Hastings

X-JE120BT 3-phase Evolution series pump E-Power e-MM/MT 230V controller/inverter Yes, it is a soft start.No spike - takes a few seconds at startup to go from 0-1200W. Other high power kit in the house: air-fryer, small kettle (1.7kW each), shower room heater 1kW work fine - battery DC voltage drops temporarily as expected, followed by rapid recovery. Also have the 170L Edel ASHP hot water tank (300-400W) working fine. Battery bank: 8x12V 210Ah (C20) Deep Cycle AGM Rolls. It'll take me a while to check through your other links and pointers (thanks).

@sharpener Thanks for taking so much trouble to help - it really is appreciated. You have educated me and put me onto some new thinking. I didn't know about the inverter rating for pumps advice from Victron. My 4kW Victron is therefore strictly too small for a 1.2kW pump, although I wonder if Victron are talking about fixed speed pumps that have big startup spikes? I will look into that. From your experience I think I would rather go with the DAB pumps as the parts are all replaceable (as with the Steelpumps pump I have). Yes, I have tried the existing pump as a submersible and found it still to be unable to achieve more than 1.5bar at zero flow. The test setup was with just a 3m length of output pipe from the tank (including the same small pressure vessel specified by the manufacturer) to a stop valve. This result is what decided for me that the pump or controller was faulty and so I sent it back for repairs. But it was deemed not faulty and was reaching up to to 8 bar in their workshop (and I believe them because they have already sold me a replacement pump at wholesale price when the original pump was destroyed by gravel in the suction line). I am now suspecting that my battery bank and/or inverter could be the problem. My uncle's motorhome had trouble with sensitive mains equipment that wouldn't work and the fault he traced eventually to poor state of the battery powering the inverter. My house battery bank, although only 3 years old (another long story) I am anyway having to replace (with exactly what you have) this autumn, so it makes sense probably to do nothing about the pump until the new b/bank is in place. I have one section of spiral reinforced pipe(from a floating intake) in the tank and the rest, 25m underground to the house, is standard rainwater MDPE (black with a green stripe) which is probably not intended for suction lines but I think is strong enough to hold up as it is strong enough to deploy underground without any protection from compression forces there. It is 32mm but the pipe inserts at the joints restrict it down to 22mm which isn't great. I might try taking those inserts out.

I would use a stop and start pressure switch - either a bullt-in one or separate one located at the house. I'm not particularly wanting VSD but just happen to have that at the moment because the supplier suggested it in order to reduce the risk of power spikes causing a problem with the house power. At the moment my pump crashes the 5kVA Victron inverter with its 1200W demand unless the battery bank is fairly well charged, which is generally only in good summer weather. Any way I can reduce the total house peak power demand means I can put off needing to replace the battery bank. If I get a jet pump and it turns out I have to put it nearer the tank it means I will have the added cost and trouble of housing it (and without spoiling the view). What do you do for winter power?

Expanding foam tape might work just for the draft-proofing, if you can get it into the bigger gaps. I used a lot of it between all my structural wall panels in building a timber frame house. It helps prevent thermal by-pass. It's also used by the best tradefolk, to fit windows.

@sharpener Thank you, that's extremely helpful info. I didn't know about jet type pumps and it sounds ideal. Steelpumps who make the pump I already have (and isn't working well as an above ground suction pump) don't seem to do them, or the UK agent doesn't import them. I'm understanding now that submersibles use less power than pumps that have to suck water from below them, so that's probably the way I will go because of my winter power scarcity. Ram pumping is out of the question because I can't afford the water use. Already limited to maximum 2 person occupation of the house by private water supply regulations (new builds): have to provide 200L per person per day (167sqm of roof in a location getting an average 1,300mm/yr rainfall yields a daily average of 480L/day.)

@markocosic Sorry, just found more info on that inverter and that answers my question. It does control motor speed, even single phase motors. Also has dry run protection.

@markocosic Interesting, thank you. Good advice about flow and rated pressure. I've studied both your units on their web pages but am not entirely clear... Your combo is a single phase fixed speed pump converted to variable speed (constant pressure) by the Archimede sensor/control unit? Seems more advanced than simple ON/OFF control, according to pressure, like the £20 https://www.ebay.co.uk/itm/272751286212 that @JSHarris describes in his system. @SteamyTea Thanks. Using that calc it looks like a 400W submersible should be more than enough for me (confirming @JohnMo's advice).

@JohnMo Thank you. That sounds like our borehole too: 45m of drilling but the level is usually at 3-4m after a short rest. Ammonium in our new borehole killed it for household use.

Is the water level 34m below ground? I'm interested to know the total head. Thanks for your time. It's really helpful.

I already have a variable speed pump, specified and installed by others, but it's never worked well. Installed above ground at the house, it can barely achieve 1.6 bar and pulls its full 1200W at all flow rates. 2 plumbers have said it must be faulty, the supplier tested it at their workshops and deemed it not faulty. The suction piping resistance seems the obvious culprit - it is 32mm black (green stripe) MDPE but includes 3 tight 90 elbows (two of them very close together) and a mesh filter close to the pump intake which are all 'no-no's in suction line design - yet when I ran a test to eliminate the suction piping entirely by putting the pump in the supply tank as a submersible, it still couldn't achieve 2 bar pressure (hence the conclusion that it was faulty). The supplier suggests selling me another pump to put in the supply tank to help the existing one. I suppose they would, but I feel it's just wrong. I can eliminate the two tight 90 elbows close to the pump by completely refitting out the entire pump house along with the pressure vessel, UV and string filters and can probably replace the remaining 90 elbow just outside the tank with two 45 degree bends (maybe even just a long gentle bend of pipe) - can do that myself I am fairly sure - then try the existing pump again. But would it make that much difference to be worth all the work? Alternatively I am considering selling the existing pump and starting afresh. The obvious solution seems to be to go the submersible route. That would involve the expense of getting the groundworker and electrician back to get power the 25m to the tank. @JohnMo So all I need is a single 500W 'ish submersible fixed speed pump to run the entire system? I only need 2 bar pressure and 15L/min (20-25L/min would be better). Does yours have the pressure switch integrated into it and can the pressure be adjusted at all?

I have a big underground rainwater tank as the sole water supply for an off-grid house. The tank base is 3m below ground floor level and it is 25m from the house. All the house plumbing is ground floor only so total head max about 5m. How do I decide between a variable speed drive (VSD) pump that only requires a very small expansion vessel or a fixed speed (FS) pump combined with a large pressure vessel (at least 300L)? I understand that the VSD pump should last longer and they are promoted as being more efficient and using less energy but the comparison is generally made against a fixed speed pump without reference to the existence of any accompanying pressure/accumulator vessel. The startup current of a fixed speed motor isn't really an issue as the power system can handle momentary big spikes in excess of 4kW and anyway 'soft start' fixed speed pumps are available. The priority is lowest overall energy consumption due to winter power generation being low (a wind or water turbine is not an option).

The requirement for a recent calibration certificate is in the 'Domestic Ventilation Compliance Guide' along with a commissioning procedure checklist. I based my own commissioning report on this in because I couldn't risk the additional cost implications of a rejection. I will never know if the BCO ever looked at my DIY report (see attachment). The hire of the calibrated (and on an approved list of models) anemometer was £150 including shipping both ways, still leaving me a saving of about £650 over the best quote I could get for having someone else do it for me. MVHR-commissioning-blank.xlsx

Be aware there is no real tech support with Victron stuff. You post your problem on a forum and wait/hope for a response from the community.

It just depends on the particular design and the loading. There are no rules. My two storey timber frame build inside an old stone-walled building had noggins (at mid height) in the ground floor walls but not in the upstairs walls. BUT that is probably because the roof structure rests entirely on the the existing stone outer walls. The mid-floor joists rest on top of the ground floor timber frame stud walls so those needed to be much stronger. Both upper and lower level stud walls had a single 11mm OSB sheet for racking and to retain the wood fibre insulation. I'm talking about the outer walls only here - not the internal partitions walls. I'm no engineer but I'm pretty sure that plywood is there to prevent racking and noggins are there to support the vertical studs from buckling under compression. The ply will also help stop the verticals failing but only to a limited extent but that might be enough, depending on the particular overall design. I had one contractor who helped a bit with the work refuse to do some ceiling insulation in a lean'to a particular way (no SE drawings to refer to, just my own past experience) and so I had to tell him to leave it to me to do.

I don't know but I have read somewhere that they're considering doing so. As well as rodent damage, plastic pipes have been known to soften or go brittle when in contact with some sealants, and fire block mastics. Wiring can suffer the same way when in contact with incompatible materials. But apparently it's errors in assembly of push-fit plastic connectors that causes most leaks.

More than in any other type of build, you have to make sure they don't! Metal, concrete/cement render outer shell might work for a while. Plast ic pipework may be cheaper to install but then make a house more expensive to insure, due to the high prevalence of leak insurance claims from houses with it.

Rodents can and do eat through anything but copper pipe. That's the reason plumbers I know don't like to use it where pipework is hidden.

Looks like the sheep wool kind that I have recently used for noise isolation of my MVHR unit where it hangs on a roof truss. Also used it for general pipe insulation where the foam stuff can't go round tight corners etc.

Pretty sure it is a regulation in Scotland, similar to the rest of UK. My first (Gas Safe) plumber put insulation on all his hot and cold water pipes (there is no wet central heating piping) and labelled them. It means leaving a good amount of spacing between. My second plumber didn't know the regulation and made it impossible for me to follow with pipe insulation where crossing pipes almost touched. As @Iceverge shows, there is little point to it in terms of saving energy. That grey foam insulation isn't a close enough airtight fit to work anyway, even on straight sections of pipe, never mind the clips and tight elbows. The only place it DOES make some sense to me is all pipes 1m connected to the hot water cylinder. But only if carefully taped and airtight to the pipe. Maybe the reason for requiring it is for frost protection in the event of the house heating system failing completely, long power cuts in freezing weather like I remember in the 70s.

Ah, that explains my puzzlement, thank you. Have been off grid for the whole 5-6 year build and loving it. Would have preferred to have less power and fewer mod cons but building standards and public health dept (private water supply police) of the local authority stood in the way of that ideal home.

Still none the wiser, sorry, but the 2000W challenge is right up my street.

Added it in to what?

I am going into my first fully off-grid winter in southern Scotland (Glasgow latitude) so I can't yet be definitive (and even then it would be just the one year) but looking at the data I am finding that my PV production is quite a bit less than the estimate obtained from online tools like PVGIS. Two days ago my 1.9kW PV array produced 270Wh on a grey drizzly day. That's not enough to power the constant background load of charger/inverter (30W), UV water filter (30W), MVHR (15W) and system losses.

Small wind turbines are only really best suited to houses where there is no affordable grid connection - which from a commercial perspective is probably not enough places in UK. PV in northern latitude winters produce little output in many places so a turbine is a good option compared to getting grid connected (I was quoted £250,000 for a 2 mile installation). My 1.9kW PV array (same latitude as Glasgow) does the job in summer but produced only 270Wh today and we're not even in Dec/Jan yet.

I chose to install a 240V inverter with my off grid 2-storey house refurb due to the considerable extra cost of heavy gauge DC wiring that is needed to run wires further than a few metres. Even 48V, which is my battery bank system voltage, can only be run the length of an artic lorry using fairly standard cable. 12V works cost-effectively around a car etc.