tank water heater

silversport · January 01, 2018, 11:49:43 AM

I am curious, has anyone done the numbers, what is the most efficient way to heat water, leaving the LP on all the time or turn on XX amount of time before use each day. Was sitting out side my coach one afternoon noticing how many times it turn on an off to keep the water hot.

Gary Hatt - Publisher BCM · January 01, 2018, 12:33:58 PM

Water heaters use a lot of unnecessary propane and/or electric if you also have a heating element in it. I recommend buying a 30 minute Potentiometer timer (maybe a 60 minute timer for 2 people) and cranking it up about 10 minutes before you are ready to shower. That is what I did and it saved me trips to the Propane filling station and also some electricity as I also had the 110V element in mine.

luvrbus · January 01, 2018, 12:36:16 PM

We turn ours on 10 minutes before we need hot water works for us

Dave5Cs · January 01, 2018, 01:23:53 PM

Same as Clifford And turn Water Heater switch off when we are done. We leave the LP tank on when parked unless we need the force air heat traveling.

Utahclaimjumper · January 01, 2018, 04:04:44 PM

Same here,, 15 minutes before use and kill it after,, it will stay hot for most of a day or night.>>>Dan

kyle4501 · January 01, 2018, 05:12:48 PM

Our 12 gal water heater has an engine coolant loop inside it to heat the water while travelling.
Often I'll forget to turn on the electric element when we park for the day. After washing evening dishes, there will be enough hot water left over for my morning shower. If the wife washes her hair, she will will be lucky to have a luke-warm rinse.

Takes almost an hour to recover with just the electric element.

chessie4905 · January 01, 2018, 05:52:45 PM

You can change to a higher wattage element for faster response.

PP · January 01, 2018, 05:53:08 PM

Running our 6 gal Atwood on Ac it uses about 2 KW/day with normal use (no showers but lots of dishes and handwashing) at 45°F ambient outside temp.
HTH Will

Scott & Heather · January 01, 2018, 09:39:34 PM

Um, doesn't the thermostat on the water heater perform the same function? It turns off when temp is reached. Temp maintains for a long time (at least on my rheem). I can go three days with the water heater off before I feel cool water in the hot tap. I only turn mine off when on genny. The rest of the time I just leave the thermostats to do their job. No need to add more switches to it in my setup.

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chessie4905 · January 02, 2018, 04:16:04 AM

A 40 gallon water heater is pretty large compared to most coaches. No wonder it can go 3 days. The internal thermostat will kick on sooner than a timer, so will be on sooner than needed.

Oonrahnjay · January 02, 2018, 05:13:44 AM

Quote from: Scott & Heather on January 01, 2018, 09:39:34 PMUm, doesn't the thermostat on the water heater perform the same function? It turns off when temp is reached. Temp maintains for a long time (at least on my rheem). I can go three days with the water heater off before I feel cool water in the hot tap. I only turn mine off when on genny. The rest of the time I just leave the thermostats to do their job. No need to add more switches to it in my setup.

I have an Atwood 10 gallon water heater. It heats off a 120V coil, propane, and has a heat exchanger coil. If you keep the electric or propane switched on, it will rise to about 190º internal temperature. It has a built-in "tempering valve" that mixes outside water with water from the heater tank to supply water at a temperature of about 118º. I'm not sure how many mixed gallons I get, but it's a lot. Also, the hot water from the heat exchanger is "free" heat if it's come from the engine cooling system while traveling; since it's also regulated to 190º, there's no difference to the temp of the water inside the bus, no subjective feel that there's any difference, and the same amount of mixed-temp water. It also seems to be insulated pretty well.
(Washing machine manufacturers recommend a temperature of about 160º for sanitizing during washing cycle with antiscald or tempering valves at other fixture locations but I don't have a washing machine on my bus. I like the 118º setting OK.)
This works well for me; since I'm often alone or only with my wife, it would probably be different for larger families or others may need or prefer something else, but that's "doing it my way".
HTH. BH NC

TomC · January 02, 2018, 07:26:42 AM

I have 2-10 gal electric water heaters that I bought at HD in 1993. I just shampooed the carpets yesterday and used the hot water from the water heaters. Still steamy hot, but not scalding. One water heater is plumbed into the next with the final one wired through the inverter to have hot water while driving. When boon docking, we run the generator in the morning to heat water, coffee, charge batteries for 2 hours and the water stays hot all day. Good Luck, TomC

silversport · January 02, 2018, 09:42:40 AM

Thanks for all the input, it sounds, like me, know has done the math, does the LP fuel use more if left on all the time and cycles or turn it on and run for 30 to 60 minutes use and turn off. I have been to lazy so far to do it myself. I do not worry about the electric side, I on a power pole and it is not my nickel.

lvmci · January 02, 2018, 09:52:17 PM

This is not a concern with a tankless water heater...

Oonrahnjay · January 03, 2018, 04:00:40 AM

Quote from: lvmci on January 02, 2018, 09:52:17 PMThis is not a concern with a tankless water heater...

Speaking of, I put in a Rennai tankless heater at my house about 5 years ago. It has been *perfect* once I got it tuned up. There is a "dipswitch" that allows you to switch from Very Warm to Pretty Hot; I found the Pretty Warm to be just not hot enough, so I pulled the cover, move the switch to Pretty Hot and now it's great. The heat is very close to instant - in the time it takes to run the cool water from the tankless heater to the shower or kitchen sink, it's fully warm. It uses less than 1/10th of an amp of electric power (for printed circuit and electronic pilot) and is easy on propane. Of course, as long as there's a trickle of electric power and propane in the tank, the supply of hot water is endless.