Hot water tips for Motorhomes and Caravans
Introduction
In this article, we will discuss the pros and cons of the different hot water systems for motorhomes and caravans.
Let's split them into two main categories: On-demand and stored hot water systems
Let's look at On-Demand water heaters first
On-demand heaters are, in my opinion, not very suitable for motorhomes and caravans that have a small or limited amount of water tank capacity, and the reason is that the heating system is fired up only when the water starts to flow through the heater, It takes a minute or two for the heating system to ignite and get hot. Whilst this is happening, the tap is open all the time and water is flowing at about 8 litres per minute through the heater, so if you only have a little bit of tank water, say 80 litres, then do the math, a lot of water will be wasted to get hot water out of your tap.
On-demand systems are great if you have a large volume of water in your tanks.
Califonts
If you decide to go ahead with an on-demand water heater, it will likely use LPG as a fuel source. Since 2013, we have needed a gas certification for vehicles with gas appliances. Califont is one example of such a heater, and it is very difficult to get gas certification for a Califont because it draws combustion air from within the living environment of the vehicle, heaters should draw combustion air from outside, additionally for certification you will need an exhaust flue through the roof, and the problem is finding a flue that meets the gas certifier's requirements plus sealing the flue which gets fairly hot on the roof of the caravan or motorhome
Built in On-Demand systems
Built-in on-demand systems, such as the Nautilus or the Camec on-demand heater, are much better than the Califont for a motorhome or caravan application because these heaters draw combustion air from outside the vehicle, making gas certification much easier. Make sure that the BTU value of the unit is as high as possible because the water heater must increase the temperature from the ambient temperature to a warm enough temperature for a shower or washing up. If the BTU output is to low the heater might only increase the temperature by 15-20 degrees, which is fine in Australia where the ambient temperature might be 25-30 degrees, 20+25= 45 to 50 degrees which is good, but in colder countries such as NZ and especially down the South Island, if the ambient is 15 degrees, 15+20=25 your shower water temperature might only be 25 degrees, that would be unpleasant.
Stored or instant hot water systems
These types of heaters are most common in modern motorhomes and caravans. They are safe because they acquire combustion air from the outside of the vehicle and are therefore easier to certify. Instant hot water systems can be split into combination and standard types. Combination heaters do two things: provide hot water and heat air in one system, and are therefore considered most efficient. We will discuss the standard instant hot water system first
Standard instant hot water heaters
The water body, usually 10-20 liters is set, heated and stored, which gives instant heated water when desired, there is no lag while you wait for the pump to push water through a cold heater using a valuable water supply as described earlier with the on demand heaters.
The hot water tank is fitted with a large burner that instantly reheats the incoming cold water when in action, if the demand for hot water is high then the temperature will decrease as more cold water comes in and burner needs time to catch up, so this is not ideal for high volume users, but as we discussed earlier, the RV user with limited tank capacity needs to be frugal anyway or else they will be refilling their tanks on a daily basis.
These heaters mostly use LPG and AC mains power as fuel sources; a wide selection of these boilers is available. Some brands, such as Atwood, have been phased out. The Suburban has been a very popular boiler until recently, when they were taken off the shelf in NZ and Australia due to a recall. They have recently become available again. I should add here that some of the boiler tanks are not made of stainless steel; the tanks are enameled mild steel and have a sacrificial anode that needs changing every couple of years
Combination hot water systems
The combination hot water system is probably the most efficient, safe, and complex, which is why the price tag is higher. They have many features and will display many fault codes. It is easy to identify faults by searching the code for meanings on Google.
The heater/boiler has sensors all over measuring CO, heat, air movement, fuel flow and pressure, water flow, etc. If the built in computer senses something is wrong it throws a fault code, and flashes, usually it will be something the user can fix by looking up the code. The gas bottle might be empty, or there might be no AC power when it is set to AC, not gas; these are mostly user errors.
When there is something more serious at fault, then the heater will shut down. It is possible to reset the system and get rid of the fault code, but if the sensor picks up the same dangerous error, it will shut down for safety purposes.
If the user keeps resetting the heater/boiler then the system will shut down completely and an approved practitioner needs look at it, we can connect our computer to the system and identify exactly what the fault is, fix it and reset the mother board and the system should be safe again.
The Combination heater/boiler uses AC electrical power, or LPG and it is also available as a diesel unit.
