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I think these “should”, by the laws of physics, as in EMF passes through coils to register the flow of energy, so should work bi-directionally in principal. Depends on whether the software is told to register the flow in each direction or not, eg it charges you but doesn’t (won’t) refund you. So to answer the question, I’m not sure.

In summary I am fitting an intello plus AVCL to 1st floor ceiling joists, these rooms will have downlights fitted in the ceiling which are about 120mm in length. I cannot create a service void below the AVCL to accommodate the downlights, therefore they will be located within the ceiling joist void, hence above the level of the AVCL. There is an off the shelf solution like these however I do not see any mention of them being used by builders on this forum. I am a carpenter so I could make plywood boxes into which the AVCL is folded up into. I'm sure this must be a common detail but I can't find much detail on solutions so keen to hear what others have done to maintain the air tight layer in this situation.

Suck out of your can. Replacing bathroom fans with dMEV like John said is the easiest and cheapest. You probably have loft space for a centeralised MEV system or maybe even a MVHR if you want to go all in.

Years ago spoke to the technical director of reliance controls about "servicing" of their PRVs etc Context was a very alkward tenant who insisted that the valves be serviced every year and wouldn't accept that getting a g3 ticketed engineer to inspect and sign off the cylinder etc was sufficient. Upshot was, there want anything to "service" - you look at the valve, make sure nothing is blocking the pipework etc and there are no visible signs of leak/degradation. I asked specifically about turning thr knob to activate the valve and he said you could be there was always the risk it wouldn't seal back properly and you'd have a persistent drip, which would mean the valve would need replacing. From the safety POV the main thing is that the valve opens when the pressure or temp are too high. They are engineered to be highly reliable and fail safe, ie anything that goes wrong makes them open easier than design. The servicing is more to check thry aren't leaking and the venting arrangements are still adequate

That's great and thanks for the detail......all seems logical so works for me

I feel being trickle fed details here is limiting how much we can help. Can you please give us a size and scale of the building. I had in my head it was a 4x4m prayer room initially but portal frames etc suggest it may be 40m X 40m. How much work has been done. What's under the floor? A house? Offices? A car park? Heating it from 6am until 11pm means a lot of energy so investment in the fabric is vital. This means insulation airtightness and mechanics ventilation. What's the approach here? Have the structural details been finalized? Direct electric UFH is of course 100% efficient like any reistive heater but heat pumps can often be "300%" efficient. It might not be an ideal fit for your building though depending on your insulation and the ability to control ventilation through public use of doors etc. Like I say more details = better advice.

OK I think I'm understanding the metering aspect, with import and export netting off, but does that play well with time of use tariffs? If I am exporting from the battery in the evening, but drawing from the grid during the day to run heating, those things won't surely net off in the same way that running the ASHP from the battery would do? We're a bit limited on the size of our solar array because only one aspect makes sense and it's low pitch (30 degrees) which means that the max we can squeeze in would be 5-6kW peak. I was hoping to put in a large battery with scope to increase capacity in the future so that during the winter we're minimising running the ASHP off peak rates (eg using Octopus Cosy to top up the battery).

So are ALL 3 phase meters installed now "net metering"?

Nice. I went bat-shit crazy balancing out a 3ph system in Leicestershire, as it not only makes sense by design, but also pays long term dividends for the client of the on-site generation and consumption are given proper consideration from the outset; I’d planned the 3ph CU and circuits well in advance of the house even being built, plus all the M&E requirements et-al, so there was a plan in place for when we were allowed on site to execute all of these works. At that early stage I could plan penetrations through steels, ahead of them being delivered to site, but my favourite () bit was being able to see quite quickly that neither the architect nor the SE gave two hoots as to a) where plant was going to need to reside, and b) how pipes and ducts were to get about the building without significant compromise. Getting your ducks (ducts) in a row early on (for power / other services entering and exiting the building) makes so much light work of 1st fix, it’s just a genuine shame to see missed opportunities when these details etc have not been discussed way in advance of the construction phase. Plan ahead people!!

I posted a while back that the national grid operator has declared there will be no more wind farm connections to the grid in Scotland (after the ones already scheduled for connection) until at least 2035 and that more wind farms are needed in England and Wales. We just need that implemented in planning policy because planning applications are still being decided for wind farms near us. If you try objecting on the grounds they will not get a grid connection the planners say that is not a planning matter. As usual no joined up thinking. If a grid connection is not possible, then planning should not be possible. Unless you want a load of wind farms built and probably paid some form of compensation for not generating because they cannot get connected?

That would work fine. U value won't meet regs though. What kind of rain screen are you planning on ? The vapour permeability of the OSB is a bit mute when you have foil faced PIR outside of it but it will work as an air control layer which is much more important than vapour control. With a 125x50 TF external to the oak frame you're building 2 houses though but that always seems to be the issue with oak frames. I think @Post and beam used SIPS. As an idea you could spec an I-Joist structure to balloon frame over the oak with an external airtight layer like @IanR. With the Oak taking most of the structural loads it hopefully could be quite minimal. Full fill with cellulose then.

Show us a picture of the build, your times seam woefully low.

Berwick Bank wind farm in the outer Firth of Forth with up to 307 turbines generating enough electricity to power up to six million homes. So that supplies all Scotlands needs when the wind is blowing. Meters on the cables to England and Scandinavia and the Holyrood budget will benefit hugely.

It’s chilly and foggy outside and the ‘Mk2’ insulated pre filter box is performing admirably. The Ubink insulated ducting being the coldest thing in the MVHR room now. It did seem to seem to be noisier/running faster than normal. I had my suspicions that the pre filter mesh may be getting clogged again, I also had my suspicion that freezing fog may be having an adverse affect on the air permeability of the fine mesh… Turns out the freezing fog was playing a major role in restricting air flow.

Our rate in East Anglia (likely to be cheaper) 900 per day 2+1. Our 55 linear metres to first floor took 14 days, majority block and they were lightening quick. (This was also round a timber frame, so apart from garage not structural/load bearing). We employed on day rate, they came recommended, if they had "qouted" they would have put some "saftey" in for time. Our bricks Ibstock blues are nothing particularly special and they we just under 1 a brick to us (not list) and that was a good deal. How many days do you quotes think it's going to take?

Quotes are labour only and they have allowed 20 days for the job. It's a straightforward rectangle build with gable ends, face brickwork on lower ground floor and then block upstairs. The issue I have, is that if I just say "Oh well, let's just pay 10k more and get going", if that same thing happens for all trades, then I am in real trouble and we'll have to sell the house once it's built.

All went well in the end. I know some on here have had a good experience with Fermacell, they are probably more experienced in that kind of thing. Me, as a rank amateur, struggled. Good luck with whatever you end up doing.

What estimator did you use. 3 weeks sounds a bit quick to me but I've not seen or can't remember the plans or elevations. Whats your quantities or brick and block. If you were to allow maybe 75 pence a brick and 2 quid a block down your way does that get you somewhere in the ballpark? Very rough and im not sure of rates your way. With regards to getting some decent quotes try to get an introduction or reccomendation off other trades or previous customers. That way your not a cold calling random you're ringing them up saying I know X who's extension you built or I know X plumber who has worked with you guys says you do a decent job etc

They use local labour rates. A brickie is not usually on more than £300/day. So I said 2 brickies and a labourer for 20 days at £800/day. That still only equates to £16000 for 20 days work. So the quotes of 30k, 42k and 60k are just a joke. Anyone would think I was hiring a legal team.

Although you should listen to the language coming out of the mouth of the electrician I use for heat pump installs when a hp installer put in a 1ph hp cascade onto a 3ph system he'd installed without telling him and without balancing!

We have a 3ph PV system for the 13kW we have on the roof and a single phase ASHP - as @Nickfromwales says the smart meter nets out the demand/generation. So if say you are generating 1kW on each of the three phases, but the ASHP is drawing 3kW on only one phase, the meter stays still. They call it "vector sum metering" I believe.

No, they don't. You only really put a gauge on the heating side. The multi-bloc should be serviced annually but everyone who does so knows the perils of opening up the various prvs and finding that they don't close back up again. But changing out a faulty multi-bloc is so quick and simple and not very expensive either. You just have to get the right one as cylinder manufacturers spec different prv pressure ratings. Off the top of my head Gledhill slimline heat pump cylinders have a 4.5bar rather than 6bar, for example.

Thanks - I like this idea. I assume I'd need to get the SE to confirm it's OK before we start drilling holes in the top flange, or am I OK if the holes are small and not drilled in the web?

Net metering at the 3ph meter has been discussed here quite a lot, and makes for great reading. In a nutshell you can consume or export on any 1 of the 3 phases, or 2, or 3, and the sum of the activity affects the meter reading in balance. So, you can have a solar system on 1ph, exporting, and be pulling in power over L2, and if it’s 1kw in and 1kw out, the meter stands still. No need for a 3ph ASHP, but 3ph solar and batteries is now pretty easy to resolve, so don’t panic too much here just get the right advice off the right people. @lookseehear If you want a very good designer and installer that doesn’t charge the earth let me know, (PM). If you choose well, then you can connect ASHP > solar > batteries > hot water > EV charger in one family of products that “talk”, with the advantage of rapid EV charging with 3ph. You can have bigger solar and batteries on 1ph, just then you’d go for a hybrid system so the number of panels and size of batteries isn’t the value you ‘ask’ the DNO for permission to connect to the AC grid, aka “AC coupled equipment’”, just the size of the inverter is declared and whatever’s behind the inverter is then of no consequence. Plenty of options and solutions, and I’ve done a good few domestic new builds where the clients had 3ph and large on site micro-generation, with a mix of 1ph and 3ph equipment on site. When I explain the many available options to my clients, with reason / rationale (and how the entire electric arrangement can be harmonised quite easily), the fog soon clears; it’s just folk don’t know what they don’t know, basically. Also, there’s way too many salespeople out there which is why I stay impartial. Lots on here on the subject.

Yes, two storey, walls and roof U factor 0.095W/m2K, floor 0.1W/m2K, 0.47ACH.