Pumps In Parallel; Summer Mode; Ii.8. Weekly Control - TECH ST-450zPID User Manual

ST – 450 z PID
pump will be turned off and the CH circulating pump will be enabled.
The central heating pump will run all the time until the boiler tank temperature
drops below its set-point by the hot water hysteresis value. At that moment the
CH pump will turn off and the HW pump will turn on (both pumps operating
alternately).
In this mode the fan and the feeder are run only up to 62 O C as measured at the
boiler (instantaneous set-point) so as to prevent overheating of the boiler.
NOTE: The boiler must be fitted with check valves on the central heating and
hot water pump circuits. The valve mounted on the hot water pump is to
prevent drawing hot water from the boiler tank.

Pumps in parallel

▪
In this mode both pumps begin to run together (in parallel) above the pump
activation temperature. However, these temperatures may vary for each pump,
depending on your settings (see Sections III.g-h). When this is so one of the
pumps will switch on earlier than the other one, but after both thresholds are
crossed both pumps will run together. The central heating pump will run all the
time while the hot water pump will turn off when the boiler tank set-point
temperature is reached. It will turn on again when the temperature drops by the
preset HW hysteresis value below its set-point.

Summer mode

▪
Once this function is activated the central heating pump will be off and the DHW
pump will turn on above the preset activation temperature (see Section III.h)
and will work continuously until the temperature drops below the activation
temperature by the hot water hysteresis value or until the following conditions
are met:
(boiler temperature) + 2°C ≤ (boiler tank temperature)
In summer mode you only enter the set-point temperature of the boiler, which
is also understood to mean the set-point temperature of the boiler tank.

II.8. Weekly control

The function is used to programme daily changes in the boiler
temperature. The preset temperature deviations are within the range of +/-
10 0 C.
- 10 -