Grey Water Recycling using a household radiator
 

So I live in a rental apartment and do not want to renovate the whole shower, but since the hot water pressure in the building is very low and wish to save on my gas bill something needs to be done.

Shower heat recovery comes in a few flavours, the vertical pipes, horizontal pipe ect ect. Since I'm not planning on renovating the shower itself these options are not possible. Then there is this guy who built a new shower floor with a heat exchanger under it, I think the project is called Meander HR. For me this seems to be the most viable option, but the costs of such a system are still around the $200 mark. One of the most straightforward heat exchangers is a simple house radiator which can be cheaply picked up at any online market place (sometimes even for free). Some radiators have a flat surface on which, I hope, I can easily stand (Maybe the surface needs to be roughened up a bit). Then boxing it in and connecting the cold water line to it.

I bet there are many reasons not to do it like this, but maybe it is not such a strange idea after all

Welcome to the site Elwin!

That is an interesting idea. Do you have an image of this heat exchanger you're thinking of using? I can't seem to picture it.

Elwin,

How about this:


This would go directly on your shower floor, preferably under an attractive wooden grate, upon which you would be standing.

Assuming you have access to the cold water flow before it gets to the temperature mixing valve, prior to the shower head, divert the water, prior to the mixing valve, and run it through the copper coil at "A", then take the water flow from point "B" and connect that back to your cold water that is flowing into the mixing valve.

The warm shower water would fall upon the copper coil, pre-warming the incoming cold water component of your shower water. You would be able to reduce the hot water level until an ideal shower temperature was achieved, thereby saving energy & money.

NOTE: I have a demand water heater, and I have it adjusted so that it only heats water up to shower water temperature, for me, that would be 104F. Most people use excessively-hot water, and they then mix enough cold water with it, that it is at the right temperature. This copper coil idea would be perfect for those people.

Best,

-AC_Hacker

@daox I couldn't post pictures so that's why. The project I saw was called meandherhr I believe, but I thought of something like this http://upload.wikimedia.org/wikipedi...pte_tegels.JPG

Just a simpel Household radiator.

@ac-hacker i like the idea since it's simple to build, but I'm afraid a lot of dirt and grit like hairs will get stuck in between it. I also have a demand heater, but would setting the temp of the heater make more sense then reusing the heat. The heater is like 1m from the shower and has isolated lines.

I haven't done any experiments on comparing the two approaches, but my intuition tells me that setting the demand heater temperature setting lower, to shower temperature would be the most economical.

I am amazed how thrifty a gas demand heater is, when it is set properly. I take a long hot shower every day, at least once, and sometimes more, and my gas use charges are lower than the charge to read the gas meter.

-AC