Gas Water Heater Repair

Most gas water heaters in San Antonio and Houston are tucked in a closet, garage, or attic and get ignored until the pilot goes out or the burner just quits. Gas problems have more to do with the age and wear of the ignition parts than anything happening in the local water, so the same causes show up whether you are in Alamo Heights or the Heights in Houston. Below is exactly what we check, in the order we check it, and roughly what each fix runs.

Pilot Light Won’t Stay Lit

This is the number one gas call we get, hands down. You hold the pilot button, it lights, you let go, and thirty seconds later it’s out again. Nine times out of ten it’s a worn out thermocouple, the little metal probe that sits in the pilot flame and tells the gas valve the flame is actually lit. Once it wears out it stops sensing heat properly and the safety valve shuts the gas off, even though the pilot was burning fine. Sometimes it’s just a dirty pilot tube clogged with dust or spider webs (yes, spiders love the smell of gas line residue, it happens more than you’d think in garages that sit closed up all summer in Houston’s humidity). Rarer, but it happens, is a failing gas control valve itself.

How we fix it: We test the thermocouple with a multimeter first since it’s the cheapest and most common fix. If it’s reading low, we swap it, usually under an hour, parts and labor typically $150 to $250. If the thermocouple checks out fine, we clean the pilot assembly next. If neither fixes it, the gas valve itself needs replacing, which runs closer to $300 to $450 depending on the unit.

Burner Won’t Ignite At All

If the pilot is lit but the main burner never kicks on when you run hot water, the thermostat isn’t calling for heat, or there’s a blockage in the burner orifice. We’ve pulled more dead june bugs and dust bunnies out of Houston garage water heater burners than we can count, that humidity brings bugs into every enclosed space looking for warmth. In San Antonio we see this less from bugs and more from just old age on units past ten years.

How we fix it: Clean the burner assembly and orifice, test the thermostat’s continuity, and check the gas pressure at the valve. Cleaning alone runs about $120 to $180. A bad thermostat replacement adds another $100 to $200.

Yellow or Flickering Flame Instead of Blue

A healthy gas flame burns steady blue with maybe a touch of yellow right at the tip. If it’s mostly yellow or dancing around, the burner isn’t getting clean air, usually from dust buildup or a partially blocked vent. This one we don’t let slide, incomplete combustion means carbon monoxide, and that’s not something to wait on.

How we fix it: Full burner and venting inspection same visit, since this is a safety issue not a convenience one. Cleaning runs $120 to $180. If the venting itself is damaged or improperly installed (common in older homes in both cities that were vented before current code), that repair varies based on what needs replacing.

Gas Smell Near the Unit

Stop reading and go check this one now if it’s happening to you. If you smell gas, leave the house, do not flip any switches, and call your gas provider (CPS Energy in San Antonio, CenterPoint in Houston) before you call anyone else, us included. Once the area is confirmed safe, we can find and fix the leak, usually a loose fitting or a worn valve seal.

One thing folks in San Antonio ask us a lot: does hard water mess with gas units the way it does electric elements? Not really, not directly. Your gas burner heats the tank from the outside, so it’s not sitting in mineral scale the way an electric element is. Where hard water does still hurt a gas unit is sediment building up on the bottom of the tank itself, which can cause popping and rumbling sounds and eventually burn out the tank bottom from uneven heat. That’s a maintenance issue more than an ignition issue, and it’s why we still recommend an annual flush on gas units here just like electric ones.