Maxi-Split ?

[jebatty]

With temps these last 10 days or so ranging regularly into the high -teens and high -20'sF, winds and wind chill temps into the -30's and -40's, I'm thinking that there must be a way to store that cold for next summer's AC, and also a way to store next summer's excess heat for the following winter heating: a Maxi-Split would be the answer. Who makes and sells these?

 

[Seasoned Oak]

I'm thinking that there must be a way to store that cold for next summer's AC, and also a way to store next summer's excess heat for the following winter heating: a Maxi-Split would be the answer. Who makes and sells these?

I saw something like this in a popular science article. Had a huge storage tank below the house for just such a project. I guess it just was not cost effective or well insulated enough.

 

[EatenByLimestone]

I think trees do a pretty good job of storing the summer's heat for the winter. If you could freeze a large enough block of ice to blow air over all summer long you could probably have free AC all year long. I suppose you would have to make it like a thick ice rink and freeze a layer every night/day. With the right insulation amount you could keep the ice all year long. The old ice houses did it with sawdust and we have much better insulators now. The question would be the size you'd need to make. You might need it to be the size of a small foundation or a swimming pool. You could probably test the size by burying a 50 gallon drum and making it a solid block of ice. Then seeing how quickly it thaws out. It's an interesting idea.

 

[woodgeek]

A 2-ton AC puts out the same coolth as melting 2 tons of ice per day. If a typical US house has a 2-ton AC that runs 50% of the time for 60 days of the year, that is ~60 tons of ice! One 15,000 gallon swimming pool would do the job.

Randy is remembering an experimental solar house from the 1940s (I think), that had a seasonal heat store. It was called the MIT Solar House #1.

The device you want is called a ground loop heat pump, and they are often not the most cost effective sol'n.

 

[midwestcoast]

In the swimming pool of ice scenario you could also loose the heat that it'd take to warm the melted water from 32 to a maximum temp useful for cooling (say 50 or 60?), so an additional 20-30 rise. Still seems pretty un-workable, but I have had these same thoughts many times Jebatty.
If only I could just open a box of winter in July...

 

[Seasoned Oak]

I always thought there must be away to take advantage of the hot earths interior in winter just a few miles under out feet. I guess it can be done but is also not cost effective YET.

 

[woodgeek]

If you live near a large lake, there are easy options....

(broken link removed)

 

[peakbagger]

Goethermal heat pumps are well established way of using the heat in the ground and have been for a few years.

I have seen references to an zero electricity refrigerator that consists of a large very well insulated box in the basement surrounding an open top water tank with a Freon loop running outdoors. In the winter when the outdoor temperature is less than the indoors, the Freon thermosyphons to the outdoor coil, cools and then sinks back to the tank until the tank freezes. Eventually they end up with a large block of ice in well insualted box and they use it for a refrigerator. Its doesn't have freezer section. Highly impractical considering that solar powered freezers are for sale that work quite well.

 

[semipro]

Geothermal versus Ground Source?
Since both are discussed here I thought I'd propose some some disambiguation.

1. Geothermal - non-renewable and resulting from heat existing or generated within the earth.
   
2. Ground source - renewable and resulting from the sun's heating of the earth's surface (ground and water).

Of course, now that I wrote that I'm wondering about the definition of "renewable" as I was thinking of the earth's core heat as finite. Of course, if that's finite so is energy from the sun.

Based on this definition from Wikipedia I guess my No. 1 above is wrong.

Renewable energy is a socially and politically defined category of energy sources. Renewable energy is generally defined as energy that comes from resources which are continually replenished on a human timescale such as sunlight, wind, rain, tides, waves and geothermal heat.​

We're heating right now with a 25 year old open-loop, ground source heat pump system. It takes water from our well uses it as a source/sink for heat and then its returned to a sinkhole nearby.
I'm starting to worry about the impact of the constant erosion/dissolution occurring from the water in going to the sinkhole. I wish our system was closed-loop -- another future project.

 

[midwestcoast]

Geothermal versus Ground Source?
Since both are discussed here I thought I'd propose some some disambiguation.

1. Geothermal - non-renewable and resulting from heat existing or generated within the earth.
   
2. Ground source - renewable and resulting from the sun's heating of the earth's surface (ground and water).

Of course, now that it wrote that I'm wondering about the definition of "renewable" as I was thinking of the earth's core heat as finite. Of course, if that's finite so is energy from the sun.

Based on this definition from Wikipedia I guess my No. 1 above is wrong.

Renewable energy is a socially and politically defined category of energy sources. Renewable energy is generally defined as energy that comes from resources which are continually replenished on a human timescale such as sunlight, wind, rain, tides, waves and geothermal heat.​

Tangent Alert!
Yes, geothermal is considered "renewable" energy. None of the above sources are INFINITELY renewable of course, but that's a pretty academic argument since if any of them ran out we'd be an extinct species long beforehand.
The majority of the heat in earth's Mantle and core comes from the decay of radioactive isotopes.
A small amount is thought to remain from friction of earth condensing from a gas cloud to a solid ball, and a small amount also remaining from gravitational sorting of elements in the planet (the heavy stuff sinking & light stuff floating to the surface). I also remember reading that the cooling of the mantle is releasing measurable latent heat like any other phase change.
The short story is yes, the earth will eventually cool & solidify, but it is predicted that the sun will engulf the planet before that happens, so we don't need to worry too much
I don't remember seeing any studies predicting the effects of large-scale geo-thermal heat extraction on the geologic cooling process, but I think it's fair to say that with the amount of energy available it's unlikely that humans can have any measurable effect. Maybe some localized impacts.

 

[DBoon]

I remember seeing a case study from years ago of a Canadian townhouse development that used a solar thermal collector system to warm ground temperatures in the summer for use by the ground source heat pump in the winter.

 

[woodgeek]

When I'm feeling grumpy, I don't like calling residential ground-source heat pumps 'geothermal'. I used to just shake my head and thought it a lame attempt to sex up an old technology. And then it became clear that a lot of the more poorly informed enviros out there REALLY THINK those heating systems provide heating without significant energy input, i.e. they conflate it with the technology of the same name for producing electricity.

I have seen blog posts where clueless folks write posts conflating the two.

As a side note....David McKay in the great book 'Without hot air' (google it), does a calculation that if every house at normal suburban density installed a ground loop system, then in heating dominated climates, the supply of subterranean heat will be exhausted in too short of a time. And of course, in a mixed hot/cold climate, then Air-Source works well enough to make the GSHPs kinda pointless.

 

[Seasoned Oak]

As a side note....David McKay in the great book 'Without hot air' (google it), does a calculation that if every house at normal suburban density installed a ground loop system, then in heating dominated climates, the supply of subterranean heat will be exhausted in too short of a time. And of course, in a mixed hot/cold climate, then Air-Source works well enough to make the GSHPs kinda pointless.

I kinda thought the heat was replenished from below. And as you know the deeper you go the hotter it gets.

 

[EatenByLimestone]

I kinda thought the heat was replenished from below. And as you know the deeper you go the hotter it gets.

That would happen, but I think they are talking about it being drawn out faster than it's being replenished. There would have to be a lot of people drawing for this to be an issue though.

 

[woodgeek]

the timescale for replenishment is thousands of years. You should really think about it as 'seasonal' storage of heat...the temp that near the surface is really just the average solar heated surface temp over the last few thousand years, plus a tiny amount from heat below.