Riello NXHM - Water Circuit Connection

90
ENGLISH
Example 1
The unit is installed 5m below the highest point in the water circuit. The total water volume in the water circuit is 100l. In this example, no action
or adjustment is required.
Example 2
The unit is installed at the highest point in the water circuit. The total water volume in the water circuit is 250l.
Result:
 Since 250l is more than 230l, the pre-pressure must be decreased (see table above).
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 The corresponding maximum water volume can be read from the graph: approximately 310l.
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Setting the pre-pressure of the expansion vessel
When it is required to change the default pre-pressure of the expansion vessel (1.0 bar), following guidelines:
 Use only dry nitrogen to set the expansion vessel pre-pressure.
 Inappropriate setting of the expansion vessel pre-pressure will lead to malfunctioning of the system. Pre-pressure should only be
adjusted by a licensed installer.
Selecting the additional expansion vessel
If the expansion vessel of the unit is too small for the installation, an additional expansion vessel is needed.
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The expansion vessel equipped in the unit should adjust the pre- pressure also.
 Calculate the volume needed of the additional expan- sion vessel:
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Vwater is volume of water in the system, V0 is volume of expansion vessel which the unit is equipped (8l).
9.4.3 Water circuit connection
Water connections must be made correctly in accordance with labels on the outdoor unit, with respect to the water inlet and water outlet.
b
CAUTION
Be careful not to deform the unit’s piping by using excessive force when connecting the piping. Deforming the piping can cause the unit to mal-
function.
b
WARNING
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If air, moisture or dust gets in the water circuit, problems may occur. Therefore, always take into account the following when connecting the water
circuit:
 Use clean pipes only.
 Hold the pipe end downwards when removing burrs.
 Cover the pipe end when inserting it through a wall to prevent dust and dirt entering.
 Use a good thread sealant for sealing the connections. The sealing must be able to withstand the pressures and temperatures of the
system.
 When using non-copper metallic piping, be sure to insulate two kind of materials from each other to prevent galvanic corrosion.
 For copper is a soft material, use appropriate tools for connecting the water circuit. Inappropriate tools will cause damage to the pipes.
NOTE
The unit is only to be used in a closed water system. Application in an open water circuit can lead to excessive corrosion of the water piping:
 Never use Zn-coated parts in the water circuit. Excessive corrosion of these parts may occur as copper piping is used in the unit's
internal water circuit.
 When using a 3-way valve in the water circuit. Preferably choose a ball type 3-way valve to guarantee full separation between the
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 When using a 3-way valve or a 2-way valve in the water circuit. The recommended maximum changeover time of the valve should be
less than 60 seconds.
9.4.4 Water circuit anti-freeze protection
Ice formation can cause damage to the hydraulic system. As the outdoor unit may be exposed to sub-zero temperatures, care must be taken to
prevent freezing of the system.
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The software contains special functions using the heat pump and backup heater (if it is available) to protect the entire system against freezing.
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In event of a power failure, the above features would not protect the unit from freezing.
Do one of the following to protect the water circuit against freezing:
 Add glycol to the water. Glycol lowers the freezing point of the water.
 Install freeze protection valves. Freeze protection valves drain the water from the system before it can freeze.
NOTE
If you add glycol to the water, do NOT install freeze protection valves. Possible consequence: Glycol leaking out of the freeze protection valves.