Econergy Installation Manual Rev G 240914
© Hot Water Heat Pumps Ltd 2018
12/03/2018
www.econergy.co.nz
5
Heat Pump Water Heater Installation Guide
Installation Design
Design to avoid cavitation
The installation must be designed so that the unit will operate reliably and
with no water flow issues due to cavitation.
To ensure successful operation of the Econergy
®
water heater on open
vent application where operating pressure is less than 50kPa (or 5m static
head), a valve vented system should be used. This has the added benefit of
increasing the pressure of supply in the house. The installer should be aware
of and avoid adding a relief valve to an old HWC of questionable structural
integrity since it could cause the HWC to fail.
Distance from Hot Water Cylinder
The Econergy
®
water heater should be mounted as close as possible to the
HWC to ensure best efficiency. This is because each leg of supply/ return
piped water loses its heat during the off-cycle despite being insulated. The
cylinder should be located within 9 metres of the Econergy
®
water heater for
retrofit installations and directly adjacent for new installations.
Wetback Systems
Wetback systems involve large bore copper pipes running into the cylinder
and back again. Because the heat source is uncontrolled, temperatures can
rise to 100°C, generating steam. Plumbing codes dictate that an open vent
is used to eliminate the possibility of an explosion occurring due to rapid
pressure rise in the system.
Cavitation of the circulating pump may occur
when there is less than 50kPa pressure at the heat
pump inlet. This can lead to a malfunction of the
Econergy
®
water heater and MUST BE AVOIDED by
ensuring adequate pressure at the system inlet.
!
The Econergy
®
system cannot be used with a
wetback system where the piping design allows a
thermosyphon to develop
!