How to save water by installing a circulation pump and get instant hot water (Part 1 – the water savings part)


Add a hot water recirculation pump to your hot water heater and get hot water instantly without waiting while wasting water. A simple installation provides comfort and water bill savings at the same time.

Over 10,000 gallons of water are wasted in a household every year by letting the water run until the hot water makes its way from the water heater in the basement to the bathroom, usually located in a second floor. The longer the distance between faucet and the water heater, the longer the wait and the more gallons are wasted.  The pipes cool off, especially in the winter months and could take several minutes until the hot water reaches the faucet and the hot water pipe is heated up.

Upgreen-Tip: That water could be collected and used for watering plants, but it is some effort and how much water do indoor plants need, especially in the winter?

The water saving solution

The Watts 500800 Premier Hot Water Recirculation Pump consists of two main components. A water circulating pump installed on the water heater is pushing the water up the hot water pipe and a control valve at the furthest faucet which allows that pressurized “hot” water to be pushed into the cold water pipe. Once the water at the control valve reached a certain temperature, the control valve will close and no more water will pass from the hot water pipe into the cold water pipe. Now the hot water is right at the faucet and instantly available once the faucet is opened – no more waiting. A small downside is that there is now some lukewarm water in the cold water pipe, but that gets flushed out very quick (within a few seconds, no comparison to the long wait for hot water without the pump).

Water savings versus increased energy:

So, we are saving several gallons of water but now we have the electricity cost for the pump (25W) which is pretty small. And the water that circulates back into the water heater has to be heated up again. One could argue that that water is not as cold as the incoming city water since it was already warmed up in the walls of your house. So it could be set up to save energy if the pump does not run too long.

The pump comes with a timer to turn on only during times when the family demands hot water. That is usually only for a few hours in the morning and again in the evening. The timer can be set to these particular times of the day in 15 minutes increments. So you could turn the pump on between 6am and 7am and in the evening between 11 and 12. That would require the pump to run for 2 hours a day at 25W which will add to 1 kWh ($0.15) after 20 days. Warm water is available at other times as well, but you have to wait for it again.

The pump operates very quietly and the installation is fairly simple and should take less than an hour.

To get an idea about how much water is in the pipes: 3/4 inch pipe holds about 1 gallon per 45 feet which cost about 0.014 cents at our water rates.

Other resources: There are several different solutions available which I have not tried out. The pump and valve combined right at the faucet (Demand Recirc Pump) and a solution without a pump (Hot Water Lobster).

Efficiency improvements – Check out the second part in this series:

In order to reduce the times when the pump has to run, it could be controlled by a remote switch instead of a timer. This improvement will be detailed in part two of this series: The energy saving part along with some details about another issue I discovered during my installation: convection losses.
Please check out the second part and let me know if you have any comments.

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