posted 11 years ago
Hi Sherri,
In order to understand how the blanket works, it might help to stop thinking about it at reflecting heat and start thinking about it as reducing the amount of heat your water heater emits to the surrounding area. If you are interested in learning more about radiant heat transfer check out this website :
web.ornl.gov/sci/ees/etsd/btric/RadiantBarrier/rb2.shtml
Adding insulation to your water tank will reduce heat loss from your water tank, but only marginally help that third person get a hot shower. Let me explain : when the first person starts taking a shower, the water tank starts out hot - usually somewhere between 120—140 degrees Fahrenheit. As the first person showers, hot water is removed from the tank and replaced with cold water. Soon the heating element in the tank will turn on to try to keep the tank at the heating setpoint. The heating element in a domestic water heater usually isn't large enough to keep up with the full flow of the shower. Usually enough hot water for a shower is provided because there is enough extra heat in the tank to make up the difference. So, after the first person showers, maybe the tank temperature has dropped 15 degrees. If nobody else gets in the shower, the heating element stays on for a little while and gets the tank back up to temperature. However, if someone else gets in the shower before the tank heats back up,the heating element can't keep up with heating the flow of incoming cold water.
When you installed the low flow shower head, you reduced the flow of cold water into the water heater. This means less load on the heating element. Maybe even low enough that the heating element can keep up completely. So now, at the end of the first shower the water temperature in the tank has only dropped 5 degrees, or maybe not at all.
Most water heaters have a thermostat somewhere on the tank. If you are curious, check out what the tank temperature is immediately before and after you shower. You could even put your old shower head back on and check the temperatures before and after.
Lastly, remember how I said that water heaters are usually kept somewhere between 120 and 140 degrees Fahrenheit? Well... and here is where the real energy savings are. If, with your low-flow fixtures, you now find that you are having a comfortable third shower, you could lower the setpoint temperature of your tank. This will reduce heat loss to the surrounding area ALL THE TIME. I suggest lowering the tank temperature 5 degrees at a time until you find the point at which the water gets too cold.
I hope this helps and that my descriptions are clear! Feel free to ask questions.