Service Bulletin: SB 083.1
Subject: New Thermocouple for FHA Heat Guns
A new design thermocouple will now be supplied with all flameless hot air sealing systems. It is much more rugged and includes an integral armored cover for the lead wires.
This superior design will be supplied on all replacement orders. To accommodate the new thermocouple the following modifications will be required:
1. Remove preheat nozzles and enlarge thermocouple hole to 7/32 dia. (5.5mm). Remove all chips and reassemble.
2. Remove bottom heater manifold liners 34218-A and 34219-A and enlarge thermocouple hole to 7/32 dia. (5.5m).
CAUTION: Liners are made of a ceramic material. They are machinable but very fragile. Recommend hand rotation of drill. Clamp only on ends on dia. Remove all chips and reassemble.
3. Install thermocouple so the tip is in the center of the air flow.
Armored cable on the new thermocouple can be routed directly to junction box. Existing wiring tubes may be removed.
To shorten lead length, hacksaw diagonally through the outer rib of two adjacent spirols of armor. Be careful not to damage insulation on wires. Bend armor back and forth until it breaks, and remove. Shorten leads to suit and install in junction box.