ToughButterCup

The relative dampness (or dryness) of the materials (in this case , sand) makes a noticeable difference. Bagged contents might be damper than normal (water is cheap) A paddle mixer might help?

Your question is close to "When will you be finished ?" There's not a month goes by without us being asked. I don't think people want to know the answer, they just want to say something to show a bit of interest. My reply.. "If you see me using a strimmer, I'll be finished"

Look up the terms 'SUDS' and 'Rain Garden' . You'll find masses of stuff to help you.

There is another approach. Kindness, small droplets of it first, followed by careful nurturing, building trust. Followed by discussion. The only fight worth having (your name for for it above is 'concern') is the one we all have with ourselves trying to make today - (and that alone is hard enough) a success. Talk, listen, reassure, build a bridge.

Exactly. Make yourself - politely - a difficult target. Very politely.

Yes. I had a close look with a graphics package. The hole - and more importantly its position - might be: might be suspicious. Where's the path in relation to that 'feature' ? If it's not a hole, but a sheet of plastic (DPM ?) , is the DPM the vector for the water from a leak source elsewhere ? Leaks are worse than having a truculent tenager in the house. Much worse.

Hello. Welcome. Tell us a bit about about the research you have done for yourself: who have you talked to , what research have you done on your LPA website, what professional advice have you sought? I ask, because - as written - you give us precious little information to go on.

Cor blimey mate: nerdish this place innit? I mean '... focal acidosis ...' I read fecal acidosis. 😔 Can't help it....

I knew it ! Gottcha! You're one of those Bad Boys.

Ditto.

@Pocster, Just in case you haven't. ... ?

I've dedicated my life to that skill....

Thanks very much Terry. This thread is about cashflow, not so much about MVHR. I know I HAVE TO have it. Now that I have some, I begrudge the money especially when the house appears to perform really quite well on its own.

450 ppm or less (I think). Window always open on tilt : better put - rarely if ever shut. The wind direction and open-window/door configuration is very important. The chimney effect is very noticeable Sensor positioning appears to be important - I have found 'dead spots' in our house. As I write this at my desk (a dead spot) its 775 - with a 3m window wide open 4 meters away. Bedroom seems to be 'OK' to the extent that I can tell. The CO2 meter needs an a/c socket nearby, so the test hasn't been as extensive as I would like (flex length). The only time I've noticed a 'red' alert ( on the meter) is when over Christmas the house was packed with friends and family, cooking on full blast and some people were vaping like it was going out of fashion. I think that MVHR might well lessen the number and extent of dead spots. It'll be interesting to do a comparison. The question is how to do a fair comparison? Because for six or seven months of the year we have at least two windows open. Maybe @SteamyTea or @TerryE could help my thinking process with a 'fair' design ? Please? The main point is I realise that our approach is not for everyone: most want to switch MVHR on - forget it - and pay the bill. But until recently we couldn't afford MVHR, and so have been forced to experiment and 'feel' what the house will do for itself. To me, it seems to do better than I expected : slow temperature change up or down, and to an extent sauerkraut resistant. It is very clear though we have to open a combination of doors and windows every day. Whereas with MVHR we wouldn't need to think about it.

And let the smog-filled air into your Berlin high-rise ? There's a standing joke in Berlin ... Stossluften (shock ventilation) is really about neighbours being able to chat to one another: Old Mother Schmidt opens her window wide, puts a cushion on the window shelf, and hoists her décolletage onto a longsuffering cushion, bangs on her neighbours window. Frau Dumke (old Berlin name) opens her window, stands on a chair, sticks hers out of the window too : both of them put the world to rights. I'll spare you the teenage jokes about that process. No wonder they cant use MVHR properly. They open the window to talk to one another. Not because their flat is chock full of sauerkraut and the consequent farts.