Hello Danni Webbers:
Here is a way to save up to fifty percent on your water heating bill. I have been using this device for almost twenty years now, and it has never needed any maintenance at all. You will need a old plastic fifty five gallon drum, or something like it. Do not use steel, unless you can obtain a stainless steel drum. Also, you will need about seventy feet of one inch plastic pipe, several dozen ninety degree one inch pipe couplings, pipe cleaning solvent, and plastic pipe cement. Do not buy high temperature plastic pipe as the extra expense is not warranted. You will also need a two and one quarter inch steel or plastic bulkhead fitting, two rubber gaskets, and two bulkhead nuts. Paying top dollar for supplies will cost no more than one hundred dollars, and if your a good scrounger, you might get by for forty dollars or less.
Construction: At about four inches from the top of the plastic drum, using a magic marker place a dot, and place the bulkhead fitting in such a way that the dot appears in the center of the fitting when it is placed on the drum. Then draw a circle around the fitting, and cut a round hole for the bulkhead fitting that will act as a drain. A small electric jig saw should work nicely. In this case the drain will be located near the top of the drum. Now install the bulkhead fitting in such a way, so that the same length extends on both sides of the hole in the drum. For the heat exchanger to work properly, it has to be filled with water at all times. During normal use, the excess water will flow out of the drain from the top of the barrel.
The reason why you put the drain four inches from the top of the drum, is if you are using, say the shower at the same time as the washing machine. The water level will rise in the drum sightly, and could overflow the top.
Depending on the type of container you decide to use, and I've heard that C+++ programmers use cardboard, but QBasic programmers use plastic, I've managed to coil seventy feet of one inch plastic pipe inside, in such a way that all of the pipe is under the waste water when in operation.
The next thing you do, is redo your plumbing in such a way as to run ALL of the waste water, except from the toilet, that leaves your home, to pass through the drum, on it's way to the sewer.
NOTE: The wastewater pipe from your plumbing, MUST extend almost to the bottom of the drum. If you drain to the top of the drum, the waste water will simply run out of the overflow, without heating the cold water in the coils of pipes in the drum. The best way to do this is place a two inch ninety degree fitting on the bottom of the wastewater inlet pipe. This will cause a slight stirring action in the drum.
The last thing that needs doing, is to connect one end of the plastic pipe to the cold water line. The other end of the plastic pipe is connected to the cold water inlet of the water heater.
Theory of operation: If you own your own home, you own two water heaters. One of them is your home. You will notice this during hot weather, when in the morning, you have to run the cold water tap for a minute or so, before the water finally gets cold. By the same token, if you were to turn on the shower first, the same amount of warm water would go to the water heater.
This is the way the heat exchanger operates. Instead of discarding hot water down the sewer, you can reuse it, without of worrying about the water being contaminated
The type of plastic pipe or fittings you use is not critical, but connecting them IS. You MUST first clean the shiny "skin" from the outside of the pipe, AT EVERY CONNECTION, and the skin from the inside of the couplings, with plastic pipe cleaner, prior to using the pipe cement for final assembly. If not, you risk a leak at every connection.
There is no contamination between the waste water and the clean water, because the clean water in the plastic pipe is under pressure, typically fifty pounds per square inch. If a leak does develop, it will be from the one inch pipe to the used water, rather than the other way around.
Also your water heater will last longer, so far my forty gallon unit has been in use for seventeen years, and there will be less lime buildup in the unit, because it will run less.
The water in the barrel will not get hot enough to melt the plastic pipe.
At worst, the how water supply in your home will change from hot to warm, rather than hot to cold. As you will always be reclaiming some warmed water back.
At any rate, If you decide to build such a unit, you can make it any size you want, but I would not go any smaller than fifty gallons. You can also cascade two units together if you want. For example: a five hundred gallon unit could be used in a large apartment complex.
At any rate you should be able to continue from here on your own. For those of you C++ who get confused, consult a QBasic programmer.