Under sink water heaters aren’t so different to their larger heaters that stay in closet spaces. They suffer similar difficulties like with a valve that leaks or a pipe related problem.
To avoid experiencing difficulties with your under sink hot water heater, it’s a good idea to perform some basic checks and light maintenance infrequently to avoid bigger issues cropping up later on that are costlier too. In a worse case scenario, when unmaintained, a heater could become a fire hazard or get damaged internally when a part suddenly malfunctions, comes loose or disintegrates within the apparatus itself.
Water Leakage :- Your under sink water heater can experience leakage from the pipe joints, around the valves directly, or within the pipes themselves. When using PVC piping, it doesn’t hold up as well as metal piping, but it’s cheaper. Similarly, when a joint is positioned in a way that puts excess pressure on it with no relief, eventually that joint is likely to suffer a fracture that allows water to escape.
It’s also possible that rummaging around under the sink for other items stored can knock a pipe causing it to crack. Fittings may work looser over time and eventually to the point where water leaks because they’re no longer tight enough. It doesn’t happen overnight obviously, but over a couple of years, it might.
When water leaks, it might just be condensation runoff as the heater sheds water covering it. This happens in kitchens and other places where an under sink water heater is fitted that gets unusually cold at night and then into the morning. Also, be aware that topping up cold water to a tank with heater water will produce extra condensation leading to a water runoff.
With smaller tanks, they get filled up more frequently and so produce greater condensation. As a result, their runoff is greater and nothing to be concerned about. Do be aware of the passage of any water runoff though because if it drops onto electrical wires or apparatus (or that’s stored below the level the heater is positioned) that could cause a fire.
Blocked Pipes :- Under sink hot water heaters are diminutive compared to their large brethren. With short pipes and a tortuous journey for the pipe, there’s a greater likelihood of a blockage. No matter though because a drain cleaner in powder/liquid form or using a plumber’s snake will resolve that. Minerals from soft/hard water are a problem in some areas and cause more regular blockages too. A water softener run through the pipes handles that nicely.
Electrical :- Ensure all electrical wires are covered up and maintain their insulation. This is especially important when there’s both electricity and water in close proximity. We cannot stress this enough. Valves, seals and pipes must be in a good condition to prevent moisture getting into the electrical works and being a fire hazard.
Also, with gas-based water heaters, remove all flammable liquids from the heater installation area. You do not want the pilot light near any flammables as this could ignite the gas. It’s best to not store anything in the under sink area where the heater is located. Play it safe!!