LAARS Rheos+ RHHV - Install and Operating Manual - Manual (Page 15)

LAARS Heating Systems Page 14
7. All threaded joints should be coated with
piping compound resistant to action of liquefied
petroleum gas.
8. The appliance and its individual shutoff valve
must be disconnected from the gas supply piping
during any pressure testing of that system at test
pressures in excess of 1/2 PSIG (3.45kpa).
9. The unit must be isolated from the gas supply
system by closing its individual manual shutoff
valve during any pressure testing of the gas
supply piping system at test pressures equal to or
less than 1/2 PSIG (3.45kpa).
10. The appliance and its gas connection must be
leak tested before placing it in operation.
11. Purge all air from gas lines.
WARNING
Open flame can cause gas to ignite and result in
property damage, severe injury, or loss of life.
NOTE: The Rheos+ appliance and all other gas
appliances sharing the gas supply line must be firing
at maximum capacity to properly measure the inlet
supply pressure. The pressure can be measured at
the supply pressure port on the gas valve. Low gas
pressure could be an indication of an undersized
gas meter, undersized gas supply lines and/or an
obstructed gas supply line. A bleed line from the
diaphragm-type automatic valve shall be vented per
local code requirements. Rheos+ units are equipped
with low and high gas pressure switches that are
integrally vent limited. These types of devices do not
require venting to atmosphere.
Section 4A
WATER CONNECTIONS —
RHEOS+ BOILER
4A.1 Heating System Piping:
Hot Supply Connections — Boiler
NOTE: This appliance must be installed in a closed
pressure system with a minimum of 12 psi (82.7kPa)
static pressure at the boiler.
Hot water 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. It is recommended that padding be used
when rigid hangers are installed. Maintain 1" (2.5cm)
clearance to combustibles for hot water pipes.
Pipe the discharge of the relief valve (full size)
to a drain or in a manner to prevent injury in the event
of pressure relief. Install an air purger, an air vent,
a diaphragm-type expansion tank, and a hydronic
flow check in the system supply loop. Minimum fill
pressure must be 12psig (82.7kPa). Install shutoff
valves where required by code.
Suggested piping diagrams are shown in Figures
4, 5, and 6. These diagrams are meant only as a guide.
Components required by local codes must be properly
installed. The Rheos+ boiler’s efficiency is higher with
lower return water temperatures. Therefore, to get the
most of low return temperature with multiple boilers,
pipe as shown in Figure 4.
The Rheos+ boiler has an internal mixing
system that ensures that the condensation does not
occur on the finned copper heat exchanger, with
boiler return temperature down to 50°F (10°C). This
system, that consists of automatically actuated
and linked valves, is set up at the factory, and is
non-adjustable. The return water goes through the
stainless steel heat exchanger, then to the mixing
system (see Figure 7).
If the water at the inlet of the copper heat
exchanger is less than 140°F (60°C), water from the
outlet of the copper heat exchanger will be directed
back to the inlet of the copper heat exchanger, and will
mix to bring the inlet water up to 140°F (60°C). Once
through the copper heat exchanger, the water picks up
another 20-25°F (11-14°C) (when at high fire), and
it leaves the boiler at 160-165°F (71-74°C). This hot
water is then sent to the system.
If the water at the inlet of the copper heat
exchanger is 140°F (60°C), or higher, the water will be
allowed to flow through the copper heat exchanger and
directly to the outlet of the Rheos+, and there will be a
20-25°F (11-14°C) temperature rise between the inlet
and outlet of the unit, when the unit is at high fire.
The pump in the boiler is sized for the boiler’s
heat exchangers, the internal mixing system, and 30
feet of full-sized piping, with a normal number of
fittings taken into consideration. The piping must be
primary/secondary, ensuring that the boiler’s pump is
only used for the boiler, and that the system pump(s)
do not interfere with the Rheos+ pump or mixing
system.
The minimum inlet water temperature for the
Rheos+ is 50°F (10°C) to avoid condensing on the
copper coils.
4A.2 Cold Water Make-up — Boiler
1. Connect the cold water supply to the inlet
connection of an automatic fill valve.
2. Install a suitable back flow preventer between the
automatic fill valve and the cold water supply.
3. Install shut off valves where required.
NOTE: The boiler, when used in connection with a
refrigeration system, must be installed so the chilled