Bramco

It depends - as with many things.... Your base load will be between 250W and 500W depending on the time of day - more lights on more base load. There are many people on the forum that have their base load down to very small levels by disconnecting all wall warts etc. But let's say you're a typical family, so between 250W and 500W. The ASHP will draw it's 4kW continuously unless it's doing a defrost, when for a short period, it will draw a lot less. Your oven will draw about 3kW until it's up to heat - 5 to 10 mins? Then will turn on and off at 3kW when it needs more heat. Induction hobs tend to turn on and off repeatedly - more often on a higher setting. So assuming everything is on, that's at least 500W + 4kW + 3kW + 3kW as a maximum - 10.5kW but only 4.5kW is continuous. 2 x 3kW is on and off. If you have let's say a 4.5kW inverter, then each of those 3kW has to come from the grid, so at the expensive rate as it's during the day. And we've not taken into account the dishwasher, washing machine and EV charging.... If this is the case and I'm not sure it is, it could be because the maximum PV you can install without contacting the DNO is just less than 4kW, so a smaller inverter would match that. However, if you have a battery system sized for your typical consumption, in our case 15kW, then a larger inverter makes sense and means we almost never take peak priced energy, it's all at the 7p Oct Int Go rate, because we load the batteries at night and our solar does the rest. As for most appliances drawing a peak for a short time, this is true for washing machines and dishwashers but not for ovens and induction hobs and EV chargers and ASHPs draw at the peak rate all the time. And even dishwashers and washing machines can draw 3kW for 5 or 10 minutes as they heat the water. Hopefully your experts will be expert.... What's right will depend on the appliances you have, how often they are used, what your base load is and also, what you want to get out of this. Do you effectively want to only use cheap rate electricity, or is the plan to reduce as much as you can your use of higher rate at a reasonable rate of return for the investment. EDIT PS - the power output of your ASHP is the higher figure, the electricity usage is the lower figure

We had no issues with our mainly corrugated metal roof and cladding timber frame. Also partly timber and render clad. Although we didn't need a mortgage for the build or now. Our insurers weren't interested but put us on to Gallaghers who found an underwriter for us. Bit more expensive but not much. Timber frame is great for getting the frame up, windows in and watertight. If we ever built again we'd go this route.

Too late to do an edit...... @Archer - you were the OP I think - and I know you said my post was useful, so please take note of the above second thoughts......

Rob, I need to go back and edit my post - I was thinking about this yesterday and actually, I'm pretty sure, the real reason for having a larger inverter is if you have more PV than the 3.7kWp (or whatever the number is that you can install without having to talk to the DNO), then you need a larger inverter because they top out at their maximum rating. The usage thing isn't actually that important - especially if you can get the other half to work serially rather than having everything on at once. We have a 5kW Sunsynk and a 6.5kW ground mounted array - in the summer, the Sunsynk tops out at around 5.4kW, so we lose some PV. Not a lot in our case, as the array is at 45deg, to give us lower summer output and higher winter output. We had a standard inverter on the array before we installed the batteries and this was larger and didn't top out. So I should have written above that it depends on your PV array - apologies to anyone I've misled on that - I'll go back and edit the previous post.

Ah yes - I remember this now... Getting old, memory not what it was. Doesn't work for DIY installs though, you have to have a supplier do the install to reclaim the VAT - or, I guess, have a friendly sparky that will do the paperwork for you.

Check out the price on ITS Technologies - £690 + VAT. It pays to shop around....

Friends found one of those - he managed to set things up so that they never seemed to use any Solar and the battery never discharged - not sure how he managed to do that. DIY is pretty simple if you are competent and trust yourself - and AFAIK, doesn't need a sparkies sign off, if everything is connected to an existing properly rated spur that has been signed off. Someone will be along in a bit to either confirm this or tell me I'm wrong. The Sunsynk inverter above, may not be man enough for many homes, ideally you want one that can supply enough power for a couple of big white goods needs, so something closer to 6kW. Also, look at the Sunsynk batteries. The last time I checked these were cheaper than Frogstar. And in terms of battery sizing, you need to match the amount you might need to cover at the higher rates, if you're installation isn't big enough, you'll still be using expensive electricity. There are a couple of other good sites TradeSparky and ITS Technologies with products from many suppliers. We bought and installed a Sunsynk 5kW hybrid inverter and 3 5kWh batteries from ITS for £5k inc VAT. Works very well for us with the 6.5kW Solar array. Loading everything at night on the 6 hours of Int. Octopus Go, means we very rarely use any full price electricity, it's all at the 7p night rate. One thing to think about, is that Solar installs can be zero rated VAT, if done by a sparky (not sure if it has to be an MCS sparky). So you could 'install' 1 panel and get the VAT back on the whole installation. Also, not many systems can cover you during a power outage - Telsa and some others can - if this is important, then make sure you've checked this.

Take a look at the specs for either the Shelly device above, or the Sonoff mini. It's very simple, from memory, you take the power and switched live from the wall switch, put them on the wifi switch and take leads from the wifi switch to the wall switch live and switched live (and maybe a neutral). Once you switch the circuit back on at the CU, you can search for the new device in the app. Also, Sonoff do versions for Zigbee as well as wifi - I think zigbee has a better range and is less susceptible to a poor signal. I might be wrong there. If you do go Zigbee, you'd need a Zigbee to wifi bridge to get the devices visible on wifi. Buy one and have a play... they're very cheap. EDIT - if you can wait, go on a Chinese site, they are cheaper there than Amazon. And there's black Friday deals around at the moment.

Or the Shelly or Sonoff app, or Google Home or Alexa if you have integrated them into those environments. There are many ways to do this. But it is great that you can simply drop these into the light switch back box, connect up and then either use the switch, or have a command or automation turn them on and off. Don't think they'll fit in the really shallow back boxes though. But with them, if you can extract the back box, the wiring can be passed through one of the holes in the back box, so that the wifi switch sits outside the back box in the cavity. Probably not allowed in the regs mind you but it works. We have a couple in our garage on a double switch, I've added another back box alongside the normal switches to site the wifi switches and put a blanking plate over that.

Ditto - and if you just want to turn lights on and off etc., then they can be included in Google Home (or I guess Alexa) and then simple things like turning some lights on at dusk and off on a command are v easy to do without having to get into Home Automation which is pretty techy by comparison. The only mistake I made was to create an command/automation 'OK Google good morning' which turns on a light, says 'where's my tea' on the Google speaker in the main room and starts to play radio 4 on the speaker in the main bedroom. (I get up earlier than my wife). So it's a bit like those bell systems in old country houses, to summon the butler... I should never have done it as a demo of what automations can do......

They would say that wouldn't they...... Should be quite easy to price up 1 of the bathrooms according to their spec using the interweb and check out the quote. Use the simplest for speed. We used our builder and his tiler and plumbers to do the bathrooms - worked out very well. We did client supply on all the fittings and tiles, with the exception of the wet room sealing and traps which were specced by the architect. We have 2 en-suites (1 with a £1k egg shaped bath), one family bathroom, with shower over a bath and 1 wc. Sanitaryware was £9500 ex. Tiling is a bit difficult to strip out as the floor tiles were part of the flooring we used throughout. Wall tiles for 1 of the en-suites and the family bathroom was about £500. So let's say £11.5k for the client supply items, that's without of course the labour provided by the builder's subbies. That was 2.5 years ago. EDIT - should add that it's all wall hung loos, top of the range taps, showers etc. from Hansgrohe, Geberit etc. PS - if Brexit hadn't happened, we could have bought everything from Germany for about 30% less than we actually had to pay - don't believe it, check it out for yourself, I did because we'd bought from German outlets before.. :-(((((

We have zehnder - it was professionally installed. But having seen the guys do it, it's something someone with DIY skills could do. We didn't bother with a manual boost, we use the auto boost feature which boosts soon after someone starts a shower and clears the steam within a few minutes. One of our bathrooms doesn't have any opening windows, the others have roof lights. The one without opening windows takes longer to clear than the ones with roof lights (assuming of course you've cracked open the roof light a bit). We installed the interweb gizmo, but never use the app, the unit just does it's thing 24/7/365 and occasionally asks for new filters. I guess on reflection, having the interweb gizmo and the app is useful, in that you get a notification a few days before the filters need changing.

I wonder how many of these there are..... Maybe we need a new section for folks to upload their manuals (duly redacted) so that other folks can glean useful help/ideas, re headings, cross referencing etc. Even whole sections could be plagiarized, for example one on Sunamps...

There's been quite a bit on here about 3 phase smart meters being a pain to get hold of and (iirc) being difficult to re connection to the suppliers. Given a new build will have 3 phase to the meter box, you can have a single phase meter connected for the supply and then at a later date trade up to a 3 phase if needed.

AFAIK, what's down the road is 3 phase and in the past, they tapped a single phase off for each house, having a balance of houses on each of the phases. Again AFAIK, all new builds have 3 phase connected to the meter box, future proofing things for when everyone is all electric. So the supply to the meter box is 3 phase. Then, for a normal house, they tap off a single phase with a 100A rating, i.e. fuse. This is then your supply. Our region is National Grid. They did a site visit - it's more to work out how much cable is needed, where to tap into on the road and to sketch out where their cable will run. So don't worry about the site visit, unless you're kms away from the nearest road. We load our batteries, run the ASHP and have the DHW immersion running at the same time on the cheap night rate. Sometimes the dishwasher will also be on and the highest I've ever seen the load is about 12kW, which is well within the 100A rating of the supply. It's normally about 9 or 10kW while everything is on. I guess, with an EV charger pulling 7.5kW it would take you close with absolutely everything on.

So how many have you got?!!

We looked at Scotframe but found the pricing for the erection difficult to navigate and we wanted something a bit more turnkey, so went with MBC who do the insulated slab and timber frame. We found a local builder who would do the foundations, that left the insulated slab and frame to MBC and the builder came back to do the cladding, roofing, internals etc. It was 2 separate contracts with the builder and we asked 3 or 4 to tender both times. The builder was main contractor for both of those phases. So it is possible to do it. I should add that we also separately contracted for the windows and sliding doors. So we had effectively 4 major contracts to sort out which worked for us. Simon

I would ask this of our MVHR supplier but he's in 'fit and forget' mode, as in not responding to voice or email..... The question we have, is whether the position of the fire dampers on the inlet and exhaust for the MVHR should both be within the plant room from a fire safety perspective. Due to various reasons, the inlet is within the envelope of the plant room but the exhaust damper is outside the envelope. The dampers are designed to spring shut at temperatures just above 70C, so you could imagine that one might trigger but the other one not. We're a bit concerned that if they don't trigger at pretty much the same time, then there's the potential for fire to spread. There isn't any gas in the house, or open fires or log burners, so the chance of fire is pretty small but nonetheless.... Anyone any expertise in this area? Are there any standards that should be adhered to? Simon

Be careful what you wish for - we have black corrugated cladding and roofing on the 2 storey section of your build. Looks great and fits in with the rural location. But in the summer months as the sun comes up you can hear bumps (best word to describe it) as the metal catches the sun and begins to expand. I'm assuming this is the same for SS? Wouldn't change it for anything though, it's just one of those things you hadn't thought about and have to learn to appreciate. Feature, not fault... Simon

To avoid a penetration in the roof, we ran a pipe parallel to a downpipe outside the house. This was connected to the last manhole before the long run to the main sewer. The top of the pipe was fitted with a slatted vent and sits up against the gutter. It was a suggestion from BC when we asked how we could avoid penetrating the roof. Simon

Maybe something for another thread? But I'm guessing that if it has degraded to 0.8kWh, then it will only take 0.8kWh - why would it require 1.05kWh to charge it to 0.8kWh? Our Sunsynk inverter app shows the rate of charge and discharge which seems to show that there are higher losses when charging or discharging at low rates. Ours is a hybrid inverter, so we couldn't put any kind of meter on the system - would be easier with separately ac coupled PV and batteries.

But they are 11.86 vs 7 on Int Go. So a no brainer if it works for you to use Int Go rather than Cosy.

Haven't seen that and don't recall any condition like that. We actually have 2 chargers (planning condition!!) - only one of them is connected to the Octopus app. So how could they know whether we'd charged or not? An EV is easily sorted though, if it ever rears it's head.

Isn't there something to be said for it being environmentally friendly to only use off peak electricity? I think peak time electricity is the 'dirtiest', i.e. gas vs nuclear or renewable. Simon

AFAIK, you have to have one of their accredited chargers.