Pros and Cons of Tankless water heaters in RV

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.

Unless tankless water heaters have changed considerably over the last few years, they have absolutely no temperature adjustments.

You have two designs, one with full on/full off burner that requires a min of .6 gpm flow or a modulated burner that varies the burner according to the flow.

Both however still have a minimal water flow required to turn on the burner.

Both use a very high BTU burner.

Both can only raise the water temperature to a certain point over the incoming water temp and the amount of temp rise is a factor of how fast the water is flowing. Slow moving water will have a much higher rise in temp, but now you risk the burner not staying on and you get a cold burst of bone chilling water or even worse end up with unanticipated scalding hot water..

In sticks and bricks instant water heaters are often installed with a tempering valve to help smooth out the cold/hot/cold variation with water flow.. Tempering valves are not typically built into water heaters.

Something else never mentioned is the need to periodically having to clean the tubes in a instant water heater. Water contains a certain natural amount of minerals (calcium, lime, iron) suspended in the water. Instant water heaters are prone to clogging from this mineral build up in the tubes. Water sources like unfiltered/unprocessed water wells can clog an instant water heater in a relative short amount of use.

In a RV, there is no advantage for using a instant water heater..

Standard 6 gallon RV water heater can easily supply you with 10-15 minute scalding hot shower. They are typically set to 130F-135F and you only need to mix a small amount of hot water into a lot of cold water to get a really nice steamy shower.

If done correctly, it works a bit like 5:1 ratio, 5 parts cold to one part hot. If you use .5 gpm of hot water, 6 gallon water heater can get you about 12 minutes of scalding hot water and as new cold water mixes it will cool down some towards the 15 minute mark and you simply reduce the cold water some..

I have found that if I turn on just enough hot to get water flowing and then add a bunch of cold just enough to make the shower head spray lightly three of us can get back to back (very little recovery time between) showers without anyone getting a cold shower.

Are you going to have a RV shower pin you against the shower walls like sticks and bricks?

Nope.

But, it will be plenty of water to get the cleaning job done..

Camping is not the same as home, there are compromises and if you want to be pinned to the shower walls then use the campgrounds showers or stay at home.