JohnMo

Basically nothing wrong with that. Have heated mine a few times just via the immersion.

Heat geek - love or hate them, have done a couple recent videos on cylinder heating may be worth checking it out. Of note is Telford do a cylinder designed by heat geek and mixergy have changed their heat exchanger (bigger) and control logic in line with what is discussed on the video. For me bigger is better (m2).

Does that work? I suspect it's not a very good thing to do for the refrigerant side of the heat pump. Are you possibly better to set a higher target flow temp and increase the compressor restart delta. So it's off slightly longer and runs longer but means temp stays the same.

You may find there is very little in it, a lot of heat pumps are badge engineering and some software tweaks. So the 7 and 5kW could be fundamentally nearly the same unit. One overlooked feature most heat pumps have, is a setting to limit hertz the unit runs at or how much noise it makes (depending on the setting is labeled), so you increase or decrease the rated capacity. Below is a snap shot of a cycle from my heat pump, its done in 5min data change cycle, so pretty well averaged. What you see is a higher electricity demand at startup, it reduces quite quickly for a about the first 5 mins. Basically it is playing catch-up to get water temperature back where it should be. The next 15 mins it's slowly modulates down down until it has no where left to go. In this case it hit a thermostat in the garden room. Of note are the heat pump is set to min hertz setting, at peak load the heat pump is drawing around 1kW. A much longer run and slightly different settings - this time the heat pump had been off for 12 hours or more, doing batch charging the floor, the heat pump ran at full load for 7 hours, the dip at the end you see is a defrost. The first 30 mins increase is the water temp slowly getting hotter. Min hertz in not set, target temp is 35, the heat pump only achieves around 33 Deg. Generally the heat pump is drawing around 1.5kW (50% more than above). Similar flow temperature, colder oat, not being allowed to modulate.

You be surprised how little difference that makes to energy consumption. While you are set back you are using less energy, but once set back has finished the heat pump plays catch up trying to reheat the house for quite a few, using more energy that it otherwise would running steady state. You also have to run higher temps so CoP takes a hit compounding the issue. "Proton for breakfast" website has a spreadsheet, I tried it consumption was the same setback or not, if the setback was about 4 degrees the setback results in greater consumption, not less. That's so when you sell the house the next owner can walk about how they like. Take the grant play by their rules, or DIY it. Most heat pumps modulate to below 50% of the max load. They then quite happily cycle 20 mins on 40mins off when needed to run well below min modulation. All normal stuff, if it runs less than about 10 mins, you don't have enough water volume engaged (to many zones or you need a volumiser)

Solar is a fickle thing.

That's good, we have had so much rain in April the solar has been pretty rubbish. Plus the heating stayed on a lot longer this year.

Makes you wonder, they would install single glazed given half a chance, and still leave a big gap and make it look pretty with a big dollop of silicone or a bit of trim.

You have to be careful anything more than 10W/m2 at passivhaus airflow rates as the air starts to smell of burning apparently. Assume 200m2 house that's about 2kW. A better way is decent amount of screed and you can easily dump at a rate of 6kW in to the same floor area. Adding control to manage the air flow heating is just another layer of complexity. Thick screed, heat source, 3 port valve, UFH manifold with no actuators. Thermostat to start heat source. If you need over temp protection a pipe stat to remove heat source permissive or close a two port valve (or both ideally)

Max drop of the worst duct run from MVHR outlet to and including the outlet nozzle / terminal. As this run will also determine your fan running speed the nozzle should be in the fully open position, so its lowest pressure drop.

First day with no imported energy. Good solar day yesterday and battery starting to earn it space in the home. So no battery charging required overnight, the battery ran down to 54% before PV started to charge this morning. Snap shot from home assistant Energy page, showing current status A further shot from the GivEnergy page in home assistant, shows current generation (cloudy), target charge point (overnight on E7) and current battery charge status.

We have a shallow chamber with pipes from borehole pump. With 25mm blue water pipe. Almost exactly what I did. But I had an off cut of 25mm PIR, so used that. Just made a circle to slip in the chamber. Been ok down to -7 for a week or more.

Be aware of quotes that look too good to be true. They normally are too good to be true. Also ask the architect who they like to work with, they are normally the ones that get on with job are zero hassle - that's what you want. 5m bi-folds, cheap will leak air like a sieve, so get specifics on what is being quoted and look at the item. Get whole window U value (Uw) if double glazed you want 1.4 U value or better. If they give you Ug value that is just the glass and not what you are looking for. One of our quotes for windows, came with recommendations, we went to the showroom and half the opening mechanisms didn't function correctly (broken) and frames really bulky - we went elsewhere .

Hi and welcome Just incase you aren't aware, you still have to go through the warrant process, before you start any real work.

High cost build? Hope that lots of insulation and airtightness, and not added unneeded complexity and just a scrape through building regs or not just being ripped off? Lots of users on here, look in relevant sections, and can see the miles of cable they install, to add to your costs. Personal opinion, waste of time and money. Your high cost build got more expensive.

What?

Dulux trade every time, water down for first primer coat on new walls, then straight out of tin after. Covering power is great. Buying from Screwfix or B&Q is cheaper than trade account with Dulux.

I did mine from a kit, it's 70mm thick wood, easy and quick to build. Then built a standalone from inside for additional insulation, same with floor and roof. Things to consider Lightweight building equal really hot when sun comes out. But quicker to heat up in winter, but cools soon after switching the heat off. Heavyweight more stable temperature but takes longer to heat up in winter, but slowly cools. Timber frame and dense insulation. Yes, PIR no. Block work, mineral wool batts in deep cavity yes, PIR no. SIP no

The expensive one looks ok and more controllable than the cheaper one. Really depends on what you want.

Not really, we use huge long hose pipes (200m) so happy with every drop of pressure.

On an UVC the thermocline rises up the cylinder as hot water is consumed. The hot water coming out when nearly depleted is still usable as hot water. On a thermal store the thermocline will operate in the same way, climbing up the cylinder, but leaving more and more of the coil in warm to cold water. So not getting the heat transfer. A plate pack helps as you get more useable hot water. The other issue can be, you may have to heat the thermal store via coil or plate exchanger also, as with a lot of boilers, nearly all heat pump needs a closed pressurised system to work with. This just makes less usable stored heat as now you operate via two heat exchangers.

Yes

That's a big pipe, are sure you need that big? Our water comes into the house through a duct under the foundations. Up to the stop cock, prior to any pressure reduction the pipe takes a turn left and down to its own isolation and the down through the same duct and then up to the outside tap. Stop cock stops all water flow, and outside tap has its own isolation also.

Did all the calcs and just couldn't justify Marmox as they adding nothing in real terms from the design I posted. The Thermolite blocks are in a dry space so thermally stable and twice the height of marmox. Ours came out at 0.09 U value. As I said our was a standard ground work contractors, doing most of it, but I did all the insulation and UFH, they can back concreted over the top. I then built the walls.

Similar build to ours, but we are 195m2 and 3 bed, 210L cylinder and a 6kW ASHP, although max heating load is 3kW. I would be your own heat loss calculations. May have seen big house made up the numbers, you can afford it quote.