Hot water problems are easier to diagnose when the symptom is described precisely. The three common complaints point at different parts of the system, and confusing them leads to replacing equipment that was never the cause.
No hot water at all
This points at the heat source or its controls: a tripped safety cut-out, a failed thermostat, a failed element or burner, an ignition fault, or loss of power or fuel supply. On storage units a reset device may have operated for a reason that also needs finding.
Hot water that runs out too quickly
This is a capacity or recovery issue. Sediment occupying the bottom of a storage tank reduces usable volume and insulates the heat source from the water. A failed lower element in an electric unit halves effective capacity. Demand may also simply have grown beyond the unit's size.
Water that is never hot enough
Check the thermostat setting first, then the mixing arrangement. A tempering or thermostatic mixing valve that has failed toward cold will limit delivered temperature no matter how hot the stored water is. Long uninsulated runs also lose heat between the unit and the outlet.
What servicing involves
- Flushing sediment from the base of a storage tank.
- Inspecting the sacrificial anode, which protects the vessel lining and is consumed over time.
- Testing the temperature and pressure relief valve and checking the discharge route.
- Confirming expansion provision, since heated water must have somewhere to expand into.
- Descaling tankless heat exchangers where water hardness makes it necessary.
Storage or tankless
Storage cylinders hold a volume ready to use and handle short, heavy peaks well, at the cost of standby heat loss and a finite supply. Tankless units heat on demand, never run out, and avoid standby loss, but their output is limited by flow rate and the temperature rise required from the incoming supply, which is why the same model performs differently in different climates.
Repair or replace
Controls, elements, valves and thermostats are ordinarily repairs. A leaking vessel is not repairable. Between those extremes the decision weighs the unit's condition, its remaining expected service life and whether its capacity still matches how the building is used.
Need this looked at rather than explained?
Submit a service request describing what you have observed. Details like when it started and which fixtures are involved shorten the diagnosis considerably.
Request service