Desa NTH35 Continued, Service Procedures, 35,000 Btu/Hr Model, 50/70/100/150,000 Btu/Hr Models

OWNER’S MANUAL

SERVICE

PROCEDURES

Continued

Spark Plug

(35,000 Btu/Hr Model)

1.	Remove upper shell (see page 8).
2.	Remove fan (see page 13).
3.	Remove fuel and air line hoses from
	nozzle assembly.
4.	Remove spark plug wire from spark plug.
5.	Remove two screws using 5/16" nut-
	driver and remove burner strap.
6.	Place hex-body of spark plug into vise
	and tighten.
7.	Remove spark plug mounting nut us-
	ing 11/16" open-end wrench.
8.	Remove burner strap from spark plug.

	Spark Plug
Combustion	Mounting Nut
Chamber	Burner Strap
	Spark Plug
	Spark
	Plug
	Wire

Nozzle

Assembly

Air Line	Fuel Line
Hose	Hose

Figure 11 - Spark Plug Removal, 35,000 Btu/Hr Model

Bend Here to Adjust

Spark Plug

(50/70/100/150,000 Btu/Hr Models)

1.Remove upper shell (see page 8).

2.Remove fan (see page 13).

3.Remove spark plug wire from spark plug.

4.Remove spark plug from burner head using 13/16" open-end wrench.

5.Clean and regap spark plug electrodes as follows:

50/70/100,000 Btu/Hr Models:

1.9 mm (.075") gap

150,000 Btu/Hr Model:

2.8 mm (0.110") gap

6.Install spark plug in burner head.

7.Attach spark plug wire to spark plug.

8.Replace fan (see page 13).

9.Replace fan guard and upper shell.

9. Clean and regap spark plug electrodes

Gap

Burner

Spark

to 1.4 mm (.055") gap.

10. Replace burner strap onto spark plug.

Rotate burner strap to position spark

plug electrodes (see Figure 13).

11. Tighten spark plug with spark plug

1.4 mm (.055") Gap

Head

Plug Wire

	mounting nut.
12.	Release hex-body of spark plug from
	vise.
13.	Replace burner strap onto combustion
	chamber.
14.	Attach spark plug wire to spark plug.
15.	Attach fuel and air line hoses to nozzle
	assembly.
16.	Replace fan (see page 13).
17.	Replace fan guard and upper shell.

Figure 12 - Spark Plug Gap, 35,000 Btu/Hr Model

Burner Burner

StrapStrap

Figure 13 - Spark Plug Rotation, 35,000 Btu/Hr Model Only

Spark

Plug

Figure 14 - Spark Plug Removal, 50/70/ 100/150,000 Btu/Hr Models

Bend Here to Adjust Gap

Gap

Figure 15 - Spark Plug Gap, 50/70/100/ 150,000 Btu/Hr Models

Continued

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