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25.
Feed the two brown wires through the top hole
on the left side until the conduit elbow is against
the jacket.
26.
Fasten the conduit by sliding the retaining nut
over the two brown wires (inside the control
compartment) then screwing it down finger-tight
on the conduit elbow.
27.
Straighten the capillary tubing and fasten it to the
side of the heater under the channel. Use the self-
tapping screws to fasten the channel to the
jacket.
28.
Feed the two white wires into the control
compartment. Attach one wire to the terminal in
the manual reset hi-limit switch. If one is not
installed, attach it to terminal No. 1. Connect the
other wire to the red wire attached to the fuse
holder.
29.
Attach the two brown wires to terminals No. 5
and 6 on the terminal strip. Keep all wiring away
from surfaces that will get hot during heater
operation.
30.
Replace the gap closures and tighten the screws
securely.
31.
Replace the three grommets and the cap.
32.
Reinstall the drain plug and drain valves.
33.
Slip the flue collector assembly back down inside
the enclosure.
34.
Carefully slip a hand inside to make sure there
are no gaps between the heat exchanger and the
flue collector.
35.
Check to make sure the wiring is not pinched
against sharp edges, or resting on the collector
assembly.
36.
Replace the two flue collector holddown clamps.
37.
Replace the top assembly and fasten it with the
hex-head screws.
38.
Replace the front cover.
39.
Reinstall the vent cap or drafthood if one was
removed.
40.
On indoor installations (sizes 175-250), insert the
draft hood switch plug into the receptacle on the
left side of the heater.
2F-2. Water Chemistry
Natco equipment is designed to be used in a
variety of water conditions. With the proper pump, the
water velocity in the heat exchanger tubes is kept high
enough to prevent scaling from hard water, yet low
enough to avoid erosion by soft water.
NOTE: It is possible to have hard and soft water
in the same city. Check with the local water
companies.
Figure 18. Hole location, left side.
Attach Capillary
Covers on
Left Side
0.9 in. dia.
(23mm)
(Two holes)
LEFT
FRONT
1.9 in.
(48mm)
2.4 in.
(61mm)
2.4 in.
(61mm)
3.1 in.
(79mm)
13.
Use a pair of diagonal cutters to cut the plastic
tie around the wire bundle in the control
compartment.
14.
On the terminal strip, disconnect the two brown
wires from No. 5 and No. 6 terminals.
15.
Remove the flow switch conduit retaining clip
and the elbow leading into the jacket.
16.
Reach inside the control compartment and
release the retaining nut in the upper right corner.
The nut should only be finger-tight.
17.
When the conduit is pulled away from the jacket,
pull the two brown wires out of the control
compartment. Coil the conduit and wires on top
of the heat exchanger.
18.
Use a chassis punch to put two 7/8 inch (22 mm)
holes in the front left side of the jacket (see
Figure 18).
19.
Remove the front and rear tile covers (see
Figure 15).
20.
Lift out the heat exchanger assembly, turn it 180
degrees, and reseat the unit in the heater with the
water connections on the left side.
21.
Reinstall the front and rear tile covers.
22.
Push the capillary tube(s) out through the lower
hole in the left side of the jacket.
23.
Install the sensing bulb(s) into the appropriate
temperature control (keep in mind that the
positions of the inlet and outlet have been
reversed. The inlet is now behind the outlet).
24.
Fasten the capillary tube(s) by squeezing the
retaining clip together, then tighten the screw.
