chestercheeto48

I had an idea the other day while sitting around the house on how I could boost the efficiency of the water heater in the house that we bought. My basic idea is this - add an extra tank to the inlet side of the water heater to hold water and let it warm up to ambient room temerature before it goes into the water heater to be heated.

Is this a dumb idea or is there some merit to it? As I see it we would get a tank bigger than the capacity of the water heater. I doubt we would rarely go through that much hot water. I would think that the water in the tank would be warmer than the water in coming straight from the water main therefore saving me some money. It would probably be small in terms of saving but hey it was just an idea.

I know that there are some solar based systems like this on the market but does anyone know of a system that is just a tank that sits in your basement?

How hard would it be to build?

ScrapinSTi

Not worth it... The water will already be ambient or close enough for the mostpart... The coils will heat it up just as fast at 70 degrees as it would at 45 degrees... Its getting the heating process of the water started that takes more time...

petriej

The water in your standby tank will have too much thermal capacity and not enough surface area to conduct heating


The law of heat conduction, also known as Fourier's law, states that the time rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area at right angles, to that gradient, through which the heat is flowing:
where
Q is the amount of heat transferred, t is the time taken, k is the material's conductivity. (this generally varies with temperature, but the variation can be small over a significant range of temperatures for some common materials.), S is the surface through which the heat is flowing, T is the temperature.
Linear heat flow


The above differential equation, when integrated for a simple linear situation (see diagram), where uniform temperature across equally sized end surfaces and perfectly insulated sides exist, gives the heat flow rate between the end surfaces as:
where
A is the cross-sectional surface area, ΔT is the temperature difference between the ends, Δx is the distance between the ends. This law forms of the basis for the derivation of the heat equation. R-value is the unit for heat resistance, the reciprocal of the conductance. Ohm's law is the electrical analogue of Fourier's law.

Courtesy of wikepedia: Heat conduction - Wikipedia, the free encyclopedia