Installation and Maintenance Manual

ManualsBrandsTrane ManualsVentilatorTrane HUVC Horizontal Classroom Unit Ventilator

ECM Overview and Setup

UV-SVN02C-EN 57

work correctly unless the ECM engine board is

configured to perform these functions.

• Customers are advised to locate the changeover coil

temperature sensor on the bypass line if possible, to

avoid measuring standing water temperature.

• If a 4-pipe unit with changeover function is selected,

the heating input will drive the main coil if hot water is

detected, but will always drive the auxiliary coil or

electric heat (where available).

• Where electric heat is available with a changeover coil,

the electric heat is factory-configured to be deactivated

if there is hot water available and if there is a fan failure.

The CSTI board comes with courtesy valve inversion

relays that allow both normally open and normally closed

two-position valves to be used with simple thermostats

that do not have the configurability to adapt to the

customer choice of valves. Independent switches, SW1

and SW2, are provided for 2-pipe or 4-pipe units, or 2-pipe

units with an optional reheat coil. The functions of SW1

and SW2 is downstream of the changeover function (SW3

and ECM engine board). Decisions made by the

changeover circuits will be flowed to the inversion circuits,

if they are selected.

SW3 enables or disables the changeover function for

2-pipe changeover coil units, or 4-pipe units where the coil

has both a heating/cooling circuit and a heating circuit

piped internally. If SW3 is turned off, the changeover

function will be disabled, and the unit will then be

configured as a cooling only coil, a heating only coil, or a

combination of cooling only/heating only coil. Thus,

customer cooling requests will drive the main valve, and

heating requests will drive the auxiliary valve.

The changeover function is designed to work with

customer controllers that request heating or cooling

(based on customer request), but have coil water

temperatures that are “changed over” from heating to

cooling (or cooling to heating) depending on the season

and the building equipment available. Customer

thermostats MUST be hooked to the correct terminal strip

locations (V1 and V2) for the changeover function to work.

Cooling

In general, the (CSTI) changeover function will provide

cooling if:

1. A unit is factory configured with a changeover coil

(cooling/heating) as the only coil or as the main coil

portion.

2. SW3 on the CSTI adapter board is turned on, and the

 parameter set to  or  to use the

changeover functions.

 parameter should be chosen if the unit has a

changeover coil without electric heat.

 parameter should be chosen if the unit has a

changeover coil with electric heat. Generally, this

will perform the same as the

 parameter but

will in addition, disable the heating function on

electric heat and on the changeover coil heat if there

are fan failures. The auxiliary heating coil valve will

continue to respond to customer heating requests.

3. The ECM engine has sensed that there is cold

water

available on the supply/bypass line for the changeover

coil. In this case, “cold” water is inferred by the ECM

engine if:

a. A 10K NTC thermistor (similar to T

rane part number

X13790374010) is wired properly to the engine

board, through the crossover cables and CSTI

adapter boards.

b. The input impedance of the thermistor circuit must

be set correctly (the

 parameter should be set

 for CSTI units).

c. The temperature sensed is lower than the



parameter.

d. The

 parameter is higher than the 

parameter.

e. The temperature is not in the dead-band between

the

 parameter and the  parameter (in

this case, previous state will be retained).

4. The customer thermostat is properly hooked up the

put strip 1TB3, and is requesting cooling input (V1)

based on the customer cooling setpoint being lower

than the space temperature.

Heating