Pros and Cons of Tankless water heaters in RV

wanderingaimlessly wrote:

CavemanCharlie wrote:

wra wrote:

wanderingaimlessly wrote:
Your in florida, for home or rv use you only need to heat the water 30-40 degrees to get the temp you want, from an rv tank you may not need even that much, but as temperature range changes increase, the difficulties regulating it do as well.

I have used changing water pressure less than 20 lbs to 60 lbs (a well pump system) with no problem regulating water temperature.

The main point is to have only the hot water faucet turned on. Having he hot and cold water turned on provides a path for cold water to the shower head, and causes the tankless heater to have less water go through it. That situation causes the tankless heating unit to turn off prematurely, and cold water continue to flow.(burr!) The tankless heater should be set to the desired shower head water temperature. Let it do its job.

So it sounds like in a home that it's a learning curve. Most people don't want to change their habits and don't want to learn new things.

That being said, it also sounds like it might not work as well in a RV where the parameters of flow usage and other things can change.

AND AGAIN, you are in Fl. ground water from a municipal system will typically be near 60 degrees when it enters the home. Well systems are often even warmer because the reservoir tank is in a garage or other heated area.
And in an RV, if it is coming from a holding tank, it may be 80 degrees, but, take that same RV to an area with an ambient temp in the 30's or 40's, and everything changes. The water going through the heater has to go much slower to be warmed the extra 30-40 degrees. Meaning your flow has to become nearly nothing or you live with lukewarm (at best) water.

You don't need much 135F water to mix into 90F tank water to get to 110F at the shower head. That means a 6-10gal water heater can easily provide 30-60gal of hot water. Of course when in Florida with 90F temps, I generally don't feel the need for a really hot shower. In fact just running the cold water which will be around 90F is fine. (Even down around 80F, it won't bother us much).

When camping in 30-40F, that's when a piping hot shower at 110-115F feels really good but now you are asking the hot water heater to bring the water temp up by 80-90 degrees. A tank based heater will be limited in duration but it can get the water up to temperature. Most of the smaller tankless units struggle to get the water that hot on a consistent basis.