I have a single wide trailer. (The main gas line blew out the back and is under code so $4,000.00 to fix it plus permits because the main need to be moved from under the Trailer).

I would like to put in an on-demand water heater that uses propane from a tank. Usage would be for 2 people, 2 showers a day and washing dishes

Can I use the small propane tanks like for a barbecue? I have one old tank about 2 times the size of the usual barbecue tank — I think 40lbs. I think barbecue tanks are 20 LB. I am a little rusty at home repairs but I have to do this one myself due to my funds being low. I am in Phoenix, Arizona so no worries about freezing lines. Can I run the flue through the roof where the old water heater ran through, or does it need to be made larger than 4"?

3 Answers 3


I usually encourage DIY projects, but when it comes to gas applications, I have to strongly caution you to consider using a licensed gas installer to connect an on demand water heater. Nothing in a home is more dangerous than gas and it MUST be installed correctly and pressure tested. Venting the exhaust is extremely important as well, and a mistake can be fatal.

An on demand water heater is a great idea as long as it is sized correctly. I don't thin you will be happy with a 20 or 40 pound tank however. Your local propane dealers will usually supply you a larger tank at no charge as long as you buy the gas from them. The other advantage is that they will come and swap out spent tanks or refill them on site so you don't have to be lugging a tank back and forth to a refill station, and re-priming and firing the system every time you change tanks.

Bottom line is that if you are not experienced with gas installs, don't take a chance with the health and safety of your family. You are not hooking up an outdoor BBQ!!


Yes, you can run a tankless water heater off a standard Propane cylinder. However, that will limit the amount of hot water you can make.

Even if you want to do the install yourself, you're going to need to buy the parts somewhere. I suggest that you start by looking at what models are available at stores near you. The sales people will be able to tell you which models can run off a small propane tank, and which will serve your needs.

Alternatively, instead of replacing everything, why not just have a natural gas supplier drop a tank on your property? That's less work you have to do because it's just one change: connect your existing gas line to a new tank.


It is illegal to install a propane tank-less hot water heater in in any mobile home. a few ways around it is to 1. install an electric tank less heater, or install an outdoor heater, or build a small addition on to your home that is large enough to sustane the heater you must check with your town to see how large of a building you will need. Check with your town about installing any propane utilities inside a mobile home.

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    Do you have a citation for a propane fueled tankless heater being illegal in mobile homes? Is this a local Code thing where you're at, or some sort of national law I'm not aware of? Mar 5, 2017 at 3:41

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