Checking The Diaphragm Expansion Vessel And System Pressure; Check Proper Expansion Tank And System Pressure; Water Quality - Viessmann Vitocrossal 200 CM2 500 Service Instructions Manual

Commissioning, Inspection, Maintenance

Checking the Diaphragm Expansion Vessel and System Pressure

Check proper expansion tank and system pressures
See expansion tank manufacturer's instructions.
IMPORTANT
The diaphragm expansion tank must be able to hold the
heating water expansion volume inside the boiler, and must
be properly sized for the system.
CAUTION
Damage on boiler or other system components may
result if these recommendations are not followed.
CAUTION
Carry out all check in accordance with the expansion
tank manufacturer's instructions. Limit pressure
fluctuations to the lowest possible differential. Cyclical
pressure fluctuations and greater pressure differentials
indicate a system fault. Immediately remedy such
faults, otherwise other heating system components
may become faulty.
This diaphragm expansion vessel reduces the frequency
and severity of pressure fluctuations; the service life
of the circulating pump is improved and therefore
the operational reliability and service life of system
components increased.
IMPORTANT
Carry out this test on a cold system.
1. Drain system or close cap valve on the diaphragm
expansion tank and reduce the pressure until the pressure
gage indicates "0".
2. 60°F (15.5°C) water fill pressure must equal diaphragm
expansion tank pressure.
30
Vitocrossal 200, CM2 400, 500 and 620 Service

Water Quality

The lifetime of the entire heating system is influenced by
the water quality. A water treatment system will protect
against damages caused by corrosion and lime formation.
Hard water conditions (i.e. calcium carbonate) must be
avoided as it will cause deposits to accumulate on the
heat exchanger surfaces.
If in any doubt about the water quality, please have a
proper water analysis done. Check with regional chemical
suppliers for boiler water treatment or with Viessmann
Manufacturing Company Inc. directly.
Total output (MBH) Total Hardness (ppm as CaCO
> 1 Total [ 680 [ 200
> 680 to [ 2050 [ 150
> 2050
[ 2
The pH value of the heating water should be between 8.2
and 9.5
)
3