ProDave

We have discussed before, an unvented HW cylinder fed with mains water, there is no way for bugs to get in, so no need for a high temperature. Mine heats to 48 degrees only.

Their little infographic talks of a temperature range from 118F to 78F That's 48C to 25C In a typical UK house with indoor temperature 20C and outside temperature much less than 20C, I fail to see the relevance of this 48 to 25C band they are talking about? I could see it stopping, or substantially slow a house from heating inside in a very hot climate? Is that it's aim? Oh and it looks remarkably thin and like a multi layer foil type product and I don't think a lot about them. If it really is a pcm then surely even that would need some mass of material to store the heat in, not an ultra thin sandwich of materials?

I fitted a repair coupler in our first house, with UFH in pug mix, after we changed the shower layout slightly and fitted a bigger shower tray, and jig sawing the opening for the shower trap resulted in a fountain. Oops, especially as it was me that laid the UFH pipes so I should have known.

Unless you are having full MVHR, building regs stipulate you must have an extractor fan in a kitchen, and there are different extraction rates for extraction via a cooker hood to extraction elsewhere.

You would be doing exceptionally well to self build for £1000 per square metre. That would put your build cost at £300,000 We just got under £1000 psm finishing a couple of years ago and doing 5 years of a mostly DIY build. Most are now saying with the price rises since then that you would do well to achieve £2000 per square metre, I will let you do the maths on that figure.

What @Onoff needs is a WBS in his bathroom.

So the structural warranty providers certificate is what they want. That is after all about the only use for it.

Have you considered just emptying a can of expanding spay foam in there?

I would be surprised if it has frozen. Much colder here and our unheated sun room has not gone below 2C yet.

Try it and see. At 37, radiators will not "feel warm" but will still deliver heat to the room. But it may not deliver enough heat so try it and see.

Yes run the flow temperature at the lowest that will deliver enough heat into the house. What is the temperature at the UFH blending valve set to?

It really should not be frosting up much now. the worst temperature is just above freezing where the evaporator will be below freezing and the moist air will condense and freeze. Once you get a day or 2 of air temperature below 0 there really is little moisture in the air, and icing is very rare. -7 here last night and daytime high of -2 and hardly any defrosting.

Yes that spreadsheet, based on simply physics and some sums, is also pretty much bang on for my house as well. FAR better than the EPC which was fed all the same information that over estimates my heating usage by some margin. Today was one of those "good" winter days here, yes it was cold, but still, and clear blue sky, and plenty of solar gain from the low sun, and as good as it gets PV generation at this time of year.

What I was getting it is radiators or UFH upstairs, or as we have, nothing because the house is so well insulated. Flow temperature should be easy to find on the indoor control panel. You want that as low as possible, radiators upstairs may force it to be higher. DHW can usually be on a timer but if not it will just re heat the tank when it needs to. Keep DHW tank temperature down to no more than 50C, Many of us find 48C is the sweet spot.

Defrost mode is quieter than normal on my unit. But different ones may work differently. To defrost mine seems to do the following. Stop the fan and the compressor. Actuate the 4 port reversing valve. re start the compressor only, not the fan. Run for a minute or 2 until the evaporator has warmed up and thawed (presumably using a temperature sensor) Once the evaporator has thawed, start the fan, and a puff of steam comes out. Stop the fan and compressor Revert the 4 port valve Start the compressor and fan for normal operation. It is a surprisingly quick operation, but it does draw heat out of the house doing so (more correctly sends chilled water to the house while doing so) Mine makes most noise when it is running flat out, compressor and fan at maximum speed, which is usually in the latter stages of DHW heating when the cylinder is nearing it's set temperature so the flow temperature from the ASHP is at it's highest. Some basic questions: Who built the house and how well insulated? What heats upstairs?

For use under 11M which is most domestic buildings?

I would still put ALL the insulation following your green line so all insulation is at the roof level. but that only shows 35mm PIR which is way to little. I assume you will be insulating between the rafters as well, leaving a ventilation gap above it?

I would insulate the whole roof space as in all the insulation follows the line of the roof, easier to detail and you don't have to worry about a cold eaves space. Even better still if it is not too late for you is make it a warm roof (insulation on outside of trusses) really easy to detail and makes a very nice cosy house. This is one of the decisions I am best pleased with.

To adjust the temperature, turn the white valve just below the pump. You can adjust the flow rate through each loop, the flow meters are the two things on the top manifold, prise the red cap upwards and then you can turn the black part of the flow meter in it's thread to adjust the flow rate in each loop, so the one that is heating up too fast, reduce it's flow rate. Be careful you can unscrew it too far and screw it right out, then you get wet.

I can see why yo can't do much above the stairs, but there is no reason you can't insulate the wall below the stairs, that will be about half of it insulated. And a thick pair of curtains over that suicide door / window.

I am not sure the installer is asking the question clearly. There is an optical communication port on most meters, is he talking about that? Or is he suggesting you don't need to install your own generation meter as he thinks the smart meter can do that function? It won't, it will register how much has been exported but not generation, so Iwould fit your own generation meter regardless.

So you will be looking at essentially a petrol generator with an LPG conversion. You will need a proper generator changeover switch, not difficult.

Forget worries about damp. ICF is a good build method, just go ahead and fit MVHR and you will have a very good damp free house.

I better not say my ASHP used 50kWh in the last WEEK heating the house.

I do the same with a wireless operated 600W convector heater, for those times when the surplus PV is more than my immersion heater can absorb which seems to be about 2.8kW