Condensation / warmth

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#795769 9-Apr-2013 18:30

leo0787sx:
leo0787sx: We are in Christchurch so one of the colder areas, it wasn't too bad this morning but I still had to wipe the windows. I guess I'm clueless due to the face I'm from the UK, I miss radiators :(

Most rooms have blinds and curtains, some only blinds, wheere we can we have both closed to try and keep warmth / stop condensation.

Kitchen has an extractor fan on the hub

The bathroom has one of those light fans but it seems to do a good enough job as there's only two of us.

The main room (living and kitchen) has an aircon

Main Bedroom has a small eco heater

No wall or ceiling insulation and probably no special light fittings.

Clothes are outside unless it rains otherwise in the main room with a window open - have thought about getting a dryer

All rooms have a gap under the door and windows leaked. Should we cover the bottom of the doors and close and seal the windows instead?

Landlord has said they are happy to buy a dehumidifier around a few $100 so looked at: http://www.noelleeming.co.nz/shop/heating-cooling/dehumidifiers/sheffield-pl420-dehumidifier/prod46101.html which we would put in the corridor to work on the 3 bedrooms and bathroom probably an hour before bed and an hour when we get up? Would this work?

Thank you for all the help guys, really appreciate it.

Anyone got any answers to the dehumidifier? :)

Dehumidifiers with brands like that are all very similar. Mitre 10 mega the warehouse etc all buy them from the same place (CDB) they are generally just rebranded.

With dehumidifiers its all about the temperature they can work down to cheap ones used to only work down to around 15 degrees however this has changed in the past few years most work down to 5 degrees now. More pricey ones go down as low as 0.
With there litre rating they are tested in ideal conditions as the temperature gets lower the less they will extract from the air.

A humidistat is useful this works like a thermostat for humidity.

The cheap basic ones work ok for the price however if you are after better quality/performance option Delonghi and Mitsubishi are considered to be good brands dimplex is not bad also.

Stan

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#795770 9-Apr-2013 18:37

kiwirock: I'm firmly against roof space air or possitive pressure units that push moist air in to walls where it's likely to condensate worse and the damage = $$$.

Worked in heating and ventilation industry for a while and I have never seen this happen with PPV. Can you elaborate I am genuinely interested. I can not see how it would push moisture into the walls and cause damage.

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#795771 9-Apr-2013 18:40

Elpie: I've discovered the down side to having a moisture barrier under the house. A water pipe (only two years old) failed and we didn't notice it until the water was running from one end of the house to the other. The soil was so dry that it may have been broken for awhile before the ground was so sodden it started running along the surface. The pipe was buried and was right next to the edge of the underfloor barrier. It was fixed yesterday but now, not only is the ground under the entire house oozing water, the moisture barrier has a lake on top of it. Just as the barrier will stop water coming up so does it stop water draining away.

Needless to say, the house is pretty cold and damp right now :-(

That's no good Elpie. It sounds like you need a pump to pump out all that unwanted water.

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#795791 9-Apr-2013 18:56

The $200 dehumifier has a humidity control so will cycle on and off which is better than the really cheap ones that is on all the time. Our Mitsubishi has an electronic humidity control so it actually slows down when it is not too humid instead of full on/off.

If the doors are closed only when you go to bed, then dehudifying the living space with the aircon will still spread to the bedrooms until you close the doors.

All houses need to breath, if fully sealed then you will die. The question is just how much.

If you have a shade cloth on the South side of the house then it will keep dew further away from the house and the air outside the window will not be as cold and condensation on the inside will be less (not nothing, just less).

A Bosch automatic tumble dryer will be your best investment ever. Look around, RRP is in the order of $1400 but you can buy it for almost half that. We got ours from either Betta Electrical or 100%, but had to go to a specific store as they do not share all specials. The Bosch tumble dryers are well insulated and the automatic function works much better than others. We've had a few dryers over the years and do minimum 1 load a day. You can duct it to outside your bedroom window so you heat up the surroundings while in use.

Run the aircon in cooling mode while the oven is on. Works very well to drop the humidity. But be careful of too low humidity, then your sweat evaporates faster which cools you down.

In our old home we had lots of trouble with mould in the bathroom until I painted it with a mould suppressing paint. Still can't remember what it was, but in a post last Winter someone recognised the one I was talking about. Think I got it from Mitre10. For a number of months the walls would sweat out the additive, but over about 6-8 years we never again had any mould in that bathroom. It also had an added bonus that it killed insects especially moths and midges (kind of small flies).

Mould remover does not work, by the way. It only bleaches the mould so you don't see it, and the roots go deep into gib etc. where you cannot kill it with a "spray and wipe". However, the paint I used was effective due to being there 24/7. I'm sure there are also additives you can add to normal paint, but I'd go for one that is pre-mixed as it is known to be fully compatible.

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samsam

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#795792 9-Apr-2013 18:56

Have you tried decreasing the night time temperature significantly? 17-20 from 30 that should reduce the temperature difference and the condensation problem. For keeping warm at night you could use blankets

stuzzo

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#795810 9-Apr-2013 19:44

Stan:
kiwirock: I'm firmly against roof space air or possitive pressure units that push moist air in to walls where it's likely to condensate worse and the damage = $$$.

Worked in heating and ventilation industry for a while and I have never seen this happen with PPV. Can you elaborate I am genuinely interested. I can not see how it would push moisture into the walls and cause damage.

I guess the argument might go along the lines that the vapour or moisture drive in any situation is from hot to cold, which in the winter is from the interior of the house towards the exterior which can lead to condensation in the walls if the dew point is reached. Positive pressure ventilation might increase that effect.

The reality is probably that iin the NZ milder climate areas (most of population) this is unlikely to be an issue. I would argue that PPV is unnecessary, though, as long as basic good house management is in place. Often, it's not the house but the practices of the occupiers that are most important.

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TwoSeven

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#795827 9-Apr-2013 20:28

Just out of interest, it is my understanding that condensation would form on the coldest surface first, so windows and frames would be a logical place to see it.

Also, as far as I am aware, the air in the room would have a specific temperature, humidity and pressure. Decreasing the temperature by moving it up against a cold surface I suspect would cause condensation as the air temperature drops below the due point.

It would occur to me that a fix would be to place a dead air zone between the cold surface and the warm air so that the two don't mix. This might be achieved by the application of thermal drapes as an example.

Just my thoughts.

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Stan

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#795830 9-Apr-2013 20:36

stuzzo:
Stan:
kiwirock: I'm firmly against roof space air or possitive pressure units that push moist air in to walls where it's likely to condensate worse and the damage = $$$.

Worked in heating and ventilation industry for a while and I have never seen this happen with PPV. Can you elaborate I am genuinely interested. I can not see how it would push moisture into the walls and cause damage.

I guess the argument might go along the lines that the vapour or moisture drive in any situation is from hot to cold, which in the winter is from the interior of the house towards the exterior which can lead to condensation in the walls if the dew point is reached. Positive pressure ventilation might increase that effect.

The reality is probably that iin the NZ milder climate areas (most of population) this is unlikely to be an issue. I would argue that PPV is unnecessary, though, as long as basic good house management is in place. Often, it's not the house but the practices of the occupiers that are most important.

Interesting I got into PPV around 4 years ago and sold it along side installed heating (wood gas and pellet fires heat pumps etc) when I got told some horror stories about various companies sales techniques kinda wanted to bring some facts to the table and offer a cheaper solution. PPV seems to be rather popular amongst landlords who do not want their tenants to ruin their houses with excess mold.

I would agree I have come across many cases where people have no bathroom extraction, unflued gas heating and they dry cloths inside.

alasta

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#795880 9-Apr-2013 22:20

The main problems with cheap dehumidifiers are the effectiveness of the defrosting feature if they even have one (i.e. how well do they work below 15 degrees), and noise levels. I had a cheap Goldair unit which I replaced with a Mitsubishi about a year ago, and honestly the Mitsubishi sounds like having a small electric fan in the corner of the room whereas the Goldair was like a truck idling right outside the room.

Here's how I use mine:
- Run it in the kitchen/bathroom area whenever I'm cooking or having a shower. I shut the door to isolate this part of the house until the humidity has dropped to around 60%.
- Run it in the bedroom for a couple of hours each night before going to bed. This brings the humidity down to around 60%, although it creeps up towards 70% overnight.
- Run it as needed to dry laundry in the conservatory.

The appliance has power consumption rated at 250w but if left on for long periods of time it will shut itself off (depending on operating mode) when it's not needed, hence the real power consumption is effectively much less than this.

I don't know how 'bad' my place is, but the economic reality is that my power consumption peaks around 400kwh per month in the middle of winter, so if I were to move to a more modern place I'd be saving no more than a couple of hundred dollars a year in power but I'd be spending thousands more in rent. Having said that, I'm fortunate enough that I live alone and work long hours so the numbers would stack up differently for busier households.

Aredwood

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#795904 9-Apr-2013 23:26

One advantage of dehumidifiers is they give you free heating (sort of). How? Due to the latent heat of water (amount of heat needed to turn water from a liquid into a vapor) 1 liter has a latent heat of 2260kJ which is 0.62kW This means that for every liter of water your dehumidifier collects you have gained an extra 0.62kW of heat that was trapped in water vapor.

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#795927 10-Apr-2013 07:24

leo0787sx: Hello,

As the cold is coming I was wondering if you had any ideas / advice or something I can do to reduce condensation / warm up the house?
Currently we:
Leak the windows
Use the vent in the kitchen/bathroom
Use heating in the bedroom and the air con in the living room
Wipe the windows every day
Leave doors open leading to the corridor

I still feel like sometimes its a loosing battle as this morning I wiped the condensation from the bedroom but 20 minutes later it was back because it was so cold and we would hate to get mildew / mold.

We were considering renting or buying a Humidifier and our Landlord mentioned putting in some insulation but just wondered if there's anything else. Last year I tried a tip I found, which was to put bubble wrap on the windows to keep them warmer but this just seemed to trap the condensation.

Is there anything we can do? Can we got to our Landlord about it or is it the homeowners responsibility? Thank you for the help,

i'm sorry to break the bad news - there is nothing you can do apart from suck it up and move on before next winter hopefully to a better insulated home

you can ask the landlord to give you some heatpumps or even install some ceiling insulation as these would be the cheaper ones for them to do - but they have no obligation apart from compassion to do these

imagine heat as water and the house as a tub with a hole at the bottom - if there are holes everywhere the tub will be void of water no matter how fast you try to fill it up

when i was a student, in the winter you put your hand in the fridge it is warm. assuming the fridge was 4 degrees you can imagine what the room temperature was

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Azzura

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#795976 10-Apr-2013 08:57

I feel for NZ. It seems to be the Goldilock Zone (and in the middle of an ocean) for moisture on windows during NZ winters.

Some winters in Canada....I would see the humidity level as low as 18% outside during winter, not much chance of moisture in the air...even in a sealed up house. I can remember as a kid (during winter)...dad would run a humidifier to get the humidity up (back in the early 1970's).

I'd be quite amazed if anyone could prevent condensation forming on single glazed windows during NZ winters in an old house.

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#796982 10-Apr-2013 09:48

As an experiment, why not do a little test on a small south facing window if you have one - by making some pseudo double glazing.

Get a small piece of wooden beading and run it down each side of the window frame on the inside to make a spacer (about 20mm or so) - alternatively, just put a small piece in each of the 4 corners of the window. Then put a sheet of transparent acrylic sheet or perspex over it, and tape it in place by using some tape as a seal aound the edge. This will create an air gap between the window and the room - the test would be to see if one gets as much condensation on the window as without it.

Hopefully someone here might have a better way of doing this experiement. I believe there was another thread on doing this some time back.

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#796990 10-Apr-2013 09:54

TwoSeven: As an experiment, why not do a little test on a small south facing window if you have one - by making some pseudo double glazing.

Get a small piece of wooden beading and run it down each side of the window frame on the inside to make a spacer (about 20mm or so) - alternatively, just put a small piece in each of the 4 corners of the window. Then put a sheet of transparent acrylic sheet or perspex over it, and tape it in place by using some tape as a seal aound the edge. This will create an air gap between the window and the room - the test would be to see if one gets as much condensation on the window as without it.

Hopefully someone here might have a better way of doing this experiement. I believe there was another thread on doing this some time back.

That's basicly what retrofit double glazing is - a sheet of thick clear plastic, mounted nicely, with that air gap. There's also the temporary stuff that looks like big pieces of glad wrap, it works ok to reduce condensation but I found it pulled all the paint off my windows when I removed it.

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#797123 10-Apr-2013 13:00

Azzura: I feel for NZ. It seems to be the Goldilock Zone (and in the middle of an ocean) for moisture on windows during NZ winters.

Some winters in Canada....I would see the humidity level as low as 18% outside during winter, not much chance of moisture in the air...even in a sealed up house. I can remember as a kid (during winter)...dad would run a humidifier to get the humidity up (back in the early 1970's).

I'd be quite amazed if anyone could prevent condensation forming on single glazed windows during NZ winters in an old house.

I've just had that experience and was amazed at how comfortable and warm I was in Quebec in winter. Housing was all heated to 22C, nobody bothered pulling curtains over windows, and it was just lovely. I've been back almost 3 weeks and have been cold the whole time - mainly due to humidity.

However, the very low humidity in hotel rooms resulted in nose bleeds. I found out too late that we could have asked for a humidifier. The idea of putting moisture back into the air was such a foreign one to me. I'm so used to outdoor humidity being 90%+ that experiencing really low humidity was weird.

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