Propane or natural gas.
Most tankless hot water heaters are electric. I've never heard of a propane one.
Yes, the tankless water heaters do cost more than the normal water heaters because tankless water heaters are designed to supply hot water only when needed unlike normal ones.
Tankless water heaters are available at most hardware/construction retail stores or online stores. Tankless water heater are much more expensive than regular water heaters.
While tankless water heaters are significantly more efficient than traditional water heaters, it can take up to 22 years to break even on the cost, due to the initial expense of the tankless water heater itself. Unfortunately, by the time the tankless water heater starts to pay for itself, it will likely have exceeded its 20-year lifespan. http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm
Tankless water heaters can range in price from $200.up to $1200. Depending on if you are looking to purchase a small under sink unit or a bigger gas fired unit. The benefits for purchasing tankless water heaters are the operating costs are cheaper and they have a longer life than the tank type water weaters. Models start at around $300 for small, under-the-sink units, and range in excess of $1000 for high-capacity units. Bosch and Rheem are probably the biggest names in quality tankless heaters. Also, price may depend on your choice of electric, natural gas, or liquid propane models.
Titan tankless water heaters can be purchased online at Tank the Tank, Hot Water, Local, Amazon, eBay, Titan, Titan Water Heaters, and Tankless Water Heaters.
Tankless water heaters have been around about 30 years. I believe they may have first been used on European trains.
Tankless water heaters are produced by a wide range of manufacturers. The Rheem tankless water heater has a cost range from the mid fifteen hundreds to over two thousand dollars.
Tankless gas water heaters can be purchased at your retail stores like Home Depot, their prices range from $278.43 to $1716.00. Tankless gas water heaters can also be purchased from ebay.
GE and Rheem both produce energy efficient water heaters. They each sell different sizes and models. Rheem produces tankless electric water heaters that are affordable and energy efficient.
In addition to a full line of traditional tank water heaters, Rheem also offers tankless water heaters that are designed to leave less of a carbon footprint on the environment. The company's Prestige� Series Condensing Tankless Gas and Tankless Gas units are designed for homes with busy families, luxury bathrooms or vacation homes. These units provide quick start up and ample supply to run a variety of water heating applications simultaneously. Tankless electric water heaters are smaller and designed for point-of-use applications. They fit under bathroom or kitchen sinks and are perfect for small, detached buildings.
form_title= Tankless Water Heaters form_header= Hot water without the tank. DO you need to remove an old water heater?*= () Yes () No When do you want the water heater installed?*= _  What is your budget for a water heater?*= _ 
Rheem tankless water heaters are special since they are both energy efficient, and space saving. These water heaters are also innovative due to their small size, since they can fit under sinks and small cabinets.
As long as the heater is made for propane.
Good, but expensive to operate.
Home Depot offers tankless hot water heaters for around $1000 depending on the specifications you need. These will need to be professionally installed.
Tankless water heaters are low energy because they only run when the hot water is needed.
There are two types of tank-less water heaters that run on two different fuels. There is a electric heater, and an oil heater. One gets plugged in the other uses oil
8-9ears is about average
Electric water heaters have not carbon monoxide.
Usually, house Hot Water tanks are either Electric or Natural Gas and trailer tanks are propane. Both are made the same except for the gas or electric input.
Unlike traditional tank water heaters, tankless systems do not heat a large quantity of water and hold it until you need it. Instead, they heat your water on-demand, when you turn on the tap. A small heating system warms the water as it runs past it in the pipe.
Depends if it is propane or electric, and whether you have propane or electric in the house to supply it. Usually they are identical to regular house water heaters. -I change many and have never seen a special one for mobiles.
Tankless water heaters work by quickly and efficiently heating water as it is demanded. They provide sufficient hot water because the heating implement goes on while water is turned on, avoiding the energy waste of tank water heaters.
Tankless water heaters are more energy and cost efficient than your typical water heaters. Of course, each person has their own needs and it is always a good idea to weigh out the pros and cons before making any decisions for a change. What works well for some may not work well for other.