The Homemade Heat Pump Manifesto - Page 80

peacmar · 06-25-11, 11:14 AM

Also want to throw in a quick apology for spelling errors. I usually work from an Android device which can be less than pleasant to type with at times and auto spell doesn't always read my mind correctly.

AC_Hacker · 06-26-11, 09:33 AM

Quote:

Originally Posted by peacmar

...I have searched for months for DIY gsph info. I am what I consider to be an extreme DIYer...

Mark (AKA: peacmar),

Welcome aboard!

As you surely know by now, we're all learning as we go here and we can learn as much from failures as we can from successes. Hopefully, by sharing our own personal experiences with like-minded hackers and hackettes, our successes will outnumber our failures.

Your metal fabrication background will be quite valuable to us all. I did my best to share the rudiments of brazing. If you see room for improvement, we're listening.

Your work with heat exchangers is central to heat pump hacking, and would be a tremendous contribution.

Best Regards,

-AC_Hacker

kbonk · 06-26-11, 11:48 AM

A bit off topic but worth a read.
Why aren't we considering the whole structure as a devise to equalize temperature changes and keep the space at a comfortable temperature for living. This would be done by slow changes in building mass, and air density. Now the real Question is how do we retro-fit our aging housing stock to do this? Like this http://www.isomax-terrasol.eu/en/tec...ie.htmlhttp:// Here they are tempering the hot and cold surfaces of a building to equalize the space temperature.
I have been following a project in Detroit, using earth tubes feeding "Hybrid Ventilation System", integrated to this is a "earth room". This concept consists of a insulated box in the basement which has thermal mass of water in it, which pretempers the air used by a air to water heat pump (Daikin Altherma, a HT system is in europe 180d water temps)
What I am seeing in these concepts that storage of heat/ cold and transfer of said energy slowly is the key for comfortable living

peacmar · 06-26-11, 08:58 PM

First tip I would like to throw out there is cleanliness. Clean and keep clean. Copper, along with most of its adhesive bonding agents (types of solder, brasing, ect.) Generally oxide extremely easily. Especially under heat. Mechanical cleaning is generally sufficient such as sanding or wire brush but occasionally chemicals can be more economical, especially in repair work where severe amounts of tenacious oxide have formed due to environmental circumstances. Next is protection under heat. As mentioned earlier, purge gas of some type can be used. Generally any non reactive gas can be used, but those that displace oxygen and nitrogen are best. They have their own slight hazards, but we're already melting metal here so I hope you can think about ventilation before you start. The careful use of propane is not all that far fetched. I used to recycle large underground gasoline tanks from gas stations when I did pressure vessels and would cut them apart with an oxy-propelyne outfit still with a couple hundred gallons gas inside, I used old shirts soaked is diesel fuel as a wick in the top openings to burn off fumes and controlling oxygen levels within. No oxygen inside means no oxidation and in my case no explosion. Except there was always a spectacular mushroom cloud flame when it finally laid open. Point is, prevent the chemical reaction from happening. Flux can be used if the tubes are flushed with muriatic acid before connecting to the compressor unit. Nitrogen works, but causes embrittlement in copper. So we work harden by bending, heating, the embed nitrogen within the molecular surface. It can mean the difference between 10 years and 25 of service. Getting late for me, 3 am comes fast. More on this later.

-mark

peacmar · 06-26-11, 08:59 PM

I inadvertently double posted last night. Guess I just upped my count

ThomSjay · 06-26-11, 11:27 PM

Quote:

Originally Posted by kbonk

A bit off topic but worth a read.
Like this http://www.isomax-terrasol.eu/en/tec...ie.htmlhttp:// Here they are tempering the hot and cold surfaces of a building to equalize the space temperature.
I have been following a project in Detroit, using

The correct link is .... Isomax Terrasol:*Technology

AC_Hacker · 06-27-11, 01:47 AM

Quote:

Originally Posted by kbonk

A bit off topic but...

I think you are correct that the discussion you are opening is off topic. I started this thread to be a place to share methods of doing a DIY Ground Source Heat Pump. To my knowledge, there isn't anyplace on the web where this information is openly available, so this thread is pretty special real estate.

By posting an off-topic discussion here, you are diluting the DIY GSHP conversation that is in progress with an off topic discussion, additionally, you are burying your discussion in a very long and unrelated thread.

I am not at all dismissing your topic of discussion, but both 'The Manifesto' and your discussion would be better served if you started another thread.

Starting another thread is easy, just CLICK HERE.

See you on the new thread...

Best Regards,

-AC_Hacker

peacmar · 06-27-11, 08:04 AM

AC, I know you are aware of the concerns of heat control when working with the brased plates HX's. So that leads me to ask the following question:

Is any one here familiar with the use of a "water table" when brasing and soldering on heat exchangers?

If not, I will happily explain the use and theory and how to create your own with easily obtained "recyclables" for working with small and delicate parts contained within these systems we are pioneering.

AC_Hacker · 06-27-11, 01:25 PM

Quote:

Originally Posted by peacmar

Is any one here familiar with the use of a "water table" when brasing and soldering on heat exchangers?

Sounds very interesting... please elaborate.

-AC_Hacker

Ko_deZ · 06-27-11, 06:52 PM

Allright. After reading this thread and writing down some things I would like to mention, I found out that there was quite a lot. Some things to clarify, others to inform. Here is a list of the topics I wrote down that could have som interest or need clarification going through the now 80 pages this topic has:

Gardermoen GSHP system
Well spacing
Well depth
Water vs dirt in well
Series vs parallell, freezing and flow resistance
Heat excanger
Ground capacity
Floor heating self adjusting
Floor heating DX, not possible because of heat difference
Bending pex
Oxygen barrier
Heated floor sounds
Paralell flow heat exchanger

Gardermoen (osl . no) is the Norwegian main airport. Now, I have not verified that this is true, but it seems likely, and if not, someone should do this. Anyway. The groundwater level there is quite low below the surface. What I have been told that they do, is that they exploit the fact that the groundwater moves trough the ground in this area. Very slowly, but it moves. At the upper end of the runway, they have several wells that they use for direct source cooling for the terminal building. Groundwater here is usually 6-7C. (we use SI system here as that is the only logical thing to do. I do not envy you guys having to convert all the time to do calculations). This moves a whole lot of energy down into the ground and the groundwater that carries it. The speed of the groundwater is such that when winter comes, the heated water reaches the other end of the runway, where another set of wells are set up. These go to heatpumps for heating trough the winter. The warm water should give an exceptionally high COP.

Well spacing:
I have been checking a whole lot around this. I did at one point find documentation saying that unless you have moving groundwater, the temperature of the ground will be reduced quite a bit during the first 20 years or so. The document said that well spacing less than 20 meters would certainly make this temperature drop more significant.
This is some really good reading (remove spaces, cannot post links yet):
http://www.ivt.ntnu.no/igb/forskning...v_bolighus.pdf
Look at page 33. It is in Norwegian (maybe google can help translating?). Top pictures are wells that are 20 meters apart, showing temperature drop after 1, 5, 10 and 25 years. Second row of pictures show wells that are 5, 10, 20 and 40 meters apart, all after 10 years of use. These wells are in parallel, will come back to this.

Well depth:
As has been explained here, you must not go very deep before the temperature starts to be quite steady. The first hundred meters of ground have a temperature based on solar input (mostly for very sunny areas that have somewhat higher temperature), the fact that 4C water is most heavy and will move downwards, and the fact that very much of the ground is slightly radioactive. The last bit is what pushes the ground temperature above 4 degrees in temperate climates. Some rock, like granite, is quite radioactive, and that gives a higher temperature. Unfortunately it also causes ground water to move slowly, so temperature might drop after extended use.

Water vs dirt in well
Around here (Norway), it is my understanding that we never use grout. The well is just left like it is (with a pipe protecting from collapse in the top soil part, we always hit rock after a short period here) allowing ground water to fill the well up. Ground water stops usually 2-6 meters below ground level, and the collector hose is just left in the water. Convection in the water gives the collector a higher thermal conductivity to the ground than you would get from having dirt or grout in the well. That is my understanding at least, and for me it sounds logical. Also, as the top part is not covered in water, you get less heat loss to the top part of the soil that is very cool or even frozen during winter.

Series vs parallell, freezing and flow resistance
I see that AC hacker has his wells in series. That is not the ideal solution I am afraid. Maybe the situation he is in is better than most, as the energy need is not very large. Conventional water-liquid heat pumps around here might very well send the outgoing brine with <0 C (0C = 32F iirc, which means freezing. Celcius has 0 as freezing temperature and 100 as boiling at normal air pressure). If you pull too much energy from your well, it will freze. This stops the convection (and in dirt, it slows down the thermal conductivity of the ground significantly) in the well, and reduces the thermal conductivity. This makes the rest of the well freze faster as the water coming up will be cooler, and so will the water going down again as a result. If you drill two wells, having the cold brine go to one first and then the other would make sure that the first will be colder than the second, freezing up the first before going to the second if that should happen. As the first one freezes, it looses a whole lot of it's capacity to heat the water due to the reduced thermal conductivity, putting a much higher load on the second one, that will then freeze much faster. The normal procedure here is to put a valve, and adjust it so that the amount of water going to each of them corresponds to their individual lengths. That way they will both freeze about at the same load, not causing the same kind of chain reaction that wells coupled in series will. Oh, and AC hacker. The dude earlier talking about this, he was right. You should not have blown him off like that, he could very well have been a very useful and seemingly well educated asset here.
Oh, and by the way, the reduced friction and increased total waterflow of having them all in parallel does also increase the efficiency of the heat exchanger, so an added bonus there.

Heat exchanger
Looking at the heat exchanger solution used with the brazed plate exchanger for the hot side of the heat pump, I cannot see the gain of this compared to having a coil or radiator in the accumulator tank. Given a long enough copper line and coil, that would remove the need for one water pump (and then also a COP ~= 1 device in the loop), and give less turbulence in the accumulator tank. Having the coil go from the top to the bottom of a tank would probably yield a higher top temperature and lower bottom temperature, making the undercooling better. Of course, getting the water from the bottom of the tank with a pump will do this too, but it will also stir the water, reducing the thermal gradient in the tank. In a very still tank you can get a significant thermal gradient, making the top maybe 50 degrees while the bottom is maybe 30. Having the condensed gas leave the tank at 30 rather than the average temperature of 40 would give a better COP.
A completely new system I saw just some months ago was claiming better COP with a tank with a very special design. They could achieve 80 degrees in the top and 30 in the bottom of a 1.80 meter tall tank. This tank had no water movement whatsoever (except convection), all energy input and draw was trough spiral copper tubes. If you wanted hot water, you went from bottom and to the top with the waterflow, giving you almost 80 degrees. For the floor heating your spiral started from bottom and stopped in the middle, giving about 40 degrees. They claimed a much higher efficiency than other accumulator tanks, and support for any heat source, they just placed the coils at the right positions to regulate the entry and exit temperatures. Ingenious and very, very expensive to buy. Seemed to be complex to make also, as convection was reduced to small areas around coils with perforated walls to avoid stirring up the water more than absolutely nessesary.

Floor heating is self adjusting
One thing that I don't see mentioned anywhere is one of the really huge advantages of having floor heating compared to radiators. Usually the air temperature to floor temperature is one a couple of degrees, while radiators are really hot, maybe 30 degrees warmer than the air. What this does is that if the outside temperature drops significantly, the indoor air will cool down. If we say that the floor-air difference was 2 degrees, and the air temperature drops by 2 more degrees, the difference is now 4 degrees. This will in essence double the convectional thermal energy dissipation from the floor, giving a huge change in supplied heat. Compare that to the radiator solution, the difference will only increase by a fraction of the original difference giving a very slight energy boost. For the radiators to increase the heating there must be a rise in temperature of the water and/or a higher flow rate. Compared to this, the floor heating is almost self adjusting. If the temperature drops, the energy given from the floor rises very quickly, avoiding the temperature fluctuations you often see with radiators when the weather change for the better/worse.

Floor heating DX, not possible because of heat difference
DX to floor heating has some problems as discussed here. One of the really big problems with it is that you really want to undercool the coolant as much as possible. This comes in direct confrontation with the wish for an even floor temperature. If the incoming superheated gas is 50C, and the exiting should be 30, you will need some really fancy heat protection for the first bit of pipe, reduced gradually to a very high dissipation solution with heat spreaders at the returning end. It is not a good solution.

Need to make another post. Max 10000 chars :-p. See next post then.

06-26-11, 08:59 PM	#795
peacmar Lurking Renovator Join Date: Jun 2011 Location: fond du lac, wi Posts: 26 Thanks: 0 Thanked 5 Times in 5 Posts	I inadvertently double posted last night. Guess I just upped my count Last edited by peacmar; 06-27-11 at 07:01 AM.. Reason: -double post-

06-27-11, 06:52 PM	#800
Ko_deZ Helper EcoRenovator Join Date: Jun 2011 Location: Norway Posts: 63 Thanks: 3 Thanked 10 Times in 10 Posts	Allright. After reading this thread and writing down some things I would like to mention, I found out that there was quite a lot. Some things to clarify, others to inform. Here is a list of the topics I wrote down that could have som interest or need clarification going through the now 80 pages this topic has: Gardermoen GSHP system Well spacing Well depth Water vs dirt in well Series vs parallell, freezing and flow resistance Heat excanger Ground capacity Floor heating self adjusting Floor heating DX, not possible because of heat difference Bending pex Oxygen barrier Heated floor sounds Paralell flow heat exchanger Gardermoen (osl . no) is the Norwegian main airport. Now, I have not verified that this is true, but it seems likely, and if not, someone should do this. Anyway. The groundwater level there is quite low below the surface. What I have been told that they do, is that they exploit the fact that the groundwater moves trough the ground in this area. Very slowly, but it moves. At the upper end of the runway, they have several wells that they use for direct source cooling for the terminal building. Groundwater here is usually 6-7C. (we use SI system here as that is the only logical thing to do. I do not envy you guys having to convert all the time to do calculations). This moves a whole lot of energy down into the ground and the groundwater that carries it. The speed of the groundwater is such that when winter comes, the heated water reaches the other end of the runway, where another set of wells are set up. These go to heatpumps for heating trough the winter. The warm water should give an exceptionally high COP. Well spacing: I have been checking a whole lot around this. I did at one point find documentation saying that unless you have moving groundwater, the temperature of the ground will be reduced quite a bit during the first 20 years or so. The document said that well spacing less than 20 meters would certainly make this temperature drop more significant. This is some really good reading (remove spaces, cannot post links yet): http://www.ivt.ntnu.no/igb/forskning...v_bolighus.pdf Look at page 33. It is in Norwegian (maybe google can help translating?). Top pictures are wells that are 20 meters apart, showing temperature drop after 1, 5, 10 and 25 years. Second row of pictures show wells that are 5, 10, 20 and 40 meters apart, all after 10 years of use. These wells are in parallel, will come back to this. Well depth: As has been explained here, you must not go very deep before the temperature starts to be quite steady. The first hundred meters of ground have a temperature based on solar input (mostly for very sunny areas that have somewhat higher temperature), the fact that 4C water is most heavy and will move downwards, and the fact that very much of the ground is slightly radioactive. The last bit is what pushes the ground temperature above 4 degrees in temperate climates. Some rock, like granite, is quite radioactive, and that gives a higher temperature. Unfortunately it also causes ground water to move slowly, so temperature might drop after extended use. Water vs dirt in well Around here (Norway), it is my understanding that we never use grout. The well is just left like it is (with a pipe protecting from collapse in the top soil part, we always hit rock after a short period here) allowing ground water to fill the well up. Ground water stops usually 2-6 meters below ground level, and the collector hose is just left in the water. Convection in the water gives the collector a higher thermal conductivity to the ground than you would get from having dirt or grout in the well. That is my understanding at least, and for me it sounds logical. Also, as the top part is not covered in water, you get less heat loss to the top part of the soil that is very cool or even frozen during winter. Series vs parallell, freezing and flow resistance I see that AC hacker has his wells in series. That is not the ideal solution I am afraid. Maybe the situation he is in is better than most, as the energy need is not very large. Conventional water-liquid heat pumps around here might very well send the outgoing brine with <0 C (0C = 32F iirc, which means freezing. Celcius has 0 as freezing temperature and 100 as boiling at normal air pressure). If you pull too much energy from your well, it will freze. This stops the convection (and in dirt, it slows down the thermal conductivity of the ground significantly) in the well, and reduces the thermal conductivity. This makes the rest of the well freze faster as the water coming up will be cooler, and so will the water going down again as a result. If you drill two wells, having the cold brine go to one first and then the other would make sure that the first will be colder than the second, freezing up the first before going to the second if that should happen. As the first one freezes, it looses a whole lot of it's capacity to heat the water due to the reduced thermal conductivity, putting a much higher load on the second one, that will then freeze much faster. The normal procedure here is to put a valve, and adjust it so that the amount of water going to each of them corresponds to their individual lengths. That way they will both freeze about at the same load, not causing the same kind of chain reaction that wells coupled in series will. Oh, and AC hacker. The dude earlier talking about this, he was right. You should not have blown him off like that, he could very well have been a very useful and seemingly well educated asset here. Oh, and by the way, the reduced friction and increased total waterflow of having them all in parallel does also increase the efficiency of the heat exchanger, so an added bonus there. Heat exchanger Looking at the heat exchanger solution used with the brazed plate exchanger for the hot side of the heat pump, I cannot see the gain of this compared to having a coil or radiator in the accumulator tank. Given a long enough copper line and coil, that would remove the need for one water pump (and then also a COP ~= 1 device in the loop), and give less turbulence in the accumulator tank. Having the coil go from the top to the bottom of a tank would probably yield a higher top temperature and lower bottom temperature, making the undercooling better. Of course, getting the water from the bottom of the tank with a pump will do this too, but it will also stir the water, reducing the thermal gradient in the tank. In a very still tank you can get a significant thermal gradient, making the top maybe 50 degrees while the bottom is maybe 30. Having the condensed gas leave the tank at 30 rather than the average temperature of 40 would give a better COP. A completely new system I saw just some months ago was claiming better COP with a tank with a very special design. They could achieve 80 degrees in the top and 30 in the bottom of a 1.80 meter tall tank. This tank had no water movement whatsoever (except convection), all energy input and draw was trough spiral copper tubes. If you wanted hot water, you went from bottom and to the top with the waterflow, giving you almost 80 degrees. For the floor heating your spiral started from bottom and stopped in the middle, giving about 40 degrees. They claimed a much higher efficiency than other accumulator tanks, and support for any heat source, they just placed the coils at the right positions to regulate the entry and exit temperatures. Ingenious and very, very expensive to buy. Seemed to be complex to make also, as convection was reduced to small areas around coils with perforated walls to avoid stirring up the water more than absolutely nessesary. Floor heating is self adjusting One thing that I don't see mentioned anywhere is one of the really huge advantages of having floor heating compared to radiators. Usually the air temperature to floor temperature is one a couple of degrees, while radiators are really hot, maybe 30 degrees warmer than the air. What this does is that if the outside temperature drops significantly, the indoor air will cool down. If we say that the floor-air difference was 2 degrees, and the air temperature drops by 2 more degrees, the difference is now 4 degrees. This will in essence double the convectional thermal energy dissipation from the floor, giving a huge change in supplied heat. Compare that to the radiator solution, the difference will only increase by a fraction of the original difference giving a very slight energy boost. For the radiators to increase the heating there must be a rise in temperature of the water and/or a higher flow rate. Compared to this, the floor heating is almost self adjusting. If the temperature drops, the energy given from the floor rises very quickly, avoiding the temperature fluctuations you often see with radiators when the weather change for the better/worse. Floor heating DX, not possible because of heat difference DX to floor heating has some problems as discussed here. One of the really big problems with it is that you really want to undercool the coolant as much as possible. This comes in direct confrontation with the wish for an even floor temperature. If the incoming superheated gas is 50C, and the exiting should be 30, you will need some really fancy heat protection for the first bit of pipe, reduced gradually to a very high dissipation solution with heat spreaders at the returning end. It is not a good solution. Need to make another post. Max 10000 chars :-p. See next post then. Last edited by Piwoslaw; 06-28-11 at 12:05 AM.. Reason: Added link url

06-25-11, 11:14 AM	#791
peacmar Lurking Renovator Join Date: Jun 2011 Location: fond du lac, wi Posts: 26 Thanks: 0 Thanked 5 Times in 5 Posts	Also want to throw in a quick apology for spelling errors. I usually work from an Android device which can be less than pleasant to type with at times and auto spell doesn't always read my mind correctly.

06-26-11, 11:48 AM	#793
kbonk Helper EcoRenovator Join Date: Aug 2010 Posts: 44 Thanks: 10 Thanked 4 Times in 2 Posts	A bit off topic but worth a read. Why aren't we considering the whole structure as a devise to equalize temperature changes and keep the space at a comfortable temperature for living. This would be done by slow changes in building mass, and air density. Now the real Question is how do we retro-fit our aging housing stock to do this? Like this http://www.isomax-terrasol.eu/en/tec...ie.htmlhttp:// Here they are tempering the hot and cold surfaces of a building to equalize the space temperature. I have been following a project in Detroit, using earth tubes feeding "Hybrid Ventilation System", integrated to this is a "earth room". This concept consists of a insulated box in the basement which has thermal mass of water in it, which pretempers the air used by a air to water heat pump (Daikin Altherma, a HT system is in europe 180d water temps) What I am seeing in these concepts that storage of heat/ cold and transfer of said energy slowly is the key for comfortable living

06-26-11, 08:58 PM	#794
peacmar Lurking Renovator Join Date: Jun 2011 Location: fond du lac, wi Posts: 26 Thanks: 0 Thanked 5 Times in 5 Posts	First tip I would like to throw out there is cleanliness. Clean and keep clean. Copper, along with most of its adhesive bonding agents (types of solder, brasing, ect.) Generally oxide extremely easily. Especially under heat. Mechanical cleaning is generally sufficient such as sanding or wire brush but occasionally chemicals can be more economical, especially in repair work where severe amounts of tenacious oxide have formed due to environmental circumstances. Next is protection under heat. As mentioned earlier, purge gas of some type can be used. Generally any non reactive gas can be used, but those that displace oxygen and nitrogen are best. They have their own slight hazards, but we're already melting metal here so I hope you can think about ventilation before you start. The careful use of propane is not all that far fetched. I used to recycle large underground gasoline tanks from gas stations when I did pressure vessels and would cut them apart with an oxy-propelyne outfit still with a couple hundred gallons gas inside, I used old shirts soaked is diesel fuel as a wick in the top openings to burn off fumes and controlling oxygen levels within. No oxygen inside means no oxidation and in my case no explosion. Except there was always a spectacular mushroom cloud flame when it finally laid open. Point is, prevent the chemical reaction from happening. Flux can be used if the tubes are flushed with muriatic acid before connecting to the compressor unit. Nitrogen works, but causes embrittlement in copper. So we work harden by bending, heating, the embed nitrogen within the molecular surface. It can mean the difference between 10 years and 25 of service. Getting late for me, 3 am comes fast. More on this later. -mark

06-27-11, 08:04 AM	#798
peacmar Lurking Renovator Join Date: Jun 2011 Location: fond du lac, wi Posts: 26 Thanks: 0 Thanked 5 Times in 5 Posts	AC, I know you are aware of the concerns of heat control when working with the brased plates HX's. So that leads me to ask the following question: Is any one here familiar with the use of a "water table" when brasing and soldering on heat exchangers? If not, I will happily explain the use and theory and how to create your own with easily obtained "recyclables" for working with small and delicate parts contained within these systems we are pioneering.