Using a Water Heater for Space Heating Part 2
This is the continuation of a look into whether one can and should use a Water Heater to heat their house. Please see Part 1 for a look into heat load and flow rate considerations, as well as health and safety concerns.
Unfortunately efficiency is a non-exact calculation and after much deliberation most of our customers go with a personality choice rather than hard numbers on how efficient they want their heat plants to be anyway. However, we will run through some numbers on cost to give you an idea of what you need to consider.
On the market in the hydronic industry there are usually 2 efficiency categories; high efficiency and standard efficiency. High efficiency units can rise as high as 95-97% efficiency. That means 95% of the heat you burned in fuel was transferred into the fluid of the heating system. Standard efficiency max out at around 85% efficiency. Such that 15 cents of every dollar spent on fuel go up the flue. So we all want to use the highest efficiency unit available right? Well, the cost of high efficiency units may make them cost more and run over the life of the unit than a standard efficiency one, but they come with a much higher initial cost.
Let's take a look at 4 different scenarios for our project house. I will be carrying the cost out to the life expectancy of a boiler at 20 years.
So we can conclude; if we carry out the costs of the systems to the same life span of 20 years
The higher efficiency units will cost less to run over extended time and an investment in a boiler will yield almost a 15% return on your money invested in a stronger heat plant. Initial costs on a boiler will be over 3-1/2 times that of a tank style water heater. But you do get what you pay for. Will your budget allow for an investment for an investment in a high power, long lasting, high efficiency power plant or do you need to tighten the belt and take a shorter life solution.
This is a bit of a throw away point for many customers but it needs to be considered. What warranty will you receive when using your heat plant for your heating system? Since Water Heaters are designed and built for domestic hot water distribution, the manufactures will write their warranties for that application. If you install a water heater for space heating, you will either void the warranty or decrease the warranty to about 1 year. Read the Warranty fine print.
Boiler Manufacturers are usually offering warranties on the boiler heat exchangers for 15-25 years (electronic parts are less). However, if you are do-it-yourselfer and expect to install your own boiler, again read the fine print, you may be voiding the warranty and have to pay for any replacement parts need from installation problems or breakdowns.
Now that you have determined if the option of using a water heater is applicable to you, make sure you let us do a full heat loss calculation and a unit comparison to see what your best choice is. Visit our website or Contact Us at Pexheat.com for more information. We are glad to help.