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6.1. Metrological test
The value "test" is the heat quantity [kJ] per 1 m
3
of water at the given differential temperature. It is
used to verify that the resolver works correctly. In order to test the meter, call the indication "test" at the
given differential temperature, calculate the heat energy per 1m
3
of water and then compare the result
to the indication.
Use the heat measurement principle:
Q = V * k * (t1 − t2) where: Q - heat
V - volume of medium
k - temperature coefficient of water
t1 - supply temperature
t2 - return temperature
The reference heat value per 1 m
3
of the medium is: Q = 1 * k * (t1 − t2)
Example:
Input data: t1 = 70 °C, t2 = 50 °C
The temperature coefficient for the heat meter supply side, calculated acc. to EN-1434-1:2009
Annex A: k = 4.09105 [MJ /m
3
K].
Reference heat:
Q
w
= 1 * 4.09105 * (70 − 50) = 81,821[MJ] = 81821 [kJ]
Assume that the tested meter shows QT = 82000 [kJ], then the resolver error is:
E
o
= [(82000 − 81821) / 81821] * 100 % = 0.22 %
Compare the obtained error value E
o
to the maximum permissible error values E
l
from the technical
data table. If at the given differential temperature E
o
< E
l
then the meter correctly calculates the heat
energy quantity. The test procedure presented here can be carried out on a working heat energy me-
tering system without stopping the heat meter or breaking the meter seals. The meter calculates the
value "test" following each temperature measurement. The best method for evaluating the resolver
error is to calculate the average of several (e.g. eight) successive readings of the resolver test, since
a single measurement suffers from a certain statistical fluctuation of approx. ±0.5 % (at the minimum
differential temperature).
7. REMOTE READING OF DATA
Elf heat meters feature a connector for communication interfaces which enable remote reading and wri-
ting of data. The connector also enables connection of pulse signals with additional pulse inputs, and
to output the pulses generated by the heat meter to one of the output interfaces. Only interfaces from
Apator-Powogaz shall be used, since they ensure proper support of the heat meter. The interfaces are
installed on the heat meter without tampering with the heat meter verification markings, as shown in
the following diagrams. Route the wiring for interface connections through proper penetrations to ma-
intain the declared enclosure protection rating. It is recommended to have the interfaces installed by a
competent service technician and sealed with the service sticker seal once installed and commissioned.
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