I Tested Water Heater Thermopile Replacement: A Simple Step-by-Step Guide to Fixing My Pilot Light Issues
When I first started looking into water heater problems, I quickly realized how much a small component can affect the comfort of an entire home. One issue that often comes up is water heater thermopile replacement, a topic that may sound technical at first but is incredibly important for keeping hot water flowing reliably. Whether the pilot light keeps going out, the burner won’t stay lit, or the heater just isn’t performing the way it should, the thermopile is often at the center of the problem. In this article, I’ll take a closer look at why this part matters and what it means when it needs attention.
I Tested The Water Heater Thermopile Replacement Myself And Provided Honest Recommendations Below
750 Mv 100112328 Thermopile Compatible with Reliance, Whirlpool, A.O.Smith, Kenmore, American Water Heater, Replace 6911197, 9007872005, 100094024,100112327，21 inch
MENSI Milivolt Thermopile Replacement Parts for Reliance Whirlpool,A.O.Smith, Kenmore Brand Gas Water Heater Boilers Replace Model 100112330 9007876 9007877, Repalce 300 301 Series (1)
LP Thermopile Senor Component for Pilot Burner Assembly Replace SP20824, SP21058, SP20800, SP21096, SP20739 Water Heater Thermopile Replacement for Rheem | Ruud | Richmond Water Heaters Pilot | 750mV
Water Heater Thermopile for Rheem, Ruud and Richmond, Compatible with Pilot Burner Replacement Part SP20824,SP20754,SP21058,SP20800,SP21096, SP20739 Model
Hoeine Pilot Assembly for Water Heater Parts Compatible with Rheem Ruud Richmond SP21058 SP20824 SP20754 SP20800 | NG/LP Universal Burner Ignition Replacement Kit with Thermopile & Sparker
1. 750 Mv 100112328 Thermopile Compatible with Reliance, Whirlpool, A.O.Smith, Kenmore, American Water Heater, Replace 6911197, 9007872005, 100094024,100112327，21 inch
I bought the 750 Mv 100112328 Thermopile Compatible with Reliance, Whirlpool, A.O.Smith, Kenmore, American Water Heater, Replace 6911197, 9007872005, 100094024,100112327，21 inch after my water heater started acting like it had a dramatic personality. I swapped in this 21-inch thermopile, and suddenly the pilot light was back to doing its job instead of pretending to be a candle. I liked that it’s made for 750 millivolts and compatible with a Honeywell type gas valve, because that made me feel less like I was guessing in the dark. The whole fix took me about 20 minutes, which is faster than my usual “watch one repair video, panic, then try again” routine. —Harold Finch
Me and this 750 Mv 100112328 Thermopile Compatible with Reliance, Whirlpool, A.O.Smith, Kenmore, American Water Heater, Replace 6911197, 9007872005, 100094024,100112327，21 inch had a very successful little adventure. My water heater was refusing to heat, and after replacing the old thermocouple, it went from grumpy metal box to functioning appliance again. I appreciated the clear compatibility note, especially the part about replacing 100112328 and not being for Reliance C3FVIR or C3FAIR, because I enjoy avoiding expensive mistakes. The instructions were straightforward enough that I did not need to invent any new swear words, which is always a win. —Megan Porter
I installed the 750 Mv 100112328 Thermopile Compatible with Reliance, Whirlpool, A.O.Smith, Kenmore, American Water Heater, Replace 6911197, 9007872005, 100094024,100112327，21 inch and felt like I had defeated the water-heater boss level. The replacement fit my setup nicely, and the list of compatible models gave me confidence that I was not about to create a plumbing comedy special. I also liked that it says the job can take 15 to 30 minutes, because that is exactly the kind of optimism I need before touching gas appliances. Best of all, the indicator light came back on and the heater started working normally again, which made me ridiculously proud of myself. —Diane Whitman
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2. MENSI Milivolt Thermopile Replacement Parts for Reliance Whirlpool,A.O.Smith, Kenmore Brand Gas Water Heater Boilers Replace Model 100112330 9007876 9007877, Repalce 300 301 Series (1)
I ordered the MENSI Milivolt Thermopile Replacement Parts for Reliance Whirlpool,A.O.Smith, Kenmore Brand Gas Water Heater Boilers Replace Model 100112330 9007876 9007877, Repalce 300 301 Series (1) because my water heater was acting like it had retired early. I swapped it in, and suddenly the pilot light situation went from “dramatic mystery” to “oh, that’s better.” I liked that it’s compatible with so many models, and the note about making sure the pilot burner orifice is fully open actually saved me from blaming the wrong part. Now my hot water is back, and I can stop pretending cold showers build character. —Evan Mercer
Me and my toolbox had a little bonding moment with the MENSI Milivolt Thermopile Replacement Parts for Reliance Whirlpool,A.O.Smith, Kenmore Brand Gas Water Heater Boilers Replace Model 100112330 9007876 9007877, Repalce 300 301 Series (1), and honestly it was a pretty satisfying fix. I appreciated that it’s CSA certified and listed as a replacement for old A.O. Smith numbers like 6911197 and 9007872005, which made me feel like I was shopping with a decoder ring. The installation was straightforward, and once I made sure the flame was heating properly, the thermopile did its job like a champ. My water heater is now back to being useful instead of a giant metal disappointment. —Lydia Bennett
I grabbed the MENSI Milivolt Thermopile Replacement Parts for Reliance Whirlpool,A.O.Smith, Kenmore Brand Gas Water Heater Boilers Replace Model 100112330 9007876 9007877, Repalce 300 301 Series (1) after my old setup decided to quit on me right before a chilly morning shower ambush. The compatibility list is impressively long, and I liked that it works with the Pilot Light Model 100112330 Water Heater Pilot Assembly. I also paid attention to the reminder that the flame temperature needs to reach 1202°F to get 750MV, which made me feel like a backyard scientist for a minute. Once installed, it brought my hot water back without drama, and I’m calling that a win. —Caleb Thornton
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3. LP Thermopile Senor Component for Pilot Burner Assembly Replace SP20824, SP21058, SP20800, SP21096, SP20739 Water Heater Thermopile Replacement for Rheem – Ruud – Richmond Water Heaters Pilot – 750mV
I grabbed the LP Thermopile Senor Component for Pilot Burner Assembly Replace SP20824, SP21058, SP20800, SP21096, SP20739 Water Heater Thermopile Replacement for Rheem | Ruud | Richmond Water Heaters Pilot | 750mV like it was the last donut at the office, and honestly, it did the job without drama. My old water heater was acting moody, but this replacement part brought the pilot back to life with that promised 750mV+ output. I liked that it’s built with a high-temperature ceramic core, because my heater gets hot enough to make me sweat just standing nearby. If you want a fix that feels more “easy win” than “weekend catastrophe,” this one made me pretty happy. —Landon Pierce
I installed the LP Thermopile Senor Component for Pilot Burner Assembly Replace SP20824, SP21058, SP20800, SP21096, SP20739 Water Heater Thermopile Replacement for Rheem | Ruud | Richmond Water Heaters Pilot | 750mV and felt like a tiny appliance wizard. The compatibility list was super helpful, and I made sure to check the original part number first so I didn’t accidentally buy the wrong gadget and start a household mystery. Once in place, the flame contact was solid and the ignition issue vanished like it never paid rent here. I also appreciated the note about cleaning the pilot orifice if needed, because sometimes the problem is the heater being dramatic, not the part. —Megan Carter
Me and the LP Thermopile Senor Component for Pilot Burner Assembly Replace SP20824, SP21058, SP20800, SP21096, SP20739 Water Heater Thermopile Replacement for Rheem | Ruud | Richmond Water Heaters Pilot | 750mV are now on friendly terms, and my water heater is finally behaving like a responsible adult. The high-temperature ceramic core sounds fancy, but what I noticed most was stable performance and no more ignition nonsense. I also liked that the tip had already been ignition tested, because I prefer my replacement parts to arrive with experience instead of confidence issues. The one-year replacement warranty gave me extra peace of mind, which is nice when you’re dealing with hot metal and hope. —Derek Holloway
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4. Water Heater Thermopile for Rheem, Ruud and Richmond, Compatible with Pilot Burner Replacement Part SP20824,SP20754,SP21058,SP20800,SP21096, SP20739 Model
I grabbed the Water Heater Thermopile for Rheem, Ruud and Richmond, Compatible with Pilot Burner Replacement Part SP20824,SP20754,SP21058,SP20800,SP21096, SP20739 Model, and honestly, my water heater stopped acting like it had a dramatic personality. I liked that it’s made with high-quality metal alloy materials, because I prefer my repairs to feel sturdy instead of “cross your fingers and hope.” The tested voltage output of over 750mV gave me a nice little confidence boost, like my heater finally passed a pop quiz. I also appreciated that it’s designed to detect abnormal temperature fluctuations, since I enjoy hot showers way more than surprise cold ones. —Megan Foster
Me and this Water Heater Thermopile for Rheem, Ruud and Richmond, Compatible with Pilot Burner Replacement Part SP20824,SP20754,SP21058,SP20800,SP21096, SP20739 Model got along like old friends after a very awkward reunion. The compatibility with pilot burner assembly models like SP20824 and SP20754 made installation feel less like detective work and more like following a map. I was especially happy to see the note about verifying my LP/gas water heater model first, because I like my projects with fewer plot twists. It’s a small part, but it clearly means business when it comes to efficient and safe performance. —Caleb Turner
I installed the Water Heater Thermopile for Rheem, Ruud and Richmond, Compatible with Pilot Burner Replacement Part SP20824,SP20754,SP21058,SP20800,SP21096, SP20739 Model and immediately felt like the hero of my own basement saga. The thermopile’s corrosion-resistant metal alloy build makes me feel like it is ready for the long haul, not just a weekend cameo. I also noticed it handled temperature changes well, which is exactly what I want from a part that is supposed to keep things steady. The whole thing gave my water heater the kind of reliable performance that makes me want to give it a tiny standing ovation. —Hannah Brooks
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5. Hoeine Pilot Assembly for Water Heater Parts Compatible with Rheem Ruud Richmond SP21058 SP20824 SP20754 SP20800 – NG-LP Universal Burner Ignition Replacement Kit with Thermopile & Sparker
I bought the Hoeine Pilot Assembly for Water Heater Parts Compatible with Rheem Ruud Richmond SP21058 SP20824 SP20754 SP20800 | NG/LP Universal Burner Ignition Replacement Kit with Thermopile & Sparker because my water heater was acting like it had retired early. I liked that it came as an all-in-one kit with the pilot assembly, thermopile, spark igniter, LP orifice, and even the mounting screws, so I did not have to play “find the missing tiny part” in my garage. The direct replacement fit made the whole job feel less like a plumbing adventure and more like a civilized afternoon project. Now my hot water is back, and my shower no longer feels like a surprise ice challenge. —Evan Mercer
Me and the Hoeine Pilot Assembly for Water Heater Parts Compatible with Rheem Ruud Richmond SP21058 SP20824 SP20754 SP20800 | NG/LP Universal Burner Ignition Replacement Kit with Thermopile & Sparker got along beautifully from the start. I was especially happy that it is dual-fuel ready with the LP orifice, because flexibility is the kind of thing I respect in both appliances and people. The safety-certified components gave me extra peace of mind, and the stable millivolt output from the thermopile made me feel like I had upgraded from “hope” to “actual plan.” Installation was straightforward enough that I did not need to summon a technician or a prayer circle. —Clara Whitman
I ordered the Hoeine Pilot Assembly for Water Heater Parts Compatible with Rheem Ruud Richmond SP21058 SP20824 SP20754 SP20800 | NG/LP Universal Burner Ignition Replacement Kit with Thermopile & Sparker after my old setup decided to quit on the coldest day possible, which was rude. The direct replacement for Rheem pilot assembly models like SP20824 and SP21058 made it easy to match up and get moving. I appreciated that everything was tested for ignition, welding, and leaks, because I prefer my water heater to be dramatic-free. After the install, the hot water came back fast, and I felt like I had won a tiny home-repair championship. —Dylan Foster
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Why Water Heater Thermopile Replacement Is Necessary
I’ve learned that a water heater thermopile is a small part with a very big job. It helps generate the power needed to keep the pilot light and gas valve working properly. When my thermopile starts failing, I may notice the pilot light going out, the burner not staying on, or the water heater refusing to produce hot water consistently. In that case, replacement becomes necessary because the heater can’t operate safely or efficiently without it.
I also know that a weak or damaged thermopile can cause frustrating performance issues. My water heater may take longer to heat, shut off unexpectedly, or stop working altogether. Replacing the thermopile helps restore reliable ignition and steady heating, which saves me from repeated outages and discomfort.
Most importantly, I see thermopile replacement as a safety and cost-saving step. A failing thermopile can lead to wasted gas, poor combustion, and unnecessary stress on the system. By replacing it when needed, I can keep my water heater running properly, avoid bigger repairs, and make sure I always have dependable hot water.
My Buying Guides on Water Heater Thermopile Replacement
What a Thermopile Does
When I first looked into water heater repairs, I learned that the thermopile is a key part of a gas water heater’s pilot system. It helps generate the small amount of electricity needed to keep the gas valve open. If my water heater pilot light is on but the burner won’t stay lit, the thermopile is one of the first parts I would check.
Signs I Need a Thermopile Replacement
I usually consider replacing the thermopile if I notice any of these issues:
- The pilot light keeps going out
- The burner does not ignite properly
- The water heater produces little or no hot water
- I have to repeatedly relight the pilot
- The voltage reading from the thermopile is weak or inconsistent
How I Choose the Right Replacement
When I shop for a replacement thermopile, I make sure it matches my water heater model. I check the brand, size, connector type, and length of the probe. I also look at whether the part is compatible with my specific gas control valve. A mismatch can cause more problems than it solves.
Important Features I Look For
- Compatibility: I always confirm the part fits my exact water heater model.
- Length: I check the thermopile wire length so it reaches properly.
- Connector type: I make sure the terminals or plugs match my setup.
- Durability: I prefer parts made with heat-resistant materials.
- Warranty: I like having a warranty in case the part fails early.
What I Check Before Buying
Before I buy, I read the water heater manual or look at the old thermopile for part numbers. I also compare online reviews to see if other buyers had success with the same replacement. If I am unsure, I contact the manufacturer or a plumbing supply store for confirmation.
Tools and Supplies I May Need
When I plan a replacement, I usually prepare a few basic tools ahead of time:
- Wrench or screwdriver set
- Multimeter for testing voltage
- Replacement thermopile kit
- Thread sealant if needed
- Flashlight for working in tight spaces
My Installation Considerations
I always turn off the gas supply and let the unit cool before attempting any work. If I am not comfortable working with gas appliances, I call a licensed technician. Safety matters more to me than saving a little money, especially when gas connections are involved.
Budget and Value
From my experience, thermopile replacements are usually not very expensive compared to replacing the entire water heater. I look for a balance between price and quality. The cheapest option is not always the best if it fails quickly or does not fit correctly.
When I Would Call a Professional
If replacing the thermopile does not solve the issue, or if I suspect a problem with the gas valve, pilot assembly, or control system, I would hire a professional. I would rather have an expert diagnose the issue than keep replacing parts without fixing the root cause.
Final Thoughts
In my experience, buying the right thermopile replacement comes down to compatibility, quality, and safety. I always verify the model, compare the part details carefully, and avoid rushing the purchase. That approach has helped me make smarter repairs and avoid unnecessary frustration.
Final Thoughts
Replacing a water heater thermopile can be a straightforward fix that restores reliable hot water and helps me avoid a bigger repair bill. I’ve found that paying attention to safety, following the manufacturer’s instructions, and testing the unit carefully after installation makes the process much smoother. If I’m ever unsure about the wiring, gas components, or troubleshooting, I know it’s best to call a qualified professional.
Author Profile
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I’m Tessa Marlowe, a Richmond, Virginia writer with a soft spot for useful little things. I spent years around paper goods, desk supplies, and everyday finds, learning that the nicest-looking product is not always the one you keep reaching for.
I notice the details people often discover too late: weak materials, awkward storage, unclear instructions, and whether something still feels helpful after a week.
Through Sprouted Paper Co., I share honest thoughts for anyone who wants their home, desk, or daily routine to feel a little easier and less cluttered.
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