Testing - Bosch Worcester Greenstar HIU E Installation And Maintenance Instructions Manual

Key to Central heating performance chart, Figure 57:
[1] Supply volumetric flow rate [l/s] and [l/h].
[2] Supply flow temperature [ °C].
[3] Supply differential pressure [kPa] (Standard unit).
[4] Supply differential pressure [kPa] (Standard unit and heat
meter).
[5] Supply differential pressure [kPa] (Standard unit and Differential
pressure control valve).
[6] Supply differential pressure [kPa] (Standard unit, Differential
pressure control valve and heat meter).
Central heating example
The central heating performance chart, (figure 57, page 46) shows an
example for calculating the central heating performance.
• [a] [ °C] Supply temperature = 65 °C
• [b] 50/30 °C (5 kW) Return temperature = 32.6 °C
• [c] [l/s]/[l/h] Supply volumetric flow rate = 0.037l/s / 133.2l/
h
• [d] [kPa] Supply differential pressure
– [Standard unit] = 0.63kPa
– [Standard unit with heat metre] = 1kPa
– [Standard unit with Differential pressure control valve] =
1.05kPa
– [Standard unit with Differential pressure control valve and heat
meter] = 1.42kPa
6 720 808 928 (2017/06)
6.12

Testing

Functional checking, heat outputs and balancing flow for a system
containing multiple Heat Interface Units:
▶ For a known district supply temperature, determine the nominal
district flow rate and supply differential pressure required to achieve
the requested domestic hot water output from either figure 55 or 56
as appropriate.
The internal DPCV (if fitted) will limit the maximum district flow rate
through the HIU to 0.38 l/s for 58.6kW and 0.355 l/s for 39.1kW
models.
▶ If fitted, ensure that a Flow regulating valve (with pressure test points
at inlet and outlet) is fitted in the district return pipe work at each
Heat Interface Unit,  section 5.1.7.
– The function of the Flow regulating valve is to ensure that the
correct nominal flow rate is achieved at each Heat Interface Unit.
– For units without a heat meter.
By measuring the differential pressure across the regulating
valve, this can be converted into the corresponding district flow
rate using charts supplied by the manufacturer.
▶ With each Heat Interface Unit operating in a maximum domestic hot
water demand, adjust each flow regulating valve to achieve the
required nominal district flow rate.
– Check that the LED indication lights on top of the domestic hot
water control valve are indicating correctly. See table 12.
– Check that the LED indicator lights at the top of the HIU control
unit are indicating correctly see table 9.
– If the nominal district flow rate cannot be achieved, check the
differential pressure across the district flow and return adjacent
to the Heat Interface Unit. Ensure that the actual differential
pressure measured corresponds to the nominal differential
pressure from figure 55 or 56.
▶ Check that the required domestic hot water flow rate and
temperature rise is achieved for each Heat Interface unit. By using
the following equation, the domestic hot water heat output, Qdhw in
kW can be determined:
– Qdhw (kW) = 0.07 x dhw flow rate (l/min) x temperature rise (K)
▶ Set the room controller to call for heat and with each Heat Interface
Unit operating in a maximum central heating demand, check that the
nominal district flow rate is achieved.
– Check that the LED indication lights on top of the central heating
control valve are indicating correctly. See table 12.
– Check that the LED indicator lights at the top of the HIU control
unit are indicating correctly see table 9.
– Generally, the nominal district flow rate for domestic hot water is
higher than that required for central heating, so it will not be
necessary to re-adjust the flow regulating valves.
▶ Whilst each Heat interface Unit is operating in a central heating
demand, measure the temperature differential across the flow/
return connections on the central heating side at the Heat Interface
Unit. Also measure the central heating water flow rate. By using the
following equation, the central heating heat output, Qch in kW can be
determined:
– Qch (kW) = 0.07x ch flow rate (l/min) x Delta T (k)
If it is not possible to measure the CH flow rate, the heat input in CH
mode can be calculated by measuring the temperature difference across
the district flow/return connections and the district flow rate.
▶ The following equation can be used to determine the heat input:
– Qch,in (kW) = 0.07x district flow rate (l/min) x Delta T (k)
The efficiency of the CH plate heat exchanger is >98%.
▶ Alternatively, if a heat meter is fitted, the heat input (kwh) can be
recorded for both DHW and CH.
Commissioning
47