Imagine a touch screen pad next to your tub.  Enter a desired temperature and the tun fills with water at exactly that temperature.  Imagine never running out of hot water again.  Welcome to hot water on demand energy saving water heaters.

How It Works

A hot water on demand system heats water as you need it using gas or electricity.  When you turn on a hot water tap:

  1. Cold water flows into the system triggering the flow sensor.
  2. Powerful burners ignite and heat the water as it flows through the heat exchanger.
  3. Water comes out at the required temperature.  There is no tank or reservoir of water to heat up.  For this reason, a hot water on demand system is commonly called a “tankless water heater”.  

Saving Energy

A hot water on demand system is energy efficient because there is no reservoir to keep hot.  The operating efficiency is not a good measure when comparing a standard system and a tankless system because it does not account for the standby losses.  A better point of comparison is the energy factor.  The energy factor is an estimate of the total energy cost for hot water.  For example, the energy factor for a typical tank style hot water heater is about 0.55.  This means on average, for every dollar you spend on gas you get about 55 cents worth of hot water.  A modern gas fired tankless system has an energy factor of about 0.84.

Saving Money

You can save money with a hot water on demand system.  Most product literature is misleading.  A 20% energy saving is a realistic comparison of a modern tank system and a modern tankless system. Depending on your energy cost and the amount of hot water you use in a year, the payback may be 4 to 9 years. This is not bad when you consider that these systems last about 20 years compared to about 10 years for a standard hot water heater.

Skilled Technician

Thinking of installing a hot water on demand system?  A skilled and experienced technician is a must!  A hot water  on demand system requires a powerful burner to heat the water as it flows past the flame.  The burner has to be powerful enough to heat the water even if several hot water taps are running at the same time.  A skilled technician will know how to size the unit to supply the needs of the home.  A skilled installer will be able to anticipate problems such as an inadequate gas line. The burner in a tankless water heater is so powerful it needs a large gas flow rate.  If the existing gas line is not large enough, a new line will have to be installed.

This article courtesy of Pillar to Post Home Inspections~April 2014

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