40 degrees next weekend, mid July ?

[Oldgreybeard]

Colour me amazed!

The combination of the sun shading outside the windows that get direct sun and my bodgineering the heat pump to run in reverse works so well that SWMBO says I've turned the house into a fridge. It's currently 28.6°C outside in the shade at the back of the house, 20.8° indoors in the hallway.

The sun shading has made a big difference, but I am pretty sure that cooling the floor down has made as big a change, if not more. Floor surface temperature seems to have settled at around 18°C with a 12°C flow temperature. Only snag is there is no control over temperature, it's either cooling at full beans or off. The heat pump barely seems to be doing anything in terms of using power, sits at around 600W going in so it's probably drawing around 2kW of heat out of the house. Definitely cooling the ground floor well, though. The ground floor UFH pipes are set in screed and covered with tiles which probably helps. Coming in from outdoors feels like walking into an old church, with the cool floor.

The cheap awnings work so well I've ordered another one to replace my bodged bit of reflective foil stuff that I fitted over the west facing window yesterday. I'm looking forward to riding out this hot spell in relative comfort. Might invite our neighbours around as I he was out spraying a hose over the outside of his house to try and cool it down this afternoon and was saying that it was well over 30°C indoors. I'm pretty sure their house has next to no insulation which probably doesn't help, whereas our place has as much insulation as I could possibly fit everywhere.

[AE-NMidlands]

I might have to adapt our strategies too...
It is currently 29 deg outside, but "only" 25 inside... Normally at this time of day in summer we would have the sash windows open top and bottom and enjoy the cool air coming in. Today I have conclued that it will only let hotter air in to steal our "coolth."

(We have warmth, my Devon farming relatives talked about "dryth" so why is coolth not a word ?)

So we are sitting in a warm room with no ventilation to keep the hot air at bay! The BBC forecast suggests that it will be cooler outside than in by 10pm: would that be the time to open the windows?
A

[Bugtownboy]

For me, if you can get air movement, it makes for a more pleasant internal environment. I’d open as many as you can.

We open all of the downstairs doors when I get up to make a cup of tea (06:00 ish), then start to close once they’re in the sun.

We follow the sun - closing or opening depending if they’re in the sun. (We have 11.5m of bi-fold).

Overnight, leave as many upstairs windows as practical - particularly in our bedroom (French Doors). Keeps temps fine.

[AE-NMidlands]

Yes, but the pleasure of (warmer) air coming in now will be paid for by the rise in temperature upstairs in a couple of hours' time...

[Bugtownboy]

If the windows are open upstairs, surely convection will draw in the cooling air ? Accept this will work tonight, tomorrow is going to be a different scenario

[AE-NMidlands]

If the windows are open upstairs, surely convection will draw in the cooling air ? Accept this will work tonight, tomorrow is going to be a different scenario

but it's already hotter outside than in this evening. (Maybe I should have emphasised that our old house is 5 deg cooler inside than out today - even now at 9pm.) The question is whether it's better to have a hot breeze coming into the downstairs room we are in for the pleasure of the air movement, or keep it out because it will be warming up the bedroom upstairs, when we shall pay the price later on...

[Joeboy]

https://www.bbc.co.uk/news/uk-23252638

Fortunate at 19 degs here. All windows open upstairs.

[spread-tee]

I've put some old dust sheets over the west facing conservatory and kitchen window and hosed them down several times during the day, it has worked much better than I could have hoped for. In this weather even with all the windows and doors open the conservatory gets to the mid to upper 40s by evening and the floor is so hot it is almost uncomfortable to touch, and will stay warm till morning. Today it has stayed below 28 degrees and has cooled the house a great deal and is pretty comfortable as i type this, also as BTB says we are able to encourage a free flow of air through the house which feels good, especially with the use of water sprayers on bare skin. Even Mrs Desps 92 year old mum has been comfortable, which has been my main worry.

For the first time in 14 years of solar thermal I actually had to throw away about 60 litres of hot water as the heat dump was starting to complain, it is sitting in a big bucket outside to cool down before watering the pot plants tomorrow, strange days indeed.

Desp

[marshman]

__

[Oldgreybeard]

The best strategy is probably to copy what they do in hot climates and "night purge". This means opening windows at night, to allow cooler air to circulate around the house, then close everything up tight during the day to keep the hot air out. When I was working in the south of France years ago everyone did this, with iron security grills over the windows with inward opening windows. During the day closed timber shutters on the outside of the windows would help keep the heat out.

For anyone that has UFH and a heat pump I would strongly recommend looking to see if it can be reversed during the day. The chap on the Buildhub forum that did this some years ago gave me the idea and after almost two days of trying it out I can confirm that it really does work incredibly well. We saw temperatures up to around 29 deg C outside today, yet indoors we didn't get warmer than 21 deg C. It needs some work to turn it into a practical and easy to use system, as I need to come up with a way to make it easy to turn on and off and to regulate the temperature, but I think it should be possible to make a box with relays to switch the UFH valves and the heat pump, using a second thermostat and a changeover switch to switch between heating and cooling. From what I've read pretty much every air source heat pump is reversible. Ours is a Kingspan, but I've discovered that this is just a name plate and in reality it's a Carrier.