Owner’s manual
What are the five main parts of a boiler?
The five main parts you will find in most residential boilers (including the Dunkirk XEB-5) are the burner, combustion chamber, heat exchanger, controls/safeties, and the venting or draft system. Your exact configuration and control types are shown in the XEB-5 owner's manual.
- Burner: mixes fuel and air and creates the flame.
- Combustion chamber: contains the flame and directs heat safely.
- Heat exchanger: transfers heat from combustion into the boiler water.
- Controls and safeties: manage temperature, pressure, and safe operation (examples include high-limit control, pressure switch, rollout switch).
- Venting or draft system: moves combustion air and exhaust; many systems use a draft inducer blower.
From the XEB-5 documentation, common system components include a circulating pump (required for forced hot-water systems), a blower (draft inducer) that pulls air through the boiler and exhausts flue gases, and an air pressure switch that helps prevent firing if draft is inadequate or venting is blocked. These are all part of the “controls/safeties” and “venting/draft” functions.
| Boiler function | Typical parts included | What you notice when it fails |
|---|---|---|
| Make heat | Burner, combustion chamber | No heat, ignition issues |
| Transfer heat | Heat exchanger | Poor heating, unusual noises |
| Move heat to the home | Circulator pump, zone valves | Some rooms cold, no circulation |
| Keep operation safe | Limit control, pressure switch, relief valve | Lockouts, overheating, pressure problems |
Knowing these five “core” areas helps you troubleshoot faster: a no-heat problem is often a burner/control issue, while uneven heating is often circulation-related. It also helps you choose the right replacement part when you are diagnosing a specific symptom.
Last updated: February 2026
What boiler spares do I need?
For a Dunkirk XEB-5 boiler, the most useful spares are the safety and control parts that commonly stop heat or protect the system, plus a few basic hydronic items (valves, gauges, seals). Use the XEB-5 owner's manual to confirm what your system requires and what your local code mandates.
These are the parts we see most often needed to restore safe operation or prevent downtime:
- Safety relief valve (correct pressure and temperature rating for your system)
- Limit control / aquastat control (manages boiler water temperature and safety limits)
- Low water cutoff device (often required when the boiler is installed above radiation level)
- Circulator-related items (common gaskets, isolation valves, flange hardware)
- System fill and purge items (fill valve components, drain valves, hose washers)
- Basic electrical service items (wire connectors, correct fuses if used, strain reliefs)
If you want spares that match parts listed for this model, these are good starting points:
| Spare part | What it does | When it’s most useful |
|---|---|---|
| Relief valve | Opens to relieve excess pressure/temperature | Dripping valve, nuisance discharge, safety replacement interval |
| Limit control (aquastat) | Controls water temp and high-limit safety | No heat, short cycling, temperature control issues |
| Low water cutoff (if used) | Shuts boiler down on low water | Boiler installed above radiation level, code requirement |
Boilers are safety-critical. The manual calls out that installation and service must be performed by a qualified installer, and it emphasizes keeping combustion air openings clear and maintaining safe operation of controls. Keeping the right spares reduces downtime while helping you restore safe, code-compliant operation.
- Match fuel type (natural gas vs propane) and your venting setup.
- Match system pressure; this boiler type is designed for low-pressure hot water systems (typical residential hydronic ranges).
- Stock spares based on your failure history (for example, relief valve seepage vs control failures).
- Keep at least one spare for any part that would cause a no-heat condition.
Last updated: February 2026
How do I find the model number on my XEB-5?
The model number for your Dunkirk boiler is printed on the boiler’s rating plate (data tag). On an XEB-5, look for a label that lists the XEB series models and safety certifications; it will show XEB-5 as the model.
Check these common rating-plate locations on Dunkirk gas-fired hot water boilers:
- On the jacket (outer front or side panel)
- Near the control panel area
- Near the burner compartment access panel
- Inside the front panel (after removing the cover)
- On or near the heat exchanger area where the manufacturer label is mounted
Use the diagrams and labeling details in the XEB-5 owner's manual to match what you see on your unit.
The rating plate usually lists more than just the model number. Look for:
- Model series and specific model (XEB-5)
- Fuel type (natural gas or propane)
- Input and heating capacity ratings
- Certifications (for example, CSA/ASME markings)
- Manufacturer information
| Item on tag | What you should see |
|---|---|
| Model | XEB-5 |
| Series | XEB series |
| Fuel | Natural gas or propane |
| Ratings | Input and capacity values |
Using the exact model number ensures you get the correct Dunkirk XEB-5 boiler parts and service information. It also helps you match safety and control components correctly, such as a limit control 240009863 when troubleshooting temperature or high-limit issues.
Last updated: March 2026
