Bruce
Herd Master
Mobile homes used mostly 110 hot water heaters, usually 5-20 gallon size. Also, there are hot water heaters that are "ON - DEMAND" (most are propane) and will heat the water almost instantly and will keep heating it as long as it is run thru the lines. Most dairies now are replacing the old hot water tanks with on demand water heaters as it keeps the water hot and there is no recovery time. If I get my own house that is one of the first things I will get. They cost about twice what a hot water heater costs, but the life is way longer with no heating elements to burn out ( for electric) and no tanks to leak, and constant hot water...The one that is motion activated is made specifically for places with no electricity. Way more efficient than having a tank keeping water hot for only a couple hours usage a day.
Or NOT! We had one put in when we redid half the house (the half with water usage ) Worst thing for residential use since moldy bread. Why?
- Turns on only after 0.5 gallons/minute is detected for 3 seconds. Great for showers, baths or other "constant running" usages, totally sucks for everything else. Unless you let the water run constantly you get 3 seconds of cold water put in the pipe every time you turn it off then back on. Think washing a couple of dishes without filling the sink. I hear the propane water heater kick on then off every time I turn the water on for a quick rinse. And the propane is wasted since it isn't on long enough to heat any water. Or non electric shaving, followed by a shower. That is where I figured out the hit from this. Ran the hot water until it reached the sink, that left about 24' of 3/4" pipe full of hot water. While shaving I would turn the water on briefly many times to rinse the razor. Cold water filled in behind the hot water in the pipe every time. Then to the shower. Run it until hot, not too long since the hot water has already made it to the sink 8' away. Get in the shower, a short time later that slug of cold water hit then it got hot again.
- It takes time to get the propane heater up to temp once it "starts". I watched the gauge on the outlet side while someone was taking a shower. It wasn't up to the 120F set point for a couple of minutes IIRC. When it turns on AFTER the 3 seconds, it has to run the evacuation fan before it lights up. No hot water flowing then. And the heat exchanger isn't hot right away, water coming out of it is WARMING but not HOT for a period.
- Most water using appliances today use WAY less water than they did when the on demand water heaters came out. Our washer sprays a bit of water, then tumbles to get the clothes wet, spray more water, tumble some more. It will never get anything but cold water until it starts to fill and even then it isn't pulling in much water.
- They are frigging expensive, especially after you pay the plumber to install it. Lots of parts and electronics to go bad. Mine also has a filter screen I have to remember to take out and clean with some frequency even though I have a filter between it and the well pump pressure tank.
Another option, assuming your basement (unlike mine) doesn't freeze or you put it in heated space, is a heat pump (hybrid) that uses the electric elements only when the heat pump can't do the job due to demand. The heat pump is a more efficient user of electricity than the electric elements.