Es Tresidder

That’s encouraging, thanks Robert. Heated seats should also reduce need for cabin heating, although on our Leaf we often need heating to keep windscreen clear.

Hi Rob. Sorry for slow reply, not been on socials much.

Don’t know if any examples off the top of my head. Happy to help if I can, drop me an email.

Had nearly decided on an MG5 as our new car, but just learnt it doesn’t have a heat pump. Some models do have heated seats though. Interested to hear folks experience of this EV or others without heat pumps to get a picture of how much more of an impact on range that makes in winter. Thanks 🙏

Soz not been on Bluesky much.

Found a small amount of asbestos in one place. Didn’t test concrete.

With PV I expect our electricity bills for everything, including charging an EV, to be ~zero. 💪

*possibly won’t cover the standing charge.

This includes an increase in average internal temps (from 17° to 20°). Couple these sort of demand reductions with well designed and commissioned heat pumps and you get super low energy bills; our heating and hot water comes in at less than £170 a year before factoring in PV 🌞

@aecb.bsky.social retrofit standard and #Passivhaus EnerPHit typically deliver much higher reductions in heat demand than that. I’m working on half a dozen timber-frame deep retrofit projects, and an 80% reduction in annual heat demand is typical.

This is excellent from @richardlowes.bsky.social. Absolutely agree that super deep retrofit isn’t always appropriate, but one thing I’d say here is that the heat demand reductions mentioned here as the top end of what can be achieved (40-50%) are lower than what can be achieved at the top end.

Electricity demand for our air to air heat pump (blue), internal temperature (black) and external temperature (purple) for the 24th January, during storm Eowyn. Average outdoor temperature 5.4°C and total electricity use 6.7 kWh.

Electricity demand for our air to air heat pump (blue), internal temperature (black) and external temperature (purple) for the 24th January, during storm Eowyn. Average outdoor temperature 4.0°C and total electricity use 7.0 kWh.

How did storm Eowyn impact the heat demand in our #EnerPhit retrofit? Looks like hardly at all!

Gale force 💨 yesterday, calm today. ⚡️demand for heat a bit higher today (colder). Suggests impact of even gale force 💨 is small/negligible due to good wind-tightness & excellent airtightness. #Passivhaus

Didn't really feel this episode was pushing back against MVHR, just highlighting that it needed to be done well. Did you?

I’m not sure what the deal is with condensate on those single room units, I’ve never had one on a project, see what the manual says.

- Clean filters (change every 6 months or more often if very polluted area)
- cross-talk attenuators if using branched ducting rather than radial.

- Quiet units, mounted in a room where the noise won’t matter, ideally on an external wall (see bit about duct lengths).
-silencers between unit and rooms (for both supply and extract)
- appropriate ventilation rates
- high quality ducting sized to allow low air speeds in ducts and as direct as poss

Some other things I’ve seen and heard of being done wrong, thankfully none of these on my projects:
- looping excess ducting in the loft to reduce noise transfer to rooms
- failing to put a downslope on pipe from condensate drain, causing unit to flood (bearings needed replacing)

I’d always recommend getting a Passivhaus certified unit (quieter, more efficient fans, realistic efficiency %s) and getting it designed, installed and commissioned to Passivhaus requirements, even it’s a 🏡 that is going nowhere near PH standard in other areas. Quality assurance v important here.

Even if the ducts are super short they still need to be well insulated (I’ve seen them long *and* uninsulated), otherwise they are a risk for condensation and heat loss.

Even with the best (43mm EPS) pre-insulated ducts on the market each additional metre added to both ducts reduces the total system efficiency by ~1.3%. If your unit is in the middle of your house, 5m from an external wall, then suddenly your 90% efficient unit is only 83% efficient.

One thing not mentioned in this podcast but that I’ve seen done loads, is the length of ducts between the MVHR unit and the thermal envelope. If the unit is inside both the fresh air and the exhaust air ducts are cold, and heat losses from the building to them are significant.

There’s loads of evidence that shows the conventional way of ventilating homes (trickle vents, extract fans and opening windows) leads to poor air quality, poor comfort and high energy use. Done well, MVHR will radically improve all of these, but done badly it can be a disaster.

Useful podcast here on some things that can go very wrong with MVHR.

I like to think of MVHR as a bit like pneumatic tyres on a bike. Installed properly and maintained they are *way* better than solid tyres, but if you don’t maintain them they are even worse (try riding a bike with a flat tyre).

Thanks. Mistake was I had ‘the’ at the start of the address. Have resent now.

Cheers, Es

Share your concern for the horizontal ones (suspect they need regular cleaning). Vertical ones are just a vertical pipe within a pipe, so shouldn’t be any more likely to block than a normal down pipe.

Here’s the PHPP calc for mine. 69% efficient unit ends up as 56% efficient for 5min shower.

Also worth factoring into the payback calc:

- does it allow you to choose a smaller tank. It did for me, and that saved £200
- might allow you to do more/all of your water heating during cheap ⚡️.

There’s a bit more to it than just the HR efficiency, also depends on length of drain pipes between shower and HX, and whether connected to cold side of shower and cold feed to tank or just one or the other, so system efficiency ends up less than heat exchanger efficiency.

Several of the units are Passivhaus certified so solid efficiency data from which you can do the calcs on whether they stack up economically. My vert set up more than halves the energy requirement for a typical shower.

Yes, you can do it, it’s what I have in my house, with the showers in neighbouring upstairs rooms. What Alan says plus check the flow rates of the two showers don’t exceed the recommended total for the HX.

Hi @evanhd.bsky.social, I tried to send an email to the email address provided at the end of the flats podcast but got an address not found failure. Could you let me know the email address please? Thanks!🙏

Cool, is there a way for me to see a dot and work out which unit it is on Heat Pump Monitor?

Good work John! 👏 I didn’t know there were heat pumps in the Cairngorms getting an SCOP>4. I’ll have to do some digging on those. Although I think the location is not quite right! I’ve stayed at the Hutchinson hut, pretty sure it doesn’t have a heat pump!

Good to read this. Whereabouts is your house Stuart?