1) Determine the Amount of Hot Water You Will Use at Any One Time-
To determine the required capacity of the unit, you will need to look at your family’s hot water use and the potential for multiple sources of hot water use at any given time. By adding together the Gallons Per Minute (GPM) for the most hot water in use at one time, you can determine the size of the unit that you will need.
Kitchen Sink- 3.0 – 5.0 GPM
Dishwasher- 1.0 – 2.5 GPM
Bathroom Lavatory- 0.5 – 1.5 GPM
Shower- 3.0 – 5.0 GPM
Clothes Washer- 1.5 – 3.5 GPM
For example, many families find their peak hot water use may occur in the mornings, as multiple showers and lavatories are being used at the same time. This can be managed by staggering shower time or washing clothes and dishes at non-peak times.
2) Determine the Temperature Rise for Your Home
You will need to determine the difference between the temperature of the water coming into your home and your desired hot water temperature. In Charleston, SC we range from 55 degrees F to 60 degrees F according to the EPA’s map for average groundwater temperature. I have always just used 57 degrees F for these and other calculations. If your desired hot water temperature is 120 degrees, then your Temperature Rise will average 63 degrees. If your supply lines are not insulated, the Temperature Rise may be greater.
3) Shopping for Your Tankless Water Heater
There are many brands and vendors to choose from when looking for a water heater. Compare the Energy Factor or “Energy Guide” for different units as well as bundling of items such as remote control thermostat to select which model is best for you in the short term and long term.
4) Pick a Central Location
Many people confuse an exterior tankless system with the “instant hot water” or “point of use” units that are used under cabinets in certain situations. You should find the location that balances the distance to your most heavily used fixtures and appliances with the access to and availability of existing gas lines, electrical circuits, and plumbing. Also consider how well the proposed mounting location is ventilated, and whether there are combustible materials in the immediate vicinity. The required clearance will vary per manufacturer, but you should assume a minimum of 1” to the sides, 12” to 36” on the front, and 18 “ from the floor (not including flood zone requirements).
5) Have Your Tankless Water Heater Installed by a Certified Technician!
I cannot stress this enough! Aside from the obvious safety concerns, “do it yourselfers” may find that their warrantee is void or that they are not eligible for any rebate offered by their power company or their federal tax benefit. Any savings will be offset by potential costs later!
Call or email me today if you are interested in finding out how quickly you can add value to your home, reduce power consumption, and increase the resale price all at the same time!