Tankless Water Heaters – Color Yours Green!

Going green is getting to be quite a popular thing to do these days.  Many people are purchasing tankless water heaters with the idea that they are purchasing a “green plumbing product”.  But just how green are they?

Well, are they greener than a standard tank type water heater?  They are not more efficient at heating water than electric storage water heaters or gas water heaters.  However, they do not have a storage tank and therefore do not suffer the standby losses that a tank type heater has.

Water Heater Standby Losses

Standby losses result from heat energy leaking out of the tank of hot water.  Even if you don’t use any hot water, the heat keeps leaking out, and eventually the water temperature inside the heater drops to below the thermostat set point and the heater comes on heating the water back up to full temperature and the process continues in an endless cycle.

With a well insulated tank the standby losses aren’t particularly large. You will save some energy but not a lot with a tankless water heater compared to a tank type water heater.

Endless Hot Water VS Human Behavior

Human behavior is probably a more significant contributor to going green.  For instance, since you never run out of hot water with a tankless water heater, you may end up taking longer showers.  It doesn’t take much additional shower time to completely obliterate any savings due to reduced standby losses.

It takes tankless water heaters longer to get hot water to the fixtures than it does a storage type water heater, so more people will turn on the hot water and do something else before coming back to take the shower. By that time hot water is running down the drain; a waste of both water and energy.

Point of use water heaters

Just the fact that the tankless water heaters take longer to deliver hot water to the fixtures means that more water will be wasted with tankless units.  That is hardly going green. 

Point of use tankless water heaters do not suffer this water conservation problem.  If the plumbing layout is such that the water heater is very close to the fixtures then you have a green plumbing system… saving water and energy both at once.  If you are contemplating building a new home you should consider using a green plumbing layout.

Both water and energy will continue to get more expensive and by planning ahead you could end up saving thousands of dollars over the life of your home.

Water Heater Pumps

If you don’t have a green plumbing layout then you might want to consider using a water heater pump to speed up your hot water and eliminate running the cooled off hot water left over in your pipes from the last hot water use down the drain.

You gain the convenience of faster hot water and you save a lot of water. 

Hot water recirculation pumps

One class of pumps is the old standard circulating pumps, often referred to as “recirc pumps”.  They slowly circulate hot water through the hot water piping system to keep hot water in the pipes at all times.  You have “instant hot water” whenever you want it.

These pumps can be placed on timers so they don’t run during periods when no hot water is expected to be needed… like late at night.

They are extremely wasteful of energy, but save plenty of water.

Laing Autocirc, Watts Premier, and Grundfos

Laing, Watts, RedyTemp, and Grundfos all manufacture hot water pumps that are basically a modified version of the old standard recirc pumps.  Instead of keeping the piping full of hot water these pumps keep the pipes full of lukewarm water and generally utilize the cold water pipes as a return line.

They don’t waste as much energy as the older systems, but they still waste significant amounts of energy, and many users complain that the cold water is no longer cold…it’s lukewarm and they don’t like that.

These systems generally will not work with tankless water heaters because they don’t pump enough water to turn on the water heater.  Many tankless water heaters are not compatible with circulating system and will void the warranty when one is used.

Metlund, Chilipepper – Tankless Water Heater Pumps

There are a class of pumps known as “hot water demand pumps” that are compatible with tankless water heaters and standard storage water heaters as well.  Demand pumps are only activated when the user pushes a button “demanding” hot water.  The pump comes on and sends hot water to the fixture at high speed and shuts off when the hot water arrives.

As long as the pump you use is powerful enough to turn on the tankless water heater, then it will work and won’t affect the warranty.  It provides you with water savings and after the pump shuts off you have instant hot water at your fixture. Some models are as little as $179.00.  They use very little energy since the pump only runs when you request hot water and typically use less than $2.00 per year in electricity costs.

Hot water demand systems are truly green plumbing products and should be at the top of your list of water conservation products.