Wil

I ended up boosting the immersion for an hour with my final 4.30-5.30am cheap rate to make sure there’s always enough for the morning showers. Couldn’t get the time settings to reliably boost the heat.

@NickfromwalesThank you, I’ll insist he changes it.

Yep, it certainly makes the meter spin when it all runs together. Ah yes, only one can ever do the DHW, currently the 18. I would aim to drop the 26 altogether in the future. In the CE diagram 18 is on the left and 26 on the right. The intent of the proposed was to allow them to run in parallel for heating and one for DHW but that’s not what is shows! I’ve read in the other threads about removing buffers and using volume of system (my house is plenty cold enough there’s valves open). But specifically at the moment is is the pumped UFH system the correct approach? Can I simplify as per JohnMo’s example or is the current setup optimal in terms of feed.

@JohnMoThey’ve been installed per top scribble for 3 years. I appreciate the ridiculous oversizing but I have another project this 26unit will move to once I finish the upgrades to the main house and can prove just the 18 copes. this is the ASHP setup as per CE:

I’ve got an 18 and a 26 in a weird parallel situation (blame Cool Energy for the upsell!) I’m hoping to get to just the 18, but it does defrost a lot and the 26 helps carry through those moments.

@Nickfromwales see scribbles below. Current above, planned below. The idea is I could eventually drop the oil and the 26kW ASHP but they’re there anyway so might as well use them.

A pretty terrible scribble, give me a few mins to tidy it up!

@Nickfromwales Thank you. If it was just an ASHP, would it be acceptable to have no control? Is there any point in the 4 port and pump? Why not just run it as a big radiator?

First of all- HOLY THREAD RESSURECTION! But hoping @Nickfromwales might be able to confirm if the advice above has been superseded- The builder’s plumber turned up, saw an ASHP and looked no further. He then supplied a manifold with a pump and no mixing valve- just some sort of fixed 4 way and a pump. I have the ability to run the oil boiler in to the heating circuit and the Buffer tank has an immersion in it- so I would consider a TMV still required. He just keeps saying ‘it’s fine for an ASHP’ - is it ever fine to not have a TMV?

Ah yes, I missed the sqft, not sqm. Still 512m2 is pretty damn impressive! Unless you can get a large scale turbine PV will outperform it- I have a 1kWp unit and on its best day ever it managed 2kWh of generation often the daily is nothing or a few tens of Wh. The 5kWp PV regularly outputs 20-25kWh peaking at 35kWh in a day. The turbine isn’t ideally sited, but you’d need planning permission for a full tower and a much bigger unit to get a decent output. I’d have to say the PV looked better at that point.

Can I come see it, I’m near Titchmarsh and being nosy about a 9000m2 Barn conversion? 🙂 Sounds like there’s lots to consider with GSHP and secondary circuit. Do you have an PV or anything you can divert into the newly wired immersion?

TBF the biggest issue with the Powerwalls is that they aren’t a UPS and can allow a brownout as the power drops which means a lot of stuff switches off. Once they get hold of the load they can output 10kWp (14 for short duration) and keep the basic inverter online so the power keeps running. The power drop almost always gives a big enough spike to take out my main 100mA RCD though, so they can’t return to grid until I reset it. I’m very jealous of some of the consumption figures- I imported 20.1MWh last year…

Impressive Mike! My solar only produced 785kWh (unshaded SSW array in the Midlands) in May! £150 back would be a pretty nice payday! My installer has now enabled export on the batteries so I can dump what’s left in them at the end of the day at 15p and then immediately charge them back up at 7.5p. Will see how that goes for a bit before deciding how much I want to fully cycle them every day.

I’m assuming that I would have used the import energy anyway and been paying for it. So every penny in export is effectively ‘gain’ from my previous situation. It’s probably too simplistic as the solar charging the battery would have meant less charging the following night. Either way- today I’m at 25.4kWh import and 20.5kWh export so figure I’m up for the day. The £250 is also a LOT less than I would have paid for an MCS install- am I allowed to offset that cost?

Turns out by changing the tariff in my Tesla App, it’s sorted itself out and is now exporting all the solar and just slowly discharging the battery to cover the house. Haven’t seen what it does when the house loads look like they’re going to exceed the battery capacity during the day but got 13kWh of export yesterday vs 34.3kWh of off peak input (house/car/battery charge). Once it settles down I should be able to see what my break even on the £250 is going to be! 1667kWh of export either way.