Strip naked, open shower door, switch hot tap on, wait, scratch nuts, wait, check temperature of water with hand, wait, scratch bum, wait, check temperature of water with hand again, almost there, wait, yawn, check again, great, step inside.
Sounds familiar? Apart from having to stand naked on a freezing winter morning waiting for the water to run hot, have you ever considered how much cold water goes to waste every time you run a shower. What a waste. Surely there is an easier and less wasteful way to get the water to temperature. My shower is reasonably close to a geyser, but what about the bathroom far from the geyser? That hot water tap takes ages to run hot.
So I got thinking while having my shower this morning, and I present my invention for comment. I’m sure this problem has been solved a million times but I don’t know of a solution. Here is my idea.
When you switch any hot water tap in the house on it activates a timer. No water immediately comes out of the tap. The timer activates a non return valve (NRV) which send all of the cold water in the hot water pipes back into the cold line coming into the geyser. Another NRV stops this water from going back up the cold line. After a couple of seconds all of the cold water in the hot water line has been replaced by hot water from the geyser. The NRV switches off and hot water flows out of the taps. Here is a rough sketch.
All that is missing in the above sketch is possibly a valve on the shower side of the line to hold water from the taps until the timer switches the valve to the cold line off. The timer and NRV#2 obviously has to be as close to the taps as possible to replace as much of the cold water with hot. Maybe a timer and valve at each tap?
OK, now go and improve on it.
Very clean.
Synaptoman
P.S. I was going to write about the Nationwide jet that lost an engine on take-off from Cape Town yesterday under the title “Only in Africa”, but I have decided to be more positive in my outlook for a while, but trust me, there was plenty of ammunition for me in that story.
S Y N A P T O M A N 
Hi Synaptoman.
Your proposal sounds great and I am sure may well be quite feasible. (Not sure about this as I am not a plumber.)
I got over this problem of cold water (as well as hot , spent water) wastage — by installing a grey water collection system (Known in my case as a -“Water Rhapsody”) to which all my waste water outlets (excluding obviously- toilets, dish washer and kitchen sink outlets) are connected and which is in turn pumped onto the garden (good fertilising, especially from washing machine powder) AND nothing is wasted! Let me know if you need any further info on this system. Had them in operation for 10 years now!
you need to consider the conductive power of the metal pipes which deliver the hot water, this is the main cause of initail cold water delivery. only once the pipes are hot (or at least warm) will hot water be provided. Therefore changing the pipework, you’ll probably be able to sell the scrap copper pipes for the same as the new plastic ones, therefor no investment needed, also insulating the pipes would mean that in a family house only the first person has to wait those who follow will benefit from your initial input.
Clive and Richard. Good points. The power of collective thinking strikes again.