How to troubleshoot common issues with your RV hot water systems

How to troubleshoot common issues with your RV hot water systems

There are few more important items in your travelling rig than your RV hot water system and it is one of the appliances guaranteed to get regular, often heavy usage. Hot water in your RV is an essential element in making camping immeasurably more comfortable and convenient. It is also one of the more complex items on board if you are not too familiar with how it works and this can be a major, frustrating issue at times when the system refuses to cooperate and function as intended.

Here at RV Parts Express, we are all too aware of the potential for upset when things go wrong, so we put our heads together and came up with a list of things to try when troubleshooting your RV hot water system. We thought about issues with everything from no hot water at all to only getting lukewarm water and any other potential problems we could envisage. This will give you the best chance of locating and rectifying any obvious, non-catastrophic problems and hopefully get the water flowing piping hot again as fast as possible.

A few important facts

Before we begin troubleshooting your RV hot water system, let’s take a quick look at how most water heaters actually function. A better understanding of the subject can only help us to troubleshoot more effectively and avoid costly mistakes or accidents. To function, water heaters use either:

  • Electricity
  • Propane
  • A combination of the above

It should take around 10-15 minutes for the water to be heated using propane and about 30 minutes using electricity. The plumbing system will typically have 2 separate water pipes, one for the cold water and the other for the hot. The way they run through the vehicle and connect together will often vary but it is almost certain there will be one pipe leading from the external supply to the heater, to begin with. The pipes tend to be blue for cold and red for hot but this is not a given for all systems so please check your manual if you are not certain.

Tank systems

With standard heating systems utilising an old-fashioned water tank, the water from outside fills the tank and is then heated by the internal element. The tank itself is heavily insulated to prevent loss of temperature and is constantly topped up when the thermostat kicks on to maintain the water temperature. Although this tried-and-tested system was the preferred method of heating water for many decades, it is not the most efficient way to do it and more modern systems tend to eschew tanks.

Top tip: If you need to conserve propane, you shouldn’t leave your water heater on constantly.

Tankless systems

Modern, tankless systems are in a state of constant standby until a tap is turned and hot water is required. The water passes through narrow pipes that are super-heated, allowing the temperature to be transferred to the water very rapidly as it passes through. This system is much more efficient as it does not require heating a large volume of water, it is heated almost instantaneously and does not require insulation or storage.

Top tip: Tankless water heaters are designed to be left on permanently as they are superbly efficient and the flame is only lit when hot water is required at the tap.

Troubleshooting guide

Below is the list we put together for troubleshooting your RV hot water system, but first, a note of caution. While there are a number of reasons heating elements can fail or lose efficiency, no situation is more likely to damage them than being operated without water in the tank. Always make sure that the element is at least fully covered before testing your system.

Check for water in the tank

If you are confident there is some water in the tank, at least enough to cover the element, gently touch the brass pressure/temperature relief valve when the water heater is on. It will feel warm to the touch if you are right. If you are not sure or are inclined to think the system has no water in it, you can open that valve and check. Water will escape until it drops below the level of the valve; once it does you can remove the drain plug and any remaining water will exit the system.

Depending on the style of RV water heater you have, you may need to drain and check the tank twice a year. This might also be necessary if the water lines smell bad and the system needs to be sanitised. You can discuss the necessity of this with a trained technician at RV Parts Express whenever the time comes.

Power

The most obvious place to start troubleshooting your RV hot water system might also be most easily fixed if you’re lucky. Many RV water tanks operate on a combination of propane gas from a tank and electrical power from an external source when available. If this is not functioning as desired then there are some things to check:

  • Your connection to the external power is solid 
  • The breaker in the campground power supply is switched on
  • The breaker in your RV is also switched on
  • There is ample gas in the tank and the valve is open

Lukewarm water

If the water is getting warm but not hot, this gives us some valuable information. For a start, it would appear the heater is attempting to work but cannot cope with the amount of cold water it is encountering. Things to check:

  • Confirm that the bypass handles on the back of the water heater tank/water bay compartment are in the correct position
  • Ensure the water pressure to the shower heads is not restricted anywhere along the line. A common problem occurs when the water is turned off to the outdoor shower but not at the tap which causes the cold and hot water to mix
  • Make sure the push buttons on handheld shower heads are open and not restricting water flow

Ignition

Most ignition issues are easily solved once discovered but it is always better to exercise caution if you are not confident you are contemplating the correct action. Pressurised, flammable gas is no joke and it is never a bad decision to seek professional advice if you are uncertain. Otherwise, here are some things to check:

  • Your RV’s 12-volt fuse inside the electrical panel
  • The tank has enough gas 
  • The valve is fully open

Any problems persisting once these items have been checked are likely to involve one or more of the following:

  • Faulty solenoid (gas valve) 
  • Damaged ignitor
  • Dirty burn chamber
  • Flame blockage

At this point, it is probably better to reach out to professional technicians and have them service your RV’s water heating system

Reset the water heater

It may be your water heater’s internal safety feature has been activated if the water temperature is exceeding the maximum limit. This is a built-in failsafe which prevents the system from overheating and causing damage or injury. Resetting the water heater may address this issue but it will simply be triggered again if the problem lies elsewhere.

Resetting the system is usually as simple as turning it off at the main power switch and back on again. Some systems may have a reset button to depress so be sure to check the unit’s manual if you are not sure. You might also find a power switch inside the tank-style water heater compartment. This is for RV technicians to turn the water heater on and off quickly when performing repairs and should be left switched on.

Common reasons the safety mechanism might be tripped, disabling the heater

  • Faulty thermostat

With tank systems, a faulty thermostat may be the culprit; if it is sensing the temperature incorrectly, it is likely to continue heating the water past the required point or never reach the required temperature at all. This will probably require the assistance of a trained technician to rectify.

  • Calcium deposits

Tankless systems might require a process of decalcification from time to time depending on the hardness of the water passing through. Harder water causes calcium or limescale deposits to build up and these can cause blockages. This process can be undertaken with some basic tools and know-how, by draining the tank and adding vinegar to the water used to refill it. Bleach also works for this but is much less environmentally friendly and no more effective in terms of the results.

Unlit/unresponsive interior panel

The interior panel that allows you to control and operate your RV’s water heating system run off a 12-volt DC system. Be sure the check the fuse and battery are in place and intact/charged.

Contact us

Here at RV Parts Express, we offer a wide selection of parts for RV and caravan hot water systems when you are done troubleshooting your RV hot water system and discover you require certain key parts. We also stock full RV water heating systems for times when the issues are too large to be worth fixing, or it is just time to upgrade to the very latest hot water system and treat yourself to many years of stress-free travelling.

Please do not hesitate to get in touch if you have any questions or comments as our advisors are extremely knowledgeable about all aspects of RV hot water systems and any other issues you may wish to discuss.