Camus Hydronics DFH/W500, Installation, Operation And Service Manual

Page: 27 / 90

22
4.11 LOW WATER CUTOFF (If Equipped)
If this boiler is installed above radiation level, a low water cut-
off device must be installed at the time of boiler installation.
Some local codes require the installation of a low water cut-off
on all systems. Electronic low water cut-offs are available as a
factory supplied option on all models. Low water cut-offs
should be tested every six months. The normally open switch
contact of the low water cutoff is to be wired in series with the
flow switch. A diagnostic light will be indicated on the control
display on a low flow condition.
Caution: remove jumper when connecting to 24 VAC circuit.
Figure 21: Low Water Cut Off Electrical Connections (Watts)
Figure 22: Low Water Cut Off Electrical Connections (ITT)
4.12 RELIEF VALVE (shipped loose)
This appliance is supplied with a relief valve sized in
accordance with ASME Boiler and Pressure Vessel Code,
Section IV (“Heating Boilers”). The relief valve is to be
installed in the vertical position and mounted in the hot
water outlet. No valve is to be placed between the relief
valve, and the appliance. To prevent water damage, the
discharge from the relief valve shall be piped to a suitable
floor drain for disposal when relief occurs. No reducing
couplings or other restrictions shall be installed in the
discharge line. The discharge line shall allow complete
drainage of the valve and line. Relief valves should be
manually operated at least once a year.
CAUTION
Avoid contact with hot discharge water
4.13 CONDENSING HEAT RECOVERY
MODULE PIPING CONFIGURATIONS
Caution: If isolation valves are provided on the CHRM,
the provision of a relief valve at the outlet of the secondary
is recommended .This valve is to be sized at minimum for
10% of the input of the appliance and is to be piped to
drain in a manner similar to the appliance relief valve.
4.13.1 CHRM IN SERIES WITH PRIMARY HEAT
EXCHANGER (INTEGRATED LOOP)
The supply water (Cold water) is pre-heated by CHRM
and fed into the outlet of the primary Heat Exchanger.
Provisions must be made to prevent cold water below
115ºF (46ºC) entering to the Primary Heat Exchanger.
BOILER APPLICATION (HYDRONIC HEATING)
In case of boilers (Hydronic heating boiler) application, the
return water (supply water) may be more than 115ºF
(46ºC), therefore there is no need for a recirculation loop
and the primary heat exchanger and CHRM can be piped
in parallel. Since the inlet water temperature to CHRM
exceeds 110ºF (44ºC) it will not condense fully and
therefore the CHRM will not perform to its maximum
efficiency capacity. If water colder than 110ºF (44ºC) is
available it can be fed to the CHRM.
WATER HEATER APPLICATION (HOT WATER
SUPPLY)
In case of domestic water supply (Water Heating), the
fresh inlet water temperature will be less than 110ºF
(44ºC), in this case the CHRM may be fed directly with
part of the supply water using a secondary pump.
4.14 CIRCULATING PUMP SELECTION
The appliance has a low mass finned tube heat exchanger
for fast response and high heat absorption. Selecting the
proper pump will ensure that temperature rise does not
exceed recommended maximum
Δ T and that heat
exchanger tubes are not prematurely scaled or eroded.
4.14.1 CIRCULATING PUMP OPERATION PRIMARY
HEAT EXCHANGER
MOST IMPORTANT
This appliance is designed for continuous pump operation
when the burner is firing. The circulating pump will run
continuously when the power switch is in the “ON”
position. As an optional feature a pump control system can
be provided. The pump control option allows the appliance
circulating pump to be cycled “ON” prior to the burner
firing and cycled “OFF” some time after the set point is
satisfied.