Table of Contents
Water Heater Appliance Types 2 - Gas, Electric, Oil, and Tankless water heaters were covered on page one, and on page two we cover boilers with domestic water heater coils, heat pump water heaters, and solar water heaters. Please navigate back to page one if you want to peruse gas, oil, electric, or tankless hot water heaters.
Water Heater Appliance Types 2 | HVAC and Plumbing
Boilers with Domestic Water Heating Coils - Many people who use hot water boilers for their heat also use a domestic hot water coil in their boiler which produces hot water for domestic use such as showers, washing clothes, dishes, and other hot water domestic uses. After all, a hot water boiler is used for making hot water so what better to use it than use it to make hot water for domestic use?
The hot boiler domestic coil is located inside the boiler heat exchanger and uses a constant supply of water from the city or pump and heats this water as it passes through the coil. This water supply is separated from the water supply which is in the boiler loop.
It is not the same water and has a different pressure than the water inside the hot water loop used for heating the home or business. The controls for a hot water boiler with a domestic coil are different than just a standard hot water boiler used only for heating.
Similarities Between Boilers and Tankless | Water Heater Appliance Types 2
This way of heating water for domestic use is similar to a tankless water heater although many hot water boilers with domestic coils use a hot water storage tank to store the hot water until it is needed.
Some of these systems do not have a storage tank and they need a way to temper the water before it is delivered to the user for hot water use because the boiler setpoint is typically 180° F. and this simply too hot for domestic use.
Anything over 120° F. can scald you so hot boilers with domestic coils uses a tempering valve. This tempering valve mixes cold water with the hot to temper the water to a more useful temperature.
Some of these tempering valves are automatic and some are manually set by the installer when they start the hot water boiler system up. One disadvantage of using the hot water boiler for domestic hot water production is that the boiler will also run in the summer. This will add heat to the location where ever the boiler is installed. If the hot water boiler is installed in the home then this adds heat to the home and makes the air conditioner work harder.
This is definitely a long-term decision to make if you choose this method for hot water heating because boilers typically have life spans of 30 years or more especially the cast iron boilers.
Supplemental Storage Tanks | Water Heater Appliance Types 2
I would recommend to you that you have a storage tank that feeds off the hot water boiler domestic coil. The water can be better tempered for domestic use and you can always convert the storage tank to a regular hot water heater if you are less than happy with the use of the domestic coil for the production of your hot water.
Heat Pump Water Heaters - Water Heater Appliance Types 2
A few manufacturers have come out with heat pump water heaters where the heat pump is integral to the tank and completely separate from your heating and cooling system that heats and cools your home. Rheem, AO Smith, General Electric, Stiebel Eltron, and others are currently manufacturing heat pump water heaters where the heat pump is integral to the tank of the heater.
The heat pump uses the process of refrigeration to add heat to the water. A heat pump water heater is very efficient compared to the conventional gas or electric hot water heater. Efficiency ranges for heat pump water heaters can exceed the conventional water heater by a factor of 10 or more on the efficiency ranges.
The downside is these water heaters can be slow to recover and many have a backup heating source such as electric heating elements for quicker recovery times so during times when you need the heater to recover faster you may not realize the high-efficiency ranges of using only the heat pump process for heat.
Regardless, this water heater will save you money on utility bills because of the higher efficiency ranges compared to conventional heaters.
Geothermal Heat Pump Water Heaters - Water Heater Appliance Types 2
(Geothermal Heat Pump with Desuperheater) - I have not seen too many of these around probably because the cost of the installation is higher than the cost of a conventional or tankless system. However, a heat pump water heater can be up to three to four times more efficient than any of the other types of water heaters excluding solar systems which are also costly to install.
They do exist and the few heat pump hot water heaters I have had the opportunity to work on are good producing systems as reported by the end-user. Basically, the heat pump makes the water hot using the refrigeration process.
The refrigeration process moves heat from one place to another and in this case, for a heat pump heater, it moves heat into the water from the air or for geothermal heat pumps into the water from the ground.
A geothermal heat pump is good for most geographical locations but an air source heat pump is only good for Southern climate regions (Northern Climate Regions if you are in the Southern Hemisphere) where the winters are very mild. Most heat pump systems use the geothermal heat pump process to produce heat.
Solar Water Heaters | Water Heater Appliance Types 2
Solar Hot Water Heaters - As with the heat pumps the solar systems are rare but they do exist. The most likely reason solar heaters are rare is the fact that solar heater systems are costly to install. However, over the long term, the payback for having a solar system installed is vastly different than the conventional heater.
With payback in less than two years compared with the payback for other heating systems being four to five years plus factoring in the cost of the system to install you can easily save mucho dinero (lots of dollars) in the long run for having a solar system installed for your hot heater heat production.
It is important to have an expert size these systems and they are usually sized by making a calculation on the amount of hot water you intend to consume based on the number of people living in the structure. There is also occasionally required maintenance for the loop system in the solar system.
Usually, a glycol mix of water and glycol is used for the loop and it is necessary to check this mixture from time to time and change it if necessary.
Water Heater Appliance Types 2