Burnham, Hydronics & Real-World Maintenance: 8 Questions from the Field
If you're a contractor or homeowner digging into a Burnham boiler manual, troubleshooting a sensor, or just trying to figure out how to flush a hot water heater, you're not alone. I've been reviewing HVAC equipment and parts specs for years as a quality compliance manager. These eight questions come up more often than you'd think.
Jump to a question:
- Where do I find the Burnham ES2 boiler manual?
- How do I test a Burnham return water temperature sensor (105910-01)?
- Why does my Burnham boiler keep short-cycling?
- Can I install a burner from a different brand into my Burnham boiler?
- How often should I flush a hot water heater?
- Do outdoor heaters and Lasko fans help with boiler room ventilation?
- What's the difference between indirect water heater maintenance and a standard tank?
- My Burnham boiler is over 30 years old. Should I replace it proactively?
1. Where do I find the Burnham ES2 boiler manual?
It's tempting to just Google the model number and grab the first PDF. But don't. Some sites host older versions or re-host manuals without the latest safety addendums. I've rejected field installations because the contractor used a manual revision that didn't reflect updated venting requirements.
Go straight to the source. Burnham's parent company, U.S. Boiler Company, keeps the official ES2 manual documents on their website. You're looking for the ES2 Series Gas Boiler Installation, Operation & Service Manual. The actual document number usually ends in something like "ES2-I-OM" followed by a revision letter. If you're pulling a manual off a site that isn't USBoiler.net, I'd cross-reference the revision date with the official publication list.
In my opinion, the single most overlooked section is the piping schematics. The ES2 is often retrofitted into older systems. Get that wrong, and you'll have a call back for air locked circulators in a month.
2. How do I test a Burnham return water temperature sensor (part 105910-01)?
Most buyers focus on the price of the sensor. The real question is whether the sensor is degraded — not just failed. A failed sensor throws an error code immediately. A degraded sensor gives incorrect readings that cause your boiler to short-cycle or overheat at the wrong times.
The 105910-01 is a thermistor, not a switch. That means its resistance changes with temperature, not just on/off. Here's the quick bench test:
- Set your multimeter to ohms.
- Reference the resistance chart in the ES2 manual. At 77°F (25°C), you should read approximately 10,000 ohms. At 194°F (90°C), you should read approximately 1,000 ohms.
- Compare your reading to the chart. If it's off by more than 5%, I'd replace it.
The question everyone asks is "Is it good or bad." The question they should ask is "How far off from the curve is it?" We had a batch a few years back that drifted after 18 months of operation. The system didn't throw a fault code, but efficiency dropped noticeably.
3. Why does my Burnham boiler keep short-cycling?
Short-cycling drives everyone crazy. You see the burner fire, run for a minute, shut off. Then fire again. It's usually not the boiler itself. More often than not, it's a symptom of something else.
From my perspective, working through service calls, the culprits rank like this:
- Oversized boiler. The classic symptom. The boiler heats the water faster than the system can dissipate it. The water hits setpoint quickly, boiler shuts off. Water cools slightly, boiler fires up again. It's a cycle of 2-3 minutes. The solution is sometimes adding a buffer tank or lower-firing-rate input, but that's a scope-of-work conversation.
- Faulty return water temperature sensor. As mentioned above — if the sensor reports the water is hotter or colder than it actually is, the control board makes bad decisions.
- Improper circulator operation. If the pump isn't moving water effectively, the heat transfer stalls.
- Air in the system. Air pockets cause erratic flow. Purge the system thoroughly.
I'll say it: replacing the entire boiler for short-cycling is usually a waste of money. Diagnose before you spec a new unit.
4. Can I install a burner from a different brand into my Burnham boiler?
Short answer: Don't. Longer answer: I've seen it happen, and the results are never good.
I assumed that a burner was a burner once. That a generic replacement would work. It didn't. The flame shape, the manifold pressure drop, the air/fuel ratio — all specific to the burner design for that specific boiler model. The Burnham ES2 uses a burner matched to its combustion chamber geometry.
Installing a Weil-McLain burner or a generic replacement means you're flying blind on those critical specs. The result is either incomplete combustion (sooting, carbon monoxide) or inefficient firing. The cost difference between a genuine Burnham burner kit and a generic is usually under $100. On a professionally installed system, that's a non-issue.
If you're stuck because a part is discontinued, call the supplier. Sometimes there's a factory-issued cross-reference that's validated.
5. How often should I flush a hot water heater?
This one depends entirely on your water quality. The "once a year" advice is a decent starting point. But it ignores everything about your specific situation.
If you have hard water (10+ grains per gallon), I'd flush every six months. If you're on a municipal soft water system, annually is fine. The real indicator is what comes out when you drain a bucket. If it's cloudy or has sediment in suspension, you're late.
Here's a quick process I use when inspecting installations:
- Turn off the gas or electric supply.
- Attach a hose to the drain valve at the bottom.
- Open a hot water faucet somewhere in the house to prevent vacuum lock.
- Open the drain valve. Let it flow until the water runs clear.
- If the water never clears, the tank has built up too much sediment.
I will say this: sediment buildup is the number one killer of water heaters, indirect heaters and storage tanks. An indirect water heater needs a flush at least once a year. The heat exchanger coils in an indirect will scale up and lose thermal transfer. I've seen indirect heater output drop by 40% after two years without maintenance.
6. Do outdoor heaters and Lasko fans help with boiler room ventilation?
I get this question more than I expected. The short answer: no. An outdoor heater is designed to heat people, not a space. A Lasko fan just moves air. Both are solving the wrong problem for a boiler room.
Boiler rooms need combustion air. The Burnham ES2 manual will specify the minimum air openings required (usually two openings, within 12 inches of the floor and ceiling, sized based on total BTUs). An outdoor heater adds heat to the room, which actually increases the air temperature and can affect combustion efficiency in some marginal installations.
If you're trying to fix a cold boiler room, insulate the pipes and seal the envelope. Adding a 1500W heater just to keep the boiler room above freezing is fine — but it won't help with air supply.
7. What's the difference between indirect water heater maintenance and a standard tank?
The principles overlap, but the weak points are different.
Standard tank: The tank itself corrodes. The anode rod is your sacrificial lamb. Replace the anode every 3-5 years, and the tank can last 12+ years. Skip the anode replacement, and you're lucky to get 8 years out of it.
Indirect water heater: The tank is usually stainless steel or glass-lined, but the coil that transfers heat from the boiler to the water is the failure point. Scale builds up inside the coil (from the boiler side) and outside the coil (from the storage water side).
That's a nuance most buyers miss. They focus on the tank being non-corroding and assume it's maintenance-free. It's not. A coil that's scaled up on both sides has dramatically reduced heat transfer. The boiler has to run hotter for longer. That's wasted fuel.
In my opinion, an indirect water heater is still a better product than a standard tank — hot water on demand is excellent — but the yearly flush is mandatory.
8. My Burnham boiler is over 30 years old. Should I replace it proactively?
The numbers said: "Your 30-year-old boiler runs at 82% efficiency. A new >95% condensing boiler is a big savings." My gut said: "That old boiler is built like a tank and has been reliable for thirty years."
What did I do? I advised the customer to run the numbers with their actual fuel usage. The math depends on your fuel type, regional gas prices, and how many months you run the system. For many, the payback on a new boiler is 5-8 years. For others in milder climates, it's longer than the equipment will last.
But there's a catch: parts availability. Burnham has decent support for older models, but not everything is still in production. A used controller is getting harder to find every year. I had a customer whose pump relay failed on a 35-year-old boiler. The replacement part was a ".used" pull from a supplier — no warranty.
I'd argue you don't replace a 30-year-old boiler because it's old. You replace it when you can't source a part, or when the efficiency gap justifies the cost. That's a different calculation for every house.
Pricing data on replacement boilers as of January 2025: Expect $3,800 to $6,200 installed for a residential Burnham gas boiler (like the ES2), depending on your region and complexity of the install. Verify current pricing with your local supplier.
