Running 5000 BTU air conditioner solar

[J.P.M.]

Even at night a passive heat pipe could work. A fan would help and even run off battery would still be miles ahead energywise compared to any AC. I suppose a small windmill could power the fan somewhat but then it gets all swiss family robinson looking.

A buried heat pipe will need some way to move the cooler (and thus more dense) air from a lower elevation (underground) to a higher elevation (above ground). That will take some power, therefore not passive. On the whole, to be effective at all, such ground source methods of heating/cooling require careful design and in addition are usually more costly to build and maintain than most folks realize, not to mention the safety considerations with respect to air quality that need to be addressed. Maybe not a bad idea on paper or in the mind, but the devil is in the details.

[jflorey2]

If we were real serious about minimizing the sweat we would move to a cot or hammock. I here there are new bed topping devices that help shed heat and wick moisture. Anyone tried them?

I used a tiny chiller (called Chillpad I think) that just cooled the mattress. It's active cooling of course, but since it's only trying to cool you and not the room you use much less energy. (80 watt draw when the compressor is on.) Seemed to work OK.

[Bala]

Even at night a passive heat pipe could work. A fan would help and even run off battery would still be miles ahead energywise compared to any AC. I suppose a small windmill could power the fan somewhat but then it gets all swiss family robinson looking.

On a night here that you would like a/C there is no wind to power a windmill. It's summer so fridge and freezer are working hard at using up battery storage.

We are acclimatised and prefer not to have A/ C if we can. There are some uncomfortable nights but we are ok as is.

A/C in cars is never turned off.

[Sunking]

If we were real serious about minimizing the sweat we would move to a cot or hammock. I here there are new bed topping devices that help shed heat and wick moisture. Anyone tried them?

You can sure the the age of some posters from their questions and answers. None of them have ever heard of a Water Bed us ole Hippies use to make waves rocking the boat.

[J.P.M.]

There are some uncomfortable nights but we are ok as is. A/C in cars is never turned off.

So do this: Run the cars all night w/the vehicle A/C running full blast and duct it out of the vehicle and into a bedroom. Then return from the bedroom to the vehicle. Classic redneck engineering.

[jflorey2]

So do this: Run the cars all night w/the vehicle A/C running full blast and duct it out of the vehicle and into a bedroom. Then return from the bedroom to the vehicle. Classic redneck engineering.

You'll need some good insulation around that duct to make it all the way to the bedroom. Time to order some fast food in to-go containers!

[nomadh]

A buried heat pipe will need some way to move the cooler (and thus more dense) air from a lower elevation (underground) to a higher elevation (above ground). That will take some power, therefore not passive. On the whole, to be effective at all, such ground source methods of heating/cooling require careful design and in addition are usually more costly to build and maintain than most folks realize, not to mention the safety considerations with respect to air quality that need to be addressed. Maybe not a bad idea on paper or in the mind, but the devil is in the details.

My thinking was the chimney, where the hot air would naturally gravitate, would rise as it is inclined to do. As it rises it would pull air from below to fill the vacuum.
Now the practical part depends on the math I suppose. Maybe to be functional enough to matter maybe the chimney and pipe need to be 10" or 5 ft across. OR if the chimney needs to be 5 ft or 90ft and corrugated steel or 4" thick concrete to absorb the heat of the day I know not. Just wondering if its been done.

[nomadh]

So do this: Run the cars all night w/the vehicle A/C running full blast and duct it out of the vehicle and into a bedroom. Then return from the bedroom to the vehicle. Classic redneck engineering.

Or just sleep in the car. Not out of the question if it only happens a few days a year and you have an important meeting in the morn.

[nomadh]

On a night here that you would like a/C there is no wind to power a windmill. It's summer so fridge and freezer are working hard at using up battery storage.

We are acclimatised and prefer not to have A/ C if we can. There are some uncomfortable nights but we are ok as is.

A/C in cars is never turned off.

Water can be a good store of energy. Maybe double the PV panels so you can freeze or chill lots of water during the day then sleep on or in it at night. I'll do anything to not have to deal with or pay for batteries

[J.P.M.]

Water can be a good store of energy. Maybe double the PV panels so you can freeze or chill lots of water during the day then sleep on or in it at night. I'll do anything to not have to deal with or pay for batteries

There is a way to add insulation and add thermal mass to a dwelling with the goal of increasing something called the thermal time constant. The rough goal is to have the heat loss low enough and the thermal mass high enough so that the dwelling heat cycle is about 24 hours long and about 12 hours or so out of phase with the daily ambient temp. cycle. So, during warm season, ventilate at night and bring thouse mass temp. down. Then in the morning, button up the house and use the insulation to keep the heat out as much as possible and use the thermal mass to SLOWLY absorb the heat that does leak in thus avoiding a large temp. rise. Then, open up at nite when/if it cools down. In the winter or cool season, reverse the cycle and ventilate during the warm hours and button up at night.

It's not perfect, but it does work. if nothing else, it'll keep the bills for heating/cooling down during hottest/coldest times and probably eliminate them in the shoulder seasons.

[SunEagle]

On a night here that you would like a/C there is no wind to power a windmill. It's summer so fridge and freezer are working hard at using up battery storage.

We are acclimatised and prefer not to have A/ C if we can. There are some uncomfortable nights but we are ok as is.

A/C in cars is never turned off.

Years ago while I lived in New Jersey we would roll down the 4 windows and drive 40 mph to get cool air. We called it the 440 cooling system.

[Bala]

There is a way to add insulation and add thermal mass to a dwelling with the goal of increasing something called the thermal time constant. The rough goal is to have the heat loss low enough and the thermal mass high enough so that the dwelling heat cycle is about 24 hours long and about 12 hours or so out of phase with the daily ambient temp. cycle. So, during warm season, ventilate at night and bring thouse mass temp. down. Then in the morning, button up the house and use the insulation to keep the heat out as much as possible and use the thermal mass to SLOWLY absorb the heat that does leak in thus avoiding a large temp. rise. Then, open up at nite when/if it cools down. In the winter or cool season, reverse the cycle and ventilate during the warm hours and button up at night.

It's not perfect, but it does work. if nothing else, it'll keep the bills for heating/cooling down during hottest/coldest times and probably eliminate them in the shoulder seasons.

On good summer day if will be +30c, it won't drop much for the night. High humidity. I designed the house for air flow, it's not designed to stay warm at all. We generally get a katabatic breeze at night but some nights are just hot

I remember years ago on the previous forum sunking told me my batteries were a bit hot, they were just ambient temp.
cold here is 14c, very cold 12c, that is only a few nights per year, 25c would be a cool day time temp.average rainfall 5 meters

[J.P.M.]

On good summer day if will be +30c, it won't drop much for the night. High humidity. I designed the house for air flow, it's not designed to stay warm at all. We generally get a katabatic breeze at night but some nights are just hot

I remember years ago on the previous forum sunking told me my batteries were a bit hot, they were just ambient temp.
cold here is 14c, very cold 12c, that is only a few nights per year, 25c would be a cool day time temp.average rainfall 5 meters

Understood. High dew points tend to keep overnight low temps. warmer than low(er) dew points.

[Bala]

Water can be a good store of energy. Maybe double the PV panels so you can freeze or chill lots of water during the day then sleep on or in it at night. I'll do anything to not have to deal with or pay for batteries

For us winter is out best time for solar production, cooler, and a lot less rain.

Summer is the worst time for production due to rain and when we would really like A/C it is the build up to rain. Extremely humid and overcast and possible thunderstorms.

So having standalone solar if we were to be trying to freeze water all day we would end up on generator all night to charge batteries.

A reason not to have A/C is that if we did we would not leave the house, as it is I am just as cool if not cooler up in my shed working on projects.

Always remember off grid power has IMHO very few advantages, if any. It has been good after Hurricanes but they have been may years apart.

[jflorey2]

Water can be a good store of energy. Maybe double the PV panels so you can freeze or chill lots of water during the day then sleep on or in it at night. I'll do anything to not have to deal with or pay for batteries

There's a chiller out there called the Ice Bear that does just that - freezes water when energy is available and uses that heat sink at night to cool a house.