Tankless Water Heaters

[Kstills]

I'm getting ready to do an install of a recirculating shower, and the design includes an inline hot water heater. Because of that, the only hot water I'll need now is for the kitchen sink which means I can potentially free up a lot of space by getting rid of the 6gallon hwh I have now and replace it with a tankless model.
I'm wondering if anyone has gone this route and could provide some insight into the pros and cons? I'm guessing a 1-2 gpm unit would be adequate and would fit up under the sink. That would get the current hw heater out of the rig and give me more room to remodel the bath.

Thanks in advance.

[Aironius]

When I installed a small water heater under the kitchen sink at our house, I discovered that most of the tankless units require 220VAC at rather high amperage. I had to go with a 1 gal. mini tank that runs on 110VAC to use the existing wiring for a garbage disposer. How will you power a tankless unit?

[islandtrader]

Originally Posted by Aironius

When I installed a small water heater under the kitchen sink at our house, I discovered that most of the tankless units require 220VAC at rather high amperage. I had to go with a 1 gal. mini tank that runs on 110VAC to use the existing wiring for a garbage disposer. How will you power a tankless unit?

Most RV tankless heaters are run off the LP.

[jefflew]

I understand the new AS all have tankless water heater (LP). I've used it myself on my previous teardrop trailer and I thought it was great, near instant (about 5 seconds to get it to the temperature I was expecting). There was one AS owner who complained that it took too long for the hot water to start (apparently up to 30 - 40 seconds), which impacts ability to boondock.
Can anyone else share their experience with the new tankless water heater?

[richard5933]

The downside to tankless water heaters is the increased flow necessary to trigger the burner/heater to turn on. When dry camping this can result is going through your water much more quickly than you would with a tanked water heater.

[rugjenkins]

Look at the excel tankless water heater. They are small (14h x 10w x5d) and use propane. I installed 2 on my argosy. One for the kitchen sink and one for the bathroom. We really like them. The price is nice too. You can get them on Amazon.

[foobar]

Originally Posted by richard5933

The downside to tankless water heaters is the increased flow necessary to trigger the burner/heater to turn on. When dry camping this can result is going through your water much more quickly than you would with a tanked water heater.

Yeah the water waste while you wait for the water to heat up is one issue. Another issue is the dreaded "cold water sandwich" when you are trying to take a Navy shower to conserve water.

For those not familiar with this, in a Navy style shower you wet down quickly, shut the water off, soap up, then turn the water on for as short a time as possible to rinse off. This minimizes water consumption on a Naval vessel at sea and for an RV'er when boondocking.

So, what is the "cold water sandwich"? With tankless water heaters, when you turn off the water flow for a few minutes while soaping up during a Navy style shower, the tankless shuts off almost immediately in order to avoid overheating. Of course, when you restart the flow again, it takes the tankless heater another 30-40 seconds to fire up again for the second time. Meanwhile, you can hear the screams of your wife echoing up and down the mountain valley as the cold water sitting in your water hose hits her body for up to 40 seconds or so while waiting for the tankless to kick on and make a dent in the water temperature (40 seconds seems like an eternity for the poor soul in the shower). That blast of cold water in between the episodes of hot water is referred to as the "cold water sandwich" between the two slices of hot water, lol.

Other than point of use water heaters with small buffer tanks, you can take a look at the Truma tankless heater. It has a built-in small (1 liter or so) water tank that it preheats in order to provide instant hot water at even "trickle" levels of hot water flow rates and to provide a buffer to absorb the cold water coming into the tankless before the tankless unit has had a chance to fire up and heat the water adequately.

[Voyager-Two]

I went with the Shower Miser and it works great. Very happy with it. No more cold water sandwiches when taking Navy shower. Almost no water goes in gray tank.

[Mullers]

We went with a truma combi combined water heater and furnace, similar to what they have in the base camp and some of the smaller airstreams.

Truma USA are hard to deal with, as they only sell to OEMs, European dealers are easier to deal with. We didn’t buy through airstream but have pondered if that could work - parts listed here on page 9: https://www.airstream.com/wp-content/uploads/2021/10/2022-Basecamp-Parts-Book.pdf#page9