The right gas water heater thermostat or control valve depends on the heater’s brand, model, fuel type, and existing part number. The Reliance 100112336 options are best for shoppers matching that specific valve; the Rheem AP14270G and SP20832E are better choices when the heater calls for those Rheem part numbers. The Richmond AP15255A-1 is intended for a matching Richmond replacement. These parts are not presented as universal replacements, so verify the appliance’s model and the part number before buying.
| Product | Best suited for | Key identifying detail |
|---|---|---|
| Reliance 100112336 | Matching A.O. Smith, Reliance, State, or American-branded heaters | Professional installation is advised in the listing |
| Reliance 100112336 / WT8840B | Buyers matching the listed trade number and specifications | 160°F; 1-inch cavity |
| Rheem AP14270G | Rheem heaters requiring this OEM part | Natural gas control thermostat |
| Rheem SP20832E | Rheem heaters requiring this OEM replacement | Natural gas control thermostat |
| Richmond AP15255A-1 | Richmond heaters requiring this replacement number | Upgraded OEM replacement listing |
Reliance 100112336 Gas Control Valve
This gas control valve and thermostat is listed as compatible with A.O. Smith, Reliance, State, and American-branded water heaters. The description identifies it as a replacement part rather than a universal valve. Compatibility should be confirmed against the water heater’s model information and the number on the existing control.
Best for: Owners whose heater documentation or current part identifies the Reliance 100112336. It is also a practical candidate for shoppers seeking this part number across the listed brands. Brand names alone are not enough to confirm fit; model and part-number matching are important.
- The listing identifies the item as a gas control valve.
- It names A.O. Smith, Reliance, State, and American-branded heaters as compatible brands.
- The listing advises professional installation and warns that homeowner installation could potentially affect a warranty.
Limitation: The product information does not provide a full model-by-model compatibility list. The listing specifically recommends professional installation, so this is not the best choice for a buyer looking for a clearly homeowner-installable part.
Reliance 100112336 WT8840B Valve
This listing describes a Reliance water heater gas control valve with part number 100112336 and trade number WT8840B. It also specifies a 160°F rating and a 1-inch cavity. Those details give buyers additional identifiers to compare with the existing valve, beyond the brand and general product category.
Best for: Buyers who need the listed 100112336 or WT8840B designation and can confirm the 160°F and 1-inch-cavity details match their appliance. It may be easier to assess against an existing component when those specifications are visible in the heater’s documentation or on the old part.
- Trade number: WT8840B.
- Listed temperature rating: 160°F.
- Listed cavity dimension: 1 inch.
- Ambient temperature range in the provided features: 0°C to 60°C.
Limitation: The provided features do not give a complete list of compatible water heater models or installation guidance. Do not assume a matching brand name or one dimension proves the valve will fit; confirm all relevant identifiers before ordering.
Rheem AP14270G Gas Control Thermostat
The Rheem AP14270G is described as a natural gas control thermostat. Its listed functions include regulating water temperature and controlling gas flow from the main supply line to the burner. The listing identifies it as a genuine OEM part, a useful detail for buyers whose water heater calls for this specific Rheem number.
Best for: Owners of a Rheem water heater whose model information or existing part specifies AP14270G. The stated gas-flow and temperature-control roles make the product category clear, while the OEM description helps distinguish it from a generic part listing.
- Natural gas control thermostat.
- Controls gas flow from the main supply line to the burner.
- Regulates water temperature.
- Identified in the listing as a genuine OEM, factory-authorized part.
Limitation: The listing does not supply a model-by-model fit chart in the provided features. Do not select it solely because the heater is Rheem-branded; confirm that AP14270G is the specified replacement part. The listed physical dimensions are 12.7 by 7.5 by 6.6 inches, but dimensions alone do not establish compatibility.
Rheem SP20832E Natural Gas Thermostat
The SP20832E is listed as a natural gas control thermostat and a factory-authorized replacement part. The product description says it controls gas flow to the burner and regulates water temperature for consistent hot water delivery. These functions make it a relevant option when the water heater’s replacement documentation names SP20832E.
Best for: Buyers searching for the exact Rheem SP20832E part number. Its stated OEM status may be useful to shoppers prioritizing a factory-authorized replacement, but the part number—not the general Rheem name—should guide the fit decision.
- Natural gas control thermostat.
- Controls gas flow from the main supply line to the burner.
- Regulates water temperature.
- Described as a factory-authorized replacement part.
Limitation: The provided product information does not identify specific compatible heater models, dimensions, or an installation process. Confirm the SP20832E number against the heater’s documentation or existing part before purchase. Do not treat it as interchangeable with another Rheem control valve based only on similar function.
Richmond AP15255A-1 Gas Valve Thermostat
This product is described as an upgraded OEM water heater gas valve thermostat that directly replaces the older AP15255A-1 number. Its stated function is thermostat control. The part number is the most useful selection clue in the supplied information, so buyers should compare it with their old valve or the replacement number in the heater’s documentation.
Best for: Owners of a Richmond water heater whose records call for AP15255A-1. The listing’s direct-replacement wording and OEM description make it a relevant option when that exact number is required.
- Listed as a new, upgraded OEM water heater gas valve thermostat.
- Identified as a direct replacement for AP15255A-1.
- Described as a thermostat control.
Limitation: The provided features do not list compatible model numbers, fuel details, dimensions, or installation requirements. Verify the replacement number and appliance specifications before choosing it, rather than assuming it fits every Richmond heater.
Buying Guide: How to Choose a Gas Water Heater Thermostat
How do you identify the correct replacement part?
Start with the water heater’s rating plate, manual, and service documentation. Record the complete model number and serial information, then locate the part number on the existing gas control if it is readable. Compare those identifiers with the replacement listing. A thermostat or control valve can look similar to another part while having different specifications, so appearance alone is not a reliable fit check.
For these five options, the key numbers are 100112336, WT8840B, AP14270G, SP20832E, and AP15255A-1. Treat each as a distinct part unless the heater manufacturer’s documentation confirms interchangeability. The listings do not provide complete fit charts, so the product title alone cannot establish that a part works with every heater from the named brand.
Does natural gas versus propane matter?
Yes. Match the valve to the fuel type specified for the water heater. The Rheem AP14270G and SP20832E listings specifically identify natural gas. Do not infer that a natural-gas control is suitable for a propane appliance, or that a valve suits both fuel types, unless the manufacturer’s documentation explicitly says so.
The supplied details for the Reliance and Richmond listings do not fully establish fuel compatibility across every model. Check the appliance label and the replacement-part documentation for the exact fuel requirement before ordering. If the information is unclear, ask the manufacturer or a qualified service professional to identify the correct part.
What is the difference between a thermostat and a gas control valve?
In these listings, “thermostat” and “gas control” often describe a combined water-heater component. The product descriptions say the controls regulate water temperature and manage gas flow to the burner. The terms are not enough to identify a specific replacement, however. Use the required part number and appliance model to distinguish one control from another.
When comparing options, look for the functions and identifiers stated in the listing. The Rheem descriptions explicitly mention gas-flow control and temperature regulation. The Reliance and Richmond product names identify gas control valve or gas valve thermostat parts, but their supplied feature lists contain less detail about operation.
Should you install a gas water heater control yourself?
The first Reliance listing advises professional installation and warns that homeowner installation could potentially affect a warranty. Gas-control work concerns a fuel-burning appliance, so buyers should take the listing’s caution seriously and follow the heater manufacturer’s instructions. The supplied descriptions do not provide step-by-step installation directions for these products.
Before any service, consult the appliance documentation and use a qualified professional when required by the manufacturer or when the work is outside your experience. Do not rely on a product image or a general online description as an installation guide. Ask the service professional to verify the part number and compatibility before the replacement is made.
Which specifications should you compare?
Compare the full part number first, then check the heater model, fuel type, and any listed control specifications. For the Reliance WT8840B listing, the stated 160°F rating and 1-inch cavity are additional identifiers. The same listing gives an ambient temperature range of 0°C to 60°C. Do not substitute a component based on one matching measurement if other requirements remain unverified.
For an OEM-labeled part, check that the exact OEM number matches the appliance’s required number. “OEM” or “factory authorized” language is useful product information, but it does not mean the part fits every appliance from that manufacturer. The Rheem AP14270G and SP20832E are separate part numbers and should not be treated as interchangeable without confirmation.
How should you compare these five options?
- Choose Reliance 100112336 if the heater’s documentation calls for that number and the listed brand compatibility matches the appliance.
- Choose the WT8840B listing if the trade number and its stated specifications match the existing control.
- Choose Rheem AP14270G or SP20832E only when the relevant Rheem documentation calls for that exact part number.
- Choose Richmond AP15255A-1 when the heater’s required replacement number is AP15255A-1.
When two listings appear to describe similar functions, prioritize the exact part number and official compatibility information. Avoid choosing by price, product photograph, or a broad brand match alone. If the old control’s label is missing or unreadable, use the water heater model number to request a verified replacement recommendation.
Frequently Asked Questions
Are gas water heater thermostats universal?
No. These listings identify specific part numbers and do not establish universal compatibility. Match the replacement to the water heater model, fuel type, and required part number.
Can I use a natural-gas thermostat on a propane water heater?
Do not assume so. The Rheem AP14270G and SP20832E listings specify natural gas. Confirm fuel compatibility in the heater and part documentation before buying.
Are the Rheem AP14270G and SP20832E interchangeable?
The supplied information does not say they are interchangeable. They are different part numbers, so use the number specified for the particular heater.
What does WT8840B mean on the Reliance listing?
WT8840B is the trade number given for the listed Reliance 100112336 gas control valve. Compare that number and the listed specifications with the existing part and heater documentation.
Should a professional install a replacement gas control valve?
The first Reliance listing advises professional installation. Follow the heater manufacturer’s instructions and use a qualified professional when required or when you are not equipped to perform the work safely.
What information should I have before ordering?
Have the water heater’s complete model number, fuel type, and existing control’s part number available. Verify the replacement against the appliance documentation or with the manufacturer or a qualified service professional.