We have a lot of residential plumbing customers who want to become more environmentally friendly. Most want to start with the purchase of a tankless water heater in hopes that they can save substantial amounts of money on their utility bill and it is considered "green".
However Floridians and other warm climate residents should be mindful of over zealous marketing of tankless water heaters. When it comes to looking at all of the costs involved, you may not be able to save as much money as advertised with this type of water heater.
It is true that tankless water heaters are more efficient than their counterparts. Tankless water heaters can operate at over 80 percent efficiency, while tank water heaters generally operate at 50 or 60 percent.
This will allow you to save a little bit of money on your heating bills at the end of the year.
However, here in Florida both water heating methods have less work to do. Considering they have to warm the incoming cold water more in Michigan than Florida since the groundwater coming into the unit can be 30°F colder in Michigan (42°F) than Florida (72°F). According to Florida Power and Light, the water heater uses a large amount and the average household spends about $15 per month to heat water.
Tankless efficiency comes at a price quite a bit more than what you could buy a traditional water heater for. In fact, many of them cost as much as three times more than a regular water heater. In addition to that, you will have to run special lines into the water heater which can get very expensive if you are installing one into an existing house.
With this large initial investment, it would take you many years to be able to break even on your original investment with the savings that you are realizing from the utility costs. Many estimates have said that it would take you over 15 years to repay the initial cost of purchasing the tankless water heater.
For a much less investment and efficient alternative, consider a Hot Water Recovery Unit. Most in Florida have and use central Air-conditioning or a Heat pump system that the Hot Water Recovery Unit on the cooling cycle uses heat that would normally be wasted to outside air to help heat the water.
Using a Hot Water Recovery Unit to recycle wasted heat from your central A/C to provide free hot water to your tank hot water heater, thereby removing the cost of hot water from your electric or gas bill.
A hot water recovery unit added to your central A/C unit can almost offset the cost of running the air conditioning.
If you have a heat pump unit then the savings are even greater. A heat-pump unit typically uses 1/3 (33%) the electricity to make heat as straight electric heat. Of course, an electric water heater uses 100% electricity to make heat. If connected to a heat-pump whenever the unit is running, hot water is being made at a reduced rate.