Technical heating guide
Boiler Pump Sequencing
Multi-pump hydronic systems require correct sequencing between boiler pumps, system pumps, zone demands, hydraulic separation, and control logic.
Safety: Do not open gas-fired equipment, alter gas settings, bypass safeties, or work inside electrical controls without the proper qualification. For a gas smell or CO alarm, leave and call the utility or 911 from outside.
Timing matters
A boiler can lock out or overheat if firing begins without proven flow, or if pumps stop too early during post-purge.
Primary-secondary systems
Closely spaced tees, low-loss headers, hydraulic separators, and variable-speed pumps each affect how boiler and system flow interact.
Controls and sensors
Relays, enable contacts, pump outputs, flow switches, temperature sensors, and building controls should be tested through the actual sequence.
What to send before the visit
- Clear photo of the rating plate and model number
- Photo or exact wording of any error code
- Whether the issue affects space heating, hot water, or both
- When the problem started and whether a reset temporarily restores operation
- Your city and preferred service timing
Need service? Call 647-699-2474 or use the request form. Heating Experts will confirm the diagnostic visit and review repair pricing before approved work begins.
Technical service standards
Technical resources
Understand the system before approving the repair.
Use our knowledge hub for plain-language explanations of boiler lockouts, pressure problems, hydronic flow, combustion testing, condensate faults, OEM parts, and maintenance planning.