Dual Water Heaters - parallel or series

[An HI]

Originally Posted by gromicko

One should note that in predominantly colder climates, it doesn't matter anyway. The energy loss from heating up water on a parallel system that isn't immediately used doesn't disappear. It is lost to the air eventually, which someone is paying to heat anyway.... and besides, tanks are super insulated these days. Turn off your water heater, go on vacation, come home and feel the water... it's pretty warm. Most of the heat loss is suffered in the piping to the fixtures.

Not necessarily.

Some electric tanks have EF's (Energy Factor = efficiency rating) as low as .81 and gas tanks are as low as .56-.57 . The R values of today's foam tank insulation are about 10-13, hardly super insulated, but much better than the fiberglass of past with only R 5-6.

If your electric tank is in a cool spot such as a storage room or not fully or directly heated basement, extra tank and pipe insulation, heat traps (some are now internal to the tanks) plus bottom insulation has a short payback period of probably less than a year. The extra 20 or so degrees lower temp. in these spaces certainly warrant the above.


Here is what the DOE has to say:

"Insulate Your Water Heater Tank for Energy Savings

Unless your water heater's storage tank already has a high R-value of insulation (at least R-24), adding insulation to it can reduce standby heat losses by 25%–45%. This will save you around 4%–9% in water heating costs.
If you don't know your water heater tank's R-value, touch it. A tank that's warm to the touch needs additional insulation. (this is a poor statement-HI)
Insulating your storage water heater tank is fairly simple and inexpensive, and it will pay for itself in about a year. You can find pre-cut jackets or blankets available from around $10–$20. Choose one with an insulating value of at least R-8. Some utilities sell them at low prices, offer rebates, and even install them at a low or no cost.

Insulating an Electric Water Heater Tank

You can probably install an insulating pre-cut jacket or blanket on your electric water heater tank yourself. Read and follow the directions carefully. Leave the thermostat access panel(s) uncovered. Don't set the thermostat above 130ºF on electric water heater with an insulating jacket or blanket—the wiring may overheat.
You may want to see our instructions for installing an insulation blanket on an electric water heater.
You also might consider placing a piece of rigid insulation—a bottom board— under the tank of your electric water heater. This will help prevent heat loss into the floor, saving another 4%–9% of water heating energy. It's best done when installing a new water heater.
Download high-resolution diagram:
JPG (ZIP 86 KB) | EPS (ZIP 480 KB)

Insulating a Gas Water Heater Tank

The installation of insulating blankets or jackets on gas and oil-fired water heater tanks is more difficult than those for electric water heater tanks. It's best to have a qualified plumbing and heating contractor add the insulation. If you want to install it yourself, read and follow the directions very carefully. Keep the jacket or blanket away from the drain at the bottom and the flue at the top. Make sure the airflow to the burner isn't obstructed. Leave the thermostat uncovered, and don't insulate the top of a gas water heater tank—the insulation is combustible and can interfere with the draft diverter.
Related Information

• Install Heat Traps on a Water Heater Tank for Energy Savings
• Lower Water Heating Temperature for Energy Savings
• Reduce Hot Water Use for Energy Savings
• Insulate Hot Water Pipes for Energy Savings
• Drain-Water Heat Recovery
• Install a Timer and Use Off-Peak Power for Electric Water Heaters
• Select a New Water Heater. "

[KEVIN WOOD]

Good Info HI!