lol, low 40's :) frosty!! relax mom, the kids are safe! is your Can set up out in the yard? is it layers deep or just started? do you have the "lid" for it? if there's a decent volume of material in multiple trays, with the day temps you're likely having, 40° will be refreshing for them, likely not dropping the actual temp of the bedding more than 10-15° below what it was during the day if there's not much material in it or you have it in a shaded place that stays cool in the day, 40° might slow them down a bit, but won't hurt them at all - my outdoor bin is large, but we're still having night temps as low as 32-38, and with days only about 50-55, the worms are smokin Bill

You will save, but how much? Try this: with heater on a fully up to temperature until it clicks off, measure the temperature at the closest hot water tap after it runs long enough to get hot. Let it heat up fully again, shut it off, wait 10 hours, and measure the temperature at the tap again. I'm going to guess about 10 degrees lower. The energy lost, in kilowatt-hours, is E = dropT(f) * Gallons * 8 / 3412 where dropT(f) is the difference in water temperature in degrees F, and Gallons is the capacity of the water heater. "8" is the number of pounds per gallon for water. Dividing by 3412 converts from BTU to kwhr. Multiply by (30 days * 24 hrs /10 hrs) to find kwhr per month, and see how that would affect your bill. If the drop in temperature is a lot (say 30 degrees), you should repeat the test with less time -- problem being that the tank loses heat slower as it cools, which makes the error in the simple calculation get worse. I can provide an exponential equation that is accurate if you are interested, but you'd need to know the ambient temperature. Anyway, that gives you the rate of heat loss from the tank when it is close to hot. That is approximately the amount you could save by turning off the heat totally while gone for months vs. just leaving in on, and represents an upper limit on how much you could save. In your case, you are going to have to heat that water again after only a few hours, and the tank will stay pretty hot, so you will not save as much. Come back with the test results, including the ambient temperature around the tank, and we can estimate that pretty well.

Yes, they do make electric tankless water heaters. You can find some at the link below. Contrary to wild claims, In a standard home usage, there is almost no energy savings with an electric tankless heater. There is about a 25-30 % savings with a gas tankless heater. There might be more of a savings with an electric tankless in your application since hot water isn't being used often. Electric tankless, like electric tank heaters, don't require venting. There is a serious drawback with electric tankless in that they draw very large amounts of current and produce relatively small flow rates (measured in gallons per minute) If I remember right, a tankless electric unit that produces about 3gpm will pull about 100 amps. (the gpm will depend on your water temp going into the heater). Three GPM is a shower or would fill the washing machine slower than normal (washing machines are about 4gpm) If you don't have an extra 100 amp capacity to the barn, I wouldn't go with an electric tankless. I would go with a very well insulated electric tank unit. Pick up a unit with 2" of foam insulation and add a water heater blanket to it. Here is a link that might be useful: Electric tankless

I can remember back in the late 50s and early 60Âs when fuel was cheap the water heaters were operated at 180degF and they had no insulation or external jacketing. In those days there was a great concern that people were accidentally bumping up against the water heaters and receiving severe burns. The standards were then amended requiring that all water heaters must have a minimum of ¾" of fiberglass insulation, a sheet metal jacket and under no circumstance could the external temperature of the unit exceed 140degF under normal operation. During the first fuel crisis in the mid 70Âs people were encouraged to install additional insulation blankets to reduce the standby losses from the water heater, however it was soon realized that if an insulation blanket is improperly installed it interferes with the normal function of the water heater thermostats and temperature & pressure relief valves causing very erratic temperatures and in some instances creating safety issues. In addition, quite often when the insulation blankets are improperly installed they interfere with the normal flow of combustion air and result in very high levels of carbon monoxide. In the late 80Âs the plumbing codes were again amended requiring that ALL water heaters must now have a minimum of R-12 insulation. REF: International Residential Code IRC-504.2.1(en) Uniform Plumbing Code UPC-150(j)1A(c ) The codes specifically sayÂ"No external blankets required" Many local codes have amended that wording to say "External Blankets Prohibited". In my jurisdiction there is a $50 fine for even selling a water heater blanket. In order to meet the new insulation standards most water heater manufacturers have discontinued the use of fiberglass insulation and they now use cast in foam insulations, which often far exceed the required R-12 minimum Everyone seems to be fixated on the supposed high energy wasted to standby losses from a tank type water heater, but in reality such is not the case. Two years ago our plumbing apprenticeship class, in co-operation with the local gas company and a number of local hardware stores, appliance dealers and plumbing suppliers set up a project to test the actual cost of water heater standby losses. Twelve different makes and models of residential contractor grade 50gal gas tank type water heaters were installed in an unheated warehouse. All 12 units were fed from a common water line and each water heater is supplied through a separate gas meter. Each water heater is then fitted with one line on the output side that terminates into a keyless hose bib beside the unit, thus there is no demand from these water heaters therefore they represent standby losses only. The water heaters were then filled and left standing with the thermostats set at the code maximum of 120degF. Every month the gas meters are read and the fuel cost is computed at the standard residential rate for this area. After two years of following this project it has been determined that the monthly average standby loss is $5.02. (The worst case in the test is averaging $5.87mo.) I might add that two of the water heaters in this test have specific wording in their installation manuals that states the addition of an insulation blanket will void the warranty.