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Old 08-26-09, 07:52 AM   #11
Daox
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Wow, that is very small. Do have any info or an image that shows a cross section of the heat exchanger? I understand there is an inlet and outlet for each liquid, but would like to see the inner workings. A link that explains them would be great. I have heard these units can be very impressive performance wise despite their small size.

Where did you get the one you are holding? What was the cost if I might ask?

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Old 08-26-09, 11:44 AM   #12
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Default brazed plate heat exchangers...

Daox,

Here's a labeled pic of the inlets & outlets on a a brazed plate exchanger:


Note the cross-flow scheme...

Here's a manufacturer's illustration of the cross flow scheme:



As far as I can tell, the idea was developed by the Germans and is currently most widely manufactured in China.

The prices for brazed plate exchangers seem to be all over the map, from very reasonable to absurdly expensive.

People who do home brewing seem to be using a fair share of these things. Not only that, but people who do home brewing are not willing to pay very much money for them. They seem to use them for 'chilling wort' what ever that is.

So if you start a relentless quest on ebay and also maybe Craig's List you will find what you are looking for.

Here's a link for ebay:

heat exchanger brazed plate, great deals on Home Garden, Business Industrial on eBay!

I got the one in the photo for about $40.

For heat pump purposes, you want to have brazed fittings (AKA: sweat fittings) for the refrigerant side and pipe thread fittings for the water side.

As noted elsewhere, refrigerant connections need to be brazed and not soldered, even silver solder is not good enough. You need to braze it. To add to confusion, I have heard refrigerant people say "solder it up" to refer to brazing a system together. Don't be fooled. Refrigeration systems are subject to substantial vibration and soldering, even silver soldering will not hold up.

Regarding brazed plate selection, these links address this:

http://ecorenovator.org/forum/projec....html#post3023

http://ecorenovator.org/forum/projec....html#post3027

The downside of using a brazed plate exchanger is that the very thing that makes them efficient, namely closely-spaced flow channels, also makes them subject to fowling if there is a high probability of that. There's not a fowling issue with refrigerant, and if clean, distilled water is used on the water side and if dis-similar metals with the potential for galvanic action are carefully avoided, the fowling potential can be dismissed.

Brazed plate exchangers would be a very bad choice for open loop systems.

Hope this helps.

Best Regards,

-AC_Hacker

P.S.: It might be a good idea to put a link to the 'Homemade Heat Pump Manifesto' in the Geothermal section:

Geothermal - EcoRenovator
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Old 08-26-09, 12:14 PM   #13
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Excellent explanation. Thank you.

My interest is more on the solar hot water side of it to use to heat a tank of water. But, we'll not get off track too much more.
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Old 01-28-11, 07:11 PM   #14
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Default any progress??

Hi - saw your posts above. How far did you get??
I am in the process of doing something similar in pulling the outside coil out of the case and simply dipping it a tub of constantly pumped well water - not sure I can braze and recharge the system to add in a completely new exchanger as you're trying.
Thanks
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Old 01-28-11, 08:40 PM   #15
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Quote:
Originally Posted by Ron342 View Post
Hi - saw your posts above. How far did you get??
I am in the process of doing something similar in pulling the outside coil out of the case and simply dipping it a tub of constantly pumped well water - not sure I can braze and recharge the system to add in a completely new exchanger as you're trying.
Thanks
Hi Ron,

The whole story can be found here:

Homemade Heat Pump Manifesto

It's a pretty long thread, don't attempt it without lots of beer & chips.

But I got the ground loop in and it's working just fine. I got the heat pump done and it's working, too. I started running the heat pump continuously, 24 hours a day, about two or three weeks ago to warm my completely un-insulated basement. It's a reasonable 66F down there right now.

So I'd say it's a success. The loop field may be somewhat undersized, it's really too soon to tell until I get the radiant floor in and the test-room insulated properly. So, a next step is to put in a radiant floor.

I'm also beginning to build a bigger heat pump. The heat pump will be detailed on the thread above.

The radiant floor will be detailed on the DIY Hydronic Floor Heating thread.

If you have more questions or comments, post them to the 'Manifesto' thread at the link above, because I monitor it daily.

Best Regards,

-AC_Hacker
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Old 04-30-12, 06:29 PM   #16
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Quote:
Originally Posted by Ron342 View Post
Hi - saw your posts above. How far did you get??
I am in the process of doing something similar in pulling the outside coil out of the case and simply dipping it a tub of constantly pumped well water - not sure I can braze and recharge the system to add in a completely new exchanger as you're trying.
Thanks
Hey Ron did you try this? I am thinking of doing the exact same thing with a 5 ton Goodman heat pump, basically just sticking the air coil in a tank of circulating ground water.
Carry on!
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Old 05-01-12, 02:12 PM   #17
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I’m a new Geothermal lurker on this forum, great stuff you guys!

35 GPM H2O at 65 degrees 24/7 is a god send!
Apparently it flows on the surface from an artesian well.
Can it be contained in a 4” plastic pipe nearby in which you could have a single loop of Cu. tube long enough for the required heat transfer?
Lucky man!
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Old 01-23-13, 09:58 PM   #18
Ron342
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Quote:
Originally Posted by 7shannon View Post
Hey Ron did you try this? I am thinking of doing the exact same thing with a 5 ton Goodman heat pump, basically just sticking the air coil in a tank of circulating ground water.
Carry on!
Hi 7Shannon - did you ever get any further on this??? I have a window unit to try this with and am waiting for spring to drill some geo hole.

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