Dreadnaught

@IanR, he sent me a PDF on it. If you're interested I am sure he'd send it to you too. There is an enquiry form on the (pretty minimalist) website.

My house is built on 26 screw piles. I was just chatting with my piles designer and he mentioned a new product he is offering: piping for a ground-source heat pump (GSHP) built-in to the screw piles used for a foundation. I thought it was be a nice solution. If you're planning to build a screw-piled raft foundation, you an add in GSHP loops for a low marginal extra cost. He is based in East Anglia. https://www.enviga.co.uk

Keep in mind that the Part M requirements are for "adequate provision" within the zone. In mine build I have some outside the zone where it is desirable but in each case put another socket nearby within the mandated zone. My electrician is fine with it.

I have a Vigor W325 MVHR (was Brink), a very nicely built unit. I run mine on its lowest speed setting too which is 50 m³/h and monitor CO₂ level. What's the lowest speed setting on yours? I wish mine could go even lower.

I have a refurbished "Atlantis AT350" softener and paid £275 inc. VAT for it, collected from their warehouse in Cambridgeshire. It's very economic with water, uses a tried-and-tested valve, and has a single tank. Very nice people to deal with and very knowledgable as they manufacturer them.

Correct, purest PIR.

I did indeed! Seems to be working fine. Tanners designed it to my specification. Strictly speaking, my concrete team installed the PIR not me. The only thing I would do differently next time: bump-up and improve the edge insulation.

@AartWessels, yes, my raft includes: 1) hot and cold plumbing (Hep2O, 15mm and 10mm depending on destination), installed in the PIR insulation layer below the concrete. 2) various big fat ducts for external pipes and cables (water, power, heat-pump control cable, fibreoptic, etc). 3) cable internal ducts for floor sockets in the living room (one of which I have decided not to use). 3) lots of reinforcement rebar. 4) UFH pipe (737m of 16mm PERT piping, 10x loops at 125 mm spacing) embedded in the concrete. This was the last item to be installed before the concrete pour. Private message sent about photos.

Here is the one from Ikea that is A-rated for "Grease Filtering Efficiency class" … https://www.ikea.com/gb/en/p/underverk-built-in-extractor-hood-stainless-steel-50392326/

It poses the question as to why 10º minimum exists. I have my MVHR unit within the thermal envelope of my house. I notice that condensation is huge in the winter. Warm moist air from the house hits the heat exchanger cooled by incoming air at say 0º. Huge amounts of water vapour condenses. Is the risk if the unit is below 10º that that condensate, if it were to freeze elsewhere within the unit away from the heat exchanger, and not drain, could cause problems? Just a guess as to why the 10º limit exists.

To be fair to Ovo Energy, they are now fixing the problems I reported with the "Heat Pump Plus" addon. And it appears that the underlying issue was not their fault (a component of my system had been swapped by Vaillant under warranty, which interrupted the connection to them). I will likely stay with Ovo Energy now as I think its the best tariff for my circumstance (no battery, no PV), at least until Octopus or someone else launches a tariff that integrates similarly with my Vaillant heat pump as rumours suggest they will.

Based on my past experience of Octopus Energy, I'd much rather swap back to them from Ovo Energy. Perhaps in due course I will.

Ovo Energy sent me an invitation to be part of their "Heat Pump Plus trial", where they will indeed control one's heat pump, aiming to heat the home when the grid is greenest. They don't control your heat pump with the vanilla 15p/kWh heat-pump add-on.

I moved to Ovo from Octopus in October and am having problems with the "Heat Pump Plus" addon. I am giving them the benefit of the doubt for now but am not very impressed so far. I hope they will fix things soon. My baseline tariff with Ovo is just their basic variable-rate one. No tie-ins. Given the problems thus far I am keen to be ready to depart at short notice.

Interestingly Ovo is also offering a trial* of an add-on that incentives users to shift consumption away from the peak period (4pm to 7pm). It's a monthly refund for such usage shifting and can be taken along with the "heat pump add on". I wonder if the "Heat Pump add on" might be eventually replaced by a new version that has the same low rate but excludes the peak period. A combination of the two. * called "Power Move" and it runs to at least December as an experiment.

Very interesting @scottishjohn.

That would be me then. Do you have any LVT at yours? I cannot imagine you would give the job to anyone else.

Oh, because I am not going to do the whole house in one go. I am thinking two rooms at a time. Usually it will be the same thickness on each side of the threshold. The only possible exception is the Plant Room to Utility Room threshold. I might use floor paint in the Plant Room, but LVT (3mm) on top of self-levelling compound (3mm) in the neighbouring Utility Room.

A related question … When applying a self-levelling compound across a floor, what do you use at the door threshold as a barrier to limit the flow?

Fabulous, thanks guys. I am not sure I can match the high-levels of workmanship on display in both those, but I will do my best!

In my Plant Room around the UFH manifold I have a big hole through the concrete floor (filled with PIR insulation). See photo. I would now like to pour a 3mm self-levelling compound across the whole floor and add LVT (stick-down), including across the area of the hole. What to do about that hole - and give a stable base for the self-levelling compound and LVT?! I am unsure.

Trying to decide on basin wastes: "Flip" vs "click-clack" vs "pop up". Has anyone got one of these? I wonder what they are like in reality. Looks quite nice. (It's a McAlpine BW60SPH-CB). It's a McAlpine BW60SPH-CB.

Just to clarify… the Energy Integral for the "Vaillant Arotherm Plus" heat pump is the name given to a way that the heat pump's microprocessor controller decides when to turn off the compressor pump, and hence stop heating. And the same Energy Integral also then informs the controller when to subsequently to turn it back on again. (There is also another way the compressor turns on and off unrelated to the Energy Integral, but that's by-the-by). The Energy Integral in this case has the units of "º minutes" ("degree minutes"); note this is not degrees "per" minute. Simplified and only dealing with heating … the controller calculates the number of degrees that the "flow temperature" deviates from the "targeted flow temperature" each minute. This is then summed cumulatively each minute to keep a running total. For example… if the flow temperature in the pipe leaving the heat pump is 42º and the controller is targeting a 38º flow temperature then (42-38) = "4" is added to the Energy Integral at the end of that minute. If in the next minute the figures are 45 and 38 then "7" is added at the end of the subsequent minute. And so on minute by minute. This cumulative sum is the "Energy Integral". Then… when that cumulative sum of these figures reaches zero (from its negative starting point; default is "-60" but this can be changed in the settings) the controller turns the compressor pump off and heating stops. There are more subtleties than I have mentioned above … such as overrun of the sum and the control of the separate building-circulation pump … but that's the essence of it. It's simple and elegant. I suspect that cumulative counters are used commonly in electronic control-systems. Perhaps an engineer here could confirm this.

Persuasion: happy to discuss offline. (Vaillant after-sales had mentioned a cost of £490 to replace the board.) Yes the new board is now installed and, as you say, I took care not to forget the cooling resistor (I even wrote a reminder note in big-black-pen and stuck it on the appliance ahead of time 😄). Firmware versions now … Heat pump: 351.09.02 HP controller: 351.09.01 Interestingly, the Vaillant engineer also modified the opening on the other side of the appliance, the opening for the power connections. As you may know, there have been some reports of water ingress there causing a short-circuit and I believe that newer models have been modified as a result. In my case, he removed that panel and put a clear sheet of thin self-adhesive acrylic over the entire opening before refitting the panel. This gives an extra layer of protection for the underlying circuit board. He said it was Vaillant's chosen mitigation method and was done for me as a precaution. I have read online that others have solved the issue with a line of sealant along the top of that panel, which I was considering adding but it is now no longer needed.

Yes, good point. You are quite right. My new-build house has huge thermal inertia. The concrete raft foundation for my bungalow acts as a 55-tonne heat store. The UFH pipes are embedded deep inside it. The internal temperature for the dwelling changes on a time scale of days (sometimes even weeks). This means that it is far less important when I add heat to the dwelling. Day or night makes no real difference. This all means that I can control the heat pump somewhat differently from most homes and I can try to maximise efficiency … to save money (and the planet). Hence the unusual slant of my questions here.