given half a chance. The worse the U value the more heat from the UFH is lost downwards, so the higher the flow temp needs to be, so you run the flow temps hotter to compensate... Will leave others to advise on the voids.

Over temp un-likely, over pressure also unlikely unless caused by freezing. What pressures are you operating at? What levels of Glycol are you running or are you using freeze valves? We had some freezing nights in April but the days were warm so heating was basically off. Could that of been an issue or are you just freezing the heat exchanger and have no glycol protection or not enough. I think if you are running freeze valves you need additional protection for the heat exchangers via secondary heaters SCOP /CoP is a result of flow temps and or short cycling. How many zones? Buffer or no buffer? Low loss header? Could you reduce the flow temperatures, run longer and at lower temps? 42 at 5 sounds high for a heat pump system.

Could your grandmother change the temperature or switch on the heating, if the answer is yes, wonderful, if no, does it belong in a house. You get run over by a bus, could a 'normal' electrician or plumber fix it? Without spending hours scratching their head? See above. Mines confusing to most plumbers - because I have a big buffer cylinder.

Unless the insulation is really good under the floor in the new and old parts I would only expect high flow temps, not the best performance and large heating bills, when compared to radiators. Are you planning for carpets or hard floors? In the kitchen living dining you will have about 3 loops, the lounge another one or two loops and toilet another, I would treat these as a single zone. Locate the manifold in the cupboard under the stairs, borrow heat from these loops to heat the hall. Locate a single thermostat in the hall to control the lot. Balance the loops to get the room temps where you want them and so they all heat up at a similar rate. Your spare bedroom and en suite I would install radiator and towel radiator.

Strange how the first diagnosis thought process is the tech has failed, not check the bulb or the fuse.

Plus UFH is a slow low temp system, linking to a PIR is point less, the room will still be cold when the person has up and gone elsewhere. If I walk into a room switch the light switch and my light doesn't come on, I change the light bulb, sorted. When I go out I switch the light off. Living in houses for last 59 years, never seen a normal light switch need to be changed. Plenty of bulbs have been changed though.