York P3DHX12F08001 Manuale Utente

 
8 

P*LBX furnaces are equipped with 
Beckett AF Series oil burners with the 
Beckett CleanCut pump and R7184B oil 
primary control. P*DHX furnaces are 
equipped with Beckett AF Series oil 
burners with the R8184N oil primary con-
trol. The oil burner must align properly 
with the cerafelt fiber chamber (firepot). 
The cerafelt fiber chamber is initially 
quite soft, but hardens and becomes 
quite brittle after the first firing. The fire-
pot is held in place by a retaining 
bracket; however, it is possible for the 
firepot to shift if subjected to rough han-
dling during transit. 

 

All furnace models are certified for multi-
ple firing rates. Choose the firing rate 
that most closely matches the calculated 
heat loss of the building. Models, firing 
rates and nozzles are listed in Appendix 
A: AF Burner Set-Up. 

Correct positioning of the electrode tips 
with respect to each other, to the fuel oil 
nozzle, and to the rest of the burners is 
essential for smooth light ups and proper 
operation. The electrode tips should be 
adjusted to a gap of 5/32”, 1/16” ahead 
of the nozzle, 5/16” above the centerline 
of the nozzle. The “Z” dimension (front 
edge of the burner head to the front face 
of the nozzle is 1-1/8 inches. 
Electrode positioning should be checked 
before the first firing of the furnace. 
The electrode porcelains should be free 
of cracks, the electrode tips should be 
tapered and free of burrs, and the con-
tact rods must be clean and be in firm 
contact with the ignition transformer con-
tact springs. The electrodes must not 
come into contact with the burner head. 

The burner air supply is adjusted to 
maintain the fuel to air  ratio to obtain 
ideal combustion conditions. A lack of air 
causes "soft" and "sooty" flames, result-
ing in soot build-up throughout the heat 
exchanger passages. Excess combus-
tion air causes a bright roaring fire and 
high stack temperatures resulting in poor 
fuel efficiency.  

 

Drill a ¼” test port in the venting, ideally 
at least 2 flue pipe diameters away from 
the furnace breeching, if venting horizon-
tally from the furnace, (typically P*LBX) 
or from the flue pipe elbow if venting 
vertically (typically P*DHX) before reach-
ing the furnace. (see Figures 4 and 5). 

The test port will allow flue gas samples 
to be taken and stack temperatures to be 
measured. 

Before starting the burner, check the 
burner alignment with the combustion 
chamber (fire pot), check that the correct 
nozzle is tightened into place, and that 
the burner electrodes are properly posi-
tioned. 

The Beckett burner bulk air band should 
be closed, and the air shutter initial set-
ting should be approximately 7.00. 

: Locate hole at least 6 inches on 

the furnace side of the draft control. 

: Ideally, hole should be at least 

12 inches from breeching or elbow. 

Start the burner and allow it to run at 
least ten minutes. Set the air shutter to 
give a good flame visually. The combus-
tion air supply to the burner is controlled 
by adjusting the air shutter on the left 
side of the burner, and, if necessary, the 
bulk air band. To adjust, loosen the bolt 
on the movable shutter. Move the shutter 
gradually until a good flame (visually) 
has been achieved. Re-snug the bolt. 

Check the initial draft setting as the fur-
nace warms up. The draft may be meas-
ured at the test port. The final breech 
draft should be  - 0.02 inches w.c. to 
provide adequate over-fire draft.