Your hot water meter buck meter is dependent upon 4 items, only two of which you can control once a system is installed.  The 4 items are temperature rise, energy conversion efficiency, hot water consumption and cost of the energy. Let's take a look at them.

First the water temperature change that occurs in your water heater is called a temperature rise.  You raise the normal incoming water for your home or business from about 50°F to the water temperature setting at your water heater, usually set at 120°F.  The difference is a 70° temperature rise. 

Are there variances in the above numbers? Yes and it varies by the season and place to place.  The incoming water temperature to the home or business, regardless if it is a well or city water source averages 50°F around here, but can seasonally change between 45 and 55°F.  Greater or smaller variations can occur if your lines are at some other depth than 4 feet.  A tank type water heater with the newer controls hold the water at 120°F within a 10 or 15 degree range. 

The tankless water heater holds the outlet temperature pretty close to the 120°F setpoint and may be +3 to 5 high momentarily and has what is known a cold water sandwich due to system time delays.  Sudden restarts can cause excessively hot surges in some cases.  An improvement on the so called tankless is the mini-tank that dampens out those thermal excursions giving a very uniform delivery temperature.  For almost all applicatons, the best performing units on the market are direct vent, condensing, mini-tank, recirculating units.  Although it may look somewhat simple, the quality manufacutuers require a professional to install them to just validate the warrantee.

The water heater should be set at 120°F.  Some people set them higher, but the risk of scalding and personal injury is present.  You should have some other things to protect people from burns with the 120°F setpoint that Dan can provide and install.  Any water at the tap or shower over 110°F can easily burn you and especially children and older.  Setting the temperature under 120°F only invites biological growth in your water heater.  Commercial kitchens need at least 140°F and higher.

Second is the water heater's efficiency.  Efficiency is the measure of how well the energy in fuel you buy is transferred to the water as heat.  Nothing is 100% efficient.  Gas (natural gas, propane) fired water heaters, tank style or the tankless kind have an efficiency in the range of 78 to 83% pretty much regardless of the brand.  There are a few condensing type and their efficiency get up to the 92 to 94% range.  There are open condensing water heaters with USDA and FDA approval that are in the 98% range.  Oil fired water heaters are in the 80% range when properly set up and maintained.  Coal and solid fuels are anywhere from 5 to 50%.  An electric water heater has a nominal 98+% efficiency at your user point, but when you add in the power generator station and transmission efficiency the net result is in the 40 to 45% range.  Unless you know differently you can safely assume an 80% efficiency for gas, oil water heaters, 98% for electric and 20% for coal and solid fuel.

A word of caution.  Some people think that a DIY blanket around an existing water heater makes the unit more efficient.  Actually, you may void the manufacturer's warranty and increase the risk if a fire by melting wires besides increasing standby heat loss.  Heat loss increase has something to do with a log ratio of the various insulating systems and increased surface areas.  If you want to reduce your standby losses, the goal of the added blanket, it is better to obtain a new and better insulated water heater or upgrade to tankless water heater.

Third is hot water consumption.  The consumption is flowrate, duration and frequency dependent.  These factors are ones that you have control.

Flowrate is device limited.  A shower head or a faucet are the two most frequent devices that use hot water and can be handled much like a light bulb.  With an Unlimited Hot Water Flow Limiter or an Unlimited Hot Water Aerator flows and thus consumption can be significantly reduced saving water, but more importantly saving energy bucks.

A normal water faucet has a 2.2 GPM aerator.  The average handwashing is 1 minute duration and occurs about 5 times per person each day.  Thus on the average each person uses 11 gallons of water.  The mean wash water temperature is 105°F, which says the faucet is blending cold water with the hot.

When a correctly selected Unlimited Hot Water Aerator rated for 1.5 GPM is installed, the average water usage drops to 7.5 gallons per day, a saving of 3.5 gallons of water.  Because the water is blended the net effect on the water heater is 2.96 gallons per day less of hot water drawn.

For discussion purposes let us use the cost of natural gas at 12.00 $/million BTU.  I have been tracking the costs of fuels for over 35 years and when the efficiencies that I stated above are factored in, all the fuels come out to about the same cost per million BTU with some periodic savings on one fuel or the other for a limited time.

We now have enough information to figure out a savings, but first we need to cover some technical stuff.

We’ll start with the definition of one BTU.  A BTU, short for a British Thermal Unit, is a unit measurement for energy in the English Engineering Unit system.  By definition a BTU is the amount of energy to raise one pound mass of water one Fahrenheit degree between some specific temperatures at a constant defined pressure.  A gallon of water weighs about 8.34 pounds.   

There is a formula that we can write that ties all this information into dollars and for us to make sense out of what we are doing.  The question is, does an Unlimited Hot Water Aerator pay for itself and save me money.

(temperature change x (1 / equipment efficiency) x (mass) x (fuel unit cost) x (period of time evaluated) = Bucks

Subsituting our values into the above formula and examining the annual energy savings:

(70F° temperature rise) x ( 1 / 0.8 equipment efficiency) x ( 2.96 gallons/person-day x 8.34 pounds/gallon) x (12.00 $/1,000,000 BTU) x (365 days per year) = 9.46 $/person-year

Most Unlimited Hot Water Aerators when part of a service call usually cost under $9.00 each installed.  That is a simple payback on investment of 1 year or so.  The nice part of this type of an investment is that it keeps on saving for the life of the installation which is 10 or more years.

This simple example is just one of many places that Dan can help you save energy bucks, water bucks and maintenance bucks. 

Call Dan at 330-268-9208 for an engineering evaluation of your current hot water supply system or for your new Unlimited Hot Water system.