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Pneumatic Control Manual 717.1

VAV Controllers Section

Product Bulletin P-3800

Issue Date 0692

Part No. 24-7570-9, Rev. E

Code No. LIT-7171270

P-3800 Reset Volume Controller

Features and Benefits

• Superior Performance

- Furnishes a Constant

Reset Span, Thus

Eliminating Hunting

and Improving Zone

Comfort

- Provides Controllable

Flow Down to 0.01 in.

WG Velocity Pressure,

Meeting the Most

Demanding VAV

Specifications

- Rugged Design

Withstands Shock,

Ensures Stable

Operation

• Universally Applicable

- Isolated Diaphragm

Design Accepts Any

Sensing Line

Length/Diameter,

Providing Universal

Applicability

- Multi Functional

Device: Two Models

Available, Satisfying

All VAV

Box/Thermostat

Configurations in

Both Cooling and

Heating Applications

- Fully Adjustable

Reset Start Point,

Reset Range, and

Minimum and

Maximum Flow Set

Points; Allows

Control Loop

Customization

• Inherently Simple

- Retrofit/Replacement

is Easily Performed

via a Universal Body

Design that Enables

the P-3800 to Fit into

Most Competitor's

Mounting Brackets

- Barbed Fittings on All

Ports, Providing

Secure Air Line

Connections

- Replaceable

Filter/Orifice

Assembly Eliminates

the Need for

Complete Unit

Changeout/

Recommissioning

When Used in

Contaminated Air

Supply Systems

The P-3800 Reset Volume

Controller is a pressure

independent, submaster device

designed to regulate the flow of

air in Variable Air Volume (VAV)

boxes. The P-3800 controls the

output volume, between

adjustable minimum and

maximum set points, in

response to a reset signal from

a thermostat or some other

master controller. Two models

of the P-3800 are available to

satisfy all VAV/thermostat

configurations, in both cooling

and heating applications

(see Table 1).

Both models of the P-3800

feature an isolated diaphragm

design, allowing the unit to

accept any sensing line length

or diameter, simplifying

installation.

In addition, the design of the

P-3800 provides accurate air

volume control, even down to a

velocity pressure as low as 0.01

in. WG (2.5 Pa), despite the

varying supply pressures found

in many systems today. The

constant reset span feature of

the P-3800 means the unit will

maintain the desired volume

setting regardless of static

pressure and/or zone load

fluctuations, thus saving energy

and improving the comfort level

of the environment being

controlled. In addition, the reset

start point, reset range, and

minimum and maximum flow set

points of both models of the

P-3800 are fully adjustable,

allowing the installer to

customize the unit to match the

application, as dictated by the

system drawing. Refer to the

Specifications table for

adjustment ranges and factory

settings, as well as other reset

controller specification

information.

Fig. 1: P-3800

Reset Volume Controller

Summary of content (8 pages)

PAGE 1
Pneumatic Control Manual 717.1 VAV Controllers Section Product Bulletin P-3800 Issue Date 0692 P-3800 Reset Volume Controller Features and Benefits • Superior Performance - Furnishes a Constant Reset Span, Thus Eliminating Hunting and Improving Zone Comfort - Provides Controllable Flow Down to 0.01 in.
PAGE 2
Operation The P-3800 Reset Volume Controller senses the total and static pressures from the duct. The difference between the total and static pressures is the velocity pressure. The P-3800 compares this velocity pressure signal to the reset input signal from a thermostat or some other master controller. The forcebalancing principle of the P-3800 allows the unit to produce a nominal 0 to 20 PSIG (0 to 140 kPa) output signal.
PAGE 3
Application and Drawing Identification Fig. 2: P-3800 Reset Volume Controller Dimensions in.
PAGE 4
P-3800 Product Bulletin
PAGE 5
and low pressure pickup lines leading from the duct. Doing so will provide pressure indication required in future steps. Commissioning The following instructions assume that the P-3800 Reset Volume Controller to be installed is for a retrofit/replacement installation. If the P-3800 is for a new (OEM) installation, proceed directly to Step 4. Reset Range Adjustment 5. Pre-Commissioning Setup 1 .
PAGE 6
P-3800 Product Bulletin
PAGE 7
Note: A later step covers connecting the thermostat air line to the thermostat "T" connection. Air Line Connections 7. Referring to the air connection identification label attached to the surface of the P-3800 (see Fig. 6) and the notations made in Step 1, connect all air lines EXCEPT THE THERMOSTAT AIR LINE to the appropriate barbed air connections on the P-3800 (see Fig. 8). Note: To ensure leak-free connections, cut off 1/2 in. (13 mm) of the old tubing ends before making the air line connections.
PAGE 8
If desired, check the minimum and maximum flow set point settings by disconnecting the thermostat air line and repeating Steps 9 through 11. 12. Return the room thermostat (or other master controller) dial setting to the desired temperature. 13. Remove the magnehelic gage or manometer that is teed in the high and low pressure pickup lines and cap the open end of each tee using F-1000 Series Sealing Caps (ordered separately). Controls Group 507 E. Michigan Street P.O.