Table of Contents
Advertisement
Natco Fire-Coil Volume Water Heaters
4C-2. Cleaning the Heat Exchanger
An inspection and cleaning of the complete heat
exchanger can only be done by removing it from the
heater.
1.
To remove the heat exchanger, refer to Section
2F-1.
Black carbon soot buildup on a dirty heat exchanger
can be ignited by a random spark or flame. To
prevent this happening, dampen the soot deposits
with a wet brush or fine water spray before servicing
the heat exchanger.
2.
Remove the heat baffles and check for a light
accumulation of soot or corrosion on the outside
of the heat exchanger tubes.
NOTE: While the heat exchanger is out of the
heater, inspect the firewall refractory insulation blocks
for cracks, wear, and breakage. Replace if necessary.
3.
Use a wire brush to remove soot and loose scale
from the heat exchanger. Do not use water or
compressed air for cleaning.
NOTE: Use only the correct carbide tipped
reamers which are available from Natco.
4.
Ream the insides of the tubes (see Figure 32).
5.
Pull the reamer out frequently to remove lime
powder and prevent the drill from binding in the
tube.
6.
Install new gaskets. Do not reuse the old ones.
7.
Tighten the header bolts progressively, starting
with the two center bolts. Maximum torque is 20
foot pounds (27 Nm). Do not over-torque.
City
Water
Supply
Notes:
1.
When pressure relief valve is used, it must be removed and the hole plugged, as shown.
2.
Remove the plug before reinstalling the heat exchanger.
Figure 32. Heat exchanger tube cleaning.
Caution
8.
Pressure test the heat exchanger for leaks with
city water supply before re-installing (see
Figure 32).
9.
When placing the heat exchanger back in the
heater, carefully hold the refractory insulation
blocks apart and lower the heat exchanger into
place. Be sure the sheet metal covers, which
protect the insulation blocks, are replaced
carefully.
10. If a header bolt is stripped, drive it out of the
header plate and replace it (see Section 6, Parts
List).
11. To reinstall the heat exchanger, refer to Section
2F-1.
SECTION 5.
Troubleshooting and Service
5A. Gas Pressure Tests
Use the following procedures to check the main
gas and manifold regulated gas pressures. A
manometer kit is available from Natco and instructions
for its use are included in the kit. A dry gas pressure
gauge may also be used for either test.
5A-1. Checking the Main Line
Gas Pressure
1.
Attach a manometer (or a dry gas pressure
gauge) to heater jacket (see Figure 33).
2.
Open both columns on the manometer.
3.
Use shutoff valve outside the heater jacket to
shut off all gas supply to the heater.
400-500 RPM
Drill Motor
Page 21
Advertisement
Table of Contents
