Stainless Steel Tube and Shell Heat Exchanger

DOUG · Post by **DOUG** » Wed. Jan. 21, 2009 8:07 pm

Hey, Guys. Does anyone have any experience with stainless steel tube and shell water heat exchangers? How do you size them? Can they be used with a gravity or thermo-siphon system efficiently? Any thoughts? Thanks

PC 12-47E · Post by **PC 12-47E** » Wed. Jan. 21, 2009 8:36 pm

Hi Doug, Copper tubes, or Cupro Nickel tubes are the usual choice.

RS

DOUG · Post by **DOUG** » Wed. Jan. 21, 2009 9:04 pm

Here is my idea. What if I use a cast iron Bucket a Day water boiler and gravity recirculate it through a tube and shell heat exchanger to a gravity recirculated domestic hot water tank? Is it possible to just keep the one gallon or so amount of water going through the bucket a day coal water heater and the little amount of piping through a tube and shell heat exchanger without popping off the temperature pressure relief valve? If so, how large a heat exchanger do you think is needed to get this to work? Any thoughts?

Post by **coaledsweat** » Wed. Jan. 21, 2009 9:43 pm

DOUG wrote:Does anyone have any experience with stainless steel tube and shell water heat exchangers?

They are inexpensive compared to plate and frame heat exchangers, they are not as efficient however. I have never seen one used in a home heating application. There are calculators online, here is one.
http://www.engineeringpage.com/engineering/thermal.html

DOUG · Post by **DOUG** » Wed. Jan. 21, 2009 9:52 pm

coaledsweat: Thanks for the help.

DOUG

jpen1 · Post by **jpen1** » Thu. Jan. 22, 2009 11:29 pm

Those plate heat exchangers are cheaper than a stainless tube and shell heat exchanger. We build tube and shell exchangers for some of our machines which do have a high BTU need . That being said we use 6" 14 ga tube for the outer shell and in type 316L it goes for aound $15 per inch of linear length just for the shell material. A 5' heat exchanger I believe retails for about $12K.

DOUG · Post by **DOUG** » Fri. Jan. 23, 2009 5:29 am

jpen1: Wow! Those heat exchangers you build must be for commercial usage. It's amazing how they build them. I was thinking on the order of a small pool or side arm exchanger.

jpen1 · Post by **jpen1** » Tue. Jan. 27, 2009 9:20 pm

doug good materials are epensive and they are extremely labor intensive. The end plates take about 4 hrs just to machine a pair and about 5 or six hrs to purge weld the tubes into the plates alone as it is very difficult to get all the oxygen out of both the shell and tubes. Also if the welder makes mistake by either allowing color in the weld or by not penetrating fully the exchanger is just a pile of scrap and you get to start over.

DOUG · Post by **DOUG** » Tue. Jan. 27, 2009 10:05 pm

Thanks for the insight. I wonder if the plate exchangers would serve the purpose instead. I guess I'll have to maybe get an over sized plate exchanger in order to gravity flow between the cast iron boiler and the hot water heater without intermixing the two waters and over heating the boiler. Remember that the proposed cast iron boiler was going to be a Bucket A Day Coal Hot Water Heater I'm seriously considering I saw on ebay. Any thoughts?

Yanche · Post by **Yanche** » Tue. Jan. 27, 2009 11:17 pm

Instead of a heat exchanger, how about an indirect hot water heater with an internal heat exchanger? Check out the Weil McLain products:
**Broken Link(s) Removed**It's a stainless steel tank within a steel tank. Boiler water circulates between the exterior of the stainless tank and the interior of the steel tank. Lots of heat exchange surface area. I'm real pleased with mine. The supply and return tapings are 1-1/4 inch so even gravity flow piping should work well.

DOUG · Post by **DOUG** » Tue. Jan. 27, 2009 11:40 pm

Thanks, I didn't even know about those. That sounds just like what I've been trying to accomplish through this whole topic. I'll have to look into them. Thanks again!

DOUG