Dillsue

Exactly this. Max flow temp we've seen is 34 degrees through the cold days we've had and the living areas been at a steady 21 degrees since early november

To keep hot water available switch the immersion on and leave it on. It may not heat the whole cylinder but should give you enough for a single shower. Wait half an hour between showers and you'll all get one. Borrow a couple if electric fan heaters and use those to heat the house while the heat pump is off. For the heat pump fault if youve already cleaned and replaced the blocked strainer and repressurised the system, switch the power off using the switch by the pump and leave it off for a couple of minutes. Switch the power back on and see how things are.

Get the rads sorted out. If you turn up the flow temp you'll be paying extra for the life of the house. A reshuffle of the rads you've got and one or 2 new ones will sort the heating for the life of the house. If the rads you've got now aren't heating the upstairs enough then go back to basics with a check on room heat loss calcs and that the correct correction factors were used to size the rads for the design flow temp you want. Something has gone wrong if your rooms aren't getting up to temp and your really want to find out why

Fogstar have a list of inverters that are compatible with their battery kits so probably best to stick to one they know will work. Install from scratch is probably the best part of a day. With the kits you need to balance charge the cells which would take a bit of time to assemble and disassemble. Charging may take a few hours or maybe days. This is all on their Web site. For install you got the following to do- Batteries need assembling into the pack enclosure Battery pack DC cabling needs connecting to the inverter together with a Canbus comms cable Mount inverter and connect up AC connection to consumer unit Connect up solar if its a hybrid inverter Install meter/CT by service meter and connect up supply to the meter Run comms cable between inverter and meter If you're going for an inverter with a backup output for when the grid goes down you've got to install another consumer unit and move the backed up circuits over to the backup CU. Then run a supply cable between the inverter and the new CU. Could be best part of a day just for the backup CU!

Don't spend too much time recrunching as summers only just round the corner and PV£ will be slipping through your fingers😁

If the cable was correctly sized to carry 7 kw from the house to the garage for the charger then it will be large enough to carry up to 7kw in the other direction ie from the battery inverter to the house. FIT rules changed a few years ago and you can chop and change a system like adding batteries and probably change the inverter for a hybrid if that suited you better

This https://www.fogstar.co.uk/collections/solar-battery-storage/products/seplos-v4-kit-and-x16-highstar-314ah-bundle

If your existing solar inverter is a hybrid version then you can connect batteries to that, but..... if you want the batteries remote from the inverter then you'll need massive cables to carry the high current delivered by the battery if its a low voltage battery, around 48/50volts. If you want the batteries in your garage the probably more cost effective to have a second inverter in the garage to manage the batteries

Fogstar do 15kwh self assembly kits for £1480 so under £3k for 30kwh and showing in stock. How much money you can generate depends on so many things but you'd need to estimate usage and choose a tariff as a start

What would those same comparative figures be for a more normal winter time of say 7 degrees with a load on both pumps of 3kw?

Isn't plastic conduit used for mech protection?? Ive no idea, but do the regs specifically say metallic protection??

Put a duct in so you can easily change the cable if needed?? I don't know what the regs say but with a duct run to a "safe" area either end you may be able to run singles in the duct which will be way cheaper than an equivalent SWA.

OK, but that's the shower that may need a pump, not a vented cylinder. We're open vented for CH and DHW and have a pump only on an indulgent en suite shower. Rest of house incl a second first floor shower isn't pumped.

Our house has a calculated heat loss of 8.5 kw at -2 but we put in a 7kw HP on the basis that it would be more efficient as the days of sub zero temps are few and far between and we could always run a fan heater or switch over to an LPG boiler if the HP couldn't cope. The HP has done 100% of the space heating since september and through the few cold snaps we've had recently with temps getting down to a degree or 2 below freezing. It worked very hard and guzzled eleccy whilst it was freezing but I'm hoping that the undersizing will pay efficiency dividends for the rest of the year?? An MCS umbrella/HP supplier wanted to sell us a 12kw unit!!

Why do vented cylinders need pumps? Other than the circulator in the boiler/HP there's no additional pump needed because the cylinder is vented??

Yes, assuming you'd charged the battery from solar. If you've charged the battery from grid eleccy then you need to deduct the unit cost of the energy in the battery from the import your offsetting or the 15p export rate. When weighing all this up don't forget that when the ASHP is using the most energy in winter your solar will be generating at its lowest. Unless you've got a massive array its likely your solar will make only a negligible saving on your ASHP running costs. PVGIS will give you a monthly forecast so you can see what you're likely to generate in the winter and compare it to forecast ASHP demand.

I'm not certain on this but there was a long discussion on net metering a while ago and I think the upshot was the net metering only happened in real time ie you had to be importing on one phase and exporting on another at the same time for them to cancel each other out. If you imported one minute and exported the the same the next minute then you wouldn't get net metering??

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

It's not sugar coating, it's just a balanced view. Constant slagging of the company/engineer could well cost them work and be the start of a bad reputation if the OP doesn't consider the possible flip side.

Agreed. If I can do what I'm hoping to do I won't be using a single kwh of PV but letting the neighbours have it all whilst racking up export credit:)

Perfect, thanks. Like you say it's very much what fits the individual

Work out average daily consumption for each month. Put 20 units of each day or whatever the average is if its less than 20, into a battery at 8.5p=£1.70/day cost for 20 units to use during peak rate. At peak rate of 32p/unit the 20 units used during peak time would have cost £6.40 so there's £4.70/day saving. December's saving would be £4.70x31=£145.70. With my usage I'd get that Nov-Feb, a bit less Mar and Oct and quite a bit less for the summer when the HP isn't running and the PV is going full chat. Total for me is just under £1100/yr. 30kwh of Fogstar batteries and 6kw solis inverter is just under £4k. I'm also hoping to be increasing PV export by exporting most of what we currently use by using the battery and off peak eleccy rather than the PV. Not as lucrative as the peak to off peak saving but it's a bit more in the savings pot. That's a rough estimate based on current Octopus Go rates and doesn't include charge/discharge losses. With 30kwh of batteries I think I'll be able to use more than 20kwh of off peak eleccy which will hopefully offset the system losses?? Figures pan out for me so just fine tuning things before taking the plunge

Didn't the company send in a quote for remedial work together with a service report??

If you use Excel it's straight forward to do room by room heat loss calcs. Work out the area of each surface x U value x temp diff and that's your heat loss. If a surface has an element with a differing U value ie a window or door, deduct that elements area from the main surface and work out that elements loss separately, if it has a differing U value. Add all the losses for each surface of the room, 4x walls+floor+ceiling, and youve got the room loss. Repeat for each room and you've got the whole house loss. Simples:) After that you need to account for ventilation losses and I can't remember how I calculated that without opening up my laptop which I haven't got access to!! Someone else will likely guide you on that??

I believe IOG needs an Octopus approved EV charger which we don't have so we're stuck with the basic Go. Assuming you do all those calculations automatically with a bespoke system then that level of automation is beyond where I want to go with this, but....... If the battery inverter supports it, I suppose I could configure the inverter to dump what's in the battery to export after we've gone to bed?? Any suggestions for inverters that might do this??