Another hot water tank heat pump

randen · 10-06-13, 08:26 PM

Anyone that's been following my post on the solar space heating for shop had been introduced to the items that presented themselves to me. A slightly used hot water tank and a air-conditioner that was pushed out of the window landing on its condenser.
From here its not a great leap to know what's going to happen next. We're going to hack this into another heat-pump hot water heater.

The weather here in South-Western Ontario has been very rainy and I'm still waiting for some materials so work on the solar panels have been paused and in-door projects prevail. Saturday and Sunday produced a condenser with a threaded adaptor to replace the lower element. I'm hoping to be able to guide the tubing in and turn the threaded adaptor in. A prior twist counter clockwise of four turns and tighten into position should straighten the thing back.

Again keeping with the theme of the eco-renovators everything is scrap pieces that are cluttering up the place. Rain will be ending in two days and we can get back to the shop improvements.

In the photos a brass adaptor is turned up using the old elec. element as a model the threads are a 1" straight pipe thread sealed with a rubber ring.
The threads are test fitted in the tank before milling the hex details.
A copper cutting from a 1/2 copper pipe stub out is used to return the condensors end.
The copper tubing condensor is soldered to the adaptor.

Randen

AC_Hacker · 10-07-13, 01:31 AM

Quote:

Originally Posted by randen

...A slightly used hot water tank and a air-conditioner that was pushed out of the window landing on its condenser.
From here its not a great leap to know what's going to happen next...

Nice work. The turn-around at the end is well crafted... and then there's the threaded brass adapter.

Randen, you're relentless!

-AC

jeff5may · 10-07-13, 06:18 AM

How many BTU is the poor victim rated for? Can you still use the old condenser, or did it let out its charge? I'm asking because I have a similar project thought up. I've heard of others running the entire A/C unit as an outdoor unit to improve performance, but haven't got much follow-up after the fact. From what I've seen, the two heat exchangers in the window unit together have roughly the same heat transfer area as a mini-split outdoor unit of similar capacity.

Once again, you are the man! You could sell those water heater tubes with bung on the internet for the fame and fortune, dude. Looks perfectly industrial to me. They could be repurposed as wort chillers or moonshine condensers for even better marketability. I wish I had a garage with a machine shop.

randen · 10-07-13, 08:10 AM

Jeff5may

The unit is 5kBTU I think? The condenser took a good hit and one of the elbows on the end is crushed but it held a charge. The condenser is bent perfect for the scrap bin. As far as running it outside not an option here in Canada. COP would take a huge hit in the winter.

Thanks for the cheer but spending forty hours a week standing in front of the machines and then time spent there on the weekend sucks. The up side after 30 some years making goodies for the industries things I make for myself can be made pretty with ones eyes shut. Selling these things on-line I think one would be hard pressed to make shop-rate.
I do get the expression when someone gets to watch the machining in action " man what I wouldn't do with these machines in my garage or basement" Well yes it is cool but you can never have enough. After you have a lathe you require a drill press then a mill then drills, endmills, turning tools and the list is ever expanding.

I have been bitten by a bug. Efficiency. After spending so much money on energy and finding these technologies so effective on the bottom line. I`m hooked. It took a oil bill that I couldn`t afford to make the tipping point. I knew about these things Heat-pumps solar, LED, CFLs. But I was so caught up on traditional thinking. I`ll do what every one else does. Work harder and pay that fuel bill. Replace that light bulb with another. The brakes had to be applied hard.

I have to thank people like Gary at builditsolar and the AC Hacker for setting the course. I`m impressed on what solar and heat-pump technologies can do for us.

Randen

NiHaoMike · 10-07-13, 08:26 AM

Cut out the damaged part of the condenser and use it as a second evaporator. (Put it right after the expansion valve.)

jeff5may · 10-07-13, 05:44 PM

Right, that's what I was saying. You don't necessarily have to put the unit outdoors, just plumb both heat exchangers in the window unit to function as one big evaporator. The increased heat exchanger surface area and airflow will drop the dT on the evaporator side, raising your energy efficiency. Since there are two fans tied to one motor, you could remove one blower wheel to maybe speed up the other, but using both wheels and exchangers (especially the larger, deeper condenser) would be preferred with respect to overall performance.

If the condenser is all bent up, it's a much wiser choice to just get rid of it. Trying to milk something that may or may not hold up usually comes back to haunt you sooner rather than later... just a few days after the thing is all buttoned up. I hate it when that happens.

AC_Hacker · 10-08-13, 08:11 PM

Quote:

Originally Posted by randen

The unit is 5kBTU I think?

Did you even say if your new hack would be air source or water source?

-AC

randen · 10-09-13, 03:23 AM

AC

It is indeed air source. First attempt at assembly failed. I put a twist in the tubes so when I went to turn the bung (adaptor) in the tank the tubes would straighten out again. Not so lucky. Tubes kinked!! dam!! Working on a better simpler solution. A photo will explain best.

Randen

Acuario · 10-09-13, 01:21 PM

Do you think there is enough tube in the condenser to be able to transfer the heat?

I remember when I made my first heat exchanger for the pool it proved to be way too small so heat transfer was minimal.

The second attempt used much more copper (10 metres) in 3 concentric coils and works wonderfully, so much so I've now built 3 of them, 2 heating the pool and the 3rd in the central heating.

The difficulty you obviously have is the limited size of the hole you have to insert the tube and that you have to screw the whole ting in place.

The tanks I've been using are much easier as they have a flat plate and flange washer with bolts to hold the plate in place. I guess you could machine up something like that with the correct tools and save yourself the problem of having to screw the unit into place.

jeff5may · 10-10-13, 06:31 AM

Acquarioe,

I believe 10 meters is a magic number. The airtap hpwh unit uses this length of tubing for its hwt snake condenser. Many, many hobbyists have used this length for their water side exchangers. As long as the tubing is large enough for the refrigerant to flow, I believe one could heat or cool a skyscraper with a 10 meter exchanger!

10-06-13, 08:26 PM	#1
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 657 Thanks: 9 Thanked 191 Times in 129 Posts	Another hot water tank heat pump Anyone that's been following my post on the solar space heating for shop had been introduced to the items that presented themselves to me. A slightly used hot water tank and a air-conditioner that was pushed out of the window landing on its condenser. From here its not a great leap to know what's going to happen next. We're going to hack this into another heat-pump hot water heater. The weather here in South-Western Ontario has been very rainy and I'm still waiting for some materials so work on the solar panels have been paused and in-door projects prevail. Saturday and Sunday produced a condenser with a threaded adaptor to replace the lower element. I'm hoping to be able to guide the tubing in and turn the threaded adaptor in. A prior twist counter clockwise of four turns and tighten into position should straighten the thing back. Again keeping with the theme of the eco-renovators everything is scrap pieces that are cluttering up the place. Rain will be ending in two days and we can get back to the shop improvements. In the photos a brass adaptor is turned up using the old elec. element as a model the threads are a 1" straight pipe thread sealed with a rubber ring. The threads are test fitted in the tank before milling the hex details. A copper cutting from a 1/2 copper pipe stub out is used to return the condensors end. The copper tubing condensor is soldered to the adaptor. Randen Attached Thumbnails Last edited by Daox; 10-26-13 at 11:19 AM..

10-07-13, 08:26 AM	#5
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	Cut out the damaged part of the condenser and use it as a second evaporator. (Put it right after the expansion valve.) __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

10-07-13, 05:44 PM	#6
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Right, that's what I was saying. You don't necessarily have to put the unit outdoors, just plumb both heat exchangers in the window unit to function as one big evaporator. The increased heat exchanger surface area and airflow will drop the dT on the evaporator side, raising your energy efficiency. Since there are two fans tied to one motor, you could remove one blower wheel to maybe speed up the other, but using both wheels and exchangers (especially the larger, deeper condenser) would be preferred with respect to overall performance. If the condenser is all bent up, it's a much wiser choice to just get rid of it. Trying to milk something that may or may not hold up usually comes back to haunt you sooner rather than later... just a few days after the thing is all buttoned up. I hate it when that happens. Last edited by jeff5may; 10-10-13 at 06:06 AM.. Reason: grammer

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10-07-13, 06:18 AM	#3
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	How many BTU is the poor victim rated for? Can you still use the old condenser, or did it let out its charge? I'm asking because I have a similar project thought up. I've heard of others running the entire A/C unit as an outdoor unit to improve performance, but haven't got much follow-up after the fact. From what I've seen, the two heat exchangers in the window unit together have roughly the same heat transfer area as a mini-split outdoor unit of similar capacity. Once again, you are the man! You could sell those water heater tubes with bung on the internet for the fame and fortune, dude. Looks perfectly industrial to me. They could be repurposed as wort chillers or moonshine condensers for even better marketability. I wish I had a garage with a machine shop.

10-07-13, 08:10 AM	#4
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 657 Thanks: 9 Thanked 191 Times in 129 Posts	Jeff5may The unit is 5kBTU I think? The condenser took a good hit and one of the elbows on the end is crushed but it held a charge. The condenser is bent perfect for the scrap bin. As far as running it outside not an option here in Canada. COP would take a huge hit in the winter. Thanks for the cheer but spending forty hours a week standing in front of the machines and then time spent there on the weekend sucks. The up side after 30 some years making goodies for the industries things I make for myself can be made pretty with ones eyes shut. Selling these things on-line I think one would be hard pressed to make shop-rate. I do get the expression when someone gets to watch the machining in action " man what I wouldn't do with these machines in my garage or basement" Well yes it is cool but you can never have enough. After you have a lathe you require a drill press then a mill then drills, endmills, turning tools and the list is ever expanding. I have been bitten by a bug. Efficiency. After spending so much money on energy and finding these technologies so effective on the bottom line. I`m hooked. It took a oil bill that I couldn`t afford to make the tipping point. I knew about these things Heat-pumps solar, LED, CFLs. But I was so caught up on traditional thinking. I`ll do what every one else does. Work harder and pay that fuel bill. Replace that light bulb with another. The brakes had to be applied hard. I have to thank people like Gary at builditsolar and the AC Hacker for setting the course. I`m impressed on what solar and heat-pump technologies can do for us. Randen

10-09-13, 03:23 AM	#8
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 657 Thanks: 9 Thanked 191 Times in 129 Posts	AC It is indeed air source. First attempt at assembly failed. I put a twist in the tubes so when I went to turn the bung (adaptor) in the tank the tubes would straighten out again. Not so lucky. Tubes kinked!! dam!! Working on a better simpler solution. A photo will explain best. Randen

10-09-13, 01:21 PM	#9
Acuario Apprentice EcoRenovator Join Date: May 2011 Location: Tortosa, Spain Posts: 221 Thanks: 2 Thanked 81 Times in 46 Posts	Do you think there is enough tube in the condenser to be able to transfer the heat? I remember when I made my first heat exchanger for the pool it proved to be way too small so heat transfer was minimal. The second attempt used much more copper (10 metres) in 3 concentric coils and works wonderfully, so much so I've now built 3 of them, 2 heating the pool and the 3rd in the central heating. The difficulty you obviously have is the limited size of the hole you have to insert the tube and that you have to screw the whole ting in place. The tanks I've been using are much easier as they have a flat plate and flange washer with bolts to hold the plate in place. I guess you could machine up something like that with the correct tools and save yourself the problem of having to screw the unit into place.

10-10-13, 06:31 AM	#10
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,431 Thanks: 431 Thanked 619 Times in 517 Posts	Acquarioe, I believe 10 meters is a magic number. The airtap hpwh unit uses this length of tubing for its hwt snake condenser. Many, many hobbyists have used this length for their water side exchangers. As long as the tubing is large enough for the refrigerant to flow, I believe one could heat or cool a skyscraper with a 10 meter exchanger!