Shower hot water reclimation idea

Daox · 12-08-11, 09:16 AM

99% of the time we use our upstairs shower (standard stall with sliding glass doors approx 32"x44"). It is tiled on all three sides. One wall of the shower is an outside wall and it has glass block in it to make a window (unfortuantely facing west so you don't even get sun shine in the morning). Its a pretty shower, but really not the warmest unfortuantely.

So, I was thinking the other day, there is plenty of hot water going right down the drain. How can I use this to make a more comfortable shower and/or just put it to use? There are obviously the thin film heat exchangers that work great, but cost a lot of money as they're made totally of copper. So, the idea I came up with is pretty simple and can probably be improved upon quite a bit with input from everyone here. The idea is to stick a tube down into the trap under shower drain, pump the hot water up to the top of the shower, loop some tubing around the top of the shower, punch a bunch of small holes in it, and let it drain down the sides of the shower tile heating them up and essentially warming up the entire shower stall. I'm sure you'd need a filter of some sort to keep hair and junk out of the pump, but other than that it would be a pretty simple system.

After the shower is done, the warmed tile would contribute to heating the house also. If this is undesireable, you could simply not use it in summer. The warmer shower stall would also allow you to use less hot water to feel just as warm.

Piwoslaw · 12-08-11, 01:49 PM

The idea is good, but I'm afraid that you'd be long gone by the time the tiles would warm up enough to make any difference. Unless you have 3+ people using the shower one after another.

As for using the warm water to heat the house, just plugging the drain and letting the water cool down (as mentioned in the Home Energy Saving Tips) would be much simpler, and just as effective.

Here's a related idea: Since your shower is upstairs, then below it install a small container that will catch the drain water and let it cool off. When the next shower happens, the old, cool water is replaced by new, warmer water. This keeps the heat in the house, just one floor lower, and uses only gravity.

On a side note, I wonder exactly how much heat energy can be harvested from one shower? If you're trying to save water/energy anyway, then there isn't too much hot water going through the showerhead to begin with. Not all of it goes down the drain (some evaporates, some stays on your body and the shower walls), and what does has already cooled some.

Daox · 12-08-11, 02:01 PM

Well, from my TED usage, a ~10 minute shower takes roughly 2kWh of electricity to heat up the water. I'd imagine that 80-90% of that is wasted down the drain. Lets say we average 2 showers a day, we're looking at ~3.5 kWh/day of waste. Its not a huge amount of power, but its a constant consumption every day of the year practically.

If I shower downstairs in our tub, I do capture the water and drain it later after it has cooled (love that tip BTW). However, upstairs its just a shower stall with a ~2" lip on it. There is not much capacity for water to pool up in there.

AC_Hacker · 12-08-11, 04:10 PM

Quote:

Originally Posted by Daox

99% of the time we use our upstairs shower (standard stall with sliding glass doors approx 32"x44"). It is tiled on all three sides. One wall of the shower is an outside wall and it has glass block in it to make a window (unfortuantely facing west so you don't even get sun shine in the morning). Its a pretty shower, but really not the warmest unfortuantely.

Sounds like you have two different ideas here, warmer walls and heat reclamation.

Probably, the easiest way to warm the walls would be to have some kind of custom shower head that would spray hot water on all the walls for a short time before you got into the shower. Assuming the walls are tile, the surface of the tile would absorb enough heat to make you comfortable during the shower, and then radiate their heat into the house afterwards.

Regarding heat reclamation, there are other discussions here on ER.

-AC_Hacker

Daox · 12-09-11, 07:24 AM

I realize there are other ways to reclaim the heat. I was just trying the two birds with one stone approach.

ThomSjay · 12-17-11, 12:00 AM

Until recently, our shower/tub was a cold place to be in the winter. Then I remodeled the bathroom which included R14 rockwool in the two outside walls (where there was none before), R50 rock wool in the ceiling (R6 previously), and a double-hung, double pane window to upgrade from the original single hung 1951 window. In other words, insulate.

It's a nice comfortable place to be now.

menaus2 · 01-08-12, 12:39 PM

I like the idea of simply insulating for space heating. Maybe modify Piwoslaw's idea of a storage tank, but insulate it, stick it in the basement and run a pex coil for a heat exchanger to preheat the water heater.

12-08-11, 09:16 AM	#1
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Shower hot water reclimation idea 99% of the time we use our upstairs shower (standard stall with sliding glass doors approx 32"x44"). It is tiled on all three sides. One wall of the shower is an outside wall and it has glass block in it to make a window (unfortuantely facing west so you don't even get sun shine in the morning). Its a pretty shower, but really not the warmest unfortuantely. So, I was thinking the other day, there is plenty of hot water going right down the drain. How can I use this to make a more comfortable shower and/or just put it to use? There are obviously the thin film heat exchangers that work great, but cost a lot of money as they're made totally of copper. So, the idea I came up with is pretty simple and can probably be improved upon quite a bit with input from everyone here. The idea is to stick a tube down into the trap under shower drain, pump the hot water up to the top of the shower, loop some tubing around the top of the shower, punch a bunch of small holes in it, and let it drain down the sides of the shower tile heating them up and essentially warming up the entire shower stall. I'm sure you'd need a filter of some sort to keep hair and junk out of the pump, but other than that it would be a pretty simple system. After the shower is done, the warmed tile would contribute to heating the house also. If this is undesireable, you could simply not use it in summer. The warmer shower stall would also allow you to use less hot water to feel just as warm. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

12-08-11, 01:49 PM	#2
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 961 Thanks: 188 Thanked 110 Times in 86 Posts	The idea is good, but I'm afraid that you'd be long gone by the time the tiles would warm up enough to make any difference. Unless you have 3+ people using the shower one after another. As for using the warm water to heat the house, just plugging the drain and letting the water cool down (as mentioned in the Home Energy Saving Tips) would be much simpler, and just as effective. Here's a related idea: Since your shower is upstairs, then below it install a small container that will catch the drain water and let it cool off. When the next shower happens, the old, cool water is replaced by new, warmer water. This keeps the heat in the house, just one floor lower, and uses only gravity. On a side note, I wonder exactly how much heat energy can be harvested from one shower? If you're trying to save water/energy anyway, then there isn't too much hot water going through the showerhead to begin with. Not all of it goes down the drain (some evaporates, some stays on your body and the shower walls), and what does has already cooled some. __________________ Ecorenovation - the bottomless piggy bank that tries to tame the energy hog.

12-08-11, 02:01 PM	#3
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Well, from my TED usage, a ~10 minute shower takes roughly 2kWh of electricity to heat up the water. I'd imagine that 80-90% of that is wasted down the drain. Lets say we average 2 showers a day, we're looking at ~3.5 kWh/day of waste. Its not a huge amount of power, but its a constant consumption every day of the year practically. If I shower downstairs in our tub, I do capture the water and drain it later after it has cooled (love that tip BTW). However, upstairs its just a shower stall with a ~2" lip on it. There is not much capacity for water to pool up in there. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Last edited by Daox; 12-08-11 at 02:05 PM..

12-09-11, 07:24 AM	#5
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I realize there are other ways to reclaim the heat. I was just trying the two birds with one stone approach. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

12-17-11, 12:00 AM	#6
ThomSjay Helper EcoRenovator Join Date: Mar 2011 Location: Sarnia, Ontario, Canada Posts: 91 Thanks: 8 Thanked 2 Times in 2 Posts	Until recently, our shower/tub was a cold place to be in the winter. Then I remodeled the bathroom which included R14 rockwool in the two outside walls (where there was none before), R50 rock wool in the ceiling (R6 previously), and a double-hung, double pane window to upgrade from the original single hung 1951 window. In other words, insulate. It's a nice comfortable place to be now. __________________ TomS

01-08-12, 12:39 PM	#7
menaus2 Apprentice EcoRenovator Join Date: Feb 2011 Location: Driftless Region, North America, Earth, Solar System, Orion Arm, Milky Way Galaxy,Virgo Supercluster Posts: 116 Thanks: 13 Thanked 35 Times in 25 Posts	I like the idea of simply insulating for space heating. Maybe modify Piwoslaw's idea of a storage tank, but insulate it, stick it in the basement and run a pex coil for a heat exchanger to preheat the water heater.