Can a heat exchanger be submerged under water in an open tank??

[Dave T]

I am planning storage for next year and I am looking at different options and wanted some feed back on an unpressurized tank with the heat exchanger inside the tank under water.Is this an option,what are the drawbacks and benifits. All opinions welcome.. Dave

 

[Nofossil]

Depends on the heat exchanger type. A flat plate would not have much benefit from being under water, but coil types of course are intended to be used that way. I've also heard some speculation about immersing automotive radiators as well as cast iron radiators.

 

[leaddog]

I made a hx from 1-1/2in pipe that I laid in the bottem of my tank that I was useing before I went to propane tanks. I also had 4 finned 1/2in stainless about 14ft each in the top for the transfer to the house. It worked ok but pressurized is better. by the way the finned is avilable if interested.
leaddog

 

[sweetheat]

both pressurized and open systems have drawbacks, with open systems and coils you can store the sun and the wood heat. I don't think you can do that with a pressure tank, but you can get more BTU's out of a pressure tank. sweetheat

 

[tom in maine]

Poor heat exchangers perform poorly. A poorly designed heat exchanger in an open tank will not work well. There are a lot of poorly designed heat exchangers out there. Many heat exchangers that are commercially available have been designed for other purposes and are fitted to thermal storage systems, with marginal or expensive results.
Throwing a lot of copper into a tank does not mean a heat exchanger will perform as hoped.

A well designed immersed heat exchanger in an "open" tank will extract and input a very high percentage(90%+) of the heat that is stored in the tank.

A pressurized system will out-perform a similar sized open tank in that it can store water hotter than 180 since you will not be boiling pressurized
storage until, perhaps 230F.

It is somewhat simpler but is a lot more difficult to install (get into a basement, if that is where the system is to be) and hookup tends
to be more involved, IMHO.

 

[heaterman]

I am planning storage for next year and I am looking at different options and wanted some feed back on an unpressurized tank with the heat exchanger inside the tank under water.Is this an option,what are the drawbacks and benifits. All opinions welcome.. Dave

If you think about that for just a minute, you'll realize that is the basic principle of operation for nearly all outdoor wood burners.