HVACopediaHTP · Boiler · Heating
Central heat call
What happens, in order
- Thermostat or dry contact closes across the THERMOSTAT terminals (or 0-10 V above 1 V)
- Control checks supply temperature against CH set point minus differential
- If supply is too hot the display shows TEMPER BLOCKING and waits
- Boiler pump is on
- Control runs the ignition sequence combustion fan, spark ignition, gas valve (opens only with power and fan suction)
- Display shows GAS VALVE ON, then RUN once flame is proven (signal above 1 microamp)
- Burner modulates fan speed to hold the supply set point
- When the call ends the burner stops and the pump stops after the CH post pump time
Timings and thresholds
| Item | Value |
|---|---|
| CH set point | 180 F default |
| CH differential | 30 F default |
| CH post pump time | 0 min default (0 to 10) |
| Ignition tries per call | 4 before lockout |
Codes you may see during this
Applies to: EL-80, EL-110, EL-150, EL-220, EL-299, EL-399 (N/LP)
More HTP boiler sequences
- Ignition retries and lockout · Ignition
- Outdoor reset and warm weather shutoff · Heating
- Indirect water heater call · Domestic hot water
- Pump service mode · Pump/purge
- Standby and over-temperature protection · Standby/shutdown
- Cascade operation · Other
Related
Take it to the job
Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Elite EL-80 N Installation Manual (LP-293), p. 6, p. 7, p. 66, p. 71, p. 56. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.