ProDave

But that PDF says at 0 degree air, it can output 6.58kW at 35 degree water, or 5.63kW at 55 degree water. And @ST3VE78 has two of them so double that. So at 0 degrees he should get 13kW of 35 degree water. So either his house is consuming WAY more that 13kW of heat and it can't cope, or the units are faulty. I don't think anyone has asked the obvious question yet, has it EVER worked properly?

You are missing out batteries. I always maintain up to about 4kWp batteries are not worth it as you can quite easilly self use all of it. But above 4kWp which both your examples are, then battery storage will ensure near 100% self usage, which is way more effective than basing your sums on the pittance of export payments and allowing most of what you generate to be exported. Before you consider that much PV, check if / or for how much fee, your DNO will allow it.

So it looks like it is the old ASHP's not able to do the job then. A modern ASHP will work in sub zero weather, mine has not let us down and continues working at -10 outside. You need a good estimate of the heat input required to properly size a replacement. Have any calculations been done?

This is exactly what we have, double glass doors facing each other on opposite sides of the hall. A very versatile arangement.

Which means you got it right first time. But a service void would mean you have a fighting chance of making some alterations without needing to patch it up and re decorate afterwords.

Not having a service void then? I would never build a house without a service void.

All my B&Q till receipts and some other similar ones with no name on them were accepted. They went in a different section (I forget) on the form and I included a note explaining that even asking for a "proper VAT receipt" that was the best you could get from B&Q

Intello is probably the best for this purpose, very tough. https://www.ecologicalbuildingsystems.com/product/intello-plus (website chosen at random to illustrate the product not a recommendation to buy it from there) I was lucky, I had not encountered a Tony Tray, but my builders had and it was they that suggested it and detailed it very well indeed (though they did not call it a Tony Tray) ALL joints and folds will have to me perfectly detailed and taped with a good air tightness tape like Sega Sicrall or Tescon Vana.

So now we know is is a house, not a small bungalow. I would hate a north facing living room that never gets the sun. So even if you want to move the living room to the back, I would knock through the two left had rooms to have dining area at the front, close to the new front kitchen (but move the doors so the dining area door is opposite the kitchen door to save an irritation) and living area at the back, further from the noise of the road and overlooking the garden, but still able to see the sun. You might well want to change what doors / windows open to the back garden. That would be a hell of a treck from the living room to the downstairs WC, you would be more likely to go upstairs from the living room.

That's what I am trying to establish. Swimming pool heaters often don't have a defrost function as they are expected only to run in mild weather. If that is what @ST3VE78 has then changing for a proper ASHP would work.

I believe the limit is enforced with a supplier owned circuit breaker (not fuse) and if it trips the supplier has to come and reset it. Well this is one way to limit energy usage, it makes realise how good the UK system is with often a 100A fuse being the only thing to stop excess uses. The domestic appliances are easy to control, i.e. don;t put your washing machine or tumble dryer on while you are cooking your dinner etc. But you have to assume the ASHP can turn on at any time it wants to, so if you are installing say a 12kW ASHP which might consume up to 5kW of electricity, then increase your supply rating by 6kW so it can be on at any time without having to interfere with any of your normal usage.

This bit is puzzling me. You say it is still able to heat the hot water. Are you SURE it is heating the hot water only with the ASHP and not turning on the immersion heater in the HW tank? That is something to establish first. i.e. get it to heat the HW and while it is doing so, measure the flow and return pipe temperatures. If you have turned off most of the UFH so it is only trying to heat a small area and it still can't get hotter than 25 degrees would suggest a problem with the heat pumps. Bit do that HW check first please.

I don't know those ASHP's but what is their rated power output? To give any meaningful input we need to know a LOT more about the house, total size and as above insulation levels. Did anyone do any proper heat loss calculations?

We are not used to this in the UK, even the smallest supply with a 40A fuse is about 9.6kVA So to get a higher rating, you pay more per year? What we know here as the standing charge. Does the unit charge (charge per kWh used) also go up? Going for the maximum would be another 105 Euros per year. That does not sound too bad?

This is a house that clearly repairs and upgrades. If you are happy with that, then go ahead. If you are expecting a house to move into without needing any work, keep on looking. Have you considered insulation? EPC? Ongoing heating costs or probably significant costs to upgrade and improve that aspect ?

Most houses in England were brick, "platered on the hard" so a rewire required a plasterer to follow the electrician. such a primitive idea. I was glad to move to Scotland where timber frame and plasterboard are the norm. Occasionally I met a plastered on the hard wall and hated every second of it.

Gas fire to suplement the poor central heating in a cold uninsulated house meaning sometimes it was the only room that was warm. A valve radio and a gramophone. Carpet on the floor that nearly fitted the room. A 100W light bulb.

Workbench and soldering iron. Audio system and huge CRT tv. Remember by bedroom then was "my world"

This seems to be the bane of these units, the way the error is handled and reported, is in my opinion poor. First the context please? Is this a new install? or an old install that has run for a long time and only just started throwing this error? Is it UFH, radiators or a mixture? I had this problem right from the start. The two issues were nowhere in the manual did it state what the minimum water flow rate was, and there was no means to measure it. A phone call to LG told me it was about 10 litres per minute approximately that it needs to see, but there was a bit of tolerance in the actual value the flow switch registers as okay. I then installed a flow meter so I could actually see the flow rate I was achieving and it was only just enough. So I installed a second circulating pump in the house in addition to the one inside the ASHP which improved the flow rate and solved the issues.

A lot of my earlier career was involved with servo motion control of machines, so you would do that to tune them, put a step change to the position demand and watch the resulting actual motion and tune it to get the characteristics you wanted, be that maximum speed, or no overshoot etc. You could do that quite quickly with the position demand stepping backwards and forwards, and adjust it on the fly and pretty soon get the response you wanted. But a house is much slower time constants, hours not milliseconds, so to do the same with the heating system in a house would take days. More akin to tuning the heating system on a furnace to get to desired temperature as quick as possible without overshooting.

It can go crumbly in old houses, usually due to damp. But the same cable pulling issues applies to whatever you use. If there is no service void or duct, then any wall covering material will need cutting holes to thread new cables through with the patching up afterwards. Just think yourself lucky this is not plastered on the hard brick walls............ For fishing cables, this tool is up there amongst my "I could not do my job without it"

So if the developer does not exercise his option after the 18 months are you free to do what you want with the plots? Do they (did they) have planning permission? Is there room (without knowing the dimensions) to divide the front and put another house alongside the existing? Garage would have to go to make access I suspect.

My take on service voids. For just cables, a service void made of 25mm battens works well with 12mm plasterboard and 35mm back boxes. Safe zones are your friend. As long as you have one socket on a wall, you can run your socket cables horizontally all around the room at socket height in your service void. Then should you want to add an additional socket anywhere, the cable is waiting for you. If you want run a batten horizontally at that height making it easy to fish any new cable along the wall. Adding new cables is all very well but where are they going to / from? In each bedroom I left a strip of floor board at each end with no tongue and groove and screwed down. So it should be possible to lift the carpet, unscrew that strip of board and feed a new cable down into the service void below. What have you against plasterboard? Fermacell is an alternative but a lot more expensive and harder to fit

To get a neat cut I would be looking to rig something up to make a "table saw" out of the grinder with a fence, so you can slowly feed the beam through to get a neat cut. Or if you have a table saw, see if you can get a grinding disc to fit it?

That looks to crying out for a house in the back garden. Is that what the house to the right of yours has done?