I’m trying to reducs the condensation in our bedroom.

We have a lot of condensation forming on the glass of our window (on the glass, not between the panes) and also had rather a lot of mould growing under the window. The radiator is opposite the window. The curtains are lined with thermal / blackout liners. Condensation is higher when colder. We have chests of drawers under the window where the mould formed. No ventilation in room – previous airbricks sealed when cavitywall insulaion installed. Suspect that the wall under the window is just a wooden stud wall with pebbledash on outside.

We have recently cleaned all the mould off the wall and where it was forming around the frames / cills. We have also moved the chests of drawers further away from the bay wall.

Our plan of action is –

1) Remove plasterboard from under bay window – Establish an airbrick here to increase airflow in the space under the window. This would be at approximately 6 o’clock or for aesthetics 4 oc’cloc (when looking out of the window from inside) on the angled bit of bay window. Then stuff void with insulation and re-attach new lasterboard.

2) Retro-fit trcikle vents to DG units – Seen DIY kits that mean you drill a load of holes through the uPVC casement. Are there any brands to avoid, any to recommend?

3) Re-establish original air-brick. At about the 10 o’clock position ther should be (masked under an old wardrobe) the old air-brick which has been sealed up with sillicone sealant. I’ll put a new one in with a baffle between the 2 walls to re-establsih circulation.

Does this sound like a good plan? I know that there’s things I can do elsewhere in the house but I’d like to get this room done firstas its my bedroom.

Dehumidifer.

We had the same problems at the front of our house which is always in the shade at this time of year. Dehumidifier has helped out no end…

http://singletrackworld.com/forum/topic/positive-pressure-ventilation-loft-units-which

read this. our nu-aire drimaster took me a couple of hours to fit and has reduced the average humidity in our house from ~80% to around 55%.

all the condensation is gone on all but the coldest mornings and is gone within a couple of hours. mould has dried up, cleaned off and never returned.

great investment.

http://singletrackworld.com/forum/topic/positive-pressure-ventilation-loft-units-which

read this. our nu-aire drimaster took me a couple of hours to fit and has reduced the average humidity in our house from ~80% to around 55%.

all the condensation is gone on all but the coldest mornings and is gone within a couple of hours. mould has dried up, cleaned off and never returned.

great investment.

+1

We haven’t done the thorough demoulding of everywhere but when we do we’re going to get the house decorated top to bottom and I don’t think the mould will come back. Best thing I’ve bought in a LONG time.

We’ve had a dehumidifier running most of the time for years but it’s a fraction as effective as the PPV. We still use it when we’re drying clothes indoors though.

sticky plaster – dehumifier.

fix it , reinstate the ventalation and trickle vents on the windows isnt a bad idea – if you have ever removed the facias on upvc windows youll be surprised to note that the factory fit trickle vents seem to be little more than a few holes drilled and knocked into a line (these were cheap windows though) so id have no qualms retrofitting them.

your house is of an older design i guess and wasnt designed to be hermetically sealed.

1930s semi.

My concern withthe Nu-Aire thingy is that the roof space would need to be well ventilated as well?

Although we have quite a few tile vents and one ridge vent, it still gets condensation on the very coldest days so don’t want to be adding to the moisture in the house from the roof space.

If the rest of the house isn’t ventilated then will the nu-aire device be effective?

Dehumidifier – best £100 i’ve spent on house stuff for a while – worth every penny.

Does the condensation reduce if you don’t draw the curtains? It could just be a matter of the thermal lining keeping the heat away from the window, the window stays cold, and condensation forms on the cold. With the curtains open, or liner removed, you might find the windows no longer get cold enough to form condensation. Worth a try, as is easy and free.

1930s semi.

My concern withthe Nu-Aire thingy is that the roof space would need to be well ventilated as well?

Although we have quite a few tile vents and one ridge vent, it still gets condensation on the very coldest days so don’t want to be adding to the moisture in the house from the roof space.

If the rest of the house isn’t ventilated then will the nu-aire device be effective?

If you can see light coming into the loft with the hatch shut and lights off, then it has enough ventilation. Ours is in a 1930s semi with cavity wall insulation, all the air bricks blocked and double glazing with no trickle vents. It still works!

Obviously ventilation is good but I’d be wary about knocking another air brick into a bedroom. We tend to keep the top opener on the vent setting but it leaves us the choice of closing it when it gets really cold.

I guess you already avoid drying clothes/bath towels in the bedroom, and keep the bathroom door shut to stop steam coming into the house? I’ve fitted an extractor in the bathroom to take steam out rather than let it blow under the door into the hallway when we crack the window open.

I regard central heating as a sticky plaster, Trailrat. A dehumidifier, however is a lot more energy efficient than just heating a house to the point where there is no more condensation. If ventilation is adequate and there’s still condensation then a dehumidifier is the obvious solution. The room will also feel warmer for a given temperature.

I did a few sums on our 250w dehumidifier which produces a litre of water in about seven hours:

Consumption 250W x 7h = 1.75kWh
Condensing 1l of water yields 2260kjoules or .63kWh
Total heating = 2.38kWh for 1.75kWh of electricity consumed.

Whilst the air in a house will always be more humid than the outside air due to people breathing, cooking and washing, ventilating isn’t enough on days when the outside air is very humid. I live in the dark blue bit on the map, currently 85% relative humidity outside (14°C) but with the dehumidifier running it’s 65% inside (20°C with no heating other than the dehumidifier).

What are the sources of moisture in your house?

Fascinating, the humidity image above updates automatically.

Thats pretty cool picture.

I missed the part where it was a 1930s passivehaus designed and engineered to work as such. And not a 1930s house where someone sealed up all the holes so it cant breathe.

Can anyone recommend a dehumidifier? Meacos looking good on Amazon reviews.

We have a long unheated extension off our kitchen which sits in the shade and has signs of bubbling paint on the coldest wall. Humidity currently at 80%+ when kitchen is at 50. Thinking to try a dehumidifier for a week or two to reduce this and carry on using in the house for clothe drying etc.

House is 1900 semi. Fairly draughty, though with pvc double glazing (with vents).

Thanks in advance for suggestions

I had a similar problem. A humidifier didn’t really solve it. I now lock the window in the bedroom slightly open, about 1/4 inch, and that’s solved it. Keep your furniture away from the walls, use the extractor in the kitchen, don’t dry clothes on radiators, ventilate the bathroom.

I’m still working on the ventilation aspect Trail Rat. You’re right, I’ve sealed the place up so well it can’t breathe so I’m now making holes. The question is what to do with the holes. I’m still undecided between a heat recovery system sucking out of the kitchen and bathroom and blowing into the bedrooms, or natural ventilation with a wall mounted heat-recovery ventilator just in the kitchen and the dehumidifier when it’s mild and humid outside.

The Summer is fine, we open the windows. When it’s really cold it’s fine, the wood burner draws air and the house is warmer than outside so air flows naturally from stove vent to roof vent. The place gets humid in the Spring and Autumn when we don’t need the wood burner and it’s not much warmer inside than out, and raining. Air stagnates in the house.

I don’t like pumps and fans going all year long, my solar panel thermosyphons, and the radiator behind the wood burner to recover heat and send it to the bedroom also thermosyphons. I’m reluctant to opt for a full heat recovery ventilation system for the whole house which will run 24/7 all year round when natural ventilation is adequate most of the time.

The dehumidifier is the cheapest Blyss model from Casto, the French equivalent of B&Q. 100e which is about £85, model WDH-1012ED ref 655998.

and the radiator behind the wood burner to recover heat and send it to the bedroom also thermosyphons

Off topic (sorry OP), but can you tell me more please as I was think along the same lines.

Presumably you just fitted it into the normal central heating run, but left off the TRV? Have you painted it black? You say it ‘thermosythons’ – so I assume you have an open system with a tank, not a sealed system with an expansion vessel?

Ta
Marko

I removed the central heating system except for the radiator in the main bedroom and bathroom. I then canibalised the central heating unit for the pump, pressure safety unit, pressure/temperature gauges and expansion vessel. I changed a couple of pipe runs so no air locks could form.

It doesn’t matter if there’s a header tank or expansion vessel. I initially thought it would need the pump but found that it cycles slowly without.

I’m reluctant to opt for a full heat recovery ventilation system for the whole house which will run 24/7 all year round when natural ventilation is adequate most of the time.

I turn mine off in spring, and only turn it on again in October.

It runs on trickle speed all winter (<25W), with 10min boosts (c.150W) when cooking curry or having a shower.

=c.150KwH p.a. = c.£20 pa

150kWh would run the dehumidifier for 600h. I’m certain we don’t use it that much.

This thread has been useful in that I’ve realised that if I do install heat recovery ventilation I also need some normal vents that can be closed when it’s running so I have choice.

Did you pressure test your house, Stoner? And how impmortant is having the house completely sealed? Are both incoming and outgoing ducts driven by fans or only one side? There was a programme about passive houses on French TV and they did an elaborate pressure test on the house saying that the ventilation system wouldn’t work if the house were not completely air tight.

150kWh is gross electricity consumption. Since it is a heat recovery system, it obviously also recovers heat energy. I cant vouch for how much (and of course my heat energy costs v little as it is either wood pellet or log).

My barn is not air tight by any means, and to be most effective yes the system prefers air tight, but it certainly does work, effectively enough, even in a relatively leaky barn.

The main benefit for me was not having to add additional leaks (trickle vents to my nice new wooden frames doors and windows) increasing vent loss heat loss to satisfy building regs.

The pleasant side effect is a genuinely good quality of air in the house even in winter when the doors are not left open as they are come spring.

The circulation also helps distribute solar gain energy where it occurs in the barn in front of the big windows as well as recycle bathroom and kitchen energy.

http://www.heatraesadia.com/hru_eco_4/

this is my system

http://www.heatraesadia.com/docs/HRU_ECO_4_-_User_Manual-_36006179_issue_1.pdf

I dont have the perfect lay out, as I only have one outlet at the far end of the barn to initiate a full circulation, but each bedroom has an outlet and each bathroom and the kitchen are extracts.

Page 16 “spares” shows two fans but then lists “1 only”. I reckon/hope there are two so it will still work even if the house isn’t sealed.

Typically 80% of heat is recovered. I have no trickle vents and have sealed a couple of rooms pretty well which wouldn’t be an issue if junior didn’t insist on having his bedroom door shut all the time.

Edit: the air quality thing would be my main reason for installing, even if its only a one-room unit for the kitchen/living area

We did what urban hiker suggested above and removed the thermal linings from the curtains in our living room bay window and now have a lot less condensation (hardly any in fact). We also open the curtains slightly at night too.