Figure 4-13. - H-type downdraft hood.

UNIT HEATER MAINTENANCE

Oil-fired space heaters require periodic cleaning. Frequent checks must be made to ensure that equipment is kept clean, because accumulations of carbon and soot can cause disastrous fires. Units should be moved when they are cleaned, so they can be cleaned inside and out. Accumulations of soot must be removed from inside the fuel pipe. All piping and tubing should be kept clean and free of oil drippings.

The pot or burner assembly may be cleaned without removing the heater. When cleaning this component, remove it through the front door opening and clean all the air holes using a soft copper wire. Do not remove all the carbon from the bottom, because a small accumulation of carbon at the bottom acts as a wick and helps maintain the pilot light. In replacing the burner assembly, make sure both sides of the burner are tightened equally, so the top of the burner and the fire-retardant gasket are set firmly against the flue projection.

In checking the constant-level control valve, check the operation of the heater through a complete cycle of operation from the pilot fire position to the main fire position, and then back to the pilot fire position. Set the control valve, if it is the manual type, to high fire; and if equipped with a thermostatic device, set the thermostat above room temperature. If the heater fails to operate properly through the cycle, check the constant-level control valve and follow the manufacturer's instructions for disassembly and cleaning. A parts breakdown of the valve is shown in figure 4-14.

Some of the common problems with pot and sleeve oil burners, gas-fired space heaters, their causes, and possible remedies are listed in appendix II, tables I and gentlemen.

Q8. What are the basic types of unit heaters?

Q9. How are electrically powered space heaters generally rated?

Q10. When you select and install an electric space heater, what factor should be paramount?

Q11. On vented gas-fired space heaters, it is important to install the venting system properly to minimize the effects of what problem?

Q12. What type of burner is used in an oil-fired space heater?

Q13. What is the only safety device on an oil-fired space heater?

Q14. To maintain a constant draft for the burner of an oil-fired space heater, what device should you install in the chimney?

Figure 4-14. - Constant-level control valve.