tankless water heater

[schoonod]

Our new travel trailer has a tankless water heater. Our first trip out was with full hookups and the shower worked great for a continuous running hot water shower. Problem: most times we dry camp. I tested the shower using the typical navy shower process and each time I pushed the shower head button back on I got cold water for a little while. With the old trailer using 6 gallon tank, this never happened. It appears for dry camping we would waste water, ie use more water, with the tankless system. Any ideas to help not use the extra water when dry camping. Of course, we can go back to the old tank system as one option. I have what is supposed to be a low volume shower head, but not sure if at the 1 gal/min rate or more.

[1492]

Moved from Forum Technical Support

[ScottG]

schoonod wrote:
thanks for the responses. I'll have to get back tomorrow on the brand in my trailer as I am away from the trailer right now. Not sure how the check valve would work as the on/off button on the shower head would work as a check valve (from my way of thinking). The insulation sounds worth a try -- I'll check tonight how hard it will be to add the insulation. I can easily get into the back area of the heater unit.

The on-off valve at the head doesn't work as a check valve because the water can flow either direction through the mixing valves.

The problem isn't the water cooling off in 30 seconds (at least with mine). The problem is the water flows backwards through the mixing valve when the water is suddenly turned off. This is because of the spike in pressure on the cold side (WH absorbs spike on hot side). This pushes the cold backward through to the hot side. In a house this is often heard as water hammer. When this happens you get a couple of seconds of cold water from the hot side as well as the cold.
Check valves in the hot supply close to the mixing valves helps a lot.

[Dick_B]

Yes, go back to the tank system and you will tank me for the suggestion. Tankless water heaters just will not work unless you have full hookups. But that's my $.03.

[schoonod]

thanks for the responses. I'll have to get back tomorrow on the brand in my trailer as I am away from the trailer right now. Not sure how the check valve would work as the on/off button on the shower head would work as a check valve (from my way of thinking). The insulation sounds worth a try -- I'll check tonight how hard it will be to add the insulation. I can easily get into the back area of the heater unit.

[Trackrig]

When you ran lots of hot while hooked up, the larger volume of hot water running through the pipes also heated up the space around and anything the hot water line touched. This helps to keep the water in the line warm. When only running a little water, that doesn't happen and therefore you have to wait for new hot water to get to you. If you can get to your hot water line, go to the hardware store and buy some of the flexible water pipe insulation to use on them. This will keep the water in the hot water line hot, or at least warmer while you have the flow off for a couple of moments.

This idea may be easier said than done. I wanted to do mine, but gave up trying to get to enough of the hot water line to be worth while.

Bill

[ScottG]

I don't believe your issue is caused by the tankless heater as this has been a subject of discussion for many years here and the vast majority of us have tank heaters.
Some have had success with installing a check valve in either the hot or cold water side. I installed one in the hot side and it cut the cold water time in half but it still does it.

I'm impressed that your tankless heater works so well, May I ask what brand it is?

[dvitale300]

While not ideal, you could keep a sanitized container / bucket / empty gallon water jug on the commode, and fill it up with the cold water until it heats up. Running out of water when dry camping is a pain.