Description; General Information - Ygnis VARJET Serie Manual Tecnico

2. Description

2.1 General information

Varjet are pressurised
condensation boilers with power range from 70 to 580
kW (78 to 625 kW when condensing). They are
designed to be fitted with gas or domestic fuel oil
burners.
The Varjet boiler comprises a steel heater with smoke
tubes arranged for "triple pass" and a stainless steel
water tube condensation recovery unit. Consequently,
by recovering the latent heat this condensing boiler
range can reach performance levels greater than
107% (on NCV). The "Heater + condenser" assembly
is originally delivered assembled and is integrated in a
single casing.
By-pass pipe only
on versions with
2-3 connections
Two tapping installation: this configuration places the condenser directly in series with the heater without separating the
"low" and "high" temperatures of the installation.
Three tapping installation: this configuration allows the separation of the "high" temperature returns from the "low"
temperature returns to obtain the maximum benefit from the condensation.
Four-connection installation: This configuration makes it possible to separate the water networks from the main body
and from the condenser.
Heating network: this configuration is particularly suitable for systems featuring circuits that are not controlled at
high temperature and networks controlled in relation to the outdoor temperature. The condenser receives a permanent
flow from the variable temperature circuit and constant flow rate from the network whereas the warm returns are fully
independent. The condensation is continuous throughout the year and the efficiency is optimized in this way.
Swimming pool water network: The management of a heating network and of a swimming pool type sanitary
network can also be suitable for a connection with four connections. The boiler inlets and outlets supply in this way the
primary network whereas the condenser warms up the swimming pool water. The condenser is then fitted with a
stainless steel water box in order to keep a domestic hot water quality.
The geometric design of the heater unit and the exchanger and their high water volumes provide a homogeneous
temperature distribution and irrigation by the thermal siphon effect. This design associated with the Ygnis patented
system of flame exit from the combustion chamber, also allows low Nox emissions.
The glass fibre thermal insulation applied directly to the boiler and condenser units guarantees very low stopped losses
and wall losses. To limit these losses, the boiler is also partly fitted with an insulating jacket. The use of a sound
proofing cover, available as an accessory, at the front of the boiler allows the burner noise to be reduced to a minimum,
reducing the thermal losses still further.
The pivoting combustion chamber door allows the parts of the boiler in contact with the exhaust gases to be reached
easily, which allows easy cleaning of the combustion chamber and tubes from the front of the boiler. The stainless steel
condenser placed in the combustion circuit in series with the heating unit is fitted with a large inspection hatch allowing
access to the whole exchanger for maintenance.
The jacket is simple and easy to fit.
1NO0P0007-D
Varjet 1 - 14
combustion chamber
The heater has a PYROFLOW system that allows it not to
have any inlet temperature constraint for the steel
exchanger (with Ygnis controller). This system consists of
heating the return water in the steel exchanger by direct
exchange with the hot water and so avoiding any
condensation in the heater unit.
The boiler is originally delivered with the (removable)
condenser fitted to the main unit and a hydraulic
connection with a blank flange for the connection of 2-3
tappings to be adapted to suite the installation hydraulic
configuration. The hydraulic connection allows the
condenser to be connected in series with the main unit in
2 or 3 tapping configuration.
The boiler can be optionally delivered as a four-
connection version This configuration makes it possible to
connect in parallel the boiler and the condenser circuit
with a minimum flow rate to be complied with for the
condenser.
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