Cooling via transfer upstairs??

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Gemini

429 posts

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#243320 6-Dec-2018 08:34

Cooling via transfer upstairs??

Our house is challenging to cool and has 3 different temperature zones.

It's a 2 story house built into the side of a hill. Downstairs is partially underground, gets almost no sun and is cold and damp, consequentially we avoid it in winter which we can because it's just garaging and some spare rooms. Upstairs we have a split pitched roof with a 4m high central hallway that runs the length of the house. One side of the house has very high ceilings, the other regular height, both sloped. The side with the normal height ceilings gets more sun in winter so is quite a bit warmer. In summer when the sun is higher, the high ceiling side is actually hotter as it gets roasted by the afternoon sun. It is a skillion roof so there is no ceiling space for HRVs, central heating ducts etc.

There are 3 places where I might be able to pump cold air up from downstairs in summer. Not sure if this is a good idea as it will be more damp. Not winter level damp but still damp.

To get more benefit I thought about reversing the flow in winter but the upstairs where we live, needs all the heat it can get.

Oh and I have priced up heatpumps, just considering all options :)

Aredwood

3885 posts

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#2140488 6-Dec-2018 12:29

Just get heatpumps.

You need a much bigger temp difference to make heat transfer worthwhile. Pretty much only when you have a grunty woodburner, that is making the lounge too hot in winter. And you have other rooms that need the heat.

Trying to move heat from upstairs to your colder downstairs rooms during summer will just give you mega dampness problems in the downstairs rooms. As assuming that the upstairs air temp is 30deg at 50% humidity. That same air piped downstairs will be 100% humidity at 18.5deg

nickb800

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#2140492 6-Dec-2018 12:46

For the summer issue, could you put a couple of through-wall extractor fans near the peak of your upper-storey sloping ceilings. This would let the hottest air escape, and boost convection of air through the house from downstairs (with downstairs windows opened). A pretty cheap option, but would need to be started early in the day, not just turned on when you start to feel hot

Gemini

429 posts

Ultimate Geek

#2140630 6-Dec-2018 15:16

nickb800:

For the summer issue, could you put a couple of through-wall extractor fans near the peak of your upper-storey sloping ceilings. This would let the hottest air escape, and boost convection of air through the house from downstairs (with downstairs windows opened). A pretty cheap option, but would need to be started early in the day, not just turned on when you start to feel hot

Interesting idea and could be possible at one end of the 4m high hallway, anyone have experience with this?

wellygary

8315 posts

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#2140658 6-Dec-2018 16:26

Gemini:

nickb800:

For the summer issue, could you put a couple of through-wall extractor fans near the peak of your upper-storey sloping ceilings. This would let the hottest air escape, and boost convection of air through the house from downstairs (with downstairs windows opened). A pretty cheap option, but would need to be started early in the day, not just turned on when you start to feel hot

Interesting idea and could be possible at one end of the 4m high hallway, anyone have experience with this?

Although the flip side is that it will likely be a source of draughts and heat loss in Winter,

Any chance of just opening a few windows (maybe with lockable stays) to create a through draught....

mattwnz

20145 posts

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#2140694 6-Dec-2018 17:18

Can you use the natural 'stack or chimney effect' by opening windows both downstairs and upstairs, and possibly upstair skylights, to let the hot air out, and draw the cold air from downstairs upwards, as hot air rises? Otherwise heatpumps? Google Stack effect cooling. Also are your ceilings getting hot from teh sun heating the roof? If so it coul dbe a lack of insulation, or is the roof painted a dark colour? Painting the roof silver or white possibly could also help to reflect the heat.

tim360

34 posts

Geek

#2140700 6-Dec-2018 17:30

Look up night purge passive ventilation. You might be able to install some windows at your high points which you can open at night in the summer. The warm air will rise and out the windows, drawing in the cooler air from downstairs.

neb

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#2140839 6-Dec-2018 21:42

Aredwood: Just get heatpumps.

Naah, this is just crying out for a Stirling engine. And it's self-regulating, as the temperature differential eases the engine stops moving the air.

Another option is to hire Maxwell's demon, but you'd have to check with your local church first.

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neb

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#2140844 6-Dec-2018 21:55

mattwnz:
Can you use the natural 'stack or chimney effect' by opening windows both downstairs and upstairs, and possibly upstair skylights, to let the hot air out, and draw the cold air from downstairs upwards, as hot air rises?

More specifically, if that's what they're after, they need a windcatcher. Those have been used for at least two thousand years for this type of cooling.

Gemini

429 posts

Ultimate Geek

#2140889 7-Dec-2018 07:16

Hot winds or still days are problematic. I think we will be lounge-bound those days as that is where the heatpump is going in. When there's a cool breeze I can use my two Vornado fans to move air around. I've had one downstairs pointed upstairs but that didn't seem to achieve much. The stairwell is not close to the upstairs living areas and several direction changes would be required. Might try pointing both outside of the hottest rooms next time

I looked at using the chimney to extract heat but I've capped it already and don't want to lose warm air in winter.

Same concern with through wall/window fans. They don't seal properly, leak heat and can let strong breezes in.

I also looked at rerouting a downstairs extractor fan to pump the air into the top of the hallway instead of outside ... but then I can't use it in winter to pump damp outside.