Thu, 25 Jun 2026 05:36:25 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123311#Comment_123311 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123311#Comment_123311 Sun, 20 Nov 2011 12:42:41 +0000 DamonHD
Our MHRV has not yet been installed, and we are experiencing the expected condensation on windows now that outside temperatures are in the region on 4C overnight.

(On the inside of older windows, and the outside of high-spec 2G!)

Normally we shut the doors and open the windows of bedrooms in the morning, with rads off, to let the moisture out.

On a day like today with fog, ie supersaturated externally, that isn't going to work!

So as a data point I'm hereby noting that I'm putting on a small dehumidifier in one bedroom with all doors and windows closed and rad off to help keep on top of things.

I'll probably be deploying this dehumdifier to the smallest room to help dry the room fabric once the plumber has replaced our toilet that decided to leak from the inlet pipe into our electrics yesterday morning...

Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123324#Comment_123324 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123324#Comment_123324 Sun, 20 Nov 2011 18:20:56 +0000 SteveZ https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123326#Comment_123326 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123326#Comment_123326 Sun, 20 Nov 2011 18:28:14 +0000 DamonHD
Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123328#Comment_123328 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123328#Comment_123328 Sun, 20 Nov 2011 18:32:33 +0000 davidfreeborough
http://en.wikipedia.org/wiki/Radiative_cooling

A low performing window will leak enough heat to keep the outside pane above the outside air temperature & the dew point. A high performing window will not leak as much heat & will thereby allow the outside pane to reach a lower temperature & collect more moisture.

David]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123334#Comment_123334 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123334#Comment_123334 Sun, 20 Nov 2011 19:17:15 +0000 SteamyTea https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123356#Comment_123356 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123356#Comment_123356 Mon, 21 Nov 2011 09:20:44 +0000 davidfreeborough
It probably just means that the outside air is close to 100% humidity.

David]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123403#Comment_123403 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=123403#Comment_123403 Mon, 21 Nov 2011 16:28:03 +0000 SteamyTea https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127250#Comment_127250 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127250#Comment_127250 Wed, 21 Dec 2011 08:55:47 +0000 DamonHD
Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127255#Comment_127255 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127255#Comment_127255 Wed, 21 Dec 2011 09:04:54 +0000 SteamyTea ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127261#Comment_127261 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127261#Comment_127261 Wed, 21 Dec 2011 09:49:04 +0000 DamonHD
Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127263#Comment_127263 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127263#Comment_127263 Wed, 21 Dec 2011 10:00:07 +0000 SteamyTea ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127266#Comment_127266 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127266#Comment_127266 Wed, 21 Dec 2011 10:05:39 +0000 Brianwilson https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127270#Comment_127270 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127270#Comment_127270 Wed, 21 Dec 2011 10:13:35 +0000 DamonHD
Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127272#Comment_127272 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127272#Comment_127272 Wed, 21 Dec 2011 10:26:06 +0000 SteamyTea https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127279#Comment_127279 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127279#Comment_127279 Wed, 21 Dec 2011 11:07:40 +0000 DamonHD
Else runs continuously (2W) which should keep out all but the stiffest of breezes. I intend to turn it off entirely in summer and let it ventilate naturally.

Rgds

Damon

PS. Starting a write-up here: http://www.earth.org.uk/MHRV-mechanical-heat-recovery-ventilation.html]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127280#Comment_127280 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127280#Comment_127280 Wed, 21 Dec 2011 11:10:49 +0000 Ed Davies
Dry air has a density of about 1.3 kg/m³ so 30g/m³ would be about 2.3% by mass which is about right for “saturated” air at 25°C:

http://en.wikipedia.org/wiki/Water_vapor#Water_vapor_density

Note on that graph, though, how dependent on temperature the equilibrium water vapour density is.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127284#Comment_127284 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127284#Comment_127284 Wed, 21 Dec 2011 11:43:36 +0000 Brianwilson Season's greetings
Brian]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127294#Comment_127294 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127294#Comment_127294 Wed, 21 Dec 2011 12:44:07 +0000 DamonHD
Because so humid today outside (~75%RH) and had all the windows open had to tweak down the setting at which the fan boosts to 'high'.

On current low setting I cannot hear it in the next room, though it may be slightly audible at night.

Rgds

Damon

PS. Pics available later...]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127297#Comment_127297 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127297#Comment_127297 Wed, 21 Dec 2011 13:22:05 +0000 borpin Is the house TF by any chance? I think you have made a dirty great hole through the lintel above your window!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127306#Comment_127306 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127306#Comment_127306 Wed, 21 Dec 2011 15:03:19 +0000 DamonHD
Yes, we have made a hole in a lintel I believe, though this is several inches above the top of the window frame.

No we don't think the house will fall down; we gave it some consideration.

Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127321#Comment_127321 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127321#Comment_127321 Wed, 21 Dec 2011 16:40:21 +0000 borpin ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127337#Comment_127337 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127337#Comment_127337 Wed, 21 Dec 2011 18:10:18 +0000 DamonHD
Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127348#Comment_127348 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127348#Comment_127348 Wed, 21 Dec 2011 18:53:49 +0000 DamonHD
Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127368#Comment_127368 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127368#Comment_127368 Wed, 21 Dec 2011 21:00:03 +0000 DamonHD
Will have to investigate more in the morning to avoid waking sprogs...

Rgds

Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127391#Comment_127391 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127391#Comment_127391 Thu, 22 Dec 2011 01:52:27 +0000 Viking House If its foggy at 4 degrees outside its still drier than 60% RH 20 degree indoor air.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127402#Comment_127402 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127402#Comment_127402 Thu, 22 Dec 2011 08:04:58 +0000 DamonHD
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Damon]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127406#Comment_127406 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127406#Comment_127406 Thu, 22 Dec 2011 08:15:06 +0000 SteamyTea Posted By: DamonHDVH: surely only if we were actually heating the house at that point?

My house, even when not heated, seems to be warmer than the ambient and the RH seems lower (tis RH rather than just H).
So it is quite possible that the RH in a house is lower than ambient. Though that does open the question about 'what is heating', people, fridges, TVs (not here, so may be the hot air on R4) and possibly even light bulbs.

Is the fan whizzing away this morning?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127408#Comment_127408 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127408#Comment_127408 Thu, 22 Dec 2011 08:17:53 +0000 Viking House https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127417#Comment_127417 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127417#Comment_127417 Thu, 22 Dec 2011 09:11:59 +0000 DamonHD
BTW, I wiggled with wires in the pattress looking for loose connections, and didn't find any, but mysteriously the fan did start operating again. So I'll have a grown-up electrician come and check it over. Fan isn't bust anyhow, it seems.

Rgds

Damon

PS. VS, I will attempt to monitor return temps. While the kids were having a bath last night humidity stayed much lower than usual and the airflow back into the room was not noticeably colder though the delta-T between inside and outside was probably only 8K...]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127584#Comment_127584 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8140&Focus=127584#Comment_127584 Fri, 23 Dec 2011 08:09:24 +0000 DamonHD
But, external temp quite high at 11C and humidity also at over 80%RH, so not a real test yet.

Rgds

Damon]]>