WOOD BOILER INSTRUCTIONS Page 59 Copyright © 2011 Seton Wood Boilers all rights reserved
Hot Water Boiler Preventive Maintenance The following only refers to boiler systems in general and is
for educational purposes only. Refer to your owners' manual or consult with your local boiler technician
for proper maintenance procedures and operation of your heating system. The procedures described here
should only perform by a qualified technician. Serious injury or death could result if improperly handled.
Boiler Pressure: Look for a temperature Pressure Gauge on the front of your boiler. Normally just above
the burners or on side manifold. For most residential and small commercial systems this pressure should
be 12-15 pounds. Read the gauge when the boiler is cold and the circulating pump is off. This will show
the static water pressure of your boiler set by the water feed regulator. If the pressure is too high the regu-
lator may be set too high or leaking through the regulator. If the feed regulator bypasses even a small
amount of water from scale or sediment trapped in the seat the pressure on the system will creep up to the
pressure relief set point and blow off water.
Expansion tank: As water is heated it will expand and occupy a larger volume. The expansion tank
should allow sufficient volume to allow for expansion. There are two types of expansion tanks. A Dia-
phragm Tank, which uses a bladder, filled with compressed air, or a steel holding tank, which traps air in
the top, half. The diaphragm tank is charged with air to the same operating pressure of the boiler set by
the feed regulator. Do not release or add air to the diaphragm tank is connected the boiler system or it will
not function properly. Tap on the tank and it should sound hollow through out. If the bladder has leaked
the tank will completely fill with water. If the tank is not properly charged with air, the diaphragm tank
will fill 1/2 way with water. For the steel holding tanks there should be a sight glass on the front of the
tank to indicate the water level in the tank. The tank should be about half full. If the tank is filled near the
top or completely filled the water will have to be drained off. Turn the boiler off and attach a hose to the
drain valve of the expansion tank. Close the valve that connects the expansion tank to the boiler and open
the drain valve. Drain the tank until it is empty. Then close the drain valve and open the valve to the boiler
system. The expansion tank should filled to the half way mark or less and trap air in the top of the tank. If
the tank fills again after a few days then there is an air leak in the tank.
Pressure Relief Valve: Every boiler has at least one pressure relief valve. If the pressure climbs too high
on your boiler it will open and blow off the excessive pressure and close again when the pressure falls be-
low the setpoint. There should be a tag on the valve to tell you at what pressure it will open. Most residen-
tial boilers will be set to 30#. If your boiler is operating close to this setpoint the pressure relief valve will
leak slowly. The cause of the high boiler pressure needs to found. At least once a year this valve should be
open to blow off water and make sure it has not plugged up with sediment and scale. Check the boiler
pressure before you begin, if it is close to the setpoint the relief valve will not close right away. The outlet
of the relief valve should be piped to 6" above the floor and to a place where it will not cause water dam-
age if opened. This makes annual blow down on the relief valve easy. It can be piped directly to a floor
drain, but the outlet should be open so any leakage can be detected. If the unit is not piped to a drain use a
bucket to catch the water if needed. Make sure you know where the boiler feed water shut off is, just in
case. With the boiler off and cold, lift the manual lever and blow off some water for a few seconds and let
the lever snap back. There should be a good gush that comes out and be fairly clear water. If the valve has
small leaks after wards, just open it again and let some more water out, sediment can become trapped in
the seat causing minor leakage. If the valve will not close at all shut the boiler water feed off and remove
and replace the relief valve. If no water comes out, then the valve is plugged or there is no water in the
boiler. In either case do not use the boiler until the problem is identified and repaired.
BOILER MAINTENANCE
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