Marvair HVPA49 Manuel d'utilisateur télécharger pdf (Page 28)

Classic Manual 9/2013 rev. 5

Once the indoor fan comes on, allow approximately three minutes for the compressor to start. Note

that the outdoor fan may not come on immediately because it is cycled by refrigerant pressures

Note: To check the system operation under different ambient conditions, the air temperature and

enthalpy sensors must be "tricked". When outdoor ambient conditions are higher than the control

setting, a component aerosol cooler may be sprayed directly into the enthalpy sensor to simulate low

enthalpy conditions, causing the economizer damper to open.

Alternately, when outdoor conditions are lower than the set point, a source of heat such as a hair

dryer can be directed on the air temperature sensor to simulate warmer conditions, which will bring

on mechanical cooling and start the compressor.

If the unit fails to operate, refer to the troubleshooting information in Chapter 4.

3.2 Check-Out of Heating Cycle

Procedure:

1. Place the thermostat system switch to "Auto" or "Heat" and the fan to "Auto".

2. Raise the heating set point temperature to a setting which is higher than the room temperature.

The fan and compressor should cycle on after time delay (standard on Classic heat pump with

economizer and all HVP models, option on all other Classic units) has cycled.

3. Move the system switch to the "Off" position. All functions should stop.

The Blower Timed Delay Relay (BTR) keeps the blower running for 90 seconds after the unit shuts

off.

Note: The damper blade should remain closed during the heating cycle (unless the minimum position

potentiometer has been set for constant ventilation).

3.3 Discharge Air Temperature Adjustment of Modulating

Hot Gas Reheat (HGR) Valve

Units with Hot Gas Reheat may use a valve, a PC board and temperature sensor to maintain a constant

discharge temperature during reheat operation. The discharge air temperature can be adjusted by the

use of a potentiometer located on the PC board. The board is located in the control box of the unit.

A Digital VOM is required to adjust the potentiometer.

WARNING - ELECTRICAL SHOCK HAZARD

The setting of the discharge air temperature requires that power be applied to the

unit and the unit operating. Use extreme caution when working in the control box.

1. Make sure the two sensor wires are connected to the TEMP SENSOR terminals on the board.

See Figure 8.

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Marvair HVPA49 Manuel d'utilisateur Page 28