JohnMo

Pretty good write up here on condensation theory https://www.heatgeek.com/condensing-boilers-efficiency/

To be in condensing mode it the return temp that is important not flow temp. You are well inside condensation mode.

If you want Aircon anyway, use the same unit for heating also - everywhere. For DHW either direct immersion heating, during off peak or get one that heats via its own heat pump. Couple of holes in the wall for air in out. Or just get an ASHP, fan coils in the bedrooms and living space, they will do heating and cooling. Unvented cylinder. Simple.

You have to careful when you compare, it's actually on an apples with apples basis. As there are several ways to calculate efficiency, for example passivhaus institute use a different method to most. The energy required to raise one cubic metre of air through one kelvin is 0.33 watt-hours, i.e. its heat capacity per cubic metre is 0.33 Wh m–3 K−1. Thus the total ventilation heat loss, Qv , will be: Qv = 0.33 × n × V × ΔT watts So using a 100m3, and a change rate via mechanical ventilation of 0.3, -3 outside and 20 inside 0.33 x 0.3 x 100 x 23 = 228W heat loss Same calc for 90% eff 0.33 x 0.3 x 100 x (1-0.9) x 23 = 23W heat loss Same calc for 80% eff 0.33 x 0.3 x 100 x (1-0.8) x 23 = 45W heat loss So we are taking quite small numbers an additional 0.5kWh a day at worst (when comparing 80 to 90%) in a boat that possibly leaks heat like seize anyway. If your boat isn't air tight and leaks enough to ventilate itself, without additional mechanical ventilation, then MVHR actually adds to the heat losses, as its ventilation is over and above normal air leakage.

Make sure you allow for wind lift. Not quite the same, but we had a wooden structure with a roof, pinned down to lawn, one very windy night, it took off and parts of it went over a 6 foot wall. Luckily no one injured or cars damaged on the road where they landed.

This what we found - We did it, sold them now. Costs You have to pay extra duties on purchase, as it classed as second home (Scotland). If you register as a business you may be able to get small business relief instead of council tax, which when we did was zero rated. But if you don't register as business, you may be hit with double council tax (a new thing the Scottish government is implementing). But you may also get clobbered with commercial water and sewage rates. You also have to pay for utility charges, and decent broadband is expected etc. General stuff People leave their rubbish, don't recycle, put used plates back into cupboards, without cleaning. You have to find someone who is reliable and good at cleaning (which isn't easy). Overall everyone made money, except us, we got all the grief and running about. Over 4 years and two houses, we made very little, made money on the houses when we sold, but both had lots of work done to them after we purchased. Buy premium bonds, zero risk. Stay in a decent hotel or someone else's holiday home.

Grant heat pumps can now use Homely if this is useful to you. Should optimise the system for you once the installer has left you to it.

Can I ask - How noisy is the indoor unit?

Are you just making life hard for yourself? If you are using ground screws for a good reason. Would you not bolt bearer beams to the ground screw and the the floor panel to the beams. You may be easier Ground screw Bearer beam 22mm floor panels Insulation (floating) either EPS or PIR Floor panels (floating)

Have looked at Larson strut for the walls? Your 225mm studs will create a thermal bridge at each strut. Which you are mitigating with external insulation. The Larson strut, uses 2 smaller studs joined together with ply or OSB. So you would have say two 4x2s, or a 3x2 and a 4x2 with a gap between, the gap maintained by several pieces of the OSB nailed to each stud. One stud is structural The other to form a depth for insulation. The thermal bridge becomes the cross section of the OSB instead of the stud. You can make a good depth of wall for insulation and could save the time and effort of external insulation as well.

I am just running E7 and it's currently averaging out 30% cheaper than normal rate on a 24hr basis. Have an ASHP and battery.

Should be called Octopus 'battery' really, that's the only real use I see with it, having an ASHP is just a bonus.

Plus make sure you have CO alarm in the room. Plus make sure you have enough air available for correct combustion, if it's not fed direct from outside, do whatever building regs or manufacturer manual says.

Why ask the question if it's all ok

The pump is there to pull flow through the mixer, the boiler pump will not do that.

Yale do a door slightly open lock you can add. No door will really stand up to a crow bar. If it's a glazed door an automatic centre punch the glass and just walk in.

Our ICF build (Durisol) I did 6 blocks high and then concrete filled.

You can get colour mixed spray cans to RAL codes. Sorry been a while since I purchased, I just did a Google search. You can get 2K acrylic, which is very wearing and not dangerous to use. You can also get different gloss levels.

I would actually ask them to quote for approved alarm and without, I did a few years ago and not one penny of difference. But having the alarm meant you had to follow a given set of rules to ensure you got paid if you were robbed. To be approved you cannot self install, it has to be a professional install, with appropriate certificates and managed and serviced.

Agreed, mine does, but means you cannot use the multi purpose contacts fir other things. The OP said So possibly his heat pump will not have on/off contacts or the installer hasn't read that far in to the installer manual.

Two resistors, 10p each and a relay in a box £5 to £10. No programming or anything special. Plus you need to output a resistance not input it. Taking an on off call for heat from the eDual and output a resistance to fool the ASHP into starting DHW heating.

The bit answered is about measuring switching via a resistive temp probe i.e NTC or PT100. I pointed out away to simulate have a cylinder temperature probe. You are not switching any load directly you are just simulating two resistance output that coincide with a temp above and below a permissive to start heating DHW via the heat pump. The wire size in the probes in the order of 0.5mm² suspect the signal voltage is in mA scale. You would not be load switching that's a different animal as you point out

Trouble with planning you have to do as agreed or amend the planning application. I would be inclined to give the minimum information, less to be tripped up over, if they need more info, they will ask for it. I had to change the location of the boiler, I just amended the drawing to show new location with make and model, they already had the datasheets.

Bit of of a strange layout would be better having the bedrooms together and living/day spaces together. Also lots of bedrooms for very limited living space. Massive hall space being used for nothing much. Lots of bedrooms (people) for one bathroom. Just looks like the wrong house, trying to be used, for way too many people. You maybe better doing a wrap around instead of two extensions, then rejigging the whole space to be a better layout. Or buy a different house

Glad to hear it seems working.