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Water Recirculating

Hot Water Demand System - Make Your Hot Water System Green!

A hot water demand system will save you time, water, and money!

A hot water demand system is an easy and inexpensive way to save water and have instant hot water (when you turn on the tap).  Your hot water is pumped quickly from your water heater to your sinks, and fixtures and no water gets run down the drain. It will turn your hot water plumbing green.

Tired of waiting for slow hot water?

If you have to stand around waiting for your hot water to reach your sink or shower while you run gallons of water right down the drain, then you need a hot water demand system.

Demand systems works with any kind of water heater including solar and tankless; the water heater only needs to have a common cold water connection with the cold water fixtures.   It makes no difference how the water actually gets heated.

Old fashioned hot water recirculating pumps raise your energy bills since you must keep your pipes full of hot water.  The newer warm water circulating systems such as the Laing Autocirc 1, the RedyTemp, the Astro Express, Watts Premier, and the Grundfos Comfort System do the same thing.  Even the thermo siphon type units such as the Nibco and Hot Water Lobster increase your water heating bill for the same reason.

Not so with a hot water demand system.  It only fills the pipe between the fixture and the water heater with heated water, which you would have to do anyway to get hot water at the fixture. The pump only runs for a few seconds when you want hot water and the cost of running the pump is negligible. A 4 person home would use less than $2.00 a year in electricity.

A hot water demand system mounts under the sink furthest from your water heater. It connects to the hot and cold water supply lines and needs an electrical outlet to plug into. Typically a push button is included and wireless remote switches are available to use from locations other than where the demand system is located.

When you push the start button the pump turns on and when hot water reaches the pump the pump shuts off.

Tankless considerations

Most hot water delivery systems will not work with most tankless water heaters.  Most tankless water heaters require from ½ gallon per minute to ¾ gallons per minute to turn the unit on and keep it on. The warm water circulating systems like the Grundfos, Laing Autocirc, and Astro Express don’t have enough flow to turn on the tankless heater. This is also true of all thermo siphon systems like the Hot Water Lobster and the Nibco device.

Not all hot water demand systems produce enough flow either. The Metlund S-50T is not recommended for tankless hot water for that reason, and the Metlund S-70T is only recommended for systems with short piping runs.

Dedicated Return Lines

If your plumbing is equipped with a standard hot water circulating system and has a dedicated return line, then in most cases you can simply replace the standard recirculating pump with a demand pump and start reaping the benefits.  You will see a substantial saving on your water heating energy bills.

Map Your Plumbing Layout

If you aren’t sure how your plumbing is configured then there is a straight forward way to find out where to locate your hot water demand system and whether you need more than one pump to cover your entire system.

When your pipes are all cold, like the first thing in the morning, go to the sink that you believe to be the one furthest from your water heater and turn on the hot water faucet.  Let it run until the hot water reaches the faucet and then turn it off. Now go to the fixture that is the next furthest from the heater and turn on the hot water faucet. Time how long it takes to get hot water.

If it shares a common hot water feed pipe then it will get hot water faster than usual.  You can get a one gallon milk jug and measure how much water gets run down the drain while waiting for hot water.

By repeating the process at multiple fixtures after letting the pipes cool between measurements you can determine where is the most beneficial location for the pump and whether you need more than one pump for your home.

Turn your hot water plumbing system green with a hot water demand system and start saving time water and money!

About the Author

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