Water Heater Identification
Water Heater Data Tag

Tank Water Heater Components

The P/T valve is designed to relieve the tank if pressure exceeds 150 psi or temperature exceeds 210° F

PT (Pressure Temperature) Valve – occasional weepeing is normal – unit is regulating pressure. Consistent weeping = possible bad thermostat (around 150 degrees), loss of air pocket, or simply a defective valve.

Dry Fired P/T Valve

Results of a Water Heater ran without any water in the tank. The symptom here would be a constant weeping.  This is not covered under warranty.

 

 

Weeping or dripping of a pressure-temperature relief valve while the water heater is running DOES NOT mean it is defective. This is normal expansion of water as it is heated in the closed water system of a recreation vehicle. The Dometic/Atwood water heater tank is designed with an internal air gap at the top of the tank to reduce the possibility of weeping and dripping. In time, the expanding water will absorb this air. To replace the air, follow these steps:

Step 1: Turn off the water heater

Step 2: Turn off the incoming water supply

Step 3: Open the closest hot water faucet in the coach

Step 4: Pull handle of pressure-temperature relief valve straight out and allow water to flow until it stops

Step 5: Allow pressure-temperature relief valve to snap shut, turn on water supply and close faucet

The Control board takes input from the switches and sends output to the appropriate components.

Symptoms of a failed control board are.

  • only working on gas
  • only working on electric
  • Gas valve opening but not sparking

When checking Ohms, if more than tolerance – one coil is open. If less than tolerance – one coil is open or shorted. This mounts via an “old sytle” L bracket. If replacing this with new style will need to drill out holes for rivets.

 

The heating element heats the water when plugged in to shore power

When testing the Heating Element 9 – 11 OHMs is acceptable

  • T-stat (non XT) calls for heat at approx. 120 F (49 C) and ends the cycle at approx. 140 F (60 C)
  • XT Model T-stat calls for heat at approx. 135 F (57 C) and ends the cycle at approx. 154 F (68 C)
  • Thermal Link wiring becomes an open circuit at approx. 208 F (98 C) – permanently disabled