"Stand Alone" Heat Exhangers and DHW

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  #1  
Old 01-15-12, 03:52 PM
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Question "Stand Alone" Heat Exhangers and DHW

I've seen more than a few diagrams, and read several descriptions, of DHW systems that utilize a heat exchanger that is a separate unit, and not a component of the tank itself. An example:


image courtesy pmengineer.com

I'm wondering about the advantages of such a system, as opposed to, say, a conventional indirect hot water tank w/HE inside of the tank...?

Thanks for any feedback.
 

Last edited by NJT; 01-15-12 at 06:05 PM.
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  #2  
Old 01-15-12, 04:28 PM
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Well in my own home i have used a boiler mate ( tank with coil inside) for the last 25 years and it has served me good. I have used the heat exchanger headers an commercial jobs with a 200 gal. tank 120degree water and than another header for 160 degree to a kit.
Are you talking about a residential system? You will probably have some one come along that has
more info on home use. Paul
 
  #3  
Old 01-15-12, 05:33 PM
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Hi Paul,

That's one of the things I'm wondering about, whether it is more applicable to commercial applications with high DHW usage (like for example, apartment buildings), where more storage (bigger or multiple tanks) is needed.
 
  #4  
Old 01-15-12, 05:57 PM
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In my house I use a flat plate heat exchanger for my 80 gal. DHW. It's a Lochnivar 4-port Solar tank with electric element in it. You really need 4 ports, 2 for HX water & 2 for domestic cold in & hot out.

Rheem has commercial hot water storage tanks with multiple ports.

Works great, has a Bronze Grundfos 15-42 on the fresh water tank side & Iron 15-42 on the boiler side, both run at once in a counter flow in the HX.

Pumps & HX have to be correctly sized for your BTU transfer rate.

GEA is a great brand HX & they have an online simulator to help pick size. OR use use cheaper brands & go double on their advertized rates.
 
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