Water Heater Parts: Burners, Thermostats, Valves & Ignitors
Voomi Supply carries replacement water heater parts, including burner assemblies, gas control thermostats, gas valves, pilot assemblies and hot surface ignitors, anode rods, aquastats, and water feeders, from brands like Rheem, AO Smith, Bradford White, Lochinvar, Allpoints, and American Standard. Shop in-stock parts with detailed technical specifications and OEM cross-reference numbers on every listing, plus US-based support to help match the right part to your existing water heater or boiler.
Same-DayShipping on in-stock orders
30-DayReturns on most items
OEM FitCross-reference part numbers listed
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MCDONNELL & MILLER
McDonnell & Miller 101A-120V Water Feeder 110V 1/2 IPS
$681.79
Out of stock
CENTURY MOTORS
Ao Smith 9005044205 - Aquastat Kit Control With 3/4 Well| 3 1/2 X 7/16
$405.85
Out of stock
KEATING
GAS VALVE 1/2 for Keating 023625
$681.09
$392.32
In stock
AO SMITH
A O Smith 100223203 18 Final Burner Assembly Kit 3.5 EXT AL #34TP
$151.09
In stock
RHEEM
Rheem SP20303D Natural Gas Water Heater Control Thermostat Replacement SP21195C
$133.66
In stock
LOCHINVAR
Lochinvar PLT3400 Hot Surface Ignitor for Copper-Fin Boilers
$195.44
$97.10
In stock
RHEEM
Rheem AP11526T-2 Magnesium Anode Rod for Water Heater
$49.21
In stock
Brands we carry
Core water heater components
A gas water heater or boiler is built from a small set of core parts that wear out and get replaced individually, without needing to replace the whole unit.
| Part | Function | Shop |
|---|---|---|
| Burner assembly | Burns gas to heat water in the tank | Burners |
| Gas control thermostat | Regulates water temperature and controls gas flow to the burner | Gas control thermostats |
| Gas valve | Controls gas supply to the burner and pilot | Gas valves |
| Pilot assembly / ignitor | Lights the burner, either with a standing pilot flame or hot surface ignition | Pilot assemblies · Ignitors |
| Anode rod | Sacrificial metal rod that corrodes instead of the tank, extending tank life | Shop water heater parts |
| Aquastat | Temperature control switch used on boilers and some tank systems | Aquastats & controls |
| Water feeder | Automatically maintains water level and pressure in a boiler system | Water feeders |
Common symptoms and likely parts
Matching a symptom to the part most likely responsible can save a service call, or at least help explain the problem to a technician.
| Symptom | Likely cause |
|---|---|
| Water heater is leaking | Failed T&P relief valve, corroded tank, or a loose drain valve or fitting |
| No hot water, pilot won't stay lit | Faulty thermocouple or pilot assembly, or a failing gas control thermostat |
| Water isn't hot enough | Thermostat set too low, sediment buildup, or a failing burner |
| Rumbling or popping noises | Sediment buildup at the bottom of the tank |
| Rotten egg smell in hot water | Bacteria reacting with the anode rod, often solved with an anode rod replacement |
| Boiler losing pressure repeatedly | Failing water feeder or a leak somewhere in the system |
If you're not confident diagnosing the cause, a licensed plumber or HVAC technician can confirm which part is at fault before you order a replacement.
Anode rod maintenance
The anode rod is designed to corrode before the steel tank does, protecting the tank from rust through a process called cathodic protection. Most manufacturers recommend checking the anode rod every 1 to 3 years and replacing it once it's worn down to a thin wire core or heavily coated in calcium. A magnesium rod, like the Rheem AP11526T-2, is the most common replacement type and also helps reduce the rotten egg odor some water heaters develop over time.
Things to consider before you buy
- Match the part number or cross-reference number exactly, not just the brand, since components vary between model series
- Gas valve, thermostat, and burner replacements involve gas connections and should be installed by a licensed plumber or HVAC technician
- Check whether your unit uses a standing pilot or hot surface ignition before ordering an ignition part
- Confirm voltage and connection size on electrical parts like water feeders and aquastats
- Some specialty and commercial parts ship on a longer lead time; check the listing before ordering if you need it quickly
Water heater parts glossary
- Anode rod
- A sacrificial metal rod that corrodes in place of the tank, extending the water heater's lifespan. Shop water heater parts →
- Aquastat
- A temperature-sensing control switch that turns heating equipment on or off at set thresholds. Shop aquastats →
- T&P valve
- Temperature and pressure relief valve; releases pressure automatically if the tank overheats or over-pressurizes. Shop water heater parts →
- Hot surface ignitor
- An electrically heated element that ignites the burner without a standing pilot flame. Shop ignitors →
- Thermocouple / thermopile
- A safety sensor that confirms the pilot flame is lit before allowing gas to flow to the main burner. Shop pilot assemblies →
- Water feeder
- A device that automatically adds water to a boiler system to maintain proper pressure. Shop water feeders →
Frequently asked questions
Why is my water heater leaking?
Common causes include a failed temperature and pressure relief valve, a corroded tank nearing the end of its life, or a loose drain valve or fitting. A leak from the tank itself usually means replacement is needed, while a leak from a valve or fitting is often a straightforward repair.
How often should I replace the anode rod?
Check the anode rod every 1 to 3 years and replace it once it's worn down to a thin wire core or heavily coated in calcium buildup. Water quality affects how quickly the rod wears, so homes with softened or aggressive water may need more frequent checks.
What does a gas control thermostat do?
A gas control thermostat regulates water temperature and controls gas flow to the burner, combining the functions of a temperature control and a gas valve in one unit on many residential water heaters. If it fails, the water heater may not maintain temperature or may not ignite at all.
Why won't my pilot light stay lit?
This is most often caused by a faulty thermocouple or thermopile, which senses the pilot flame and allows gas to flow to the main burner. A weak or misaligned pilot flame, or a failing gas control thermostat, can also be the cause.
Can I replace water heater parts myself?
Some parts, like an anode rod, are within reach for an experienced DIYer. Any part involving a gas connection, including burners, gas valves, and pilot assemblies, should be installed by a licensed plumber or HVAC technician to keep the system safe and the warranty valid.
What's the difference between a pilot assembly and a hot surface ignitor?
A pilot assembly maintains a small standing flame that lights the main burner when heat is called for. A hot surface ignitor uses an electrically heated element instead, lighting the burner directly without a continuously burning pilot flame.
Why does my hot water smell like rotten eggs?
This is usually caused by naturally occurring bacteria reacting with the anode rod, particularly in homes with well water. Replacing a magnesium anode rod with an aluminum or zinc alloy rod often resolves the odor.
How do I find the right replacement part for my water heater?
Check the rating plate on your water heater or boiler for the model and serial number, then look up the specific part number for the component you need, since parts vary between model series even from the same manufacturer. Voomi Supply's listings include cross-reference numbers to help confirm fit before you order.
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