General Description; Technical Details - SPC DERV Installation, Operating And Maintenance Instructions

1 General Description

SPC DERV(DX/CHW) units are heat recovery ventilator units incorporating heat recovery heat
pipes, dehumidifier heat pipes and an active DX cooling coil or chilled water cooling coil. DX units
are supplied with a matched condensing unit for external mounting and for piping to the DERVDX
unit which acts as the indoor unit in the split system.
The units are intended to fully condition outside air by taking advantage of the cooling potential of
dirty extract air and the cooling and dehumidifying potential of a DX evaporator coil or chilled
water cooling coil.
The units are constructed in two halves; one half incorporating the extract fan(s) and extract
section of the heat recovery heat pipe, the other half contains the supply fan(s), supply section of
the heat recovery heat pipe plus chilled water/DX cooling coil c/w heat pipe wrapped around it.
The wrap around heat pipe precools the air prior to the cooling coil and reheats it after the cooling
and dehumidifying process to generate neutral ventilation air.
Units incorporate filtration on both the supply and extract side and are designed to be mounted
out of sight above false ceilings, suspended from the ceiling slab.
The supply and extract sections terminate in sheet metal flanges for the attachment of ducting.
Ducting design will be to suit the desired distribution within the premises and is largely beyond the
scope of this manual.
Units are supplied with an on/off and three speed controller to control the rotational speed of the
backward curved centrifugal fans and hence control the throughput of air on both the supply and
extract side. Further control of the air throughput must be made as part of the ducting design with
branch sizes matched to air volumes and manual volume control dampers fitted where
necessary. DX versions supplied with matched outdoor units incorporate a relay for switching of
the compressor and an additional temperature setting switch.

2 Technical Details

The table below gives details of the nominal operating characteristics of the DERV units along
with pertinent weights and dimensions. Operating limits for the units are as follows:
Maximum outside air temperature: 55° C
Minimum outside air temperature: 5° C
Maximum extract air temperature: 40° C
Minimum extract air temperature: 5° C
Units should be installed in a non-condensing environment.
Minimum outside air temperature for condensing unit operation of DX model: 20° C
QA/IOM/63 ISSUE 2 - DERV Page 2 of 19