Dynasonics TFX Ultra Transit Time Flow Meters - Manual (Page 80)

HEATING AND COOLING MEASUREMENT
The energy meter is designed to measure the rate and quantity of heat delivered to a given building, area or heat exchanger.
The instrument measures the volumetric flow rate of the heat exchanger liquid (water, water/glycol mixture, brine, etc.), the
temperature at the inlet pipe and the temperature at the outlet pipe. Heat delivery is calculated by the following equation:
RATE OF HEAT DELIVERY
Q K dV
V
V
=
0
1
Where:
Q = Quantity of heat absorbed
V = Voluem of liquid passed
K = Heat coefficient of the liquid
Δθ = Temperature difference between supply
and return
Platinum RTD
Type 1000 Ohm
Accuracy ±0.3 °C (0.0385 curve)
Temperature Response Positive Temperature Coefficient
The RTD temperature measurement circuit in the energy meter measures the differential temperature of two 1000 Ohm,
three-wire platinum RTDs. The three-wire configuration allows the temperature sensors to be located several hundred feet
away from the meter without influencing system accuracy or stability.
The energy meter allows integration of two 1000 Ohm platinum RTDs with the energy flow meter, effectively providing an
instrument for measuring energy delivered in liquid cooling and heating systems. If RTDs were ordered with the energy flow
meter, they have been factory calibrated and are shipped connected to the module as they were calibrated.
Field replacement of RTDs is possible thru the use of the keypad or the software utility. If the RTDs were ordered from the
manufacturer of the energy meter, they will come with calibration values that need to be loaded into the energy meter.
New, non-calibrated RTDs will need to be field calibrated using an ice bath and boiling water to derive calibration values. This
procedure is outlined below.
HEATING AND COOLING MEASUREMENT
Page 80 March 2014