DIY Air-Source Water HP - Page 5

launboy · 01-21-12, 02:55 AM

AC, I have a small fan like that. It came out of our old dishwasher, was used to exhaust the hot steamy air so dishes would dry faster. It moves a surprising amount of air for its size, but doesn't like much restriction at all on either side. I feel that a typical centrifugal blower is much more tolerating of resistance. Maybe I'll have to do some rather crude testing with sheets of paper and a ruler.

ThomSjay, do you think this would make much of a difference? I did notice a lot of air blowing out around the sides of the blades of my axial fan once I added restriction. The difference between a ducted and unducted(proper term for shrouded vs non shrouded fans) may be significant.

Unfortunately all work of mine has come to an end until school lets out and I can return home again. Unfortunately about the only thing I have to experiment with at college is my minifridge the I've converted to a mini freezer. Mods including multi-layer corrugated cardboard insulation inside, and computer fans to move air over the evap coil better.

What are the chances there'd be a professor who knows something about HVAC there and would be interested in my project.... Hmm might have to look into that. Valuable resource there.

Lastly, I would like to thank everyone who has helped, encouraged, and given input for my little project.

Adam

launboy · 05-23-12, 10:14 PM

I'm Back! Finished my first year of college! Woot! I once again can work on my hottub heatpump. Set it up yesterday just like I had it in winter, only difference is it works much better now!

Starting temp of water was 54*F. After 10:45 of run time, the water was up to 85*F. A 31*F gain from heat pump alone. This averages out to about 2.9* per hour, which once calculated, means I'm averaging 8000 btu/hr, which is what the stated capacity of this unit is. I don't have a Kill-a-watt to measure accurately, but if it's drawing 800w(close to what's on the name plate, I'm getting a COP of just over 3, which I am very okay with. We'll see if the next 20* to 104 comes as easily as these 30 did. By my calculations, it should only take arund 7 more hours of run time.

Adam

AC_Hacker · 05-24-12, 10:27 AM

Quote:

Originally Posted by launboy

I don't have a Kill-a-watt to measure accurately, but if it's drawing 800w(close to what's on the name plate, I'm getting a COP of just over 3, which I am very okay with. We'll see if the next 20* to 104 comes as easily as these 30 did. By my calculations, it should only take arund 7 more hours of run time.

A COP of three is not bad, but I'm pretty sure that if you had a righteous HX you'd be able to do better than that.

The COP will be better in at the beginning of the run, when the difference in temperature (delta-T) between the water and the refrigerant is higher, and the COP will get smaller as the delta-T gets smaller.

When I was doing similar experiments, I was seeing COP of approximately 6 in the beginning of the run, also tapering off.

You might try haunting wrecking yards for oil cooler HXs, they might work better than your AC condenser coil, because you could probably get better water flow through it.

If I didn't mention it before, Acuario built some dandy water-to-refrigerant HXs out of copper tube and ABS pipe, that he is using for heating his swimming pool and also now, his house.

Welcome back.

-AC

Daox · 05-24-12, 10:58 AM

Nice to see you back and playing with this again. You need to get a kill a watt though! Spend the $20.

launboy · 05-24-12, 04:03 PM

So I realized something that will change my calculations and coop. Over night I shut it off, in the 10 hour span it was off, I lost about 10*, so I was i fact adding 3.9* gain per hour which works out to be a COP of 4.2, which is better. I'll post a graph of my temp gai vs time later tonight. It's actually fairly linear surprisingly, despite the 10* temp difference over the cours of the day and the steadily rising water temp. For the record, I left for a bit last night and when I came back I had a water temp of 106, so it definitely can heat the water up to that point and probably keep going. the temp at the top of the compressor was in the 190's at that point though. Is this something to worry about?

Adam

AC_Hacker · 05-24-12, 04:47 PM

Quote:

Originally Posted by launboy

...the temp at the top of the compressor was in the 190's at that point though. Is this something to worry about?

Does sound a bit hot to me, but there is a thermal snap switch mounted on top of the compressor that has the job of protecting the compressor from over-temp.

I'd say that if you notice the thermal snap switch periodically cutting off the compressor, then you should worry.

Regarding the Kill-a-Watt, I agree with Daox, you really should get one. The Kill-a-Watt has Power Factor corrector built in and can deliver very close to true RMS power reading. On my setup, my compressor seldom reached the rated power consumption as stated on the label. But then again I was running R-290 which is more efficient than R-22, especially in heating mode.

$20 for a Kill-a-Watt? Just think how much you have paid for college classes and how much you've already forgotten, and think how much you have already learned from your project on hacking the air conditioner... those self-directed experiences really stay with you. The lessons you will learn from the Kill-a-Watt will be a bargain, an absolute bargain.

Invest.

-AC

launboy · 05-25-12, 01:46 AM

I knew about the thermal overload switch, it's never cut off on it though. First dip in the tub today with the girlfriend. Was so nice to enjoy the water and the jets. Yes I unplugged the HP, not worth dying for some heat.

I have a pretty good set up goin now. I hacked the spa pack that has the controls and heating element in it. Now instead of the contactor switching on the resistance heat it completes the circuit to the compressor. The other half of the contactor supplies power to an outlet that runs the circ pump that flows water over the coil. Not finished though, just ran out of time today. End goal is this, Spa Pack has an air button switch for high pump speed and the low speed is controlled by timer or call for heat. I'm going to wire the low speed relay to power the circ pump(which also filters the water) and the high speed to power the jet pump. By doing this my set up will function just like a normal spa. In addition if I wire it correctly, the HP will be completely cut off from power whenever the jet pump is on so there's a safety factor there too.

Also, version 2.0 will look a little nicer and the HP and circ pump will be contained in its original metal A/C casing with just two hose nipples and some control wiring coming out of it. I'm really liking how this Window unit is performing. When the hottub water temp is above 80* ish the evap coil temp stays high enough that frost isn't and issue either.

That Kill-a-Watt is something I just might jump on, I believe that also tells hours on, or percetage of runtime doesn't it? Which would be interesting to see for this and for my other work in progress, my dorm fridge. I have to admit, heat pumps have to be some of the most amazing machines I've ever worked with. Their uses seem endless and the efficienies achievable are so great. With a good enough controller you could integrate just about everything in your house to work together and I'd imagine it'd be very efficient, I'm talking, pool/hottub heating, dehumidifier, refridgerator, DHW, home heating and cooling, all combined in a give and take system, with Air, solar, and ground sources. This is my dream for a future home. None of it seems that hard either honestly, just have to plan it all out and have an accurate assessment of each components hat input or output from the system.

Adam

MN Renovator · 05-25-12, 09:46 AM

"That Kill-a-Watt is something I just might jump on, I believe that also tells hours on, or percetage of runtime doesn't it? "

No, it doesn't monitor run-time, duty cycle percentage or anything like that. I have the newer version(the greyish one that saves data even if its unplugged) will give you a kwh energy usage since you last reset it, how long the device has been plugged in for, and a cost estimate based on whatever electric rate you put in. It also gives the voltage, frequency, amperage, and VA. I think that's everything.

AC_Hacker · 05-25-12, 10:45 AM

Quote:

Originally Posted by launboy

I have to admit, heat pumps have to be some of the most amazing machines I've ever worked with. Their uses seem endless and the efficienies achievable are so great. With a good enough controller you could integrate just about everything in your house to work together and I'd imagine it'd be very efficient, I'm talking, pool/hottub heating, dehumidifier, refridgerator, DHW, home heating and cooling, all combined in a give and take system, with Air, solar, and ground sources. This is my dream for a future home. None of it seems that hard either honestly, just have to plan it all out and have an accurate assessment of each components hat input or output from the system.

I think you have glimpsed the future...

-AC

P.S. If you're trying to get compressor run time or duty cycle...

...one way would be to get an electric counter and connect it to the compressor circuit. The Kill-a-Watt will tell you total time, the counter will tell you 'on' time.

launboy · 06-30-12, 02:40 AM

Everything I do has to be on a "college id budget", so instead of an hour meter, I just grabbed a mechanical timer, the kind you plug in then plug something into it to be controlled. Set it at 12am, and plugged it in with the H/P, so whenever the spa pack sent power to the H/P it powered the timer and would advance it the correct amount of time. This actually worked very well! It ended up running about 25% of the time to maintain 90*F.

Version 2.0 is in the works now. In my continued absolute avoidance of opening up the refrigerant circuit, I decided to swap time, for money. I stripped all of the fins off the condensing coil, and managed to do it without causing any leaks at that!

The plan is to into 2-3 halfs or thirds, and kind of push them together, then build a U or N shape pipe out of pvc(probably 2"), that the coils will go in and then flow the hottub water through there. I plan to design it so that the metal cover will fit back on and it will just have the two hose nipples sticking out for water inlet and outlet. Making it much more portable, and nicer looking.

As always thoughts, comments, concerns are always appreciated.

05-24-12, 10:58 AM	#44
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Nice to see you back and playing with this again. You need to get a kill a watt though! Spend the $20. __________________ 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.

06-30-12, 02:40 AM	#50
launboy Apprentice EcoRenovator Join Date: Mar 2011 Location: SE Wisconin Posts: 107 Thanks: 3 Thanked 11 Times in 9 Posts	Everything I do has to be on a "college id budget", so instead of an hour meter, I just grabbed a mechanical timer, the kind you plug in then plug something into it to be controlled. Set it at 12am, and plugged it in with the H/P, so whenever the spa pack sent power to the H/P it powered the timer and would advance it the correct amount of time. This actually worked very well! It ended up running about 25% of the time to maintain 90*F. Version 2.0 is in the works now. In my continued absolute avoidance of opening up the refrigerant circuit, I decided to swap time, for money. I stripped all of the fins off the condensing coil, and managed to do it without causing any leaks at that! The plan is to into 2-3 halfs or thirds, and kind of push them together, then build a U or N shape pipe out of pvc(probably 2"), that the coils will go in and then flow the hottub water through there. I plan to design it so that the metal cover will fit back on and it will just have the two hose nipples sticking out for water inlet and outlet. Making it much more portable, and nicer looking. As always thoughts, comments, concerns are always appreciated. Attached Thumbnails

01-21-12, 02:55 AM	#41
launboy Apprentice EcoRenovator Join Date: Mar 2011 Location: SE Wisconin Posts: 107 Thanks: 3 Thanked 11 Times in 9 Posts	AC, I have a small fan like that. It came out of our old dishwasher, was used to exhaust the hot steamy air so dishes would dry faster. It moves a surprising amount of air for its size, but doesn't like much restriction at all on either side. I feel that a typical centrifugal blower is much more tolerating of resistance. Maybe I'll have to do some rather crude testing with sheets of paper and a ruler. ThomSjay, do you think this would make much of a difference? I did notice a lot of air blowing out around the sides of the blades of my axial fan once I added restriction. The difference between a ducted and unducted(proper term for shrouded vs non shrouded fans) may be significant. Unfortunately all work of mine has come to an end until school lets out and I can return home again. Unfortunately about the only thing I have to experiment with at college is my minifridge the I've converted to a mini freezer. Mods including multi-layer corrugated cardboard insulation inside, and computer fans to move air over the evap coil better. What are the chances there'd be a professor who knows something about HVAC there and would be interested in my project.... Hmm might have to look into that. Valuable resource there. Lastly, I would like to thank everyone who has helped, encouraged, and given input for my little project. Adam

05-23-12, 10:14 PM	#42
launboy Apprentice EcoRenovator Join Date: Mar 2011 Location: SE Wisconin Posts: 107 Thanks: 3 Thanked 11 Times in 9 Posts	I'm Back! Finished my first year of college! Woot! I once again can work on my hottub heatpump. Set it up yesterday just like I had it in winter, only difference is it works much better now! Starting temp of water was 54F. After 10:45 of run time, the water was up to 85F. A 31F gain from heat pump alone. This averages out to about 2.9 per hour, which once calculated, means I'm averaging 8000 btu/hr, which is what the stated capacity of this unit is. I don't have a Kill-a-watt to measure accurately, but if it's drawing 800w(close to what's on the name plate, I'm getting a COP of just over 3, which I am very okay with. We'll see if the next 20* to 104 comes as easily as these 30 did. By my calculations, it should only take arund 7 more hours of run time. Adam

05-24-12, 04:03 PM	#45
launboy Apprentice EcoRenovator Join Date: Mar 2011 Location: SE Wisconin Posts: 107 Thanks: 3 Thanked 11 Times in 9 Posts	So I realized something that will change my calculations and coop. Over night I shut it off, in the 10 hour span it was off, I lost about 10, so I was i fact adding 3.9 gain per hour which works out to be a COP of 4.2, which is better. I'll post a graph of my temp gai vs time later tonight. It's actually fairly linear surprisingly, despite the 10* temp difference over the cours of the day and the steadily rising water temp. For the record, I left for a bit last night and when I came back I had a water temp of 106, so it definitely can heat the water up to that point and probably keep going. the temp at the top of the compressor was in the 190's at that point though. Is this something to worry about? Adam

05-25-12, 01:46 AM	#47
launboy Apprentice EcoRenovator Join Date: Mar 2011 Location: SE Wisconin Posts: 107 Thanks: 3 Thanked 11 Times in 9 Posts	I knew about the thermal overload switch, it's never cut off on it though. First dip in the tub today with the girlfriend. Was so nice to enjoy the water and the jets. Yes I unplugged the HP, not worth dying for some heat. I have a pretty good set up goin now. I hacked the spa pack that has the controls and heating element in it. Now instead of the contactor switching on the resistance heat it completes the circuit to the compressor. The other half of the contactor supplies power to an outlet that runs the circ pump that flows water over the coil. Not finished though, just ran out of time today. End goal is this, Spa Pack has an air button switch for high pump speed and the low speed is controlled by timer or call for heat. I'm going to wire the low speed relay to power the circ pump(which also filters the water) and the high speed to power the jet pump. By doing this my set up will function just like a normal spa. In addition if I wire it correctly, the HP will be completely cut off from power whenever the jet pump is on so there's a safety factor there too. Also, version 2.0 will look a little nicer and the HP and circ pump will be contained in its original metal A/C casing with just two hose nipples and some control wiring coming out of it. I'm really liking how this Window unit is performing. When the hottub water temp is above 80* ish the evap coil temp stays high enough that frost isn't and issue either. That Kill-a-Watt is something I just might jump on, I believe that also tells hours on, or percetage of runtime doesn't it? Which would be interesting to see for this and for my other work in progress, my dorm fridge. I have to admit, heat pumps have to be some of the most amazing machines I've ever worked with. Their uses seem endless and the efficienies achievable are so great. With a good enough controller you could integrate just about everything in your house to work together and I'd imagine it'd be very efficient, I'm talking, pool/hottub heating, dehumidifier, refridgerator, DHW, home heating and cooling, all combined in a give and take system, with Air, solar, and ground sources. This is my dream for a future home. None of it seems that hard either honestly, just have to plan it all out and have an accurate assessment of each components hat input or output from the system. Adam

05-25-12, 09:46 AM	#48
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 939 Thanks: 41 Thanked 116 Times in 90 Posts	"That Kill-a-Watt is something I just might jump on, I believe that also tells hours on, or percetage of runtime doesn't it? " No, it doesn't monitor run-time, duty cycle percentage or anything like that. I have the newer version(the greyish one that saves data even if its unplugged) will give you a kwh energy usage since you last reset it, how long the device has been plugged in for, and a cost estimate based on whatever electric rate you put in. It also gives the voltage, frequency, amperage, and VA. I think that's everything.