LJ Wing MV, Инструкция по установке, эксплуатации и обслуживанию

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STEAM/HOT WATER COILS
1. Steam pipes must be sized to handle desired steam
flows at the lowest pressures.
2. Inlet and outlet steam and hot water lines should be
fully insulated.
3. Full steam pressure must be supplied at all
times – modulating valves must not be used.
A modulating steam valve on a preheat coil can
actually cause the coil to retain the condensate due
to a reduced pressure in the coil, thus exposing
condensate in the tubes to freezing conditions. With
modulating steam below 5 psig (near valve closure)
the steam may not be fully distributed in all of the
tubes in the coil, causing the outer tubes to cool
abnormally. This will create thermal stress that can
lead to possible “outer tube failure”. Slow-acting on/
off steam valves may be used to close at desired set
points. The minimum open to closed and closed to
open time is three (3) minutes. Any time faster than
three minutes is considered fast acting and is not
allowed. If motorized steam valves are employed,
they should be of the normally open type so that if the
actuator fails, the valve will go to the open position,
thereby keeping the steam supply to the coil.
4. To isolate the coils in the off-season, slow acting on/
off steam valves may be used. If motorized steam
valves are employed, they should be of the normally
open type so if the actuator fails, the valve will go to
the open position.
5. The amount that the delivered air temperature
exceeds the thermostat setting is called temperature
override. To minimize temperature override:
(a) Insulate the top and bottom headers and/or at
least isolate them on both sides of the coils.
Eliminate airflow over the supply and return
headers by installing sheet metal isolation plates
on the top and bottom upstream of the coils.
(b) Inlet and outlet mains should be fully insulated.
(c) To eliminate coil temperature override, use slow –
acting on/off valves to close at desired set points.
(d) The installation of humidifiers with steam
manifolds internal of an air handler may provide
a temperature override to the system. Internal
steam manifolds and piping should be insulated.
6. Return steam condensate headers and hot water
supply headers must be free to float. A flexible
connector MUST be installed parallel to the coil
header, as close as possible to the coil connection
and be able to provide a minimum of 3/8" free vertical
and lateral movement of the headers.
7. Failure to install flexible connectors will restrict
expansion of the headers. This can result in bowing
of tubes, bending of fins, interference with damper
operation, or eventually tube breakage.
8. Steam and hot water mains must be supported
separately after the flexible connector to isolate piping
strains and additional expansion from the coils
9. Where more than one coil is used, each coil should
be piped independently.
10. Good engineering practices and procedures should
be applied in the design of a condensate removal
system. In particular, long piping runs to condensate
pumps should be avoided.
11. To avoid freezing of pre-heat coils when applying
steam or hot water in very cold locations, first
raise the tube metal temperature above freezing
by applying steam or hot water to the coil prior to
passing airflow over it.
Figure 3
Coil Supported From
Bottom On Angle Iron Stand
And Bulkhead In A Duct
Figure 2
Coil Supported
From Above
Note: Single row steam coil shown
Figure 4
Coil Supported On Angle Iron
Legs And Bulkhead In A Duct