Home cooling - ceiling fans?

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neb

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#1697580 2-Jan-2017 14:27

tdgeek:
Ceiling fan wont cool, it will circulate the already warm air.

+1. It'll just move the hot air around. While you could install something like a windcatcher, it's going to be vastly more work and expense than just dropping in a cheapie heatpump. If you're only using it a few times a year then you don't need to worry so much about efficiency, just get a smaller one off Trademe or something.

Gordy7

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#1697625 2-Jan-2017 15:26

Home cooling....

I had a western wall that became very hot in the afternoon and made sleeping difficult until well after midnight.

Discovered that the outside wall was painted with a dark paint with a reflectance of 23%.

Even the gib was warm even though the walls were well insulated.

Painted the outside wall with a lighter coloured paint with a reflectance of 78%.

Got rid of most of the heat...

Gordy

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kiwirock

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#1697629 2-Jan-2017 15:33

Ceiling fans in up or down rotation only do one thing with the windows closed: blow hotter air from the roof down to where you are sitting or lying.

They do help evaporate sweat quicker with the draft they create making it feel cooler but they just add another few watts of heat to the room.

If you have windows open, an up draft ceiling fan will help push hot air down the walls to where windows are.

If you have a bathroom upstairs with extraction fan, leave it on to pull hot air out of the place and crack a window downstairs so it can pull cooler fresh air in.

If the air outside is warmer, then only a heat-pump will actually cool the room.

If you're trying to move air from room to room in a heat-pump cooled house, a tower fan in a hallway outside a hot bedroom directing air in to it is good. As they are close to the floor (and heat rises) they move cooler air from where they are positioned to where ever you want it.

The best fans, are one's beside open windows when there is no wind to keep air moving.

Beside the heatpump, a balanced ventilation system that allows you to bypass any heat exchange are awesome on hot days.

MadEngineer

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#1697630 2-Jan-2017 15:39

^ indeed. Moving air has a cooling effect.

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richms

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#1697634 2-Jan-2017 15:51

Open windows. Yuck. Get the aircon.

Richard rich.ms

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#1697654 2-Jan-2017 16:15

D.W:

Another point I forgot to mention, I have an elderly family member living in the house who has concerns regarding legionnaires disease when using a heat pump on cooling mode.

I can't find anything to suggest that is a legitimate concern, just that possibly older, larger air conditioning units could have been culprits under certain conditions, but I can't definitively tell her that heat pumps can't cause the issue.

Anybody know more than I do on this matter?

First a little background on Legionella, the bacteria that produces Legionnaries Disease in humans.

Legionella requires water and if you check out the sources of legionella (wikipedia) you will see they are all water-based.

Legionella species typically exist in nature at low concentrations, in groundwater, lakes, and streams. After entering man-made equipment, given the right environmental conditions, it may reproduce

In the natural environment, Legionella lives within amoebae such as Acanthamoeba spp., Naegleria spp., Tetrahymena pyriformis, and Vermamoeba vermiformis.

There is no water in home heat pumps except where it condenses. Heat pumps don't condense water when heating so the only concern is when cooling, as you are aware. But this does not include defrosting cycles where the water temperature will be closer to 0C and legionella is dormant. See Legionella control (same wikipedia article). The main treatment is to add chlorine typically by adding bleach.

Most heat pumps don't have a condensate tray that stores the water, unlike many refrigerators. Instead the condensate simply drips down a drain tube outside the house. Therefore there are other home devices that are much greater risk of concentrating legionella because they do collect condensate:

* hot water systems heating water to less than 60C - including underfloor heating

* refrigerators and freezers with condensation trays to catch but not immediately dispose of the condensed water. These rely on water evaporating.

* dehumidifiers

I like this article because it has links to other pages with information on cleaning http://inspectapedia.com/aircond/Legionella_Prevention_HVAC.php

P.S. I should have added that most discussions of legionella naturally focus on the area of greatest risk, the hot water system, because we ingest and breath its output. Whereas we hardly ever put our face next to a condensate tray at the back of a fridge.

Here's an exampel from Geekzone topic Hot Water Cylinders and Legionella

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kiwirock

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#1697681 2-Jan-2017 16:35

I think there's a greater risk involved with asthmatics with a window open.

timmmay

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#1697683 2-Jan-2017 16:39

If an asthmatic is that bad they will know it take take appropriate precautions. I guess you'd have to be in the worst 1% of asthmatics.

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