42
Rev. 05/2020
Firebox Door Hoses and Elbows
Principle of the Door Hoses
The door hoses allow HTF to circulate between the
firebox door and the water jacket.
Operation of the Door Hoses
The door hoses allow HTF from the water jacket to
pass through the firebox door, through thermal
siphoning. Refer to “Firebox Door”
Maintenance / Result
Maintaining the door hoses and elbows ensures that
HTF is able to flow through the door. Build-up (calcium)
in the elbows is possible over time, which slowly reduces the HTF
flow through the door. If HTF does not flow freely through the
hoses to the firebox door, you may hear popping sounds in the
door. Once the hoses are around five years old or if they show
signs of wear, they should be replaced. Replacement of hoses or
cleaning of the elbows is always easier if the HTF is cool rather
than hot. To clean the elbows, remove the hoses and use a pipe
cleaning brush to clear out the build-up.
ABSOLUTELY NO FIRE IN THE FIREBOX WHEN
PERFORMING THIS PROCESS.DO NOT PERFORM THIS
PROCESS WHEN UNIT HTF TEMPERATURE IS UNSAFE.
ALWAYS WEAR PROPER PERSONAL PROTECTIVE
EQUIPMENT WHEN WORKING WITH HTF AND CHEMICALS.
Removal and Replacement Door Hoses
NOTE:
Top Door Hose is 20in, bottom Door Hose is 18in
1) Turn off power to the air combustion blowers.
2) Ensure that the fire in the firebox is extinguished,
which will allow the HTF to cool.
3) With “C” clamps or vice-grips along with two
pieces of flat steal, pinch the door hoses in the
middle of the hose.
4) Before removing the old door hose, cut the new
pieces of door hose, one at 18
inches and the other at 20 inches.
These measurements are critical.
5) Pinch the new door hose in the middle of the hose,
creating a tight seal.
6) Loosen the hose clamps on each end of the door hose.
7) Remove the first end of the door hose needing replacement.
8) Push on the end of the new door hose and repeat the steps for the opposite end of
the hose.
9) Tighten the hose clamps, securely fastening the door hose to the nipple on the
furnace or firebox door.
10) Remove the vice-grips pinching the door hoses. This will allow HTF to flow through.
11) Check for leaks.
12) Repeat the steps to change additional door hoses.
Clamping hose
Door Hose
Elbow
