Robur GAHP-W, Installation, Use And Maintenance Manual, Page: 29 / 68

Overview and technical specifacions
Ed. 2014-08
27
2.8 WATER CONNECTIONS
Piping should be supported by suitable hangers or floor stands. Do not support piping with
this appliance. Due to expansion and contraction of copper pipe, consideration should be
given to the type of hangers used. Rigid hangers may transmit noise through the system
resulting from the piping sliding in the hangers.
Use stainless steel, black steel, copper or cross linked polyethylene pipes for
heating/chilling plants. All water pipes and pipe connections must be insulated in
accordance with current regulations.
When rigid pipes are used, to prevent the transmission of vibrations, it is recommended
that the appliance inlet and outlet water lines are connected with vibration dampings.
Power outage or the, interruption of gas supply may prevent theGAHP unit from firing.
Any time a GAHP unit is subjected to freezing conditions, and it is not able to fire,
and/or the water is not able to circulate, there is a risk of water freezing in the GAHP
unit or in the pipes in the system.
When water freezes, it expands. This can result in
bursting of pipes in the system, which could result in leaking or flooding conditions.
Permanent inhibited antifreeze/glycol must be added to the hydronic loop.
A minimum 10% concentration is required in all regions.
Robur recommends the use of permenantlyinhibited propylene glycol. Maintaining the
level of inhibitor in the glycol is also required and must be checked annually.
Zinc coated steel must not be used in the water loop piping especially if there is
antifreeze/glycol.
Different glycol products may provide varying degrees of protection. Glycol products must
be maintained properly in a heating system, or they may become ineffective. Consult the
glycol specifications, or the glycol manufacturer, for information about specific products,
maintenance of solutions, and set up according to your particular conditions.
Never use
automotive
glycol (automotive antifreeze).
Glycol is denser than water and changes the viscosity of the system. The addition of
glycol will decrease the heat transfer and increase the frictional loss in the heat pump and
related piping. A larger pump with more capacity may be required to maintain the desired
flow rates in a glycol system.
The following table has to be considered in order to correctrly size the pipes and the water
pumps.
PROPYLENE GLYCOL CAPACITY CORRECTION FACTOR TABLE
Percent Propylene Glycol 15% 20% 25% 30% 35% 40% 50%
Approximate Freezing Point In °F
24° 18° 15° 9° 5° -5° -30°
Capacity Factor Multiplier * 0.992 0.986 0.972 0.960 0.950 0.928 0.878
Pressure Drop Multiplier ** 1.04 1.08 1.13 1.21 1.26 1.47 2.79
Table 15 - Approximate water freezing point temperatures. The value are strongly affected by the type of
antifreeze/glycol used.