need advice on building a small heat exchanger

[GREASE FIRE]

I need to run a piece of 3/8" soft copper (svo fuel line) through a piece of 1" hard copper pipe with coolant running through it. I figure i would need copper T's on each end where the coolant would come in; but how do i seal off the two end points where the 3/8" line goes through? I understand there are compression fittings involved but i don't yet understand how to bridge the gap between 3/8" line to compression fittings to hose barbs.
This is just for a small project - i have a few feet of fuel line between my svo tank and filter and would like to add some heat there (it's not the main source of heat for my system). I am sure if i go to a pipe supply place and ask enough questions they will tell me the hardware to use, but it is easier to go into those places with that info ahead of time - hard to explain things to those people sometimes.
any advice?
thanks,
Paul

[cgoodwin]

Do yourself a favor and buy a set of Dana's plans


Chris

[GREASE FIRE]

i was not aware that he invented this design, as i saw a picture of one on a website from somewhere in england. I certainly have no problem buying the plans from him (i have bought other plans from him as well) but at the moment i am just trying to determine how HIH systems, like the greasecar one, seal off the coolant at the point where the fuel line comes out the end. :confused: Just trying to put something together with an assortment of pipe fittings i have around here.
If i can't figure this out then i will gladly pay dana to share the secret with me. :)
thanks,
Paul

[cgoodwin]

My bad, I actually only read the first part of your post...Bad flu going around...mostly in my stomach and head!

In the "Diagrams" area you will find a "HIH" fitting diagram, the 3/8" OD compression fitting is the magic bit you are looking for.

Chris

[Twanoh Tom]

My 2 cents worth: I went to the local Ace Hardward and started going through the copper pipe fittings an had a heat exchanger assembled in about 5 minutes. I took a length of 1" copper pipe and slid a "T" on each end with the openings oriented with one perpendicular (coolant) to the 1" pipe and one in line (fuel) with the 1" pipe. I found a 2 small parts that I'll call "reducers" that slipped snuggly into the end of each "T" and allowed a 1/2" copper pipe to slide snuggly through the entire assembly. Of course, once made up, all joints need to be well soldered. I haven't got a clue as to the efficiency of this make up. The rest of the story is that I disassembled all the parts, returned them to their bins, went home and ordered a heat exchanger from Frybrid. Their coiled unit contains about 8 linear feet of heat exchanger...more that I could cram under my hood using hardware store components.

Tom

[ZukiFrodo]

Perhaps one could coil the copper "fuel line" before sealing it into the larger copper pipe. It seems like you could easily get 3 or 4 feet of tubing - maybe more - in a 12" section of pipe. I'd try to find a way to do some sort of pressure test before using it, just to make sure there's no leaks, and then insulate the unit with a bit of pipe insulation.

How long could the copper tubing be expected to last?

[Greenlion]

Zook, see comments re: Dana's Plans., personnally I've noodled the idea of 3 copper silly straws run through!

Greasefire, does the outside need to be necessarily of copper? How about something that will hold the heat in rather than a high heat exchange rate material? Instead of brazing/soldering, you could use an epoxy to seal the fittings? Also, the compression fitting acts as a bulkhead seal to the outside, and swedges the hose with a crush nut or ferrule on the inside.

[ZukiFrodo]

Yes, I know, I should buy the plans ... but it's kinda fun noolding out ideas!

I think that the composition of the large outer tube would be dictated by the material of the compression fitting.

[cgoodwin]

You can just sweat solder it and will not need a compression fitting.


Chris

[ZukiFrodo]

You know, you could just use a section of straight radiator hose instead of the larger pipe, fitted up with hose clamps. I'd like the solid better, though.

[GREASE FIRE]

i found the real trick to building it was that i had to call 4 different pipe suppliers and the prices ranged wildly from one to the next for each fitting. But i finally ended up with a remanent piece of 1" pipe long enough to build about 4 of these :rolleyes: with, and then at a "real" pipe supply place found a T that was 1" on one end, 1/2" on the other and 1/2" on the top. So that made it easy for the rest of the fittings, i only had to drill the center out of the 3/8" compression fittings on the end so the fuel line pipe could go right through.
So i now have the following set-up:
50 gallon greasel tank with coolant heater inside > racor 1000 fh with low-amp band heater around it, with coolant hose jacket around that > 1 foot long copper heat exchanger > greasel "3B" HOH taking svo the rest of the way.
I don't think i have to worry about fuel temps anymore, but soon i will put a temp gauge in just to be sure.

If anyone has a greasel system, i know they are less than perfect, but the coolant jacket and heat exchanger can be added for about $30-$40 more at most and will greatly increase svo temp.
Paul