All Activity

I think i would want a pv diverter to tell pv to charge up the water tank. How big of a cable and duct is this going to require? Am I setting myself up for problems? I am also considering extending the garage so it adjoins the house. I suppose no duct needed then can just take the cable thru

It was @JohnMo

Yeh i meant to say "crack just anywhere"

Not at all. Never in the house, and only if standing on top of it in the garden, and then it's pretty quiet.

with the eps suspended floor systems the slab kind of has to act as a raft on top of the eps. It can't just crack anywhere You did say that was the floor consruction and I forgot. Yes that makes sense. You mean eps blocks spanning between beams? For the pedantic record, it will still crack, but in millions of almost invisible cracks instead of a few big ones. The mix must be exactly as specified, so leave it to them at the plant... Never, ever, ever allow anyone to add water on site. In fact instruct the contractor and also the driver not to accept any request to do it as you weaken it and have lost all guarantees. And it isn't a raft, just levelling screed. With some systems they want a 100mm or so reinforced concrete slab over, to provide stiffness, but I assume you are following all the instructions.

@G and J Would I be right in thinking you can’t hear it at all?

Window framing and cutting out the trusses Continuing where I left off, the remaining job to finish the structure was to frame out for the pitched roof windows and the flat roof light. This was quite simple: brace across the steels either side of the planned opening, cut out the rafters, insert the trimmers and fix with the Ecotrus-supplied brackets. I ordered custom windows from Roofmaker, so I simply used the truss bay sizes to determine the maximum size of the windows. The original truss structure was still largely in place at this point, so that helped to keep things rigid during the framing. For the flat roof light, I fixed the rear trimmer first and then fitted the remaining ceiling joists up to it. This was the only bit that proved difficult because of the amount of steel required on the edge of the structure - it was a tight squeeze fitting this in the narrow truss bay, as the image hopefully shows. I added timber that was the same dimensions as the original trusses between each ceiling joist to keep the system square and to give a good fixing point for the flat roof build-up later. Once all that was complete, I was ready to cut out the trusses. This only took a morning to do (although it was 35C when I did it and I ended up a properly sweaty mess...). The sense of space when it was all opened up was a pretty special moment. System compromises As I've said previously, I think the EcoTrus system is a good one and well-suited to my requirements. That said, there are a few compromises that come with using it, most of which are just inherent limitations of the type of system it is. The first is the layout of the planned space is partially restricted by the existing truss layout. This is particularly noticeable for the stairs positioning and cut-out. It's obviously very unlikely that the existing truss structure is going to line up perfectly with internal walls (planned or existing) at first floor level. In our case, this will result in a slight bulkhead on one side of the void for the new stairs. This probably wouldn't matter if your aim was simply to have an opening large enough for the stairs and no more, but I wanted a double height space that would add a sense of volume and some much-needed light to our existing first floor landing, as this sketch shows: That leads me on to the second compromise - the system appears to be largely aimed at people who want a no fuss loft conversion which aims to maximise space and minimise disruption. This makes sense, given it can theoretically be fully erected within a few weeks and retain most of the existing roof covering. However, my experience was that anything deemed 'unusual' - like my intention to insulate externally or the planned stair void - seemed to confuse the designers. I had to pay for additional structural calculations to achieve the stair void, because it called for three rafters to be fixed solely on the wall plate. There was also a subsequent error in the design - which, to be fair, I failed to spot on the drawings - which meant the structural framing for the stairs cut-out was larger than it needed to be and arguably one truss bay further over than it should have been. I had to add a pair of timber joists to resize the opening. The final compromise is thermal - by its nature, the light gauge steel is a massive thermal bridge. The standard EcoTrus detail calls for PIR between the rafters, ceiling joists and dormer studs, with a Superquilt or similar material fixed to the internal side. They have calculations to show this meets Building Regs, but I'm doubtful about the real world performance. The flanges on the steels would make getting a tight fit on the PIR a nightmare, and relying solely on the Superquilt to prevent bridging through the steel itself seems optimistic. I'll cover my thermal build-up separately, but I'm much happier that my end result utilises the strengths of the light gauge steel approach without the obvious thermal compromise. Again, this is quite specific to my situation and wouldn't have been possible if I wasn't re-roofing as part of the project, so I realise it's not a change that everyone can make.

We always used to have windows open but have found that with mvhr we prefer not to. Ours is 12m away from house....you can come listen!

Yes , keeping existing PV system with FIT with no alterations. It is upstream of the house on another outbuilding sort of on its own loop. I will get some quotes from MCS certified installers but not really bothered. My friend who has been very busy recently with these large solar + battery farms is a residential electrician but will check with him. I assume the grid export limit on the Libbi will be set to 0.0kW so cannot back feed to grid and compromise the FIT. Think will need a formal pre installation G99 grid notification certificate. Thanks Rick.

So this is a new build. When I say do the work myself, it isn't something I would take on but employ a plumber. My plumber suggested we could do the install under the (what I have now discovered is called) umbrella scheme. However the plumber went to city plumbing and after waiting for 6 weeks I have seen a quote that includes a 6.5kw heat pump, which is too big. So I have no faith in the plumber or city plumbing and I am struggling to just get on with this. I have been quoted 12.k for a system from Installio before the BUS granthas been deducted, which leaves me with a 4.5k bill, which seems like a lot for such a simple job. The flow and return pipes are already in place and I don't need anything sophisticated in terms of control. I can't believe how much incompetence there seems to be in the industry, or am I being unfair? I am at a loss as to how to get this done, wither through the BUS route or via the Umbrella scheme.

Just over clock the inverters, fit PV to run at max amps or max voltage. We have 6.5kW PV on a 3.6kW inverter and 2kW on a 1kW inverter. Any excess is just clipped, but rarely does it clip anything. But if going with hybrid inverters and battery you can put as much PV as you want on the DC side as long as you stick each array in it's own MPPT. Battery and inverter I would investigate if you are running on a cloud and walk away if you are. Our GivEnergy is a good example it can be run in full local mode, so when GivEnergy went belly up everything just carried on working. A cloud based system you stuffed. Sig I believe need a web connection to have full functioning - so if that's the case, I would look elsewhere. Also if you want full house functionality in a power cut, look for a system that has a gateway, that will allow full inverter output to house with grid off. Most normal hybrid just give a small ups output which is great if you just want a light on.

Also makes a big difference how you actually run the heat pump, if slow and steady on WC it will just modulate down and be almost silent except for the coldest days. But you will also be running flat out doing DHW reheats, so timings makes a difference. And if you run in cheap time periods mostly, your heat pump could run at full load for an hour or 2. If your having a shed, stick it behind that. Out the way a d noise has a barrier.

If this is to taps, the taps have restricted flow anyway, so these will make very little or likely no difference. If they are in a heat pump heating system, that's a different story.

Thanks marshian, however the words 'isn't significant' is not something I greatly trust coming from most plumbers given the flow issues experienced on my new mains system. From my perspective professionals should not be fitting sub-standard components to systems when the full standard is available for pennies more. The core purpose of a plumbing system is to deliver water flow, restrictions should be avoided not added for no good reason. Plumbers seem to have a tendency to claim every component of a system 'makes no significant difference' then run a mile when the overall system disappoints.

>>> mcs sound calc Ah, good point. So, i.e. 52 + 10 log10 ( 3 (for grass) / (4 . pi . 5^2 )) - 0 (5m because distance is to 1m point and leaving a 1m gap to the hedge) = 31.8 dB(A) So, within the MCS limit of 37dB(A). But, I have no idea really how loud that is. Windows will be 21 degrees triple glazed but we do sleep with the windows open. Also, this is a quiet country location, so there's not much background noise.

If you are all on mains pressure the restriction isn't significant - if you are on gravity feed then full bore isolators are the only option as the narrow bore isolators really impact flow.

Firstly, with a 100A connection why start with the premise of only exporting 12kw? At least ask the utility if they can support higher export? Then it's simple and easy. Even if they limit export below generation it seems like keeping things simple would be better. Having said that, you might not even get 12kw so that then creates another problem for you. I'm not sure your approach does anything more than make things complex. A 24kwh battery is not enough to fully charge a car and even if you are mostly just topping up you will likely come across times when you empty the batteries in the off-grid system before you charge the car. Also, if the off-grid system had spare solar stored in it's battery but the house did not, you would have no way to use that capacity. So I would look for everything to be grid connected (with ability to continue operation without the grid). That way you get the full capacity of all batteries available. If you have significant excess generation that can't be exported what are you going to do with it? Seems like a huge waste to spend a fortune on install and not have anything to use it for. If you plan a workshop with potential for 3p machines then an alternative setup would be to use inverters to generate the 2 other phases (all connected to the same battery). 1 inverter is connected to the grid, the other two phases purely rely on solar/battery (inc charging from the grid connected inverter). I doubt this is a common option but I know you can do it with some inverters (Victron). Still I'm not sure it makes much sense from a financial POV.

OK, I'm working on the premise: 1) Panels are cheap and it's best if you install all you can at the start while there's scaffolding etc. 2) Ideally I would like to be off-grid, but PV production in the middle of winter is b....ks, so I'll still use a grid connection then. But I would like to maximise PV production in the shoulder seasons. 3) I have a 1P / 100A grid connection to UKPN. So, I'm planning about 48kWp of panels split across 4 roofs (in 2 pairs) in various orientations. And then: 1) Asking the DNO to allow a 12kW 1P inverter with grid connection for the house (ASHP, DHW with immersions, kitchen etc) which will support 24kWp of panels on the house (2x clipping). This will be integrated single stack (probably Sig) with as yet unknown amount of battery. 2) Having a separate 12kW 1P for the other 24kWp of panels on the 'cart lodge' but disconnected from the rest of the house circuits and the grid. This will only be used for car charging. What do you think?

If I understand you correctly, you are not changing the solar system but adding a battery system? There might be part P issues with option 1. Your friend might not have the ability to do the part P compliance stuff. (You need Part P compliance for any work in a house, work outside of one, maybe not, but if the garage contains a live in unit then it likely counts) Assume you aren't bothered about MCS certification? Good reasons not to be (markup by MCS folks) but MCS questions are common when selling a property so something to consider. Do you have FIT with your current system? (Maybe your existing install predates that??) If so you want to make sure that nothing you do affects that.

So I notice my plumber(s) has used isolation valves which are NOT full bore on my plumbing (See pics). Whilst I appreciate that taps commonly have a reduced bore within them, I don't really see why these reduced bore valves should be used given they will reduce flow rates, and no doubt there are others placed elsewhere to act as service valves but are flow restricting. It also means my previous measurements of internal flow rates are invalid because plumber(s) are deliberately choking off flow. I notice when these things are sold it is not made clear that they have reduced bore. The cost of a full bore valve appears to be around £3.50 and a restricted bore one £1.30. The difference is what many people would call insignificant - certainly compared to labour costs. Is it totally unreasonable to ask for these to be replaced ? Is there a way to tell the two apart by looking at the valve (while full bore tend to have a lever, the levers are of course removable) ?

Also depends on your windows and whether you routinely sleep with them open? Good windows, usually closed will block most normal heat pump noises (in a well specified/setup system)

Not another one! Just want a system that works well and ideally has full off grid back up during short powercuts. Average annual consumption from the grid is 8500kWh. ASHP 3000kWh. Solar PV 3500kWh. Our Current Setup : • Solar PV: 3.74kWp array installed back in 2011, that has averaged 3,500kWh of generation annually. Works a treat. • Diverter & DHW: We have a V1 Myenergi Eddi (Model 16A1P01) sitting in the plant room, diverting our daytime solar surplus straight into our hot water cylinder immersion. • House Spec: We are an all-electric household (no gas or oil). Heating and DHW from Mitsubishi Ecodan, monitored by an Elster meter. • Outbuildings & Sub-Main: A sub-main supply loops out 8 metres from the plant room to a garage consumer unit. This zone houses a separate full-time live-in space with its own appliance baseline. • Data Link: We have a pre-installed, active Cat6 data cable running the 8-metre span between the house router/plant room and a network switch in the garage. I am looking at the Myenergi Libbi 5kW 230V IP65 Hybrid Inverter & 15kWh Battery Kit (LIBBI-KIT-5.0K/15KWH). The plan is to install the inverter and three 5.12kWh battery blocks out in the garage outbuilding, running back to the garage consumer unit. To hook up the grid-boundary sensor, we want to split our existing Cat6 cable, to hardwire a direct RS485 Modbus data loop from the house plant room straight to the garage inverter. We will configure the system via the Myenergi ecosystem so that the Libbi Battery acts as Priority 1 and the legacy V1 Eddi acts as Priority 2 (with "Avoid Drain" enabled). I have found the 5kW / 15kWh Libbi kit online for £5,628 including 20% VAT (approx. £4,690 trade/wholesale at 0% VAT). Two options. 1. Supply Only + Electrician Friend: Buy the kit myself and have a close friend who is an industrial electrician (he installs large-scale commercial solar and container-sized utility battery networks) fit it for me. 2. Supply & Fit Quotes: Contact local independent installers to quote for the package. Your thoughts much appreciated. Thank you.

It very much depends on the noise output of the heat pump. This is always found in the specifications and you can use the mcs sound calculator to provide results for you. Measure from the heat pump to 1m perpendicular to the window door in question.

You might want to install something that needs to monitor import / export current for instance, such as a PV diverter. This would require a current clamp on the incoming cable. So if you opt for a remote incoming supply, install a separate duct between the garage and the house through which you could pull any required cable for this purpose.

Is there any downside to having the meter in a detached garage? I seem to remember a few on here over the years have had meters away from the house. I have an existing garage we hope to keep and would be handy to get meter connected there and can get site power then