Water Quality Guidelines; Supply And Return Piping; Low Water Cutoff - Riello Array AR 2000 Installation And Operation Manual

4.6 Water Quality Guidelines

Excessive water hardness causing a lime buildup in the stainless
steel coils or tubes is not a fault of the appliance and is not covered
by warranty. Water hardness must fall within the following limits:
Parameters Units
General feature -
PH value PH
Dissolved Oxygen mg/l
Total iron (Fe) mg/l
Total copper (Cu) mg/l
Na SO mg/l
2 3
N H mg/l
2 4
PO mg/l
4
CaCO ppm
3
Trisodium Phosphate ppm
Chlorine ppm
Pressure PSI
Glycol %
− Avoid an automatic water fill system.
− Use only untreated water to fill the system.
− Do not use TSP (tri-sodium phosphate)
− Do not use fill water treated with salt bedding type
exchangers (ion exchanger).
− Consult a local
recommendations if any of the above table is outside the
stated ranges.
− When using oxygen permeable PEX, the system must be
separated from the boiler by a heat exchanger.
− A correctly sized and working expansion vessel must be
installed.
− Excessive flow can cause erosion damage to the heat
exchanger.
9
CAUTION: For freeze protection use only propylene glycol, with
scale inhibitors, with a maximum volume [concentration] of
50% of glycol. Frost protection and inhibitor level has to be
checked annually during the regular scheduled maintenance
of the condensing boiler.
9
CAUTION: The boiler, when used in connection with a
refrigeration system, must be installed so the chilled medium
is piped in parallel with the boiler with appropriate valves to
prevent the chilled medium from entering the boiler.
9
CAUTION: The boiler piping system of a hot water boiler
connected to heating coils located in air handling units where
they may be exposed to refrigerated air circulation must be
equipped with flow control valves or other automatic means
to prevent gravity circulation of the boiler water during the
cooling cycle. A minimum water pressure is required for
optimum performance. Minimum water pressure required: 7.25
psi (0.5 bar).

4.7 Supply and Return Piping

The Array Boiler utilizes 3" ANSI flanges for models AR 1000 and
AR 1500 and 4" flanges for model AR 2000 for the water system
supply and return piping connections. The physical location of the
supply and return piping connections is on the top of the unit as
shown in Fig. 11.
Value
Colorless, no sediment
Min 6.5; Max 9
< 0,05
< 0,3
< 0,1
< 10
< 3
< 15
Min 50 ; Max 150
absent
< 100
Min 7.25; Max 80
Max 50% (only propylene glycol)
water treatment specialist
Gas
connection
for
Fig. 11 Array AR 1000, AR 1500 and AR 2000 Connections
9
CAUTION: Before connecting the boiler to the heating system,
flush the heating system to remove sediment, flux, dirt, and
other foreign matter. The heat exchanger may be damaged by
sediment or corrosion.
9
CAUTION: Do not use cleaning fluids that are not compatible
with the boiler materials, including acids (e.g. hydrochloric
acid and/or similar ones) at any concentration.
9
CAUTION: Introducing fresh water to the system increases
the oxygen presence and can cause corrosion of metallic
components. Immediately repair any drips or leaks in the
system to avoid constant introduction of air into the system.
9
CAUTION: Excessive fluctuation in pressure changes in the
system can cause fatigue and stress on the heat exchanger.
This is detrimental to the integrity of the boiler and system
components. It is mandatory to maintain a constant operating
pressure.
A minimum water pressure is required for optimum performance.
Minimum water pressure required: 7.25 psi (0.5 bar).

4.8 Low Water Cutoff

A low water protection is installed at two levels:
− boiler level
− heat exchanger level
Boiler level:
a Low Water Cut Off (LWCO) sensor is installed on top of the supply
header of each boiler. To check its functionality, go to the HMI
touchscreen, access the Boiler screen (see section 6.3.3), push
LWCO TEST button and confirm. The error message "33 LWCO/Air
19
INSTALLATION
Water
Return
(Inlet)
Water
Supply
(Outlet)