Install Instructions

Part number 550-100-055/0618
11
gas-fired water boilers — Heat Exchanger Block Replacement Instructions
1. Remove and discard the original igniter, igniter gasket and
mounting hardware from the heat exchanger cover plate
assembly.
2. Carefully remove any debris or residual gasket material from
the igniter gasket sealing surface on the front of the heat
exchanger cover plate.
3. Remove the heat exchanger cover plate by removing the nuts
securing it to the heat exchanger. Discard original mount-
ing hardware.
4. Remove the three (3) M4 hex head screws (7mm box end
wrench) and burner clips securing the burner to the cover
plate. Discard original mounting hardware.
5. Remove burner and original cover plate insulation. Read
the ceramic ber WARNING on page 4 before handling or
disposing of ceramic ber materials.
6. Replace the heat exchanger cover plate insulation using the
part provided in this kit.
7. Reinstall the burner using the hex head screws and burner
clips provided in this kit per instructions in your Ultra boiler
manual.
8. Secure the original cover plate to the replacement heat ex-
changer mounted inside of the boiler cabinet. For Ultra-155
through Ultra-399, follow the tightening sequence shown
in Figure 16 below making a minimum of two passes with a
torque wrench. Final torque = 50 +/- 10 inch-pounds.
1. Close external isolation valves on boiler water supply and
return. Drain water from boiler using boiler drain valve.
2. Close manual gas valve to shut o gas supply.
Wait for the heat exchanger to cool down before
proceeding
. Failure to do so can result in severe
personal injury.
Label wires before removing
Label all wires prior to disconnection when ser-
vicing controls. Wiring errors can cause improper
and dangerous operation.
3. Disconnect gas valve electrical plug and water temperature
sensors. Disconnect two (2) electrical plugs from blower
assembly.
4. Disconnect gas line union with pipe wrench or channel lock
pliers.
5. Remove air silencer by liing plastic clamp o gas line and
then gently sliding air silencer down and o valve.
6. Remove two (2) 5/32” Allen head screws securing blower
assembly to heat exchanger front cover.
7. Remove blower and gas valve assembly.
8. Loosen boiler water supply pipe nut and remove boiler water
supply pipe.
9. Loosen boiler water return pipe nut and remove boiler return
water pipe.
10. Disconnect condensate trap hose by loosening band clamp
at bottom of heat exchanger.
11. Loosen, but do not remove, four (4) 7/16” block mounting
bolts on sides of heat exchanger block.
Do not remove 7/16” heat exchanger block mount-
ing bolts, as heat exchanger block is heavy and
weight can cause severe personal injury or sub-
stantial property damage.
12. Disconnect ground wire from igniter.
13. Disconnect ignition cable at electrode.
14. Li heat exchanger block assembly and slide forward out of
brackets to remove from boiler.
15. Remove four (4) bolts from sides of old heat exchanger block
and screw into new heat exchanger block, leaving enough bolt
exposed to slide into mounting bracket in boiler.
16. Carefully li new block and slide into boiler mounting brack-
ets and allow to drop into place.
17. Securely tighten the four (4) 7/16” heat exchanger block
mounting bolts.
Figure 15 M6 sensor (Upper sensor)
Ultra-155 through 399
Cover Plate Replacement
Figure 16 Nut tightening sequence — 155 to 399 —
Gradually tighten the nuts, repeating the
sequence shown below until the torque
reaches 50 inch-pounds (+/- 10 inch-
pounds).