Water Heater Repair

Below are the five most common complaints and what typically causes each one, split by fuel type where the cause actually differs. Gas and propane units behave the same way for troubleshooting purposes; the meaningful split is gas/propane versus electric. Tankless units share some of these symptoms too, but they diagnose themselves with a specific error code rather than presenting as a vague symptom — see our tankless water heater guide for brand-by-brand code tables.

Most modern gas tank water heaters use an integrated gas control valve with a small LED that blinks in a defined pattern — a number of flashes, sometimes followed by a pause and a second set of flashes, sometimes a solid light or no light at all. Manufacturers assign these patterns per valve generation, so the tables below apply to the specific valve families named, not to gas water heaters generally. Two or three manufacturers often source the same underlying control from a supplier like Robertshaw or White Rodgers, but each brand documents its own condition list for it, which is why we always confirm the brand and generation before reading a code.

Rheem and Ruud — Robertshaw Gas Control (Guardian PowerVent)

Rheem's technical service bulletins document the Robertshaw gas control used on Guardian PowerVent residential gas water heaters. The green LED's flash pattern is read as a primary pattern, then (after a one-second pause) a secondary pattern.

Since 2007, Rheem transitioned standard Guardian PowerVent residential gas water heaters (natural gas and propane) to the White Rodgers Intelli-Vent control, which displays a numbered error rather than a flash-counted pattern.

Bradford White — White Rodgers Electronic Gas Control (FVIR Models)

Bradford White's own service manual for its current atmospheric-vent gas models documents two gas control generations. The older White Rodgers Electronic Gas Control uses a green LED with a similarly counted flash pattern to Rheem's Intelli-Vent, though the specific conditions differ.

Bradford White's current ICON System gas control (versions V1 and V2) is used across its newer residential atmospheric-vent gas water heaters. V2 adds color to the same LED — green for normal operation, yellow for low thermopile voltage, and red for a valve fault — on top of the flash-count pattern V1 introduced.

A.O. Smith and State

A.O. Smith and its sibling brand State take a different approach: rather than publish a single public status-light chart, both direct owners to a QR code on the water heater's rating plate that pulls up model-specific information, including the owner's manual and troubleshooting steps for that exact unit. We read the rating plate and pull the model-specific documentation before diagnosing an A.O. Smith or State gas control valve, the same way we do for any brand where the codes are model-specific rather than universal. That approach takes an extra step compared with reading a printed chart, but it means the information matches the unit in front of us instead of a generic model line.

ENERGY STAR's guidance is direct on age: once a water heater is past 10 years old, plan for replacement before it fails on its own schedule rather than yours. The warning signs it lists line up with what we see in the field — visible corrosion on the tank or fittings, water leaking from joints, seals, or seams, rust showing up in the hot water, a drop in available hot water from sediment buildup, and rumbling noises. Ignoring those signs risks a sudden failure, and in some cases a tank rupture and water damage, not just a cold shower.

None of that means every repair is a bad idea. A control valve, thermocouple, heating element, or thermostat failure on a unit under 8–10 years old is usually a straightforward, worthwhile repair — our water heater repairs start at $179 and most diagnoses happen on the first visit. The math changes once the unit is older or the failure is the tank itself: a leak from the tank shell means the inner tank has corroded through, and no repair fixes that. At that point we say so plainly rather than sell a repair that only delays the same decision.

A locked-out gas valve or burner is a safety device doing its job — repeatedly resetting it without finding the cause is how a minor fault turns into a bigger one, and on some of the controls above, into a part that must be replaced rather than reset.