Copper Tubing for Heater Lines

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Standing on the corner
Aug 21, 2011
Dittmer, Mo.
I need some opinions on using copper tubing for heater lines. I need to plumb in a shut off valve and run lines under the body, to the rear heater. Along with that, I'm running the heater lines to a heat exchanger. I will have some rubber hose in line, so as to dampen vibrations and the hard lines will be supported with brackets.

What do you think?
Certainly a good option, but I wanted a more rigid line, at least by the bulkhead and where I'll be putting in the tee's and shut off valve. After that I could run flexible lines. Would copper be a bad thing?
Nope, perfect. Down here all household hot water lines are copper. Plus the rocker oil delivery system on an early F is copper. There's a place we have called EnZed and they stock all types of tubing, flanges, joins, compression fittings etc. If you can find someplace like that up there then you're set. Might need a mandrel to bend larger diameter stuff though.
Seems like you could also use PEX tubing and put in the copper fittings where you want your valves. That is of course unless the PEX will be exposed to hot metal.
Would copper be a bad thing?

As long as you address the potential galvanic corrosion issues and keep the copper pipe isolated from contact with the steel I’m sure it would work fine.
On the Chevy water pump, the two nipples are 5/8 and 3/4, and both vehicle heaters have 1/2 nipples on them, so I'll be reducing the lines in some spots. I'm trying to keep the lines unrestricted, except going to the heaters. Going over to the heat exchanger and back, will be the correct size lines. I have to isolate the heaters for Summer running, but keep the lines open to the exchanger. The shower lines will be 1/2, also.

Takes some thought as to how to do it and have it done right. I am worried about vibration and the soldered joints and as I'm typing this, just read JMack's post about Galvanic Corrosion. Jim, could you explain a little deeper. I didn't know of a big problem with copper and steel.
Well, did some reading and I have to change a few things around. I never knew it was a big problem, just with electric wires, etc.

Thanks JMack, for pointing that out! The ball valves I have are stainless and was going to use the copper lines with them. I'll have to see if brass will work.
That's a good article and will think this through. I can't change the bulkhead, but maybe an insulator in between it and the copper.
Yup. The electrochemical reaction is why I mentioned the cross-linked polyethylene (PEX). It comes in various diameters, no soldering necessary ;)
I was thinking pex tubing first when I read this. Pretty think walled amd durable. Plus easy to replace/fix if need be. Also doesn't transfer heat quite as bad as copper would. (To other components)
how does it act in the cold? ie, will it break easily if below freezing?
So, you guys are saying, use PEX with plastic valves, through out the whole system? One thing I'm confused about is PEX using copper fittings, maybe that small amount of copper in system wouldn't have the same effect on the steel. Would the 200 degree limit of PEX be a problem, a motor can run hotter than that.

Something else, the heat exchanger is 99 percent copper with Stainless Steel fittings on it? I'm going to call them and ask some questions.

Thanks Guys, some good food for thought!
yeah, the pex is suspicious at best...definately contact HE manufacturer to see what their story is on the dis-similar metals in a solution...seems like they are building electrolosys into the system with the ss BH and copper body...
So, what's wrong with using high quality rubber lines?
Well, did some reading and I have to change a few things around. I never knew it was a big problem, just with electric wires, etc.

Thanks JMack, for pointing that out! The ball valves I have are stainless and was going to use the copper lines with them. I'll have to see if brass will work.

Ron like I said the potential galvanic corrosion issues. Just because you have copper and steel joined in your system doesn’t guarantee you’ll have galvanic corrosion just that the potential exist but remember other factors also need be present.

Something as simple as dielectric unions may be a good solution or if you’re considering the Pex maybe take a second look at the “Solar System Flex Tubing” it comes in lots of different flavors and is better suited to what you’re doing, you can buy it by the foot and just run pairs of 1/2" or 3/4" and reduce back to your heater hose sizes at the bulkhead.



Good luck, sorry for muddying up the water.
Pex has been used for quite a long time under pretty harsh conditions. It can be directly buried, encased in concrete, and doesn't break down with the minerals in the soil. Plumbers here run glycol through it for solar applications using heat exchangers as well. There are a lot of different brands around. Some have a inner aluminum core that allows it to hold it's shape better. It's a pretty tried an true system. Wirsbo is the brand that has a pretty good reputation. I think there are some that have a higher heat rating. Some also require special tools to expand the pipe and attach fittings. Food for thought.
I like the looks of that solar flex tubing. Seems like a good option.

PEX was just an option I suggested because I know how durable it is; certainly not married to it.

LAMBCRUSHER, PEX is used so frequently now because it is considered freeze "proof". If you ever have to repair a frozen and busted copper pipe, consider splicing in a section of PEX using "sharkbite" fittings. Good bye to "sweating copper".

As abqcruiser said, you may need special tools (some hardware stores rent them) to join fittings. Plastic valves? Definitely not. The PEX is used in conjunction with metal fittings.

Sounds like a fun project (at least better than "real" construction plumbing)!
By running PEX you’ll create a dielectric union between your dissimilar metals and you could keep your steel, stainless steel, aluminum and copper parts in place.

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