Using Δt•Hours To Calculate Heat Transfer; Temperature Monitoring; Installation - Tekmar Difference Setpoint Control 156 Data Brochure

Using ΔT•hours to Calculate Heat Transfer
To estimate the total amount of heat the system has transferred from the heat source to the storage tank use the equation:
Total Heat Transferred =
Where:
• Flow Rate is that produced by the pump in US Gallons per minute
• ΔT•hours is the temperature difference between the source and storage multiplied by the amount of time heat transfer is
taking place (time the pump runs). This variable is calculated for you by the control since the ΔT is not constant.
• K is a constant calculated by multiplying the fluid property specific heat (BTU/lbm°F) by density (lbm/USGal) by 60 (min/
hr). For example, water has a specific heat of 1 BTU/lbm°F and a density of 8.33 lbm/USGal. Therefore the value of K
in this case is 1 x 8.33 x 60 = 500.
The value of K depends on the percent volume of glycol added to the heat transfer fluid. Select an appropriate K
value from table 1.
Ethylene Glycol Solution
% by Volume Freezing Point
0 32°F (0°C)
10 23°F (-5°C)
20 14°F (-10°C)
30 2°F (-17°C)
40 -13°F (-25°C)
50 -36°F (-38°C)
60 -70°F (-57°C)
Table 1: K values at 120°F (49°C) for different heat transfer solutions based on % glycol. K increases with temperature.
Note: BTU = British Thermal Unit, lbm = Pound Mass, USGal = US gallon

Temperature Monitoring

The 156 will monitor the minimum and maximum Source
and Storage temperatures. These items are available
in the Default menu and may be reset by pressing and
holding the ▲ and ▼ buttons simultaneously for 1 second.

Installation

Caution
Improper installation and operation of this control could
result in damage to the equipment and possibly even
personal injury. It is your responsibility to ensure that this
control is safely installed according to all applicable codes
Step One — Getting Ready
Check the contents of this package. If any of the contents
listed are missing or damaged, please contact your
wholesaler or tekmar sales representative for assistance.
Type 156 includes: One Difference Setpoint Control 156, One
Solar Sensor 085, One Universal Sensor 071, Data Brochures
D 156, D 085, D 070, D 001, Application Brochure A 156.
X
Flow Rate ΔT•hours
K @ 120°F (49°C)
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X = _____________ BTU
K
Propylene Glycol Solution
% by Weight
0
10
20
30
40
50
60
'Clr' (clear) will then be displayed followed by the value being
reset to the current sensor temperature. Use this feature to
determine system performance or for troubleshooting.
and standards. This electronic control is not intended
for use as a primary limit control. Other controls that are
intended and certified as safety limits must be placed into
the control circuit.
Note: Carefully read the details of the Sequence of
Operation to ensure that you have chosen the proper
control for your application.
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Freezing Point K @ 120°F (49°C)
32 (0°C)
26 (-3°C)
18 (-8°C)
7 (-14°C)
-8 (-22°C)
-29 (-34°C)
-55 (-48°C)
© 2010
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D 156 - 06/10