For many years the American motorhome manufacturers have stuck to the same products for heating fresh water. Atwood and Suburbon have become household names in the R.V. world. Both companies offer two sizes of water heaters comprising of 6 and 10 gallon, with the options of, with or without a 120 volt or 230 volt electric element.
Whilst operating on gas they rely on a gas flame to heat the water that is stored in either the 6 or 10 gallon tank. When the stored water reaches its temperature (90 degrees celcius), the thermostat shuts off the burner, and when the water cools down to between 75 – 80 degrees celcius the burner then cuts in. This system has been fairly reliable, but the down fall is that you have to wait until the water reaches the desired temperature before use, as well as the burner being a bit noisy.
The Girard GSWH-1 is the R.V’s industries first on demand induced draft LP Gas tankless water heater. With the use of an electric fan, air is forced into the combustion chamber allowing the combustion chamber to be smaller, although with the use of the forced air system more gas can be burnt giving a much hotter flame.
The manufacturers claim that it provides higher combustion efficiency, heat transfer efficiency in excess of 90% (less heat wasted to the atmosphere), high wind resistance, no adjustments required at high altitude and a quieter performance.
All in all if you know how a domestic on demand boiler works in a house, no need to read on!
In simple terms when you open the tap the boiler senses this and fires up the boiler flame. This very hot burner (34,000 BTU’S) heats the water as it passes through a heat exchanger. The faster the water flows the cooler the water, and the slower it flows the hotter it gets. When you turn off the tap the burner switches off saving LP Gas, and as the name implies you get hot water on demand. The combustion chamber has two settings dependent on the incoming water temperature, warmer 27,000 BTU’S and colder 34,000 BTU’s as earlier mentioned.
One or two things to mention, one of which the homeowner will know, is that you need to use what water is already in the heat exchanger before you get your hot water, to know how much you will waste I cannot answer, it all depends on where the heater is fitted in relation to the taps.
It looks as if this heater is more susceptible to freezing than the old type boilers are, because a WUD (winter use device) has been fitted. To enable you to use this device the batteries need to be charged, fresh water has to be in the tank, the water pump has to be on, and you have to have LP Gas in the tank.
When the water in the heat exchanger drops to 38 degrees fahrenheit a solenoid valve opens creating a demand for water which causes the water heater to start. When the water reaches 50 degrees fahrenheit the solenoid shuts and the water heater stops. Typically the water heater will run for 45 seconds. This device only protects the water heater and none of the other water system.
I have only run the water from the boiler which was on a brand new vehicle; I didn’t think the owner would appreciate me trying it out any further (like taking a shower in their new motorhome). I think only time will tell whether the product is better than the old one, or more to the point is how much water you waste before you get the hot water you require.
The demand boilers use the same aperture size as the tank boiler, so I think without too much trouble you could replace a tank boiler with a demand boiler. Knowing what RV manufacturers are like on the amount of space, if a demand boiler is fitted without having a storage tank they are a lot slimmer which will enable the RV manufacturer to use the space behind. This will then make replacing the demand boiler with a tank version a very difficult process.