Efficient Heating for old Flat

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alasta

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#838061 17-Jun-2013 13:27

timmmay: People are a big source of moisture, plugging holes could increase humidity.

OK - I was assuming that the humidity differential between outside and inside might have been causing air to rush through the gaps in order to equalise it, but I'm not up with the science so I'm willing to stand corrected.

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timmmay

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#838065 17-Jun-2013 13:30

I'm not an expert. Air may blow in, and things tend to come to equilibrium, but I doubt water will rush in. Still plugging holes is a good thing, just don't assume it will reduce humidity. Cold air isn't humid, it's quite dry.

freitasm

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#838083 17-Jun-2013 14:01

Skolink: What make/model dehumidifier did you buy, and how much did it cost. I'm wondering if we should get one. Cheapo weather station normally reads about 70% humidity (indoors).

A DeLonghi 20l, $359 at LV Martins, almost $90 cheaper than Noel Leeming.

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Niel

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#838193 17-Jun-2013 16:26

timmmay: People are a big source of moisture, plugging holes could increase humidity.

This can be badly misinterpreted. I guess you are talking about plugging holes in the house.

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Niel

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#838202 17-Jun-2013 16:36

Normal Auckland humidity is around 80%, seldom less. Regulating at 70% is a good level for our climate. You are pushing it (the proverbial up a hill) if you try to go for 55%.

Cooking produce a lot of humidity, so extract whenever you do pasta, rice, etc. People also produce a lot of humidity from breathing. Not to mention bathrooms, wet towels, and washing. To heat humid air takes much more power because you also need to heat the moisture. However, the higher the humidity the harder it is for your sweat to evaporate so you actually feel somewhat warmer (inside the house without a draft). But then again, a draft causes moisture/sweat to evaporate and cool the surroundings.

How about taking a car turbo intercooler and plumbing your tumble dryer exhaust through it to radiate the heat into your house? We do about 2 loads per day and mostly at night.

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timmmay

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#838219 17-Jun-2013 17:23

Niel:
timmmay: People are a big source of moisture, plugging holes could increase humidity.

This can be badly misinterpreted. I guess you are talking about plugging holes in the house.

True. Plugging holes in people would help with the humidity issues, but could leave you with bigger problems.

alasta

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#838384 17-Jun-2013 22:02

Niel: Normal Auckland humidity is around 80%, seldom less. Regulating at 70% is a good level for our climate. You are pushing it (the proverbial up a hill) if you try to go for 55%.

That's really useful to know. The fully automatic mode on my dehumidifier seems to target 60% and it doesn't appear to be working too hard to maintain that level so I'll leave it at that from now on. From what you're saying it sounds like I don't need to be too worried that it's usually 70% when I get up in the morning.

Cooking produce a lot of humidity, so extract whenever you do pasta, rice, etc. People also produce a lot of humidity from breathing. Not to mention bathrooms, wet towels, and washing.

I cook a lot of rice and pasta, but I do it in the microwave - much more efficient as well as avoiding steaming the place up. I keep the door shut between the living area and the kitchen/bathroom area, never leave wet washing in the living area, and always have the dehumidifier running in the kitchen/bathroom area if I'm showering or cooking so I think I'm doing everything I can do without getting the landlord to spend big bikkies. I certainly don't seem to be having any problems with damp smells, ills and chills, etc.

timmmay

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#838468 18-Jun-2013 07:25

Why would you use a dehumidifier in the bathroom when a good fan is cheaper to buy and cheaper to run? We have quite a powerful fan, usually run on low.

To me a dehumidifier is a sign that there's a problem that needs to be fixed, it's a stopgap not a solution.

alasta

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#838486 18-Jun-2013 08:47

timmmay: Why would you use a dehumidifier in the bathroom when a good fan is cheaper to buy and cheaper to run? We have quite a powerful fan, usually run on low.

To me a dehumidifier is a sign that there's a problem that needs to be fixed, it's a stopgap not a solution.

I'm assuming you mean an extraction fan inset into the wall? That would require a modification to the building which the landlord is unlikely to fund.

Unfortunately the bathroom is not adjacent to an outside wall so there is no window - just a vent. Although I have to admit I was surprised that there isn't already an extraction fan because I always thought that the building code required this, but maybe that doesn't apply to this 1970s build.

As far as the dehumidifier goes it's only consuming 250w so if I'm running it for an hour a day in the bathroom then that's a cost of less than $2 a month. That's hardly going to send me bankrupt.

timmmay

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#838488 18-Jun-2013 08:55

Renting is a good reason not to modify the building. Exhaust fans in the ceiling are more effective, mine has an exhaust vent under the eaves - same design as the kitchen one. Water can't get in that way, though my drier vent is on a wall, I haven't noticed water in there but it could happen.

stuzzo

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#838550 18-Jun-2013 10:03

alasta:Although I have to admit I was surprised that there isn't already an extraction fan because I always thought that the building code required this, but maybe that doesn't apply to this 1970s build.

I think that it is still the case. Extractor fans (must be vented to the outside) are only required if there are no opening windows in a bathroom, though it's pretty much standard now.

Woolly

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#841305 21-Jun-2013 21:44

My 2c

If the ground underneath your house is not dry (eg dry means dirt should crumble in your hands) lay down polythene and tape it and around piles. ~$300

If you have ponding underneath your house. Then dig small trenches to the lowest point then to outside. Then lay polythene. Optional - create a trap and install a water pump to extract water to storm water drains. ~ $300

Put polystyrene insulation between floor joists. Expol ~$900

Insulate roof space - Pink Batts ~ $1000

Seal outside cladding - ~$50

Timber homes need to breath, otherwise rot will occur.

Put building paper under any corrugated iron.

Do not use a unventilated gas heater. It's like an open fire without a chimney.

You can use duveys, sheets etc to cover windows. Note condensation will form on the windows.

In a good frost or snow: note where the snow melts this will be where you need to insulate.

MPO: Good property owners will do all the above to keep good tenants. Why are people in NZ living in sub-standard housing when it's so cheap to fix?

My 2c

Elpie

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#841608 22-Jun-2013 17:30

stuzzo:
Elpie: Whatever you do, if you have an old wooden house and consider insulating the walls, do some research.

It's not sensible to generalize your situation across the board. There may be many reasons you experienced this problem. As, discussed in another thread, almost all moisture in walls is a result of external sources ( for NZ conditions) so it is important that weathertightness is assured when adding any insulation to walls. A moisture barrier added as a minimum.

You would expect an old house to be gibbed, as well, as a air barrier for external vapour drive.

Not all old houses are gibbed and, as you might note, I didn't generalise - I said "do some research". In my case, the cause of the rot has been proven to be a lack of ventilation in the wall space. Some old houses have had holes drilled in studs and/or dwangs to improve ventilation. Mine didn't and condensation forming in the wall cavity of an otherwise water-tight and damp-proofed house was enough to cause a problem. All I was saying for others was to know your house and do your research.

stuzzo

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#841685 22-Jun-2013 19:51

Elpie: In my case, the cause of the rot has been proven to be a lack of ventilation in the wall space.

I just don't think you can say that (it would require a study not an opinion from anyone) or that it's usefull to say that.

I'll try to explain why. Rot needs moisture to grow. Most rots need moisture contents in wood of 30-40%. A wooden external wall will have a moisture content around 17 or 18% which will ebb and flow a few per cent with the natural course of the seasons. It doesn't matter much if there is insulation such as batts in the wall because vapour diffusion can still occurr.

If you have rot then there must be some source of bulk water to start it off, vapour coming and going from the wall is not enough in most NZ conditions. That could come from things like leaks or rain infiltration. In colder areas the dew point could be in the wall on occasions causing condensation on the inside of the siding.

The point is that insulation is not a cause of rot, moisture (bulk moisture) is the cause of rot. Rot often occurs in walls without insulation where water is infiltrating. The absence of insulation might allow a wall to survive longer by drying quicker but there is no problem with putting insulation in a wall as long as measures are taken to ensure the weathertightness of the wall.

timmmay

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#841847 23-Jun-2013 08:50

Woolly: Why are people in NZ living in sub-standard housing when it's so cheap to fix?

My 2c

Those prices are do it yourself, getting a professional in could be triple that easily.

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