Are You In Hot Water?

by Dave on May 15, 2009

As first appeared in Coastal Sussex Weekly, April 30, 2009:

I remember vividly one cold morning when I was living in my first house – a 951 square foot townhome above my garage with an exterior stair.  I went out on a Saturday morning to pick up the paper and noticed that water was running down the bottom few stairs.  That seemed odd but for someone that has been known to use the wrong side of a hammer, I didn’t know what had happened.  I looked inside the garage and water was pouring out of the water heater.  It looked like replacement time to me….that was ten years ago and there was only one common type of water heater – what is called a conventional storage water heater.  These days there are a few more types and within those two types are varying degrees of efficiency.

It is quite popular these days to use a tankless/on-demand water heater – commonly referred to by the brand name Rinnai (which is just one of many manufacturers).  However, there are energy efficient conventional Storage Water Heaters as well.  These are the typical systems that most of us have in our homes already.  They work in a straightforward manner.  A storage tank, ranging from 20 to 80 gallons, holds hot water. When there is a demand, hot water is released from the top of the tank and replaced with unheated water brought into the bottom of the tank.  The tank is continually heated by whichever fuel source is being used – propane, natural gas, electricity and, on older models, fuel oil.

So what’s efficient/inefficient and convenient/inconvenient about these “tanked” types? Because water is constantly heated in the tank, energy is used even when a hot water tap isn’t running. This translates into energy loss and increased spending especially for those of us who work all day or have second homes.  This loss can be reduced finding a model with a heavily insulated tank (look for R-12 to R-25). Storage Water Heaters can take up a great deal of space, as well.  The amount can vary from nine square feet to as much as sixteen square feet.

Now that we have discussed the more conventional water heaters, let’s take a look at the tankless/on-demand models.  These units provide hot water only as it is needed which means there is no standby energy loss as previously discussed. How does this work? When hot water is demanded, unheated water travels through a pipe into the unit where a heating element heats the water and sends it to the source demanding the hot water.  As a result of not having a tank to heat, demand water heaters deliver a continual supply of hot water.  Natural gas and propane powered models are the more efficient of the two types.

So, what could possibly hold you back from getting a tankless water heater? Well, flow rates for one.  Depending upon hot water demands, these units could “run out” of hot water if multiple fixtures are calling for hot water.  Normally, the supply is around 2 to 5 gallons per minute – gas producing better rates than electric.  For instance, two showers running or a shower and the dishwasher running simultaneously could stretch the supply.  Another item to consider is the debate surrounding the pilot light.  The argument is that a constantly burning pilot light causes waste.  Check with the manufacturer and see how much waste is associated with that and, if you feel strongly, you can buy models with IID (intermittent ignition devices) similar to how some kitchen ranges work.  On the plus side, these units are small, about the size of a standard carry on suitcase, and can be placed in a variety of areas.  Note, however, that natural gas and propane models, just like their tanked cousins, require venting either through the roof or through an exterior wall.  In terms of efficiency, for homes demanding 40 gallons of hot water a day, you can be around 30% more efficient and if you are a heavy hot water needing group, you can still be 10% better off.

Water heaters can really help the efficiency of your home whether you are building, remodeling,     or you find water running down your stairs like I did.  Spending a few minutes researching different manufacturers and checking into your water usage could save you significant money and energy savings each year.

Matthew Peterson is the Principal of Element Design Group in Lewes. He can be reached at matthew@elementdg.com.

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