Starting DIY GSHP mainly for AC

vanderzac · 06-28-12, 06:59 PM

So I live in Tucson Arizona, and things seem very different down here from what everyone else has posted. I am interested in a GSHP to keep cool in 110F during the hot summer, while winter temperatures rarely fall below 30F, so while heating will be used, it will be of a lesser focus.

I have read much of The Homemade Heat Pump Manifesto, and am taking in everything I can in preparation for starting this project. My start date cannot be before September, and completion would be ideal before April, but I have existing evaporation cooling that keeps the house ~85 if I miss my deadline. During the time between now and September I want to get as much planning and concept nailed down as possible.

My wife and I have talked about this and decided that if I can keep the installed price below 2K it would be the equivalent cost of traditional central air, and are not willing to exceed this price point because we intend the house to be a rental in 3 to 5 years. This also means that the system must be robust in it's completion, able to work with a traditional thermostat, and low maintenance.

I intend to do all the work myself, and have access to a resourceful network of individuals in construction, DIY, and HVAC, so I do not foresee complications regarding talent or tools, especially coupled with the wealth of knowledge I have seen on this forum.

Our house is 1150sqft, and is kept cool entirely by an evaporation cooler running a 1/2hp blower 24/7 over pads that are constantly drenched with water, which raises our water bill by about $40/mo and wastes hundreds of gallons of water a day (not eco-friendly in the desert). For all this we cannot cool our house below 85~ in ideal summer conditions, and as more humid monsoon weather rolls in our situation will only get worse.

Our goal is to lower our water costs and have them translate into higher electrical cost while gaining the benefits of reliable temperature control similar to that of traditional AC. Because the house will eventually be a rental unit we do not want to put aesthetically displeasing heat exchangers in walls, but want to use either existing air ducting, or more ideally a DIY version of this (www) dot hydroinnovations dot com/product-details.php?title=ICE_BOX_Pro&pro=30 inline into each room with a central water reservoir feeding the heat exchangers, which would be kept cool by the GSHP.

I'll be documenting everything I can, and have more to post as an introduction but have to run for now, so I'm going to post this and will add more info/clarify tomorrow. In the meantime, hi everyone.

Zach

Daox · 06-28-12, 09:28 PM

Sounds like a very interesting project Zach. Welcome to the site and I hope we hear a lot more about it in the near future!

Vlad · 06-29-12, 01:17 AM

With this tight budget I would try to build "mini cooling tower". Cooling tower doesn't need much water and helps to run your AC much more efficient in high temperature desert environment. Also you need grossly oversized condenser.

vanderzac · 06-29-12, 09:07 AM

Thanks for the welcoming

Vlad: As far as I can tell the amount of my budget is not going to make a large difference. I can get a massive cooler for less than < 200, and have access to all the needed tools for modification. I'm still unsure if I'm going to need water heat exchangers, but they add little to the cost, pipe at $17/100ft, and a pump also add little concern. Near as I can tell the vast majority of my budget is going to be eaten up drilling, as the ground 2 feet down I hit caliche rock (type of hardpan). I'm looking to build a DIY drill, but my focus is going to be on keeping costs down more than quality; The drill needs to get the job done, but will be dismantled after the job is done. Unfortunately I know little about drilling, and am starting to read more about that now. Also, I do not have AC, I have evaporation cooling, which works by saturating the air with humidity, and is not compatible with an inline AC to further cool the air to the best of my knowledge. The budget I have is what I would expect to pay to switch to AC, again DIYing it, but if I can do ground source for the same amount, it is worth it to me, and I don't mind putting in the sweat and blood (though hopefully not too much).

Zach

vanderzac · 06-29-12, 10:54 AM

I'm terribly sorry Vlad. I've just finished another round of googleing and now understand that a cooling tower may be more what i'm describing, though according to Wikipedia I think I will be looking to DIY / connect an air handler that uses piped in chilled / heated water from the GSHP. Does this sound correct for air cooling? If not do you have any specific links that may be more informative than the mass of information i'm sifting through otherwise? Thanks.

Vlad · 06-30-12, 06:30 PM

Quote:

Originally Posted by vanderzac

I'm terribly sorry Vlad. I've just finished another round of googleing and now understand that a cooling tower may be more what i'm describing, though according to Wikipedia I think I will be looking to DIY / connect an air handler that uses piped in chilled / heated water from the GSHP. Does this sound correct for air cooling? If not do you have any specific links that may be more informative than the mass of information i'm sifting through otherwise? Thanks.

With your budget forget about drilling. Slinky coil might be an option but you need space and it will be more then your budget. The BEST GOOD WORKING option in your case will be:

AC/HP that one side (evaporator) cools air/water. The second side is evaporative condenser (mini cooling tower). Evaporative condenser is like regular coil but it is sprayed by water which evaporates from its surface and helps to cool it down. Read about wet bulb and dry bulb temperatures and get the concept. You use the same concept already with your swamp cooler but temperature range is limited. With AC you will shift temperature range.

It is much more efficient in hot environment and doesn't need much water. The problem is condenser corrosion, so stainless is the best choice.

Just Google "evaporative condenser" look at pictures and you will get the idea.

vanderzac · 06-30-12, 08:20 PM

Hi Vlad. After reading the entire manifesto and looking at your well drilling rig, I am dead set on building a rig like yours to drill. I live in a dense city and have enough space for 10 boreholes 16 feet apart, but no where near enough for slinky.

I feel I can reach my target price as a total expense, meaning after building the drill I would sell it whole / re-purpose it, or potentially hold on to it and try to build a side job out of drilling on weekends (considering the commercial price this does not seem unreasonable, also people around here hire unlicensed contractors a lot), and so I may spend 5K up front, and recover 3K when I sell the drill / components.

I have a HUGE amount of time to work with, sourcing cheap parts, and the economy here is bad enough that craigslist has major deals. My goal is to begin sourcing/building the well drill ASAP, and have holes (down to 100ft maybe less, still figuring that out) done between Feb and April, while sourcing the AC components between now and then. I also have the entire winter to work, as it doesn't get below freezing for more than a couple hours now and then (even at night).

So here's what I'm planning/working on now:
1) drilling regulations (laws and permits)
2) sizing of system
3) determine best way to move heat out of the air and into the water (cooling and airflow).

1) I took a cursory glance at our drilling regulations, which mention geothermal but are mostly targeted for well water, or oil and gas wells (regulating 20,000ft wells). The city website says a permit costs $10K, but that permit exemptions are a possibility. Unfortunately I will have to wait till Monday to get more information, but will report back for those US urban individuals interested in DIY GSHP, and really hope there is some way around this.

2) system sizing. I'm not sure on this, unfortunately. AC started in the manifesto saying a bit too small is better than too big for 2 reasons: COP will be worse (lower) when the compressor runs for shorter duty cycles, and the cost / labor of the boreholes.

I feel building a large water storage tank (1,000 gallons maybe) will allow me to run the compressor for long cycles to get to temperature, then let it taper off over hours/days, which should give me higher COP and relatively stable temps. If my thinking here is wrong please let me know.

Because I will be building my own drill and providing my own labor, the monetary cost for the first hole will be around 3K, but each additional hole seems to be around $100 or less. I am also expecting I will not have the drill long term, so I would rather spend $300-$500 for extra boreholes and make sure my system is large enough the first time around (similar to Vlad's views on building a drill; over engineer it so you cant fail). If I decide it is too large I can always disconnect boreholes from the loop, but after the drill is gone I can't build more.

3) Currently my house is circulating air with a dual speed 1/4 and 1/2hp blower 24/7 in an evaporation cooler and moves a huge amount of air. As such I imagine I can use the same blower to circulate air across the existing evaporator of whatever AC I end up cannibalizing. This would be extremely convenient if it works, but so far I have no clue if this would be effective as I'm still wrestling with the underlying concepts of how cooling coils work. If I luck out I may find a salvage commercial air handler that is designed for water to air central cooling.

If anyone has relevant information I would hugely appreciate it. I'm sorry if it seems I'm dismissing your idea for the cooling tower Vlad, I just don't have any idea how effective it would work, while i have seen examples of chillers and know they are effective. If you have any references I could check I will, but I need to be confident the end result will function as well as an appropriately sized central air unit from Sears.

Thanks

Vlad · 07-01-12, 03:51 PM

vanderzac,

Check out the other thread more drilling and digging oriented:

http://ecorenovator.org/forum/geothe...ging-gshp.html

You can find all specs and details about my rig. Pay attention to sliding table that holds drilling pipe. It saved me ton of time and calories

.

In my location (Canada) I have to worry mostly about heating and just a bit about cooling. Because of this my focus was earth. In your case you only have one problem - heat rejection which can be achieved in very efficient manner without drilling and digging.

Here is very cool link about !!! residential !!! evaporative condensers:

http://www.pge.com/includes/docs/pdf...e/ac2eval1.pdf

Building a drilling rig is not an easy task. By the time you finish it you will double your initial budget and triple the time you expected to spend.

The system that you have now can't perform like refrigeration system because of this you waste so much water and move so much air.

vanderzac · 07-01-12, 09:55 PM

Hi Vlad. I looked at the link you provided and at several different places the report indicated the dry nature of the air was important to the overall function. Here in Tucson the hottest months (July-August) we have monsoon rains, where the outdoor temp will remain above 100F and humidity will be 90% or greater. From what I can tell this would render the cooling tower noneffective at pre-cooling air before running it over the condenser, does this sound correct?

vanderzac · 07-01-12, 11:18 PM

I think I'm understanding it better after reading and re-reading it, unfortunately concepts are sometimes a bit too dense for me the first few times and I really struggle reading something over and over to understand and comprehend it. Anyways, as I can tell in an oversimplified fashion, the condenser of the heat pump is placed in a bath of water, and that water is cooled by dripping over the evaporation pads while circulating air (AC2 example). This will keep the water temperature equal to the wet bulb temp (which is usually about 30 degree's cooler when humidity is low), but that when air is already fully saturated the system not would work nearly as well, which is coincidentally the issue we have with our current cooler during July and August monsoon, where the air becomes so humid that it cannot be cooled by evaporation. With a GSHP my water would be circulated through the ground to keep cool, thus not affected by relative humidity, and the water temp would consistently be around 50f, instead of 80 (110-30), which should also make the system more efficient.

Does this sound conceptually correct?

Thank you again for helping me through this and providing useful suggestions.

06-28-12, 06:59 PM	#1
vanderzac Lurking Renovator Join Date: Jun 2012 Location: Tucson, Arizona Posts: 10 Thanks: 0 Thanked 0 Times in 0 Posts	Starting DIY GSHP mainly for AC So I live in Tucson Arizona, and things seem very different down here from what everyone else has posted. I am interested in a GSHP to keep cool in 110F during the hot summer, while winter temperatures rarely fall below 30F, so while heating will be used, it will be of a lesser focus. I have read much of The Homemade Heat Pump Manifesto, and am taking in everything I can in preparation for starting this project. My start date cannot be before September, and completion would be ideal before April, but I have existing evaporation cooling that keeps the house ~85 if I miss my deadline. During the time between now and September I want to get as much planning and concept nailed down as possible. My wife and I have talked about this and decided that if I can keep the installed price below 2K it would be the equivalent cost of traditional central air, and are not willing to exceed this price point because we intend the house to be a rental in 3 to 5 years. This also means that the system must be robust in it's completion, able to work with a traditional thermostat, and low maintenance. I intend to do all the work myself, and have access to a resourceful network of individuals in construction, DIY, and HVAC, so I do not foresee complications regarding talent or tools, especially coupled with the wealth of knowledge I have seen on this forum. Our house is 1150sqft, and is kept cool entirely by an evaporation cooler running a 1/2hp blower 24/7 over pads that are constantly drenched with water, which raises our water bill by about $40/mo and wastes hundreds of gallons of water a day (not eco-friendly in the desert). For all this we cannot cool our house below 85~ in ideal summer conditions, and as more humid monsoon weather rolls in our situation will only get worse. Our goal is to lower our water costs and have them translate into higher electrical cost while gaining the benefits of reliable temperature control similar to that of traditional AC. Because the house will eventually be a rental unit we do not want to put aesthetically displeasing heat exchangers in walls, but want to use either existing air ducting, or more ideally a DIY version of this (www) dot hydroinnovations dot com/product-details.php?title=ICE_BOX_Pro&pro=30 inline into each room with a central water reservoir feeding the heat exchangers, which would be kept cool by the GSHP. I'll be documenting everything I can, and have more to post as an introduction but have to run for now, so I'm going to post this and will add more info/clarify tomorrow. In the meantime, hi everyone. Zach

06-28-12, 09:28 PM	#2
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Sounds like a very interesting project Zach. Welcome to the site and I hope we hear a lot more about it in the near future! __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-01-12, 03:51 PM	#8
Vlad Apprentice EcoRenovator Join Date: Aug 2010 Location: Windsor ON Canada Posts: 229 Thanks: 4 Thanked 30 Times in 22 Posts	vanderzac, Check out the other thread more drilling and digging oriented: http://ecorenovator.org/forum/geothe...ging-gshp.html You can find all specs and details about my rig. Pay attention to sliding table that holds drilling pipe. It saved me ton of time and calories . In my location (Canada) I have to worry mostly about heating and just a bit about cooling. Because of this my focus was earth. In your case you only have one problem - heat rejection which can be achieved in very efficient manner without drilling and digging. Here is very cool link about !!! residential !!! evaporative condensers: http://www.pge.com/includes/docs/pdf...e/ac2eval1.pdf Building a drilling rig is not an easy task. By the time you finish it you will double your initial budget and triple the time you expected to spend. The system that you have now can't perform like refrigeration system because of this you waste so much water and move so much air. Last edited by Vlad; 07-01-12 at 03:54 PM..

06-29-12, 01:17 AM	#3
Vlad Apprentice EcoRenovator Join Date: Aug 2010 Location: Windsor ON Canada Posts: 229 Thanks: 4 Thanked 30 Times in 22 Posts	With this tight budget I would try to build "mini cooling tower". Cooling tower doesn't need much water and helps to run your AC much more efficient in high temperature desert environment. Also you need grossly oversized condenser.

06-29-12, 09:07 AM	#4
vanderzac Lurking Renovator Join Date: Jun 2012 Location: Tucson, Arizona Posts: 10 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks for the welcoming Vlad: As far as I can tell the amount of my budget is not going to make a large difference. I can get a massive cooler for less than < 200, and have access to all the needed tools for modification. I'm still unsure if I'm going to need water heat exchangers, but they add little to the cost, pipe at $17/100ft, and a pump also add little concern. Near as I can tell the vast majority of my budget is going to be eaten up drilling, as the ground 2 feet down I hit caliche rock (type of hardpan). I'm looking to build a DIY drill, but my focus is going to be on keeping costs down more than quality; The drill needs to get the job done, but will be dismantled after the job is done. Unfortunately I know little about drilling, and am starting to read more about that now. Also, I do not have AC, I have evaporation cooling, which works by saturating the air with humidity, and is not compatible with an inline AC to further cool the air to the best of my knowledge. The budget I have is what I would expect to pay to switch to AC, again DIYing it, but if I can do ground source for the same amount, it is worth it to me, and I don't mind putting in the sweat and blood (though hopefully not too much). Zach

06-29-12, 10:54 AM	#5
vanderzac Lurking Renovator Join Date: Jun 2012 Location: Tucson, Arizona Posts: 10 Thanks: 0 Thanked 0 Times in 0 Posts	I'm terribly sorry Vlad. I've just finished another round of googleing and now understand that a cooling tower may be more what i'm describing, though according to Wikipedia I think I will be looking to DIY / connect an air handler that uses piped in chilled / heated water from the GSHP. Does this sound correct for air cooling? If not do you have any specific links that may be more informative than the mass of information i'm sifting through otherwise? Thanks.

06-30-12, 08:20 PM	#7
vanderzac Lurking Renovator Join Date: Jun 2012 Location: Tucson, Arizona Posts: 10 Thanks: 0 Thanked 0 Times in 0 Posts	Hi Vlad. After reading the entire manifesto and looking at your well drilling rig, I am dead set on building a rig like yours to drill. I live in a dense city and have enough space for 10 boreholes 16 feet apart, but no where near enough for slinky. I feel I can reach my target price as a total expense, meaning after building the drill I would sell it whole / re-purpose it, or potentially hold on to it and try to build a side job out of drilling on weekends (considering the commercial price this does not seem unreasonable, also people around here hire unlicensed contractors a lot), and so I may spend 5K up front, and recover 3K when I sell the drill / components. I have a HUGE amount of time to work with, sourcing cheap parts, and the economy here is bad enough that craigslist has major deals. My goal is to begin sourcing/building the well drill ASAP, and have holes (down to 100ft maybe less, still figuring that out) done between Feb and April, while sourcing the AC components between now and then. I also have the entire winter to work, as it doesn't get below freezing for more than a couple hours now and then (even at night). So here's what I'm planning/working on now: 1) drilling regulations (laws and permits) 2) sizing of system 3) determine best way to move heat out of the air and into the water (cooling and airflow). 1) I took a cursory glance at our drilling regulations, which mention geothermal but are mostly targeted for well water, or oil and gas wells (regulating 20,000ft wells). The city website says a permit costs $10K, but that permit exemptions are a possibility. Unfortunately I will have to wait till Monday to get more information, but will report back for those US urban individuals interested in DIY GSHP, and really hope there is some way around this. 2) system sizing. I'm not sure on this, unfortunately. AC started in the manifesto saying a bit too small is better than too big for 2 reasons: COP will be worse (lower) when the compressor runs for shorter duty cycles, and the cost / labor of the boreholes. I feel building a large water storage tank (1,000 gallons maybe) will allow me to run the compressor for long cycles to get to temperature, then let it taper off over hours/days, which should give me higher COP and relatively stable temps. If my thinking here is wrong please let me know. Because I will be building my own drill and providing my own labor, the monetary cost for the first hole will be around 3K, but each additional hole seems to be around $100 or less. I am also expecting I will not have the drill long term, so I would rather spend $300-$500 for extra boreholes and make sure my system is large enough the first time around (similar to Vlad's views on building a drill; over engineer it so you cant fail). If I decide it is too large I can always disconnect boreholes from the loop, but after the drill is gone I can't build more. 3) Currently my house is circulating air with a dual speed 1/4 and 1/2hp blower 24/7 in an evaporation cooler and moves a huge amount of air. As such I imagine I can use the same blower to circulate air across the existing evaporator of whatever AC I end up cannibalizing. This would be extremely convenient if it works, but so far I have no clue if this would be effective as I'm still wrestling with the underlying concepts of how cooling coils work. If I luck out I may find a salvage commercial air handler that is designed for water to air central cooling. If anyone has relevant information I would hugely appreciate it. I'm sorry if it seems I'm dismissing your idea for the cooling tower Vlad, I just don't have any idea how effective it would work, while i have seen examples of chillers and know they are effective. If you have any references I could check I will, but I need to be confident the end result will function as well as an appropriately sized central air unit from Sears. Thanks

07-01-12, 09:55 PM	#9
vanderzac Lurking Renovator Join Date: Jun 2012 Location: Tucson, Arizona Posts: 10 Thanks: 0 Thanked 0 Times in 0 Posts	Hi Vlad. I looked at the link you provided and at several different places the report indicated the dry nature of the air was important to the overall function. Here in Tucson the hottest months (July-August) we have monsoon rains, where the outdoor temp will remain above 100F and humidity will be 90% or greater. From what I can tell this would render the cooling tower noneffective at pre-cooling air before running it over the condenser, does this sound correct?

07-01-12, 11:18 PM	#10
vanderzac Lurking Renovator Join Date: Jun 2012 Location: Tucson, Arizona Posts: 10 Thanks: 0 Thanked 0 Times in 0 Posts	I think I'm understanding it better after reading and re-reading it, unfortunately concepts are sometimes a bit too dense for me the first few times and I really struggle reading something over and over to understand and comprehend it. Anyways, as I can tell in an oversimplified fashion, the condenser of the heat pump is placed in a bath of water, and that water is cooled by dripping over the evaporation pads while circulating air (AC2 example). This will keep the water temperature equal to the wet bulb temp (which is usually about 30 degree's cooler when humidity is low), but that when air is already fully saturated the system not would work nearly as well, which is coincidentally the issue we have with our current cooler during July and August monsoon, where the air becomes so humid that it cannot be cooled by evaporation. With a GSHP my water would be circulated through the ground to keep cool, thus not affected by relative humidity, and the water temp would consistently be around 50f, instead of 80 (110-30), which should also make the system more efficient. Does this sound conceptually correct? Thank you again for helping me through this and providing useful suggestions.