Optimum size for new home

woodburner · Post by **woodburner** » 10 Oct 2013, 10:21

Domestic dehumidifiers are ineffective unless the temperature and humidity are high, and in the uncomfortable range, and the building is sealed.

"Which" did a report on them many years ago, with a contribution from John Arrowsmith (now deceased) who made dehumidifiers. His view was they were as useful as standing under a waterfall with a mop and bucket, unless the above conditions were met.

A better way was to have ventilation. Air comes in from outside, and is warmed, which reduces the humidity. Meanwhile, humid air goes out with its water load.

If it happens to be in a thunder storm in the summer, you're probably stuffed as it will be warmer outside than in.

The cure for humidity is ventilation.

ujoni08 · Post by **ujoni08** » 10 Oct 2013, 21:43

Yes, that corresponds with what I'm seeing. The dehumidifier starts to really produce a good drip rate of condensate when the temperature reaches about 19 or 20 degrees in the bathroom (where the dehumidifier is fitted to the wall). I usually switch it on while showering and for about an hour afterwards, then switch it off and open the window. I empty out about 3 litres of water per week. The average humidity in the living room is about 55%, just from my subjective observations. There is no mould to be seen anywhere.

Next on the list is to order some polycarbonate sheets cut to size for the windows and doors. They're already double glazed and draught-proof, so this will make them triple glazed. I will continue to use the thick fleece drapes and curtains too.

woodburner · Post by **woodburner** » 11 Oct 2013, 01:36

I extended the shower cubicle up to the ceiling, and have an extractor running to the outside directly in the cubicle. Have fan running for 10 mins after shower. If yu are going t open a window, just don't use dehumidifier anyway.

You are able to detect humidity levels? Is that without a meter?

ujoni08 · Post by **ujoni08** » 11 Oct 2013, 10:46

Yes, I have a small Oregon Scientific 'weather station' in the living room with temperature, relative humidity, atmospheric pressure, etc. It used to have an outside sensor too, but that has been damaged by harsh weather. Anyway, yes, I just keep an eye on temperature and humidity in the living room, but don't log the data every X hours and do any calculations or anything scientific like that. It's siting at 54% RH at the moment, temperature at 20.1 degrees.

On a related theme, I must say I'm very chuffed with the chimney liner I had fitted last week. I can now control the air flow into the stove very accurately, and also control the fuel burn (and therefore the temperature in the room) very precisely. It used to be an open chimney with a badly fitting register plate above the stove.

Related to the discussion about ventilation... I've been considering a small MVHR unit in the bathroom, fitted in the hole where the existing extractor fan is. Do people think it's a good idea? I've been all round the house and sealed any drafts, plus the windows and doors are all double-sealed DG units. The chimney is now lined and sealed, too.

emordnilap · Post by **emordnilap** » 11 Oct 2013, 11:05

ujoni08 wrote:I've been considering a small MVHR unit in the bathroom, fitted in the hole where the existing extractor fan is. Do people think it's a good idea?

Renewable Candy is quite a fan (!) of them; I bought one one the strength of her enthusiasm (Kiltox) but I haven't reached the point on the to-do list where fitting it appears.

If you've 'normal' (i.e. modern) walls, it looks like a doddle to fit. Ours are 3ft thick plaster/rubble/stone/render and the disruption it will cause has shoved the job further down that list.

ujoni08 · Post by **ujoni08** » 11 Oct 2013, 17:01

Our 1820s stone cottage has walls over 500 mm thick, but at least the hole is already there where the extractor fan is currently fitted, so I'm hoping for an easy job of fitting an MVHR. I just have to find the time to do it...

emordnilap · Post by **emordnilap** » 11 Oct 2013, 17:13

ujoni08 wrote:Our 1820s stone cottage has walls over 500 mm thick, but at least the hole is already there where the extractor fan is currently fitted, so I'm hoping for an easy job of fitting an MVHR. I just have to find the time to do it...

Right. You'll need the extension pack if you get the Kiltox because the ducting has to be a precise length; the standard pack is for walls up to 356mm thick.

Another possibility is the Ventive, which was very briefly discussed on this forum some months back.

ujoni08 · Post by **ujoni08** » 11 Oct 2013, 17:24

I do like the look of the Ventive, but can I keep the woodburner? It seems like the Ventive uses an unused chimney...

woodburner · Post by **woodburner** » 11 Oct 2013, 19:45

I hope Kiltox's technical info is better than their eco-MHVR data sheet.

Extractor fans in the UK potentially waste over a million kilowatts of energy every year. This is comparable to the total output of two large power stations. Replacing conventional extractor fans with heat recovery systems could save at least half of that energy loss.

RenewableCandy · Post by **RenewableCandy** » 12 Oct 2013, 18:18

emordnilap wrote:
ujoni08 wrote:I've been considering a small MVHR unit in the bathroom, fitted in the hole where the existing extractor fan is. Do people think it's a good idea?
Renewable Candy is quite a fan (!) of them; I bought one one the strength of her enthusiasm (Kiltox) but I haven't reached the point on the to-do list where fitting it appears.

If you've 'normal' (i.e. modern) walls, it looks like a doddle to fit. Ours are 3ft thick plaster/rubble/stone/render and the disruption it will cause has shoved the job further down that list.

Yes, yes and a packet of crisps please

Post by **adam2** » 10 Nov 2013, 14:06

Update time, with data.

Recent indoor temperatures, cool and very windy outside. wood range used only on alternate days.

Main open plan living area, average 25 degrees when stove lit, 21 degrees otherwise.
Bedrooms average 16/17 degrees with very little variation.

When the stove was not lit, one heat pump was used in heating mode and maintained a comfortable temperature throughout the downstairs.

Although temperatures upstairs remained reasonable, air qaulity seemed very poor with high humdidity and the odd spot of mould.
When a visitor smoked, the smell lingered for days, and whilst smoking indoors is now prohibited, that does not cure the underlying problem.

Opening the windows produces very variable results depending on the strength and direction of the wind.

I suspect that the structure is more airtight than expected and that continual trickle ventilation may be needed.
As a temporary measure I have wired the bathroom and shower room extract fans so as to run at low speed continually, and at high speed when the facility is used.

Post by **kenneal - lagger** » 10 Nov 2013, 20:37

ujoni08 wrote:I do like the look of the Ventive, but can I keep the woodburner? It seems like the Ventive uses an unused chimney...

Ventive do a system for new build which doesn't require a chimney.

ujoni08 · Post by **ujoni08** » 11 Nov 2013, 11:48

Thanks, Ken. I do like the look of the Ventive S+. I'd probably choose to have it fitted to the side of the house, as I don't want to interfere with the integrity of the roof, nor with my luvverly loft insulation.

Does anyone know what the price is, fully fitted?

PS_RalphW · Post by **PS_RalphW** » 11 Nov 2013, 12:47

We've been in our thatched cottage 3 months now. We are making more use of our (main) woodburner, it is on all day at weekends. It keeps the core house and the kitchen reasonably warm. We have the oil heating on up to 4 hours a day, but this doesn't stop our bedroom (modern cavity wall, probably unfilled, DG casement window panes) from chilling considerably. The office (large single glazed window, wood frame construction, flat roof) has been abandoned for the winter. I have started applying shrink fit clingfilm secondary 'glazing' to windows. as much to cut the condensation as save heat.

We had a thatcher inspect the roof, at least half of it has started to decay and should be replaced in the near future (next few years). We will probably replace it all, and will look at adding extra insulation at the time.

The oilburner is 25+ years old, so that is also on the todo list. Unfortunately, so is the oil tank, and I am nervous of it leaking. Replacing that will require demolishing either a garden shed or the (asbestos) garage.

Post by **kenneal - lagger** » 11 Nov 2013, 19:06

ujoni08 wrote:Thanks, Ken. I do like the look of the Ventive S+. I'd probably choose to have it fitted to the side of the house, as I don't want to interfere with the integrity of the roof, nor with my luvverly loft insulation.

Does anyone know what the price is, fully fitted?

They're absolutely foaming at the mouth in their search for installations so ask them for a price. I would think that they would be very competitive at the moment.