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On-demand hot water for shower

PostPosted: Tue Apr 13, 2021 9:34 am
by Doug Coulter
"Don't try this at home" - everyone told me it wouldn't work, would burn down the house, kill me with carbon monoxide. whiteboard wouldn't do as it'd rot or sag - even though it doesn't get wet.. Well, nope.

I got a small propane on-demand heater intended for camping (who the heck needs that - some new definition of camping?). Cheap stuff, but careful installation and don't twist off the connectors and it's good.
A friend, Jeremiah, came over and installed it with some whiteboard Bill had brought me. The quick coupling for the shower head was drippy at my line pressure, so I installed a ball valve, mostly because it was not dissimilar metal and was F-F npt - and a nipple and hose clamp instead of their arrangement - not one drip.
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Side view. It's a tiny room so I couldn't get back far enough to get the whole thing in frame.

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My mod to the hot water side.


The CO monitor (another donation from Bill) I put in the room didn't go off. Because "everyone knows" it's going to burn the house down - despite being an on the spot fire extinguisher...I used the thermal camera to take some pics after a good long wash. Heh. It's efficient, most of the energy goes into the water, as it should. Only the exhaust port gets actually hot.
Here's the thermal pix.
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Ceiling above the unit
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And the unit. Of course, the clock in the camera is way off...as is the registration between the visible and IR. But it was cheap!
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Only the exhaust port gets hot.
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Here's a link to the unit on Amaon.
The reviews about the crappy shower hose can be disregarded, they fixed it with a better one. But the quick coupler for the output leaks like a compressed air fitting (which it's a copy of).
Can't have that, so I added the ball valve and a real hose nipple and clamp.


So, after some years having to make sure I had surplus water, and surplus electricity, which rarely happen together...now I can wash my sorry butt pretty much anytime. This doesn't waste water or propane.

Re: On-demand hot water for shower

PostPosted: Thu Apr 15, 2021 4:20 am
by johnf
A big improvement

keep them coming

Re: On-demand hot water for shower

PostPosted: Fri Apr 16, 2021 9:49 am
by Doug Coulter
Well, with some parts from Amazon, and some help from Bill, this project seems pretty complete other than the usual workout of any bugs.
Got a seat, some handle/hangers etc installed.
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Shower head hanger - I lost the original and it wasn't great anyway.

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Grab bars, seat


We also fixed an issue with my auto-fill setup that transfers water from the rain barrel to the basement cistern and auto stops when it's full. I thought it was the valve, but nope, just a wire that corroded through somewhere I didn't notice it. Oh well, those aren't expensive valves and they are super good. And now I have a few spare ones. That's another thread, but this is all controlled by an esp8266 down there in the crawl space that also collects water level and in/out weather data for this building. A pi polls it once in awhile to get the data we plot from a mysql database on the pi. It's even got over the air updates...nice little sketch.

Re: On-demand hot water for shower

PostPosted: Fri Apr 16, 2021 1:18 pm
by Doug Coulter
Just did a test shower to see how all this works in real life. It's very nice! It uses a lot less water than the old low flow setup did as well and not putting as much past the shower curtain onto the bathroom floor.
Just a lot more efficient, took a lot less to refill the cistern afterward.
And now I know where to put the second shower head/washcloth hanger, which was the point of the exercise as well as getting clean. I'll be able to shower a lot more often now, which is nice to say the least.