If you have a tankless water heater then you probably already know that it takes longer to get hot water with a tankless water heater than with an old fashioned storage tank type water heater. While you wait for the hot water to arrive, you are running water down the drain. What a shame to have to waste water to save energy. But there is something you can do to change the situation.
There are hot water pumps designed specifically to get you your hot water faster, and they eliminate running water down the drain while you are waiting. These pumps or pumping systems are called “Demand “hot water systems. There are several manufactures of such systems.
Let’s take a minute and examine the reasons for the lengthy delay in obtaining hot water at the fixtures. Back in the old days, when there were no low flow fixtures, you could get your hot water pretty fast, but you still used just as much water. When you have a faucet that spews out 6 gallons a minute your wait is pretty small. For example, a ½” diameter pipe 63 feet long holds a gallon of water. So if your fixture allows water to flow at 5 gallons per minute, it would take only 12 seconds for the water to flow through the 63 feet of pipe. If you have a low flow faucet at the sink which only allows a maximum of 1 gallon per minute, it will take 60 seconds for the water to reach the fixture. Quite a difference.
But wait, there is more. Since the pipe material is cold, (unless you recently used hot water), it will absorb heat from the water as it flows to the sink until the pipe warms up to the temperature of the water. The colder the pipe the longer it takes to get hot water to the sink.
Tankless water heaters don’t have a tank full of hot water waiting to be piped to the fixture at a moments notice…first you have to heat the water. A tankless water heater is like a coil of pipe with a burner under it. In order for the water to get hot it must stay in the flames for a certain period of time. When you turn on your hot water the water in the middle of that coiled up pipe won’t be in the flames long enough to get hot. The water needs to travel through the entire coil pipe to reach full temperature. So add the time it takes for the water to travel through the coiled up pipe in the tankless water heater.
So what do we do about it? We can pump the water in a loop from the outlet of the heater through the hot water piping and cold water piping back to the water heater inlet. If we turn the pump off just before the hot water reaches the fixture we won’t get hot water into the cold water piping and our hot water arrives much more quickly. And as an added bonus no water gets run down the drain at all. It turns your hot water system green!
These demand hot water systems put a small pump at the furthest fixture from your water heater and connect them between the hot and cold water lines. There is a temperature sensing element in the pump that shuts the pump off when an increase in temperature is detected. This prevents hot water from getting in the cold water line. You do need a power outlet under the sink to plug the pump into.
Now when you want hot water you just push a button, and the pump takes over delivering hot water to the fixture fast without wastefully running water down the drain. Most manufacturers also have remote control accessories to activate the pump from other sinks that may benefit from the same pump, and even to activate it by detecting motion etc.
There are a number of systems that will work with tankless water heaters, but not all do. Standard circulating systems will not work, it must be a “demand” system, otherwise it will void the warranty. Even some demand systems won’t work unless they have a pump powerful enough to activate the tankless water heater. Tankless heaters need a minimum flow rate to turn on and stay on.
Hot water demand systems range in price from about 0.00 to over 0.00. Studies have shown that a typical family of four can save over 10,000 gallons of water per year. Needless to say, by not using all of that extra water you help reduce the energy required for pumping and treating the water before it gets to your home, and after it’s send down the sewer. Reduced energy usage means reduced amounts of green house gases being released into the atmosphere.
If you have a tankless water heater think about helping preserve our planet and reducing your carbon footprint with a demand type hot water delivery system.