Splitting and rejoining water supply lines

[aerie]

Wow.
Hardly “free heat” if you have to spend a lot of money trying to engineer a system to work for you. Seriously? Tiny house? Undersized water heater? Undersized electric service? -30 F temperatures? AND you want nice hot showers as if you lived in a normal sized house in a slightly different climate without all your limitations?
I’m sure there is some code about gray-water heat exchangers and implementing them safely. Even if you live off the grid in some unincorporated mountain area, following some code standards makes sense even if not required or inspected.

If a commercially manufactured unit can’t work for you regardless of the reasons, give up the science project.

Hope that was fun for you to write because it in no way addresses my question. I wasn't asking what you thought of the heat exchanger or how I live. Clearly you have little understanding of the unit, as the supply water and the grey water do not come in any closer contact than in any other house plumbed to code, each contained in their own system, divided by a double wall. So don't worry, I'm not breaking any codes but thanks for ALL your concern.
Spending money is exactly what I'm avoiding by not buying the commercial product, I'm getting copper cut offs from local plumbers so yes it's basically free. And I've found it to be an interesting "science project" so I'm not bothered about spending my time on it.
Hope you've enjoyed participating in this thread because your 2c is absolutely worthless to me.

 

[Mitchell-DIY-Guy]

Actually I have considerable experience with heat exchangers, and what you are doing. I’ve bought them, owned them, and engineered several systems with them. I read enough about gray water heat exchangers to understand them quite well. Even considered one for my house, but unless you plumb from scratch there’s no savings whatsoever. Any apparent operational savings overshadowed by increased plumbing and deployment cost.

I understand exactly what you are trying to do. You’re trying to fit a square peg in a round hole. You want the advantage of a larger lifestyle in a minimalist environment. You’re dismissive of dozens (if not more) of commercially engineered and proven systems out there in lieu of your own Jerry-rigged system for gray water heat recovery.
Go ahead and reinvent the wheel—and good luck with your project.

 

[aerie]

Actually I have considerable experience with heat exchangers, and what you are doing. I’ve bought them, owned them, and engineered several systems with them. I read enough about gray water heat exchangers to understand them quite well. Even considered one for my house, but unless you plumb from scratch there’s no savings whatsoever. Any apparent operational savings overshadowed by increased plumbing and deployment cost.

I understand exactly what you are trying to do. You’re trying to fit a square peg in a round hole. You want the advantage of a larger lifestyle in a minimalist environment. You’re dismissive of dozens (if not more) of commercially engineered and proven systems out there in lieu of your own Jerry-rigged system for gray water heat recovery.
Go ahead and reinvent the wheel—and good luck with your project.

Your comments didn't exactly convey your high level of expertise. It's not a complex device to "jerry rig". Pipe A touches pipe B. If that sounds problematic to you, you are welcome not to do it at your house. But I'm not really sure why you're so upset about what I'm doing, or why you feel the need to share your criticism of my lifestyle on a forum intended for actual plumbing advice. And it doesn't seem like you have anything useful to contribute to answering my actual question. If you're here because you've got nothing better to do than troll people on the internet, I'm really sorry for you. Like I said, your advice is worthless to me so if your time is worth anything to you, I suggest you move on.

 

[JG plumbing]

I forgot to ask. Have you looked into a solar collector? I have recommended these to people who have asked about the heat recovery system you want to make. You can fill the system with glycol and use a heat exchanger and get some pretty hot water even in winter. They aren't that expensive and will give you many btu's for free.