MHG Heating ProCon HT 150, Manual

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2. Installation
ProCon HT 150 / HT 225
MHG recommends room air independent operation because this
operation mode has major advantages:
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Additional energy saving due to preheating of the combustion air
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No cooling-off of the building because there are no air inlets
and outlets.
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Improvement of the condensation ratio of existing systems with
high design/flow temperatures (condensed water accumulation
is higher because the supply air/ flue gas system functions as an
additional heat exchanger), especially when the condensing
boiler is in constant operation mode
Installation and routing of the flue gas pipes are distinguished as
follows:
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Routing of the flue gas pipes within ducts.
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Routing of the flue gas pipes with no installation in ducts.
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Flue gas systems should be installed in ducts as defined by the
State ordinances for combustion equipment, if they bypass floors
within a building.
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Flue gas pipes do not have to be installed in ducts within the
installation room of the furnaces if for instance the ceiling of the
installation room of the furnace is part of the roof, or even
outside buildings.
The horizontal part of the gas pipe should be connected to the
gas-condensing boiler and must be gas and condensate proof. At
the same time, there should be a 3% minimum clearance from the
vertical part of the flue gas pipe to the boiler, so that the
condensed water that accumulates in the flue gas pipe can be
drained off via the condensed water line of the flue gas collection
pipe located in the boiler.
2.6.1 Excerpt from the model building code
The following excerpt from the model building code is representative
of the State building code.
Furnaces and flue gas systems such as chimneys, flue gas pipes, and connecting
pieces (heating equipment), systems for discharging combustion
gases of stationary combustion motors as well as tanks and pipes for
combustible gases and liquids must be safe to operate and
fireproof and other than that, they should not cause any potential
danger or disturbances. The sound conduction in remote rooms
must be adequately insulated.
Flue gas systems must be easy and safe to clean.
The flue gases from the furnaces should be discharged through the
roof.
Flue gas systems should be built in such numbers and condition that
the furnaces of the building can be connected properly. Exception to
Clause 1 may be granted if there are no occurrences of danger or
unreasonable disturbances.
Flue gases from closed combustion furnaces that have inflow of
combustion air from the outdoors via leak proof pipes (room air
independent gas furnaces) , in divergence from the provisions of
the above-named clause, may be discharged through the outside
wall into the outdoors if it is not possible to discharge the flue
gases through a roof or if it is only possible with
disproportionately high costs.
Flue gases from closed combustion furnaces that have inflow of
combustion air from the outdoors via leak proof pipes (room air
independent gas furnaces), in divergence from the provisions of
the above-named clause, may be discharged through the
outside wall into the outdoors if:
1. It is not possible to discharge the flue gases through a roof or
only with disproportionately high costs and
2. The rated heating capacity of the furnace, 11 kW for heating and
28 kW hot water heating is not exceeded and dangers or
unreasonable disturbances do not occur.
2.6.2 Excerpt from the model ordinance for combustion
equipment
The following excerpt from the model ordinance for combustion
equipment is representative of the State ordinance for
combustion equipment.
The flue gas systems must be measured according to internal cross
section and height, if necessary according to the thermal resistance
and inner surface in such a way that in all normal operating
conditions, the flue gases can be discharged into the outdoors and
will not cause any overpressure to rooms. (As a result,
overpressure pipes that bypass floors within buildings must be
installed in rear-ventilated ducts.)
In buildings, each flue gas pipe that bypasses floors must be
placed in individual ducts. This does not only apply to flue gas
pipes in installation rooms for furnaces but also to flue gas pipes
that are operated under reduced pressure and have fire rating of at
least 90 minutes. The placement of several flue gas pipes in a
joint duct is allowed if:
1) The flue gas pipes are not made up of non-combustible
building materials,
2) The corresponding furnaces are installed on the same floor or
3) Fire transmission between the floors is prevented by
automatic shut-off devices.
The ducts must have a fire rating of at least.
90 minutes and at least 30 minutes in low-rise residential
buildings.
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