Flow And Return Connections; The Expansion Vessel; Pressure Relief Valve - Slant/Fin VGH-299-CH Installation And Service Manual

When mounting the bottom part of the condensate trap, before commissioning the boiler
and/or after maintenance, the condensate trap must ALWAYS be completely filled with
water. This is a safety measure: the water in the condensate trap keeps the flue
WARNING
gases from leaking out of the heat exchanger via the condensate drain.
Figure 7. 4

Flow and return connections

Use T-pieces for externally mounting the pressure relief
valve and the boiler drain valve for servicing the boiler. We
advise to install two service ball valves in the flow and
return pipes underneath the boiler, so the boiler can be
isolated from the heating system and eventually
disconnected, when needed.
When using a boiler circulator, this circulator must always
be mounted in the return pipe of the heating system.
Do not use chloride-based fluxes for soldering any pipes
of the water system.
It is recommended to install service valves, so the boiler
can be isolated from the heating system, when needed.
Make sure that the pressure relief valve is mounted
between the boiler and the service valves.

The expansion vessel

The capacity of the expansion vessel must be selected
and based on the capacity of the central heating system
and the static pressure. Suggested is to fit the expansion
vessel in the return pipe of the central heating system. It
can be combined with the drain and feed valves for
service. See figure 7.5

Pressure relief valve

The boiler has no internal pressure relief valve, but a relief valve, specially selected for this boiler, is added to the
boiler shipment and can be found in the box. This must be installed close to the boiler in the flow pipe of the
heating system and no shut off valve shall be placed between the relief valve and the boiler. When having
cascaded boilers, each boiler must have its own pressure relief valve. The pressure relief valve's discharge must
be piped to an open drain and to within 6 inches of the ground/floor. Always have an air gap between the
pressure relief valve discharge piping and the drain to prevent a vacuum. No valve may be placed between the
relief valve and the discharge line, do not plug or obstruct in any way the pressure relief discharge line.
22
The condensate trap must
always be filled to the edge with
water, before replacing to the
unit.
Supplied with
boiler
pressure
relief valve
Figure 7-5
E93.1601EN032.C VGH installation manual
Supplied with
boiler
Boiler bleed valve
for service
Boiler drain
boiler service
valves