RV Water Heater Repair and Replacement in Yorba Linda

The bypass exists so the water heater can be isolated during winterizing, letting antifreeze circulate through the plumbing without filling a six gallon tank. It is normally two or three valves at the back of the heater compartment or inside an adjacent cabinet.

Left in the bypass position, cold water routes around the tank and straight to the fixtures. The heater dutifully heats whatever is in it and none of that water reaches the tap. Owners report no hot water, and it is the first thing we check because it costs nothing to rule out and it resolves a meaningful percentage of calls.

There is a worse version. With a single valve bypass partly open, hot and cold mix upstream of the fixtures. The result is lukewarm water at every tap regardless of setting, plus hot water appearing at the cold tap. That symptom sends people chasing mixing valves and faucet cartridges when the cause is a quarter turn on a valve behind an access panel.

It also matters in reverse: running the heater dry after winterizing, before refilling and purging air from the tank, will destroy an electric element in minutes. Sequence matters, and it is worth having done properly.

Because one needs an anode rod and the other must not have one, and getting this wrong destroys a tank.

Suburban tanks are porcelain lined steel. Steel corrodes, so a sacrificial magnesium or aluminum anode rod is fitted to corrode preferentially and protect the tank. That rod is consumable. It should be inspected annually and replaced when it is significantly consumed, typically every one to two years depending on water chemistry. A Suburban tank run without a functioning anode will perforate, and a perforated tank is a replacement.

Atwood tanks are aluminum clad with an internal lining that does not require sacrificial protection. Fitting an anode rod to an Atwood introduces dissimilar metal corrosion and actively causes the damage it was meant to prevent. Atwood units use a plain drain plug instead, and that is correct.

Identifying which you have takes seconds at the access door, and it should be the first thing any owner learns about their own coach. The rotten egg smell many owners report is another anode consequence: magnesium anodes react with sulphate reducing bacteria in the water to produce hydrogen sulphide. Switching to an aluminum zinc anode and sanitizing the system usually resolves it.

• Suburban: porcelain lined steel, anode rod required, inspect annually
• Atwood: aluminum clad, no anode, plain drain plug is correct
• Rotten egg odour: anode reaction with bacteria, change anode type and sanitize
• Truma and tankless: no tank to corrode, flow and scale management instead
• AquaHot: hydronic loop heated by diesel burner and electric element

On gas operation the usual suspects are the thermocouple or flame sensor, the gas valve, a blocked burner tube and, very frequently, an obstruction in the burner area. Mud dauber wasps build nests in RV water heater burner tubes with remarkable consistency, and a nest produces exactly the symptom of a failed igniter: the unit sparks, fails to establish flame, and locks out.

On electric operation it is the element, the thermostat or the high limit cutoff. The high limit, sometimes called the ECO, trips on overtemperature and has to be reset manually. A unit that works for a while then stops until the reset is pressed is telling you the thermostat is drifting or the tank has scale insulating the sensor from the water.

On tankless units the failures shift to flow sensing and scale. These units need a minimum flow rate to fire, so a partly blocked aerator or a low pressure supply will produce cold water with a perfectly healthy heater. Scale accumulation in the heat exchanger is the long term issue and is managed by periodic descaling rather than by replacement.

AquaHot and similar hydronic systems heat a glycol loop with a diesel burner and an electric element, then use that loop for both domestic hot water and coach heating through zone exchangers. They are found on high end diesel coaches and they are excellent systems that are genuinely expensive to neglect.

The service items are specific: burner nozzle and electrode maintenance, glycol condition and level, circulation pump condition, zone valve operation and the domestic exchanger. Diesel burner faults present much like a small furnace, meaning failure to light, sooting, or lockout on flame sense.

Published service on AquaHot and hydronic systems runs $750 to $8,500 across 3 to 35 labor hours, and the range reflects that a burner service and a full circulation and exchanger overhaul are very different jobs. Diagnosis matters more here than on any other water heating system because the components are expensive and interdependent.