Thermo Products USDT2004 manual No Circ, OK Circ

2 OPEN	Disconnection in sensor 2 wiring
OK	System operates normal
NO CIRC	r T is more than 108 oF in last 30 minutes
OK CIRC	Pump is running
CLEAR	Clears NO CIRC display after correction

Energy calculation - Energy gain is calculated by obtaining the temperature increase of heat transfer fluid across the solar collector. The amount of fluid flow through the collector is registered by an in -line flow meter. USDT 2004 computes the energy production as a function of the temperature differential and fluid volume. In addition, the system anti-freeze (Glycol) percentage should be entered as it affects the thermal conductivity and heat transfer

rate.

BTU	Energy calculation mode
S IN	Sensor port selection for inlet temperature (1, 2, 3, --)
S OUT	outlet temperature (1, 2, 3, --)
F SEN	Sensor port selection for flow rate (1, 2, 3, --)

Energy calculation will be initiated only after temperature sensor ports are designated. Flow rate can be either a constant number to be entered by user, or from a flow meter input. To activate the energy calculation without using the flow meter's impulse input, a dash (-) must be selected for F SEN channel followed by the constant flow rate in gph (gallon per hour) unit.

LLP	Flow meter rate impulse number in liter per pulse, if flow meter is used
GAL	Constant flow rate in gph instead of flow meter reading in (--) sensor mode
GLYCOL	Anti-freeze percentage
CLEAR	Sets the BTU meter's counter to zero
DIF	Sensor calibration

The output of USDT 2004 unit is kW for system power and kWh or MWh for collected energy.

The energy calculation dependents on flow meter accuracy, the temperature sensors class, and their locations. The flow meter is a mechanical device and its accuracy fluctuates over time. Therefore, the user should calibrate the flow meter and incorporate temperature sensor tolerance.

The supplied Thermistor sensor has an accuracy of ± 2 oF. DIF represents the temperature difference between two sensors. User can increase the accuracy of reading by adjusting the DIF parameter. The energy calculation becomes accurate at temperature range that this reading adjustment is made.

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