Homemade Heat Pump Water Heater (R290) - Page 10

randen · 03-12-14, 10:16 PM

AC_Hacker

Yes looking forward to summer in more than one way. My parents basement is quite warm, as it is, a finished living quarters as such. Although, right at this moment just with the cat.

The frosting problem was just purely not enough air flow through the evaporator. I had tried to exhaust it into a 4" duct, but it proved insufficient. There is room for slightly improving increase airflow.

I want to again run a test for calculating the COP. Also I've a programmable thermostat for the HWT instead of the bi-metal original.

Get the grinder out and fire up the torch these things work great!! Well worth the effort and time. Let the other guys worry about the sports on Saturday!!

Randen

Ron342 · 03-13-14, 06:56 AM

Who needs beer and potato chips anyway?

Randen did you use commercial r290 or just squeeze your propane torch?
Vlad had a post in another thread on how to make it a little purer.
You may need a license to buy real r290, I think.

Had an idea on the Kill a Watt meter, if you connected it between either phase of 240v and the neutral and doubled the results wouldn't that give you the 240 v watt draw?? It assumes that both 240 phases draw equally but that's generally close?

randen · 03-13-14, 07:19 AM

Ron342

I had squeezed the torch bottle. I did read the posts on purifying the propane but I didn't bother. BradC had also suggested double filters and I think also deep froze his bottle to reduce any moisture the propane may have had. For me, I just draw the best vacuum I can get with my equipment and leave it sit overnight to ensure I don't have a leak, then load my propane.

I also usually install a filter drier but with this small machine I didn't bother. I guess time will tell.

Your idea with the kill-o-watt I believe will work. But I haven't tried it.!! Maybe X-ringer will chime in here.
I see that there are whole home devices like the TED that can measure all your usages 240v. My multi meter and clamp on amp meter are usually enough.

Get to it this weekend, there's a pile of money to be saved here. Make those tools in your tool box realize some savings EcoRenovator Style!!

Randen

Ron342 · 04-03-14, 07:54 AM

OK,OK I'm building the thermosiphon condenser spiraling up around the water heater. Plan to run it from the drain up to tie into the relief fitting and I have 5000 but r22 window unit to hack first using its evaporator then a water tube in tube unit if it ever gets warm enough to finish the Geo holes!
I can braze weld etc but no ac experience and a 40 yr old mech engr degree doesn'help! Here's where I'm hung - the condenser will likely be oversized and certainly will have a different flow characterstic from the window shaker condenser as will the tube in tube evap when that gets going. How will I know when to stop adding freon or propane? I assume I just charge til I get a p/t equal to 120f at the top of the condenser? Or do I look at the evap temps???????
The window unit has a cap tube.
Thanks

AC_Hacker · 04-03-14, 08:28 AM

Quote:

Originally Posted by Ron342

OK,OK I'm building the thermosiphon condenser spiraling up around the water heater.

If you include a sketch or photo, it would make communication about this project possible.

Since your ME degree is 40 years old (or you are 40 years old and have a ME?), you totally understand the importance of using images to communicate technical concepts, right?

-AC

Ron342 · 04-03-14, 01:36 PM

Degree is 40 yrs old, owner is even more hoary!

Sketch is attached - its a good way to force yourself to confront the realities of what you're dealing with.

The 7/8 soft hvac tubing spiralling around the heater goes from the 3/4" npt drain valve port at the bottom to the 3/4" relief valve port at the top, has the 1/4" soft copper condenser tubing run thru it in and out at the cross (X) fittings at the drain & relief valve ports & works out to 18 - 19 feet long.

I wonder if thats enough with the thermosiphon water flow that will result to condense the gas particularly when the tank water approaches the gas temp. If it works its a simple way to avoid having to stuff all that spagetti thru the element port!
But my greater worry is that I don't know what to look for when charging?
Thanks

AC_Hacker · 04-03-14, 03:31 PM

Quote:

Originally Posted by Ron342

...how to charge?

Dear more hoary,

The drawing certainly does help. It looks like you have a double helix going on there, yes?

It also looks like your cap tube that goes to the evaporator, is attached to a larger diameter tube that comes up from the bottom of the tank, still correct?

Although I'm not sure what all the plumbing will do, if I understand your new rig, the cap tube will be spraying liquid refrigerant into the evaporator at just about the point under the word "cap tube", near the point of the arrow.

So that will be the point where you will get a visual cue as to whether or not the change-of-state magic is working.

From my own experience, it is good to have a manifold set, and to have both Hi-side and a Lo-side Schrader valve connections.

Start with a shot of gas in the Hi-side connection, to at least get into the positive pressure range. Then change to the Lo-side valve, and add gas until you get up to maybe 25 psi, then start your compressor and start adding gas until your Lo-side begins to approach 25 psi, and your Hi-side starts into the 100+psi range.

Your visual cue will be frost on the cap tube at the point where it goes into your evaporator. That tells you that the magic is working.

Then let it run for maybe 20 or 30 minutes and add more as required.

My own experience is that I over-shoot the charge, and nothing works, and I hate myself, and then bleed some R290 out, and the machine comes to life.

That's my advice.

I'm interested to see what others may say.

-AC

jeff5may · 04-03-14, 05:12 PM

I would definitely go with a liquid receiver in this setup. Due to the rise in the liquid line, the reduction in head pressure on the way up from the bottom will encourage the refrigerant to flash off in the line. Without some sort of receiver at the top, this "burping" will go straight into the cap tube and mess up the cycle. In any case, I would try to make this liquid return line as small a diameter as feasible for good oil return. Line too large = no oil return, line too small = pressure drop and flash gas.

NiHaoMike · 04-03-14, 05:13 PM

You'll want to use a R410a compressor with R290 or similar (I'm using R433b) along with a R22 TXV. The reason is because A/C units typically don't operate at 130-140F condensing (as needed for effective dishwashing) and a R410a compressor can take the increased pressures. It can also take advantage of higher evaporating temperature, boosting efficiency.
http://ecorenovator.org/forum/geothe...ssor-r290.html

In principle, it's possible to get a similar result with R134a in a R22 compressor, but the effort it takes to change the oil makes it largely impractical. Also note that R290 or a mixture based on it is better than R22 for this application as the discharge temperatures are much lower at a given condensing temperature.

Ron342 · 04-04-14, 09:08 AM

Wow. Thanks!

Some corrections - its a single spiral - what looks like a double is over zealous scanning of bad erasing of draftsmans errors!

Yes AC, the liquid line up to the cap tube is simply a continuation of the 1/4" copper inner tube of the tube in tube condenser and comes up from where it exits the condenser at the drain connection of the tank.

I could reverse the condensing flow thru the spiral which would shorten the liquid line rise but wanted the water counterflow thru the condenser, now I wonder if its worth it?

The cap tube/evap setup is as it was in the window unit, I may add the old window condenser to the evap in series though. And I have a set of guages and 2 stage vac pump and will put taps at the high and low sides.

Here's what I took away from your great responses:

First I have no r410 compressor so am stuck with the r22 unit for this first try at least.

So I will put a receiver before the cap tube (and a filter/dryer too ? and where?)
Maybe insulate the liquid line? Reverse the condenser flow so the line comes off the top of the condenser?
Would a txv valve work that much better than the cap tube??

Use R290 instead of R22 when I charge it up. Do I do anything about oil?
And by the way Mike what do you do about oil if you use R290 in a R410 compressor?

And I charge slowly looking for frost at where the cap tube enters the evap (will the frost remain as it reaches full charge?) and for the right temp pressure (120 - 140f) at the high side just before entering the condenser?

Thanks so much guys - I hope each of you realizes that this is akin to voodoo to the rest of us!

03-12-14, 10:16 PM	#91
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 AC_Hacker Yes looking forward to summer in more than one way. My parents basement is quite warm, as it is, a finished living quarters as such. Although, right at this moment just with the cat. The frosting problem was just purely not enough air flow through the evaporator. I had tried to exhaust it into a 4" duct, but it proved insufficient. There is room for slightly improving increase airflow. I want to again run a test for calculating the COP. Also I've a programmable thermostat for the HWT instead of the bi-metal original. Get the grinder out and fire up the torch these things work great!! Well worth the effort and time. Let the other guys worry about the sports on Saturday!! Randen Attached Thumbnails

03-13-14, 07:19 AM	#93
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 657 Thanks: 9 Thanked 191 Times in 129 Posts	Ron342 I had squeezed the torch bottle. I did read the posts on purifying the propane but I didn't bother. BradC had also suggested double filters and I think also deep froze his bottle to reduce any moisture the propane may have had. For me, I just draw the best vacuum I can get with my equipment and leave it sit overnight to ensure I don't have a leak, then load my propane. I also usually install a filter drier but with this small machine I didn't bother. I guess time will tell. Your idea with the kill-o-watt I believe will work. But I haven't tried it.!! Maybe X-ringer will chime in here. I see that there are whole home devices like the TED that can measure all your usages 240v. My multi meter and clamp on amp meter are usually enough. Get to it this weekend, there's a pile of money to be saved here. Make those tools in your tool box realize some savings EcoRenovator Style!! Randen Last edited by randen; 03-14-14 at 03:25 PM..

04-03-14, 07:54 AM	#94
Ron342 Apprentice EcoRenovator Join Date: Feb 2010 Location: Maryland Posts: 120 Thanks: 26 Thanked 12 Times in 8 Posts	A little charging advice please??? OK,OK I'm building the thermosiphon condenser spiraling up around the water heater. Plan to run it from the drain up to tie into the relief fitting and I have 5000 but r22 window unit to hack first using its evaporator then a water tube in tube unit if it ever gets warm enough to finish the Geo holes! I can braze weld etc but no ac experience and a 40 yr old mech engr degree doesn'help! Here's where I'm hung - the condenser will likely be oversized and certainly will have a different flow characterstic from the window shaker condenser as will the tube in tube evap when that gets going. How will I know when to stop adding freon or propane? I assume I just charge til I get a p/t equal to 120f at the top of the condenser? Or do I look at the evap temps??????? The window unit has a cap tube. Thanks

04-03-14, 05:13 PM	#99
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	You'll want to use a R410a compressor with R290 or similar (I'm using R433b) along with a R22 TXV. The reason is because A/C units typically don't operate at 130-140F condensing (as needed for effective dishwashing) and a R410a compressor can take the increased pressures. It can also take advantage of higher evaporating temperature, boosting efficiency. http://ecorenovator.org/forum/geothe...ssor-r290.html In principle, it's possible to get a similar result with R134a in a R22 compressor, but the effort it takes to change the oil makes it largely impractical. Also note that R290 or a mixture based on it is better than R22 for this application as the discharge temperatures are much lower at a given condensing temperature. __________________ 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...

03-13-14, 06:56 AM	#92
Ron342 Apprentice EcoRenovator Join Date: Feb 2010 Location: Maryland Posts: 120 Thanks: 26 Thanked 12 Times in 8 Posts	Who needs beer and potato chips anyway? Randen did you use commercial r290 or just squeeze your propane torch? Vlad had a post in another thread on how to make it a little purer. You may need a license to buy real r290, I think. Had an idea on the Kill a Watt meter, if you connected it between either phase of 240v and the neutral and doubled the results wouldn't that give you the 240 v watt draw?? It assumes that both 240 phases draw equally but that's generally close?

04-03-14, 05:12 PM	#98
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	I would definitely go with a liquid receiver in this setup. Due to the rise in the liquid line, the reduction in head pressure on the way up from the bottom will encourage the refrigerant to flash off in the line. Without some sort of receiver at the top, this "burping" will go straight into the cap tube and mess up the cycle. In any case, I would try to make this liquid return line as small a diameter as feasible for good oil return. Line too large = no oil return, line too small = pressure drop and flash gas.

04-04-14, 09:08 AM	#100
Ron342 Apprentice EcoRenovator Join Date: Feb 2010 Location: Maryland Posts: 120 Thanks: 26 Thanked 12 Times in 8 Posts	Wow. Thanks! Some corrections - its a single spiral - what looks like a double is over zealous scanning of bad erasing of draftsmans errors! Yes AC, the liquid line up to the cap tube is simply a continuation of the 1/4" copper inner tube of the tube in tube condenser and comes up from where it exits the condenser at the drain connection of the tank. I could reverse the condensing flow thru the spiral which would shorten the liquid line rise but wanted the water counterflow thru the condenser, now I wonder if its worth it? The cap tube/evap setup is as it was in the window unit, I may add the old window condenser to the evap in series though. And I have a set of guages and 2 stage vac pump and will put taps at the high and low sides. Here's what I took away from your great responses: First I have no r410 compressor so am stuck with the r22 unit for this first try at least. So I will put a receiver before the cap tube (and a filter/dryer too ? and where?) Maybe insulate the liquid line? Reverse the condenser flow so the line comes off the top of the condenser? Would a txv valve work that much better than the cap tube?? Use R290 instead of R22 when I charge it up. Do I do anything about oil? And by the way Mike what do you do about oil if you use R290 in a R410 compressor? And I charge slowly looking for frost at where the cap tube enters the evap (will the frost remain as it reaches full charge?) and for the right temp pressure (120 - 140f) at the high side just before entering the condenser? Thanks so much guys - I hope each of you realizes that this is akin to voodoo to the rest of us!