JohnMo

That's a good price, make sure he has the G3 certificate. Once the pipes are at the cylinder, which is job from the sounds of it there really isn't that much to do piping wise. Is this new build or retrofit? What are you doing with cold water going the taps, is that coming from the cylinder multibloc control valve? If not you need to plan a pressure regulator valve where the water comes in to the property after the stop cock, so hot and cold pressure stays in balance. If going that route you also need a check valve at the hot water outlet from the cylinder. Isn't a 210L cylinder pretty big for a direct cylinder where you can easily heat to 70+ degs?

We had a similar reaction a decade or so ago in our last house. Plumber wanted to install loads of radiators., way more than needed. Start from the basics, work out room heat loss, then size radiators appropriately. Go with manufacturers data, not a finger in the air from a plumber. Ensure you size to radiator to temperature differential between mean radiator temperature and room temperature. All the data is the manufacturer datasheets.

Don't bank on any size staying around long. Just bought some 500W panels and they were actually smaller than the datasheet, things move pretty quickly. If you have space to store, buy some extra panels just in case?

Have you seen recent threads? Several failures, wouldn't touch them with a barge pole. Pretty rubbish for a heat pump as it requires heat pump running at high temperature for the whole heating cycle. Just get an unvented cylinder - tried, tested, cheap, installer friendly. Does the wheel need to be reinvented? No

Wouldn't have any locked storage on site, just an open invitation for a toe rag, to look at nicking whatever is in there. Tell trades to take tools and equipment away at end of the day. If it nicked from your site you have to replace it. Think site offices are fine on a major build site, but a self build, why? If the contractor needs one let them supply, otherwise don't. Welfare cabins end up filthy, that's why the trades sit in the vans. I didn't bother with any of it. I got a portaloo and it was serviced by the hire company.

To quote someone, so they get notified, you type '@' then start typing the name, a dropdown list appears and you choose the person. Whole front, one end and a full height gable on the rear. The rest is stone slips.

It's pretty easy to do yourself.

I do cooling (UFH) all summer until about October (weather dependent) then flick the switch to heat. As I am on the cusp of heat or cool, when I swop over the ASHP may run a few hours until it gets the slab where it wants then Weather compensation takes over, then it will just blib heat in as needed. The floor although slow, is as quick as the house when you and running at temperature response. If running WC you really don't need a responsive floor, start heating and leave it well alone, no thermostats are needed, just run nice low flow temperatures. My WC curve is something like 25 flow at 20 degs 32 flow at -9. Heating doesn't actually start to kick in until outside is about 10 degs average.

Scottish larch.

As you have approved drawings, wouldn't you have to build to those or go for an amendment? Why would it? If it does we are stuffed, but do I care - no. House wouldn't look the same or as nice with a different finish.

Isn't that way with all parties, only there for the next vote. Landlord - been there got the T shirt, but wouldn't bother again. If people don't like with rules sell up, do something else with the money. Perhaps build a house, that's what I did.

As a side note to others: On its own the decrement delay is tiny, plus if you do not respect the minimum air gaps either side of the product - you may as well not bother buying or installing it. It needs the same amount of depth as any other insulation once the required air gaps are accounted for.

In theory better u value, in practice a pain to seal against rafters to get perfect seal. If you don't get a very good fit, you get bridging. So a softer material like mineral wool fits tight and no bridging. Real U value is better generally for way less work.

And if you hadn't been watching them, the next trade would have covered it up, without even questioning. Work force skills and appreciation of airtight building is appalling.

Very different beasts from a structural perspective. A cut roof needs a ridge beam, trusses don't. Wouldn't you fill with mineral wool - perfect fit every time. Use something like Rockwool Flexi. Better decrement delay than PIR - keeps heat out better. Then under-draw with PIR?

Clearing site has nothing to do with planning (assume you aren't taking down an existing building). It's just site or land maintenance. Again digging holes for whatever reason is just digging holes. Make sure no-one can fall in them, if staying open. We did loads of similar stuff prior to getting our building warrant. The only things you are not allowed to do are foundations work as they are part of the legal process called planning and have to follow your legally approved drawings. Our work start was a photo of a digger taking soil away for development of an access road, well before the building warrant was even applied for (building warrant is similar to building control drawings). Chat with who ever does your approval - Scotland is easy it's the council - not sure what England does?

Or even a volumiser

Did this for a few days, and couldn't help but wonder if doing 3x charges per day would start to degrade the battery pretty quickly. So then when back to strategy I did before to get my head around things. Have just implemented a strategy that should work all year round and charge the battery to full all the time. SOC targets per Cosy slots 04:00–07:00 (morning cheap) Charge to 50% SOC Purpose: replace overnight usage and give a buffer for morning demand without stressing battery life. On low heat pump demand periods, this charge may not occur as battery will still be charged above this level. 13:00–16:00 (afternoon cheap) Charge to 85–95% SOC Purpose: If PV output is good this slot may be unnecessary — the battery will already be high. So grid charge would not occur. 22:00–00:00 (evening cheap) Top up to 100% SOC Purpose: ensure full readiness for overnight / early-morning loads and any low-tariff opportunities. Because it happens once a day and is predictable, it’s simple. The above for most the year, will result in one charge from grid, other times a part charge from grid or via solar. Have set charge rate at 3.7kW instead of 6kW, so if generation is pumping out 5kW some will slip past as export. Everything is inside the GivEnergy app to keep it simple.

This thread has gone a tangent - who will fix @Roger440 rabbit

MVHR is ventilation, it is rubbish at moving heat around. It is needed in all rooms. Read what is said above. Ventilation is basically designed around building regs. But pretty to design and install yourself if needed. UFH downstairs is fine downstairs, but loops need to be design to provide full house heat output. But again not difficult to design and specify if needed. ASHP when you get a grant can come with a big billy bonus to the installer, which they rip you off for. As many on hee I just didn't bother with the grant and just bought a heat pump from eBay for many thousands off list price.

You will get a battery capacity hit as it will self heat using it's own capacity or just give less capacity. Maybe better filling a reasonable sized battery and export. Cosy is 12.7p to buy and they will pay 15p to export. Keep what is cost effective to keep, sell the rest. Fires - battery chemistry is pretty safe in house batteries. Mine is in loft/plant room, fully insulated space. Other thing to look at is inverter size so you can have multiple things drawing electric without sucking in mains electricity, 6kW works well for us. Plus look what happens in a power cut, some systems shutdown most except an emergency circuit, so rest of house goes black. Good thing with AC coupled (GivEnergy AIO) house just runs as normal with no interruption.

The way (for me) to size battery is ignore solar (for now) calculate the electricity demand on your coldest day or close to that. So now you need to get a battery that deliver that electric without have to use peak electricity. Octopus Cosy gives you three cheap periods, think the longest period between cheap periods is 7 hrs. And there are 8 hours of cheap electric, so you can just draw from grid in this periods and recharge battery. So battery only needs to be able to last 7 hrs at highest demand. So in simple terms xkWh, divide by 24, then multiply by 7. Example 40kWh/24, is 1.6kWh, them multiple by 7, so just under 12kWh. With conversion losses (DC to AC) you need to add another 10% so now you are at 13.2kWh. So really an actual capacity closer to 15kWh. Or a GivEnergy AIO, with an available capacity of 13.4kWh, which is what I chose.

I used LoopCad to model house, then balanced room by room output so no supplementary heat was needed or I wasn't over heating rooms. They have used LoopCad to model house put omitted to balance heat output. I need about 3kW heat output at design conditions to heat whole house. My hall uses loops transiting though it to heat the area, by spacing them through the hallway. Did same with utility (manifold location) but some loops required to be insulated so as not to over heat room. 150mm provides a quicker response time, and maybe a degree or so cooler flow temperature. But if doing WC or batch charging floor that doesn't really matter. The compromise position is to do enough loops to get away with one manifold and have enough flow capacity within the ASHP circulation pump so you don't need a second circulation pump. 30 to 40W to drive second pump doesn't sound much, but will drop a will likely cost you £30 to £40 a year to run doing heating only. Double that if you do cooling. Entrance hall has a dedicated loop, plus it has 4 other loops passing through it. Space the 4 loops out across the hall and you have deleted 1 loop. Space ensuite and bathroom at 100 to 150mm centres - you cannot have enough heat in those rooms. Rest of the rooms in 200 to 300mm spacings. A mean flow temp of 30 degs, on 150mm centres will output 40W/m² so your living kitchen looks to be 6x8m so area is 48m² so you are putting about about 2kW into floor on your design day. That floor comprises 5 loops and about 400m of pipe. At 300mm centres same flow temperature you are putting 25W/m² or 1.2kW, which maybe more than you need. You then can do 2 loops and 200m of pipe. Saving 3 loops. Do a similar exercise with each room. Design sheet to assist, attached. The attached doesn't include floor covering tog rating.

To give you some idea on my thoughts Our house is single storey 192m² and have 600m of pipe in floor at 300mm centres and covering about 160m². Our max ASHP flow temp is 32 at -9. Your design relies thermostats to control room temperature. Your design needs to be room balanced. But like choosing a correct size radiators by room heat loss. That plan sells you lots of stuff.

You really need to get built-in circulation pump performance curve (in install manual). Calculate your system pressure drop. So flow and return piping the longest UFH loop pressure drop. Calculate your flow required. Read system pressure drop on pump performance curve and validate if your pump puts out enough flow. Advantage - purchase choices. Route all pipes from ASHP to manifolds in 28mm, so very low pressure drop. High kvs diverter valve. Look at a kvs of 10 or over. Then valve will be invisible hydraulically. If your pump still doesn't flow enough install a second pump on the return from UFH only (not cylinder side) run at a set speed to get the flows you need to see at the UFH manifolds.