Lattner Boiler Company H.E. Instruction Manual - page 15
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F. Foaming, Bouncing, & Carryover
1. Causes of Foaming
It is normal for the water line of Lattner boilers to
fluctuate about one inch. However, excessive foaming
and bouncing (an unstable water line) can be caused by
several different conditions. The presence of oil or
grease in the boiler water will cause serious foaming.
Foaming can also be caused by excessive
concentrations of boiler water solids. A third cause is
excessive alkalinity (high pH level). Water that’s too soft
will also cause the water level to bounce.
2. New Boiler Foaming
In a new boiler, foaming has two primary causes. Oil
from the steam piping and the boiler metal has
accumulated at the water line. Secondly, Lattner clean-
out compound contains trisodium phosphate. This must
be thoroughly flushed out of the boiler. Trisodium
phosphate, if left in the boiler, will raise the alkalinity,
causing foaming.
3. Carryover
Carryover (often called priming) is small droplets of water
leaving the boiler with steam. Foaming, as described
before, is a key cause of carryover. If the foaming
problem is eliminated, the carryover should stop as well.
If the system uses steam faster than the boiler can make
steam, water carryover may occur as well. Be certain that
all steam traps function properly, all piping is insulated,
there are no leaks in the steam piping, and the burner
combustion is set properly.
G. Water Treatment Summary
These are general guidelines for water treatment. Lattner
is not a water treatment company and cannot make
specific recommendations for each boiler installation. To
ensure proper operation and extend the life of the boiler,
a complete water treatment program must be used.
Contact a qualified company with experience in this field
to provide a treatment program for your installation.
Insufficient or too much chemical treatment can damage
your boiler. The following are guidelines for boiler water
quality:
Constituent
Value
pH
8.5 to 10
Total Dissolved Solids
2,000 ppm or 116.8
grains maximum.
Oxygen 0
ppm
Alkalinity
Less than 300 ppm
Chloride
Less than 500 ppm
Sodium Phosphate
Less than 100 ppm
H. Blowdown
1. Purpose of Blowdown
The boiler and the boiler level controls should be blown
down at least DAILY.
Blowdown removes a portion of the water in the boiler in
order to reduce the amount of dissolved solids.
Blowdown will also remove some of the loose deposits
that may be in the boiler.
2. Blowdown
Instructions
The boiler may be blown down at any pressure,
provided the blowdown piping is piped to a safe location
(see Installation Instructions). To blowdown, open the
boiler bottom blowdown valve (see assembly print) to
the fully open position. Watch the sight glass. When the
boiler water level drops about one inch, close the
blowdown valve. Lattner recommends 30 psi for high
pressure boilers.
NEVER blowdown a hot boiler to a level where no water
is visible in the sight glass.
3. Control
Blowdown
Scale can also deposit in the water level controls and
piping, just as it can deposit in the boiler. The
McDonnell Miller level control and auxiliary low water
cut-off water column MUST also be blown down daily. If
scale blocks these controls or the piping connected to
them, the boiler may dry fire. Dry-firing the boiler will
permanently damage the boiler shell.
I. Feedwater
System
1. General
A boiler cannot operate without water. For proper
operation, the boiler must have a reliable water supply.
2. Pump Cavitation
Always use spring-loaded check valves in the feedwater
piping. Swing check valves (even when new) are not
suitable for boiler feed applications.
A bad check valve will allow hot water from the boiler to
back-feed to the pump. When the pump starts, this
water flashes to steam. This condition, known as
cavitation, causes the pump to sound like there are ball
bearings in the water and prevents the pump from
working properly, especially when the boiler pressure
rises.
Bad steam traps may also cause the pump to cavitate.
Bad traps allow steam to return to the condensate tank
and heat the water in the tank. As the water
temperature gets above 180° F, cavitation becomes
more likely and prevents the pump from working
properly.
3. Check Valves & Steam Traps
To check for bad steam traps or check valves, look at
the vent pipe from the condensate return tank. If there is
an abnormally high steam flow from the vent, either the
traps or check valves are leaking.
A thermal sensor may be used to help detect which
traps are malfunctioning.