If there is other equipment in the room that uses air
(large water heaters, air compressors, other boilers,
exhaust fans, etc.), additional venting capacity is
required.
E.
Stack
1.
Specifications
Install all stacks in compliance with state and local
codes.
Lattner recommends double wall stack per
ANSI 221.13, appliance category
Ill for positive vent
pressure systems ..
2. Stack Size
The entire stack must be the same size as the stack
outlet on the boiler or one size larger. If the boiler stack is
connected to other equipment, the stack size must be
increased.
NOTE:
Any equipment with a forced draft
burner must be vented separately from equipment with
atmospheric burners.
NEVER
tie these stacks together.
3. Connections
Limit connections to one of the following combinations:
11
Two 90 degree elbows,
11
One 90 degree elbow and one tee,
11
One 90 degree and two 45 degree elbows, or
Four 45 degree elbows.
4. Overall Length
Avoid long runs of stack. A general rule is not to exceed
15 feet for every inch of stack diameter. For example, if
the stack is 6" in diameter then the overall stack should
not exceed 90 feet in length and height combined.
5. Horizontal Stack
Avoid any horizontal runs of stack. If unavoidable,
horizontal runs should have a minimum incline of 3" per
foot. If a long horizontal run (4 feet or more) cannot be
avoided, a draft inducer may be required to properly vent
combustion gases.
6. Draft Regulation
LATTNER REQUIRES A NEGATIVE STATIC
PRESSURE RANGE OF -0.1
O"
WC TO
O"
IN THE
STACK FOR POWER BURNERS. THE BOILER ROOM
SHOULD HAVE A SLIGHT POSITIVE PRESSURE.
A
mechanical draft regulator should be used to control the
pressure.
7. Walls & Ceilings
When passing through combustible walls or ceilings, a
stack thimble is required. The thimble must be double
wall stack, 6" larger in diameter than the vent stack. The
material used to close the opening between the stack
and the stack thimble must be non-combustible.
F. Re-assemble Boiler Controls ..
9
1. Wiring
Re-wiring the controls will be covered in
L: Electrical
Connections. DO NOT
connect the power supply at
this time.
G.
Steam Outlet
1.
Pipe Size
Size steam pipe according to system requirements.
2. Outlet Size
Refer to product literature sheet for steam outlet size on
a particular boiler model.
3. Steam Stop Valve
Install a steam stop valve in the steam line as close to
the boiler as is practical. This allows boiler to be
isolated from the system during service work and may
be helpful in throttling steam flow. Required by ASME
Code if the boiler is operated over 15 psi. Valve shall
be rising stem or gate type valve.
4. Steam Piping
Steam line should be pitched downward away from the
boiler and toward a steam trap. If using a steam
solenoid valve, the steam line should slope upward
slightly to the solenoid valve, and after the solenoid
valve, the steam line should slope downward.
5. Code Standards
Piping must comply with all industry standards (ex.
ANSI B31.1) and all state and local codes.
H. Slowdown Piping (See diagram below)
1. Boiler Bottom Slowdown
DO NOT REDUCE.
Blowdown piping and all fittings
must be the same size as the boiler blowdown
connection (refer to product literature sheets).
Low pressure boilers, operating at 15 psi or less,
require one blowdown or drain valve. The pressure
rating of the valve must be equal to or greater than the
pressure of the boiler safety valve but not lower than 30
psi.
