BTU Meter Wiring
The BTU Meter reads the consumption of the chilled water service in BTUs and converted into Ton.hrs .
Formula for consumption :
Consumption = K (constant) x Flow x ( T2-T1) .
In this case as shown in the figure , T1 = 5 C , T2 = 13 , so ∆T(T2-T1)= 9 C
The readings are taken from District Cooling Side
Common mistake in wiring
How wrong wiring affects your DC Bills
If the BTU meter is connected with T3 instead of T2 ( which is Customer CWRT ) ; This practice yield extra charges as following , assuming the temperatures were as per the figure . 1- Consumption Charges : Meter Consumption Reading : K x Flow x ( 16-5) =K x Flow x 11 Difference + ( K x Flow x 11)/( K x Flow x 9)=11/9 =22.2%. So , the metered consumption is 22.2% more than actual consumption . 2- Capacity Charges : The Contracted Capacity is being compared with the BTU meter reading . The reading values during the peak hours of the Building are recorded and averaged for few hours and compared with the Contracted Capacity. With such wiring connection , the BTU meter will read that the measured (metered ) Capacity is 22.2% more than the actual peak ; and therefore . should be avoided from being practiced.
The ideal solution for BTU Meters
It would be much more beneficial if another BTU Meter is installed on the Customer Side.
Each BTU Meter will read it sown side .
Q1 (Cooling Delivered by DCP)= Q2 ( Heat Rejected by the Customer + Q3(Cooling Loss)
The Cooling Loss is normally neglected !
Adding a second BTU Meter on the Customer Side will create a data bank of the Customer Building which some of them are :
- Flow of Chilled water rates on timely basis around the years .
- Chilled Water Supply Temp (CWST) , and Chilled water Return Temp (CWRT)
- Actual Delta T across the ETS on Customer side
- Approach Temp which is an important factor to determine the proper size of the ETS.
- The Cooling Loss ( Q3) , since it will make it possible now to compare both Q1 and Q2
- Building Heat Rate Data around the year ( kW/Sq. ft ) or Sq.ft/Ton
- By comparing the Q2 with the individual BTU meters of each apartment/office/.. an idea of how much losses are there in the general hydronic system of the Building .
- If the total values of the individual BTU meters are more than Q2 , this will alarm that :
Either some of the individual meters are not reading properly or the BTU Meter #2 itself is a faulty .
