The Homemade Heat Pump Manifesto...

[AC_Hacker]

Piwoslaw,

I really like the way you are thinking about this.
_ _ _

Here are some books that are very informative on this subject:

heat-pump-book.jpg - Loads of info on GSHP design & installation. The approach is for forced air, whole house heating.

radiant-floor-book.jpg - In the US, this is considered to be the bible of radiant heating. I'm sure that better books are available in Europe. Has computer aided design software included.

Piwoslaw, if your friend's book addresses using GSHP + radiant floor, it needs to be translated into English.
_ _ _

First off, I think that many, if not all of the people on this blog realize that energy is getting more scarce and also if the energy we use has a fossil fuel or nuclear origin, we are directly contributing to global warming and/or degradation of our environment. Whatever we can do to reduce our burden on the planet is the right thing to do. It's a serious pursuit we have here, but it can also be great fun for us and inspiring for others.

> [using water to remove heat from the condenser] ...What if you did
> that with your fridge?

Any technology we invoke to solve a problem will start a chain of events that will lead ultimately to extractive processes, and there will be depletion, pollution and inefficiency all along the way. So first, let's see if there are 'low-hanging fruit' that are lower on the technology chain that will solve our problem...

* Do we need a refrigerator at all? Until a hundred years ago, people got along quite well without any refrigeration. People used the natural coolness of the earth to delay spoilage. Can we use a cool space in our house to keep fruits & vegetables in? Around here, many houses built 100 or more years ago used what was known as 'California Coolers' to keep fruits & vegetables in. This was a small cabinet-sized pantry built on the shady side of the house, with a vent to the outside at the top and bottom. For most of the year, it worked very well. No power required, no moving parts.

Here's a link to an idea for a cooler that won international recognition:
Pot-in-pot refrigerator - Wikipedia, the free encyclopedia
...notice that here, the heat absorbing property of water evaporation was used.

* Do we need a refrigerator all the time? This depends on local weather, but in my part of the world, winter time is six months long and rarely freezes. A metal box on the back porch works perfectly as a refrigerator. No power required, no moving parts. I'm the only person I know that uses this. When I tell people about this, they think I'm strange...I think they're strange. But without resorting to technology, I have reduced my refrigeration load by half.

* Is there existing technology that successfully addresses this problem? I have attached (0.1-kW-per-day_chest_fridge_2.txt) and (fig-1.gif) a detailed description here of a super-efficient freezer-to-refrigerator conversion. The link is on this site with a photo.
DIY, Super-Efficient Fridge Uses .1 kWH a Day | EcoRenovator.org
...this link is another approach to this...
Convert freezer to refrigerator | OliNo

* Are there existing building blocks I can use? Here's a link (Welcome) to a company that makes a pre-charged refrigeration system that can be connected to an air or water heat dissipation system.
_ _ _

...So getting back to your original ideas, my thinking about the earth as a heat source and a heat sink has shifted recently. Dry earth is a good storage medium of heat and cold however, water migrating through earth moves heat with it. This can be bad if we are trying to store heat because the water will carry our stored heat away. It can also be good if, for instance we are trying to extract heat from the earth, water migration will renew the heat in the earth.

If we assume that the earth is dry, then it can be imagined to be a giant storage battery, and any heat we put into the earth from a refrigerator, or a solar panel will be there for us when we need it.

> Say you dump your A/C heat into the ground during the summer.
> How much of it will still be there when you need it in the winter,
> and how much will dissipate?

earth-temp.jpg - this is a scan from the GSHP book. Note the reducing temperature swings as you go deeper. Also note the time lag (AKA: phase shift) of temp. swings as you go deeper.

Heat travels through dry earth pretty slowly. One study I read (Passive Annual Heat Storage - Improving the Earth Shelter) specified the rate at 16 feet per 6 months. So in your case, you could use underground loops to store heat during the summer and use the same loops to retrieve heat during the winter. The temperature or the earth at a depth of about 25 feet is just about the average of year-round temperatures. Most of the heat of the earth comes from the sun. In most cases, the heat from below is so small that it is of no consequence.

> Would it be worth while to pump the sun's heat
> into the ground all summer?

I have managed to pick up 10 solar heat collectors for an embarrassingly small amount of money. My plan is to use a small solar PV panel to run a pump during the summer to store heat in the ground. Here, we have bright sunny summers, plenty of sun, plenty of heat, and cold overcast winters with little sun, and temperatures hovering around 37 degrees F. Water migration may work against me, I won't know until I try.

I'm really interested in hearing more about your friend's book...

Best Regards,

-AC_Hacker

[skyl4rk]

It is pretty common in the homebrewing craft to have a chest freezer with a temp controller. You use it to control the temperature of fermentation or the serving temperature. A cheap chest freezer and one of these controllers makes a high efficiency refrigerator that is also much cheaper to buy:

NORTHERN BREWER: Fermentation Temperature Control

I have the Johnson Controls A419 and a $100 chest freezer from Lowes, it is very dependable. I haven't run it on a KillaWatt so I don't know how much load it draws, but I doubt it is very much.

Here is a heat pump design that uses water stored in an insulated attic space to store heat. The heat is generated either by solar energy into the water and then vented into the living area, or if the stored heat is not warm enough, by a heat pump (air conditioner with the hot end pointed into the living area and the cold end pointed into the attic.

Thermal Attic - Solar Heating & Natural Cooling Systems

The designer frequents the "small houses" group on yahoo. There are some very well thought out design discussions there. If you are not already in the group, they would love to hear about your experiments.

[elhigh]

About 20 years ago I read of a built-in refrigerator that used an ammonia absorption loop to cool a heavily insulated compartment. During the day, heat from the sun would drive the ammonia off the wet end of the loop outside the house, to a reservoir inside the cooler box. During the night, the ammonia would boil off from the loop inside the box and condense with the water. Next day lather, rinse, repeat.

This cooler design used about 1/2 kwh per year - to run the light.

If heat moves through dry earth at about 16' / 6mos, then the right place for your ground source loops is directly under your own basement floor, about 16 feet down. In the middle of January, all the heat you dumped in there for cooling back in July ought to be just about creeping its way back up to you -

[Piwoslaw]

Originally Posted by AC_Hacker

* Do we need a refrigerator all the time? This depends on local weather, but in my part of the world, winter time is six months long and rarely freezes. A metal box on the back porch works perfectly as a refrigerator. No power required, no moving parts. I'm the only person I know that uses this. When I tell people about this, they think I'm strange...I think they're strange. But without resorting to technology, I have reduced my refrigeration load by half.

I thought about doing the same. Before I got married we had a north-facing porch and I sometimes put stuff from the freezer out there when it was really cold. That was a good time for defrosting the freezer (our fridge and freezer were two separate units). Since we only opened the freezer once every few days this wasn't a problem. Using the balcony instead of a refrigerator wouldn't be that easy: first, the balcony was two floors higher than the kitchen. Second, I guessed that I would waste more heat opening and closing the balcony door a few times a day than what the fridge was actually using (it was the most efficient we could get then).
Now I live at my wife's and we also have a north-facing balcony, but the fridge and freezer are one unit, so whether one is empty doesn't make much of a difference. It's very efficient (rated A+, around 0.65kWh/day, compared to 1.25kWh for the previous unit), but gets opened quite often (see: Dad-in-law ).

Back to GSHP, I remembered another rule I came across somewhere: For every square meter of area of the building you want to heat there should be 4 meters of underground piping. Also, laying the pipes about 1.5 meters below the surface is supposed to be slightly better than deep drilling, under the assumption that that area of ground gets a lot of sun. 1.5 meters is about how deep the sun's heat penetrates, but is also the the freezing depth. Of course, the difference isn't that big, but if you have a sunny southern slope next to the house, it'd be sin to start drilling instead of digging.

[AC_Hacker]

Please see new post over at the EcoRenovator site:

The Homemade Heat Pump Manifesto - EcoRenovator

Best Regards,

-AC_Hacker

[AC_Hacker]

Piwoslaw,

Originally Posted by Piwoslaw

Back to GSHP, I remembered another rule I came across somewhere: For every square meter of area of the building you want to heat there should be 4 meters of underground piping. Also, laying the pipes about 1.5 meters below the surface is supposed to be slightly better than deep drilling, under the assumption that that area of ground gets a lot of sun. 1.5 meters is about how deep the sun's heat penetrates, but is also the the freezing depth. Of course, the difference isn't that big, but if you have a sunny southern slope next to the house, it'd be sin to start drilling instead of digging.

I'm curious about the rule which says: 4 meters of pipe for every square meter of building.

Obviously this ignores the heat loss characteristics of the building, it also ignores whether the system uses heated forced air or radiant floors, and if radiant floors, whether the piping is embedded in concrete (feed temp = 90 F), is embeded in non-concrete material on top of the floor (feed temp = 100 F), or is fastened below the floor (feed temp = 120 F). It also seems to ignore whether the ground-source piping is in boreholes or is in trenches, and if in trenches, how is it arrayed? As slinkeys? as parallel pipes? So many things to consider...

Where I live, the rule of thumb (which ignores all the above factors, too...) is for every 1000 square feet (93 square meters), you'll need 12,000 BTU/hr (3517 watts), which requires about 200 feet (60.96 meters) of borehole, or about 80 feet (24 meters) of trench, with about 320 feet (98 meters) of pipe in the trench. I may have errors in my conversions, but this is quite a bit different from the rule of thumb you are suggesting. I do realize that I live in a mild climate and that it gets pretty cold in Poland...

Regards,

-AC_Hacker

P.S: There are some new posts about polyethylene welding and also proceedure for testing a borehole for thermal transfer rate over at this link:
The Homemade Heat Pump Manifesto - Page 2 - EcoRenovator

[Hugh Jim Bissel]

Hey, finally registered cause I wanted to add my 2 cents about your ground-source heat/air plans. The past year I've been helping install a commercial level ground-source system. I'm not a HVAC tech or engineer, so take my suggestions with a grain of salt (or a shaker full): I can only say "thats what we did here." (in Texas)

Originally Posted by Piwoslaw

I've also been wondering about how much heat can be stored underground?
....
Would it be worth while to pump the sun's heat into the ground all summer?

About pumping heat into the ground, I would think that would be worthwhile if your main demand is heating. Here in TX, the main draw is AC, and some systems will have "dry coolers" to pump excess heat out of the system during the winter; because the temperature of the system water (closed loop) creeps higher and higher due to the high AC demand relative to heating.

Originally Posted by AC_Hacker

They should be separated by at least 8 feet each.

Our borehoeles were spaced 20ft apart. The greater spacing will likely help increase the amount of heat that can be stored. If it's just one or two rows, the spacing may not matter as much as in our case where we had 230 boreholes in the space of about a soccer field and a half!

Originally Posted by AC_Hacker

P.S: There are some new posts about polyethylene welding and also proceedure for testing a borehole for thermal transfer rate over at this link:
The Homemade Heat Pump Manifesto - Page 2 - EcoRenovator

Just left a post there about my experience and recommendations for polyethylene welding.

All these different threads got me confuzzled: I'd been reading both this thread and that one (@ ecorenovator). I finally decided to register at ecorenovator to reply. I made the post about poly welding then went looking for this thread to reply to it. After checking my browser history, I finally found it here at ecomodder. Oh well, I guess the excuse was needed, I've been lurking here long enough.

[cptrdbrd]

Hi guys
I have looked over your thread, the threads in twister and some others. I am a commercial industrial HVAC tech for 25 years and tough it for about 10 years in the evenings. I have enjoyed watching what you and others are doing. some times I'm impressed, some times I shake my head and some times I'm just scared. I am looking to build my own Geo heat pump unit by cannibalizing my air to air HP. I have seen some comments elem ware referring to the so called secret info in this info. Please do not believe this is true, I think most techs would love to share there knowledge. the reason it seems they play there cards close to there chest is: it is a very technical field That takes a extensive back round including the laws of thermodynamics, physics, chemistry and electricity theory. this does not mean that the common man cant do what you are doing, but to make it work well and last you Need a few things under your belt. I think you guys can do very well be cos you have desire the #1 thing to synced.
I have held off interjecting be cos there is no short way to learn well the vapor compression cycle and the other things involved. I hope to make a write up that will be usefully some day. for now, till I come up with some thing I will answer your questions if you are willing to share the knowledge you have.
although I have lots of experience with water source heat pumps and water cooled units I am looking for the info for the ground source loops.
Paul

[AC_Hacker]

Paul,

Welcome to the conversation.

When I started this "manifesto" thread, I had in mind that it would be a kind of 'open source project' where people could share their knowledge. So, when folks like you join in, it is very encouraging.

I'm not sure if you know that although this is where I started this project thread, it's moved over to the sister blog:
The Homemade Heat Pump Manifesto - EcoRenovator
...it was driving me crazy trying to double post and remember what was said and where.

Anyway, on the other blog (above URL) there's a ton of additional info.

And I'm figuring this thing out as I go along, so if you see things that need correcting, let's get things cleared up.

> ...I am looking for the info for the ground source loops...

The best source of info I have found is the IGSHPA book, "Closed-Loop Ground-Source Heat Pump Systems: Installation Guide". It's not cheap, and I wasn't able to find a copy that was used that was much more reasonable.

IGSHPA manuals are here:
Publications | Manuals

What I've been able to determine is that there are different ways to get the Ground Source heat. Some are cheaper than others. ranking from cheapest to most expensive goes something like this:
1) Closed Loop Pond
2) 'Open Loop' pump & dump systems where you take water out of an aquifer and dump it back to the aquifer or to a river or use it for irrigation.
3) Trench type systems using a 'slinky' arrangement or a linear pipe arrangement.
4) Closed-Loop boreholes.

Geology or lot size may make one of the choices the only choice that will work.

So, I live on a 50 x 100 city lot and don't have enough room for anything except drilling down. I can't affford to have a professional do it, so I'm trying to do it all myself.

Sizing the loop field is a matter of knowing what your building heat load is and knowing what the thermal transfer characteristic of your particular soil is. On the other blog, I set out how to test your own soil to determine what your heat transfer rate is.

Thermal Test URL:
The Homemade Heat Pump Manifesto - Page 2 - EcoRenovator
...post #18...

So, for me and my small house, I'm figuring my house's heat load to be about 12,000 BTU/hr (a Ton).

In these parts (Portland, OR) the rule of thumb is that a borehole needs to be between 175 and 225 ft deep, per 12,000 BTU/hr. When I tested it, it came out to 214.23 ft. This would mean that I would need at least 214.23 feet of borehole. More borehole is better, and also more expensive.

I have heard that around here, a 5 foot deep by 3 foot wide trench with 300 feet of slinky loops would get you about 12,000 BTU/hr.

I also found out that the material of choice for loop fields is High Density Polyethylene (AKA: HDPE). Many states are insisting that all joints be heat-fused (AKA: welded). Installers guarantee these for 50 years, but the general agreement is that they'll last a couple of hundred years, or more.

Here's product information from a typical HDPE pipe provider:
http://www.superlon.com/supertherm.pdf

There are also considerations of providing flow turbulence, to improve heat transfer. The IGSHPA manual covers this.

Here's a link to a brief blog discussion on the subject of flow rates:
http://www.eng-tips.com/viewthread.c...227114&page=10

PVC pipe is not recommended because it gets brittle with age. I have read, however, that the first GSHP developments did use PVC. I don't know if all of the PVC installations failed, in fact, I don't know if any of them failed.

I have also heard stories about how "a neighbor buried garden hose in the back yard to heat his house". I have no way to verify the information as to whether this will actually work.

I do recommend experimenting.

I also recommend being aware of standard methods, if for no other reason than it can suggest a starting point.

Here's Washington state's standard:
http://apps.leg.wa.gov/wac/default.a...te=173-160-453

Here's from Lancaner county Pennsylvania:
http://www.co.lancaster.pa.us/planni...p?a=3&Q=268236



Does this help?

>>>>>>>>>>>>>>>>>>>>>>>>>>

And I do have a question for you:

I have this little 400 watt compressor, and I'm trying to size a pair of flat plate heat exchangers for it. By my reckoning, it will move about 1600 watts (about 5500 BTU/hr), steady state. I'll be pumping water in at maybe 47 degrees into it on the Ground Source side, and I'll want in the neighborhood of 5000 BTU/hr out on the hydronic floor side. I figure I'll run R-22 or similar refrigerant. I'm not trying to heat my whole house, just a room that needed about 4000 BTU/hr on the very worst day last winter.

I threw one together last summer and it worked pretty well, but I'd prefer to have a better idea of what I'm doing.

Do you have charts or sizing programs that you like to use?

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
NOTE: While waiting for a reply, I found what appears to be a pretty good brazed plate selection program. Found here:
http://www.flatplate.com/resources_SOFT.htm
...choose the "Refrigeration Heat Exchangers" option.

The specifications for ebay-available brazed plates is pretty much non-existent. There is some vague mention of BTU transfer for solar-heating.

Problem is that refrigerants have a very different specific heat, compared to water. So I Thrashed around through several brazed plate selection guides and found that for refrigeration purposes, both evaporation and condensing, heat-transfer seems to work out to about 5000 BTU/square-foot for small exchangers.

So the formula might look something like:

Heat = ((width) x (length) x (# of plates - 2)) x 5000

...where width & length are expressed in feet.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Best Regards,

-AC_Hacker

[tinkerbill]

Hey Piwoslaw,
There actually is a website and formula for using the earth in a big half-ball shape(insulated underneath the ball) then building new purpose-built eco-housing on top of it. I think the size of half-ball and how deep it went depended on location and size of house. As I recall, heat was dumped into the earth storage in the summer and heat was drawn back out in the winter. This pretty much made for an average temp all year round if engineered right. Perhaps I can take the time later to research my extensive bookmarks and come up with the website.
take care and stay warm/cold-average! Tinkerbill (new member from Yahoo wastewatts group)
PS: sorry I forgot to use the quote function. Newbie mistake.