Delta-T Charts

30 Points for servicing residential gas equipment


This should take approximately 1- 1.5 hours

These are general guidelines and should be performed by a qualified heating contractor only. If you are not a qualified technician, use these steps as a checklist only. You can verify the preventive maintenance is being done properly.


1. Check thermostats are level and have proper anticipator settings if applicable. Electronic thermostats do not need to be leveled. Most electronic thermostats have menus to choose cycle rates.
2. Turn off power supply
3. Check for obvious problems such as water leaks, duct leaks etc.

4. Diaphragm expansion tanks - remove water pressure and check the air charge on the tank.
5. Gain access for inspection and/or cleaning of heat exchanger. Some units will have side access plates, swing open doors or other type of access. They may be hidden under the jacket.
6. Brush down all heating surfaces if needed. If the unit has baffles, remove, brush off, and brush flue ways and re-install baffles. Keep vacuum running and close to area being cleaned
7. Re-install clean out access plates, close doors etc. These access areas may need sealed. Most will have gaskets. If not, seal with proper sealing material or gaskets.
8. Carefully remove vent pipe.  Caution - May be hot
9. Vacuum chimney base and top of boiler sections.
10. Brush the inside of the vent pipe with the vacuum running with hose in other end of pipe to avoid a mess.
11. Remove thermostat wires from thermostat wire connections
12. Place jumpers on thermostat wire connections
13. Change air filters if warm air furnace
14. Inspect/replace/adjust blower belt if applicable. Clean blower blades if needed.
15. Remove burners and inspect and clean if needed, check inside and outside.
16. Clean igniter or thermocouple
17. Turn on power supply.
18. Check manifold gas pressure
19. Allow burner to run about 10-15 minutes
20. Check all control settings for proper adjustment per manufactures spec.'s
21. Oil all motors where applicable. Newer equipment may have permanently sealed bearings
22. Locate the sampling hole in the vent pipe. This should be at the chimney base.
23. Perform an O2 or Co2 reading.
24. Check draft at chimney base and compare to manufacturers spec.'s
25. Check all safety controls for proper operation
26. Check for smooth operation of vent damper.
27. Remove jumpers from thermostat connections
28. Reinstall thermostat wires
29. Wipe down boiler jacket removing dust and dirty handprints.
30. Complete all paperwork and thank customer on way out

Disclaimer: The information found on this website is for informational purposes only. All preventive maintenance, service, installations should be reviewed on a per job situation. Any work performed on your heating system should be performed by qualified and experienced personnel only. Comfort-Calc or its personnel accepts no responsibility for improper information, application, damage to property or bodily injury for applied information found on this website.