JohnMo

Just looked at the spec of your old boiler and it has an output of 17.5 to 20.5kW. Make sure what ever you get can modulate down to below these figures, to flexibility in operation. There is also a similar thread a couple of month ago and that says the boiler they selected and had installed.

Have a look at Screwfix (70+) and others, all seem to have heat only and system boilers suitable for vented or vented systems. Using a combi can work. Not sure of your current heating system setup, but most if not all combis, have a pressurised CH system.

Do you need to freeze apples to preserve them. I though wrap in paper (discard bruised ones), put in box, put in a dark cool corner, was the way to do it. Certainly was the way to do it when I was growing up (a long time ago)

First - the process overall should be enjoyable Don't get carried away with room sizes - you can end up with a huge houses. Decide things early and documented on the drawings, ideally before getting any pricing. Any change after the contractor has priced is a cost added - in many cases even a simplification of their scope. The more decisions you can make ahead of starting the build, the less stress during the build. Once you make a decision, don't change - it will cause lots of other hidden changes and snow ball, to more cost and delays Keep it simple, often things get way to complex and can ramp up costly quickly. Don't ask forums questions with open questions, as you will get 1001 answers all different, many not relevant. Do insulate way better than you think you need. Consider thermal bridging early on. Go as airtight as possible. Consider cooling if you have large windows, this can be direct aircon or solar shading externally. Question any large windows on the north face of the building as these are just heat losses - min 4x the heat loss of a wall (high performance triple glazed), generally more. Keep heating system as simple as possible. Do not zone the heating system, 1 zone ideally, a max of 2 zones. This will give your heat source an easy time and work better overall. Well insulated houses have very low heat requirements, many builders and heating companies will use generic formulas to size boilers radiators etc, none of which work with low energy housing. So check things yourself and be aware of your requirements, ask for help when needed.

Over powered boilers sound great, but you need to be careful of short cycling, which can use loads of extra gas. Not good. Other things to consider is you will be changing from a non condensing (I assume) boiler to a condensing one, which will benefit from lower flow temperatures (return temperature below circa 53 degC), the lower the return temp the better the efficiency.

No battens under mine, but the membrane has sarking boards below it. Scottish roof design with slate is different from the rest of the UK, due wind loading being higher. Still managed to get just over 3.1kW recorded at the hieght of summer from a 3.1kW system.

Yes. That may depend on your mixers at taps and showers, as some need to balanced pressure wise, cold water will be at couple bar pressure, hot water maybe at 0.5bar with a vented cylinder Not sure you can connect solid fuel boiler easily or is allowed to be connect to an UVC?

That must the biggest tangent from the original question ever.

Think you would need an off grid inverter to switch over to. Other may have a better answer.

Would really do a Nick advised or as it mild turn the flow temp down at the manifold temp regulator so all loops flow cooler. Down to 30 leave your thermostat and time as is, the next day bump up temp 5-6 degs, then after another 24 hrs set everything back to normal.

Maybe true in very hot climate, but then only for a short period in the hieght of summer at midday for about an hour or so. Really I would worry about it, 95+% of the time it's not an issue even in the summer.

Ours are rechargable (every six months or so). Remote control, will do any one on its own or all together. Can control 16 blinds from a single remote

Aerated are fine, but it's just a matter of using rawlplugs specifically designed for aerated blocks, rather than random plugs, which split the block.

Our structural engineer missed the inner support for the lower part of the roof. There is a support from the portal frame to hold up 2x 450mm glulam beams. Neither the architect nor the structural engineering had any details of the shown on any drawings. Ended up designing it myself, steel fabricator came back and site welded it together.

We don't have big sliders, but nearly all our windows had the frame installed first then the glazing. Because of acces and weight.

That's a bit cheap for a multi thousand £, piece of equipment.

Looks like a bit of cut and paste engineering which hasn't captured all the changes needed. I would ask him to clarify.

I would do the insulation in the floor, but personally I don't believe there is enough insulation going below the UFH to make cost effective to run as the downwards heat loss will be large. So would either increase depth of insulation or just stick with radiators. You can get a couple of nice radiators for same or less cost.

Gas at 10p is £1650, energy in to house 13200kWh HP at 3.5 CoP 1320/3.5 =3771kWh 3771kWh at 34p is £1282. Best part of £400 a year saving

The temperature sensor can be remote from the fan unit, it's normally a small box 75x75x25mm sort of size. This is my temp sensor the small white spec. Your fan unit does need maintenance but not the temp sensor.

There is no maintenance

Cable length can be quite long - so shouldn't be an issue extending the cable length. Sun on it is no use, will make WC uncontrolled, which wont help you. Relocating it, is the only way to fix it, relying on plants isn't a good fix. Over or under reading consistently, isn't an issue, as you will be fine tuning the flow temps and curve when you commission.

Question how do you operate the floor at the moment, on a timer and thermostats? How long do you have the UFH on for?

If you save that much your heating bills must be huge or there was an issue with the old boiler or system and/or you have decreased the heat loss.

Section of my structural drawing attached. The 140 thermolite was changed to 100mm, as at the time there were no 140mm wide ones available, insulation width increased. The screed depth was also increased to 100mm, as without taking 35mm off each block the stub wall buildup didn't work out correctly.