- To make it easier to remove a threaded pilot tip from the 
burner in the future. Use anti-seize compound on threaded 
discharges and screw hand tight into the burner mounting. 
Installing a pipe union or a 4041  between the pilot mixer and 
the pilot tip will also speed up pilot tip removal.

- Adding at least 5 pipe diameters of pipe between the mixer and 
the pilot tip adds additional mixing length to insure good quality 
premix. 

- The preferred location for pilot tips (and UV cells) is on the top 
or side of a burner so that scale, dirt, and refractory crumbs 
cannot fall into it.

- "Zero governor" pilot systems require an atmospheric regulator 
(like the 7350-##-A) to supply gas at zero gauge pressure to the 
pilot mixer, but zero governor systems only work well in open air 
applications when there is no chance of back pressure.

If the burner back pressure varies (like in many pilot systems), 
the 7350 ratio regulator vent should be cross-connected with an 
impulse line to the 4031 mixture pressure tap or to the 4031 air 
pressure tap. Using the mixture pressure tap provides better air/
fuel ratio control (especially on suction systems).

- If the pilot regulator inlet gas pressure exceeds its pressure 
rating, install a pressure-reducing regulator upstream. 7344 
Regulators reduce up to 25 psi gas to 4-12"w.c. For capacities or 
inlet pressures beyond the range of 7344 Regulators, see Bulletin 
7337 and 7349. Use a separate pilot regulator. Do not run pilot 
gas through any of the regulators for main burner gas because 
those regulators cannot turn down low enough for pilot gas fl ow, 
and will therefore chatter or shut-off .

- The inlet pressure to the pilot gas ratio regulator (7350) should 
be at least 2 osi greater than the connected pilot air or mixture 
pressure.

- Avoid stressing and distorting valves and regulators, small pilot 
regulators may be easily damaged by incorrect use of wrenches. 
Put your wrench on the end nearest the pipe that it’s being 
threaded into.

- Undersized piping and plugged lines are common causes of 
pilot problems. Avoid corrugated connectors and hoses,  they 
cause more pressure loss than regular pipe and fi ttings. Tubing 
has ½ the area, and 4 times the pressure loss of the same “size” 
pipe. It’s OK to use tubing that has as much fl ow area as pipe. 
(Example: use 

7⁄8

"OD × .045"wall tubing in place of 

¾  

" pipe)

 
- Avoid thread dope or Tefl on tape applied over the ends of pipe 
thread, it can break loose and plug pilot tips. 

- Always blow out each fi tting and section of pipe before and 
aft er installing it, (but dont put pressure on regulators and 
solenoid).

- A fi lter on the combustion air blower inlet will help prevent 
plugging the small openings in the pilot system with dirt and 
debris.

Bulletin 4011/4021

Page 6

NO

YES

2 threads

NO

YES

4021

4041

4031

- Short run impulse lines for pilot systems should be 

¼  

" thin wall 

tubing. 304 stainless tube 

¼  

" OD x .035" wall is a good choice. 

Copper tubing can also be used, but is more susceptible to 
kinking.

Impulse 
Line

dirt

compressed 

air

7350-02 -A

Pilot Installation Tips | 4011/4021 Pilot