Wil

Sorry, left this hanging will send you a PM.

Is that a water FCU? I'm Cambs/Northants/ Beds border so could well be interested. Just need to investigate it's specs

Bit late, but Unifi In-Wall AP's can be powered from POE and have a downstream POE port. I have an AP powering a hub at the moment. The hub itself can't do further POE though...

Hi Ashthekid, I’m in a similar situation with horrendous winter bills and then almost nothing in the warmer months with solar taking care of almost all HW. Sadly I’m also collecting the RHI, so can’t make any changes in the first 7 years. When I can I’ve been looking at a WBS with backboiler to take the strain off the ASHPs for the winter months to take advantage of my free wood supply. Relatively complex to integrate the two systems however and probably needs me to replace the buffer tank with a thermal store to take the heat loads. We’re due to start a renovation shortly so will be trying to hit our air tightness issues and improve insulation in floors and sloped roof wherever possible.

Would it work to put a chock of wood in between the webs of the C section for the first screw only so that it doesn’t deflect inwards? Don’t know how you’d hold it there unless you put it in with a temp screw from the other side first… unless you start at the bottom. I’ve watched miles of the stuff go in, but most pro’s tend to use the speed guns so smash smash smash, done.

But the ASHP can’t do DHW and cooling at the same time so will need to swap between the two modes anyway? Or do I vaguely remember that you have a TS and therefore your HW comes out of the ‘buffer’ you would be cooling for the FCUs/ UFH? If that’s true then some sort of bypass of the TS with a 3P or 2P valve arrangement into a small LLH might be the way to keep DHW while enabling cooling as well?

Are you trying to have a 4 pipe system with some heating and some cooling? If not, just use the same arrangement that you use for the heating? I can’t see why it would be more efficient too cool down a central buffer first if you have the volumetric capacity to operate without one. Only benefit might be if you’re using different temps for the floor/ FCUs in order to avoid condensation?

20A radials in 2.5mm for the win!

If you ever do come to Battersea, send me a DM, I’m around here 4 days a week… haven’t noticed any bouncy floors though…

90A at 230V is 20.7kW isn’t it? Meaning in 3hrs you’d get 62.1kWh of charging at full rate?

With using the HP, unless you have some sort of direct and intelligent link between solar generation, house consumption and the HP, you will almost always end up consuming some grid electricity. This argument has been had on another thread recently and I get the proponents saying for the 'greater good' we should be exporting whatever we can, paid or otherwise. However to keep it simple, you have a solution whereby you can charge your HW tank using excess solar whenever it is available, from the moment the solar generation becomes greater than the total consumption. From that point on, all HW is free until you get a piping hot tank at 75/80 degrees. If you run your HP, you'll get whatever it's DHW setpoint is (50degrees?) but also run the risk of import an cost to do so. each time the sun goes behind a cloud or turn something else on or ((HP consumption + House) > Solar Generation) then you will be importing the difference. Personally I'd be sticking with the Solic until the PV can't cover your DHW load and then the HP comes back on. This way you also run the moving and serviceable parts of your expensive HP half as much and prolong it's life as well. Edited to say ^ ProDave's approach is ideal and could even by automated using forecasting software, but requires a fair bit of continuous input from you (him).

I've taken my diverter out of circuit (had it before the batteries were installed and they fought as above and either drained the batteries into the HW tank or just threw a fault on the diverter). Until then the solic diverter was a solid and useful piece of kit. Now I just monitor the battery state of charge and when the PV is >x and battery SOC >x I switch the immersion on for a burn. The batteries allow me to ride out peaks and troughs in production such as clouds passing the panels. I use a shelly 1PM to switch the immersion although rated at 16A this is probably right at it's limit and there are many reports of shelly devices failing with switching 3kW loads. Mine has been fine so far and I'll run it til it fails before looking for another solution. TL;DR don't bother with a diverter, just switch your immersion on full whack when the batteries are nearly charged and the sun is shining.

The heating manifolds don't (yet) exist- I'm still direct to rads so the return pump is doing the internal heating circuit. I've tried a few different running configs- ASHP1 doing HW, with ASHP2 leading heating etc, but always seems more efficient to have the smaller one lead. Sadly the heat loss calcs say I need the capacity of these two to cope. I'm hoping that once I've done my renovations I can cope with just one of the ASHPs, then I'll move the other to a class Q conversion I'm planning.

I've never seen it happen, but not sure that it CAN'T. I have the CoolEnergy 120l buffer and it definitely has an immersion which I use for dumping excess heat after the HW tank has had it's fill. The 120l immersion gets turned over bloody quickly by my system though: my heating is still just Rads, and no 3Pv on the cold return to ASHP 1 but otherwise it's pretty much ready for me to do the renovation and change the emitters. ASHP1 is HW led but primary heating and ASHP2 only comes in if ASHP1 isn't coping with the heat loss. They have two thermostat pockets at different height in the buffer tank, so I can confirm a small degree of stratification going on, it's what I use to ensure HP2 cuts off and leaves HP1 running (Hp1 stat lower in the tank). Sadly Immersion 1 doesn't exist either for a part-tank top up.

Softies… can’t believe they haven’t put ASHPs in. Imagine all those PM2.5- the WBS ban brigade will be chomping at the bit…

It gets the chance 24x7. The HW is always on if the tank temp drops 5 (or maybe 7) degrees below the setpoint, the HP kicks in and pushes it back up. If I’m particularly unlucky I guess the HP may have run from 4-5am and then the immersion kicks in and I guess the optimisation would be to look at the tank temp or last HP HW cycle before deciding on firing the immersion at 5am. Through winter I just use the boost. If I could reliably tell the HP to switch on at 5am in HW mode and run for an hour (or even 20 mins given the COP gain) heating the water til it runs out of breath I would, but the immersion does it more easily and with more headroom. Tbf once BST kicks in, the E7 period goes to 8am and I can leave the HP to do all the work and forget the 5am boost. It also has a better COP and less defrosts due to the warmer air temps. Pesky winter getting in the way of my electricity consumption.

Roof is SSE, about 20 degree pitched with minimal shading as above (the darkest days of Dec there’s a tree about 200m away that’s big enough to put a little shade on us). We got 122kWh in December ‘22, 201kWh in Jan ‘23 and 283kWh in Feb. I’ve already had more in March than Dec total. I saw your tank insulation and was very impressed. When I finally put the tank in it’s final location I will attempt to do the same. Although the losses could be argued to be straight to heating the house!

Because the immersion keeps going past 48 degrees. If at 5am my tank was at 47 (at 2/3 height where the stat is) when it starts, 3kW puts the whole tank up to about 56 (ish- wide margins etc). The HP would not even start as it’s close to 48 degrees. However a large proportion of the tank may be lower than this and when we get up and have 2 showers in succession at 6am the second shower has, on occasion, run cold. Add to that the primary HP sees the drop in temp and then kicks in. This often means it switches from heating to HW and if second shower was at say 6.30, the HP is still recovering at full chat (about 4.9kWe) past the 7am change from e7 to daytime and the jump from 15p/kWh to 43p/kWh. Which costs me a lot more. In cold weather it also guarantees at least one defrost cycle and the lost time that would have been heating the HW. All in all, it’s a lot more reliable to chuck 45p at the immersion between 5and 6am than it is to try and make the HP do it and potentially take longer, cost more and end up with a lower temp tank. Ah thanks Marvin, I guess it’s the 400hrs of extra sun (you lucky thing) and the significantly less heating demand. I’m just generally surprised that with 5kWp you’re managing to get enough extra out to do your HW through winter- I had 1kWh in total out of the solar a couple of days ago! And no shading issues here fortunately.

Edited to start with an apology to the OP for this getting a little off-topic. Out of interest Marvin, how much PV do you have that you can use it through the winter for HW diversion? I've got 5kWp, a solar diverter, a heat pump (x2), and batteries. I also have a large and inefficiently insulated house with 4 occupants. So my HPs work hard for longer than I'd like til I renovate. The HPs work hard as it is and it costs the earth. Today my batteries didn't even get to midday from full at 6am. Conversely I did have a day in the warmth a couple of weeks ago when I didn't use any non E7 energy at all because the HPs didn't have to run all day to keep us warm. My PV has done almost sod all to hot water since September frankly. There just hasn't been enough. Our background load is 300-400W when things aren't in use and the batteries suck any excess which prior to them being fitted would have gone into HW. But even without the batteries I wouldn't have had excess on my PV to divert to HW and certainly not enough to cover our 300ltr tank. I now do a 3kW immersion burn on E7 at 5am to cover morning showers and usually the HPs kick in after kids bathtime to get the water back up to 48. Rinse and repeat. In the summer/ spring, once the batteries are full I use home automation to kick in the immersion and the batteries to ride out peaks and troughs in the sun going behind clouds. Either way I'm firmly in the elec direct to immersion diversion camp for all the reasons above. Controllable, simpler to implement and costs less. I get the argument for grid scale generosity and when I run out of things to divert to they can have it. but I have an awful lot of cost to avoid before I can get there and thrashing my HP even harder isn't going to help.

If that’s the mixing valve, then sending it cold water when it’s expecting hot just means it will fully open and not mix any of the return from the UFH manifold. This is fine as the higher temp return water will just go back to your ASHP/ chiller. If it’s the lowest temp setting to get the manifold circulation pump to engage, that would be strange and definitely a problem for this idea. If you have room stats, you may need to set them excessively high in order to get those zones to open if the temperature in the zone you’re trying to cool is already high.

I had a Solic, then got my Tesla batteries. Couldn’t get them to play nicely together, so took the Solic out of circuit and now use a ‘smart relay’ to close the contact on the immersion when the batteries are nearly full and the sun is shining. This mean batteries take solar priority and then once nearly full, the immersion takes full whack until the solar input drops (say below threshold of the house). The Batteries allow for sun dropping behind a cloud and also allow the immersion to take full 3kW even if solar only producing 1kW. Then set a low limit on the batteries when it drops the immersion again. It’s a bit of a bodge and would be far better to get the Solic to ‘see’ the battery- something like Christiano has done but I couldn’t work it out!!

Yep, that’s generally how I’ve done it. Although tbf I’ve only done the rooms I’ve refurbed so far. A centralised switching position would be a far stronger call if you’re starting from scratch. Especially with the newer Ethernet devices.

Or you can put the Shelly up in the ceiling void behind the fitting if there’s not enough room in the back box…

Mine’s a Cool Energy unit with some lovely labelled terminals in the outdoor unit. I just googled Samsung 8kW R32 Monobloc and got this manual from Midsummer: https://midsummerwholesale.co.uk/pdfs/samsung-ae050rxydeg-eu-manual.pdf No idea if it’s the same as yours but it seems to imply a low flow error is on the controller. Do you have a central heating pump at all? Or are you expecting the pump in the monobloc to do all of the flow in the house? Turning the heating pump on to ‘pull’ a bit of water through in line with the heat pump water pump would also help get the flow going. I can’t see any obvious terminals to short but the control section of the manual tells you how to interrogate the display to see what the pump is up to. If you’re not confident stepping through the manual, might be time for a heating engineer Callout. Good luck!

Does that apply to all DNOs? Do the Wild Western Thieves come under this as our T/X is well under powered? (Western Power)