sharpener

As it happens I had a Building Inspector here today to look at my recent HP installation. There are also (wireless Honeywell) TRVs on all radiators in habitable rooms. I asked if they were still required on a heat pump system, but he didn't know and said he would find out in order to satisfy his curiosity and mine.

Depends on which of several different glycols, and the concentrations thereof. See this thread https://forum.buildhub.org.uk/topic/37452-are-all-glycols-equal/.

Have used simplybearings for lawn scarifier (flood damage) and oil boiler burner motor (noisy as oil leak had washed lubricant out). Excellent variety (standard, high temp, end seals etc), top brands, good advice, quick service, they get my vote.

With a delta T of 5 deg a flow of 14litres/min gives you 4.8 kW and 20 gives you 7.2 Rule of thumb: 15mm pipe is good for 3kW, 22mm for 6kW, 28mm for 12kW at reasonable flow velocites. Your original 32/26 Alpex should be more than enough for a 7kW-ish HP, do not fret about the fittings overmuch.

Have just had their 12kW installed, with the flexis. The internal pump is v powerful, it will push just under 2000 litres/hr through the HW coil on its own, even though the pipework to it is only 15mm (am amazed this is not noisy). So I would not worry about the i/d of the flexis. As @crispy_wafer says they are there to provide mechanical decoupling and not undo the good work of the compliant feet. The end result is very quiet. Good luck with yr DiY installation. I had four men here for four days, watching them it seemed fairly straightforward except for connecting to the myvaillant phone app which the lead installer did for me this morning. Are Vaillant going to give you an extended warranty though?

If you haven't got double glazing that might be a cost-effective improvement (after increasing your loft insulation). Stiebel Eltron are an expensive brand and IIRC they will only sell them with their own hot water cylinders increasing the expense still further.

Too right it does. For a rough estimate see this cheat sheet. Our 200 sq m stone barn conversion is currently having a Vaillant 12kW unit installed as I write, a 14kW Grant sounds totally OTT for a smallish bungalow. Over-sized HPs are not only unnecessarily expensive to install, but are also inefficient in operation so running costs are higher as well.

Sounds like the VFD is now doing a proper job of controlling the power according to demand. But given what you asay about the history of the batteries I would guess that as well as reduced capacity they have now got quite a high internal resistance so the terminal voltage drops a lot when under heavy load, possibly getting down to the lower limit on the Victron. Investment in newer/bigger/better batteries might be called for. You can check the battery voltage reading from the Victron front panel and see the effect of turning on e.g. a kettle or water heater. IIRC 46V is when things stop working properly. Even my brand new 7.1 kWh Pylontech stack had this issue. So in winter it would struggle to boil the kettle first thing when down to <20% SoC after powering the house all night. Have now added a third module to increase it to 10.65 kWh and is now a good deal better.

Hello @Hastings. Did reversing the motor direction make any difference to the problem of the pump tripping your battery inverter system?

Sparkie came today and is happy to go with that solution. Whether his boss ever sought Electrium's advice I did not ask, just happy about the result.

IME the colour card is not quite accurate, pH 7.5 is a beautiful cyan colour not the pale blue shown on the card. 1 drop in 5ml is adequate strength. Swirl and then leave 1 min for colour to develop/stabilise. Results are reassuringly stable, no detectable difference in colours between drops bought this month and two years ago, over the following range: 4.0 - Rice vinegar 6.3 - Rainwater supply from 5000 l tank (after bulk treatment with 900 g Juraperle and 100g magnesite, and then 100g sodium bicarbonate added per 1000 l drawn off) 6.6 - Rainwater supply via DHW tank (after cooling) 7.8 - Cold water from mains (SWW ex Avon Dam on Dartmoor after their treatment with alkali) 8.0 - Stock bicarbonate solution (100g in 2 litres)

Have been monitoring the acidity of my harvested rainwater for several years. Found litmus strips/pH test paper very unreliable and was advised against using them on low conductivity water by a helpful person at SWW technical support. Asked Camlab (reputable lab supplier) for advice but their test papers have very poor colour change. Meters are not good either for occasional use as the probes need special looking after and periodic recalibration. Ended up using these test drops, much more sensitive and economical to use, 1 drop is enough for strong colour changes, can now reliably and repeatably measure to 0.5 pH. (Have to do some tests tmrw so will check newly bought against 2 y.o. and report if there is any discrepancy.) Wouldn't buy any of the other overpriced "health" rubbish they sell though!

Depends on the topology. An external meter is definitely required if there are either loads or sources between the incoming grid and the AC connections to the inverter. If not perhaps its internal CT is sufficient (as in my Victron MultiPlus) if it has the necessary settings, the manual should tell you. The SolarEdge application note is definitely US in its flavour. Other meters to look at are the Carlo Gavazzi ET112 and the Eastron widely available in the UK with RS485 and maybe cheaper. Protocols vary, not always compatible with all inverters.

If either the Lux battery inverter cannot export at all or it can be set and locked to a zero export setting you need to reply with details of this and e.g. screen shots of the relevant settings, maybe this needs to be on a separate G100 Export Limit application, look up G100 on the UKPN web site. Then if you make a new application to export up to 10.25 kW they should grant it. This website is unfortunately not very helpful but the camelot forum has other Lux users I think, try there. If the Lux can't be restricted to no export then you are looking at third party equipment which can get expensive, or downrating your PV to the difference i.e. 6.65 kW.

Last call everyone! Otherwise it will all go for scrap next week

Some of it just plain wrong e.g. "It's not always necessarily worth testing the tap waters pH as this should always be between 7.2 and 7.4ish." The statutory range for potable mains water in the UK is in fact pH 6.5 to 9.5 see e.g. this web page. Vaillant say for their HPs (after a load of stuff about VDI 2035, at least they got the inequality in the first line of the table right) My experience of Fernox F and Sentinel X100 is that they do prevent steel radiators from corroding (based on doing the "nail test" every couple of years). Previous installer was proposing to fill system with "1x25litre SECON T Glycol", presumably it has some inhibitor action. New installer is proposing to fit anti-freeze valves, I have given in on this point, bigger fish to fry. Will ask if he intends to use inhibitor after he has flushed the system. Will also make sure he fills system with mains water as is noticeably more alkaline than the treated rainwater.

No, they are proposing to put one in a sub-board, the question is where is it to be fed from. I only unearthed this (sorry) at the w/e after I sent a reminder about the type of mcbs they would need to put in my existing CU, which was the plan agreed on a site visit months ago. They raised further objections (as you said upthread they would!), have now suggested the variant posted last night. Am now starting to worry about what other surprises are to come. Also discovered at the w/e Newark have made some small changes to the thermal store design for no reason, now too late to change it. They sent the sketch to the installers but not to me, installers did not reply or check it against my original drawing or forward it to me for checking. Am also wondering it they have remembered I have a sloping site and what they are going to do about it.

Or a flat screen TV. This also gives you the possibiity of a fish tank or a log burner.

Do you have a view on fitting a 32A Loadstar mcb into a Starbreaker board @Mattg4321? AFAICS they are 100% mechanically compatible and are of course made by the same manufacturer. If I did that I could feed it via a jumper from the incoming (line) side of the Type A RCD rather than from the busbar, so then the HP current would not go through the Type A unit at all and then there would be no risk of it being blinded. (Installer says he has been told Electrium will launch Wylex Type B RCDs later this year and so probably Crabtree ones in 2025, however that is not much help to me.)

The short answer is that in addition to the outside air temperature sensor needed to drive the WC, you also need to add a thermostat or TRVs in the room with the log burner to control the heat emitters (UFH or rads) in that room only. Same applies to any rooms with a source of heat, AGA, floor-to-ceiling windows etc. If as is sometimes done it is the living room and has a thermostat for the whole system then as the log burner heats the room up the boiler will turn down and the rest of the house will go cold. So you would need to move it to a room away from the log burner or remove it entirely.

Sounds plausible, IIRC Daikin HPs have a similar restriction, there is a minimum temp at which they will start, below that they do not in order to protect the compressor(!).

Sorry to burst your bubble but the motor can only turn clockwise or anticlockwise, there is no Third Way! 3 of the wiring options give one and the other 3 the other as upthread. There is no more to be had, focus now on seeing if the Victron inverter behaviour has got any better.

It's been an enjoyable ride and am so pleased for you. Just glad we could all help, that's the power of BuildHub. If it now draws only 600W (don't quite understand why that might be but an added bonus) then maybe it will run without crashing your battery so much, keep us posted about that too.

No it does not matter. As others will be able to confirm all three windings on the motor will be identical. And all three outputs of the VFD are electrically equivalent to each other, except for a 120 degrees phase difference in the waveform (see Wikipedia article). So it makes no difference which is connected to what, there are six possible ways. However for 3 of the six the motor will run in one direction and for the other 3 in the other direction. Swapping any two wires - as @dpmiller also recommends - will change the direction. I was only joking, there is no danger to you, the VFD or the motor in trying it out.

If only it were that easy. Terminals are U, V, W. Wires are brown, grey, black (though not in that order). Go figure! I guess we will find out shortly, if @Hastings is still with us.