Usually yes. The air/fuel mixture ratios are different, so you most likely need a different fuel orifice. Most of the water heaters I've dealt with you can buy a conversion kit with the lp orifice from the manufacturer, usually not too expensive.
Get the exact model number for your heater and then Google it or take it to your friendly Plumbing supply.
It would be very difficult to convert a solid heater into a gas.
Due to possible liability you should never convert a water heater unless the manufacturer specifically has instructions that state that it is ok to do so.
I am wondering if you can convert the lp or propane gas to natural gas on a bosch tankless hotwater heater. I am guessing it has a different orfice and regulator
There is a little orifice in the heater with a different size gas supply hole to be changed.
YOU cannot - you need to call a gas fitter.
Bosch AquaStar 2400ES-NG (Natural Gas) Tankless Water Heater will provide a endless supply of water heater.
The answer is that is may create a problem when you want to use it with natural gas. Best is just to scrap it.
It converts cold water to hot water.
the heater is a charmglow gas ventless wall heater
You don't. Do you have a hot water heater? What do you suppose happens to the natural gas when it hits the flame down underneath?
No, they should be underneath.
I am considering buying a gas water heater. How does a gas water heater work?