tankless water heater

gedervage wrote:
I am putting camping quarters in an aluminum horse trailer. I want a shower and am thinking about a tankless water heater and have several questions.

Can I use a tankless water heater designed for a home?

Maybe, but there is a bunch of "catches" so to speak..

Home GAS tankless water heaters have a very, very high BTU burner. Typically 120,000 BTU and larger. This requires larger than normal gas line "1/2" min and a higher capacity propane regulator.

Then there is the venting, typically requires 5" min Class B gas vent (double wall) which is very expensive.

Talk about expensive, tankless is going to cost at a min twice as much as a standard RV 6gallon water heater.

Home tankless heaters also typically require a min of 1/2 gal per min water flow to trigger it on.. In a RV that means you will be going through fresh water like mad and it will fill your grey tank extremely fast..

What about an electric tankless water heater?

It is possible to use an electric point of service tankless but once again you will run it a lot of challenges.. Min water flow is same as Gas so you will use a lot of water..

120V type is pretty limited in how much temp rise over the input temp and result will be more like luke warm if you are lucky..

240V types will do better than 120V but you still have a limited temp rise.

How much current do they drew?

3.5Kw (30A) for 120V HERE

9Kw (38A) at 240V for one HERE if that helps you..

There may be smaller ones, those are just from a quick search but be aware the lower the wattage the less temp rise you will get!

I can wire the trailer to handle how ever much current I need since I will be starting from scratch but what about the hook up.

You will NEED a 50A 240 service to use an electric tankless, period.

This will often be a drop cord to a 110 volt outlet in a barn.

120V drop cord with electric tankless.. Forget about it, just not happening.

if I choose a gas fired water heater what is involved in venting the burner?

Venting size depends a lot on the size of the burner.. small gas tankless types will have a min of 120,000 BTU burner.. The min is 5" vent and that vent MUST be Class "B" gas rated.. This is a double wall pipe with a layer of fire resistant insulation.. It is not cheap especially when you get into the 5" and larger sizes..

My comments in red above..

Please also note.. Tankless water heaters REQUIRE internal cleaning of the coils to get rid of mineral build up.. Water contains a lot of suspended minerals, well water can be especially high.. Failure to perform this maintenance it will clog the tubing with minerals..

Typically the installer will add in a very costly set of valves and manifolds to allow you to perform the cleaning without the need to disassemble water lines..

You don't have this problem with conventional water heaters..

Tankless heaters are a "solution looking for a non existing problem"..

I have looked into them for my home but after discovering all the pitfalls I tossed the idea into the waste can and have not looked back at it..

Do yourself a huge favor.. Buy a REGULAR RV water heater.. You can get a simple pilot type like a Atwood G6A-7 for $349.. A bargain compared to the hassle of a tankless type..

HERE

A RV water heater requires no special venting, it installs through the outside wall of your trailer and the vent is built into the outside grill work..

Pretty easy to cut a hole into a aluminum trailer.