Water Quality - Viessmann Vitoplex 200 SX2A Service Instructions For Contractors

Water quality

Using antifreeze in boilers
If a boiler system is changed to operate without anti-
■
freeze, flush the system in order to remove all traces
of the antifreeze.
■ The quality of the boiler water and feedwater must
meet the requirements of Directive VDI 2035.
The systems must be designed as sealed unvented
■
systems, as the antifreeze inhibitors decrease rapidly
if airborne oxygen is allowed to enter.
■ Diaphragm expansion vessels must comply with
DIN 4807 [or local regulations].
■ Solder connections should preferably be made with
Ag or Cu hard solder. If liquids containing chlorides
are used for soft soldering, any deposits must be
removed from the circuit afterwards through thor-
ough flushing. A higher chloride content in the heat
transfer medium can cause corrosion damage.
■ Only use oxygen diffusion-resistant hoses or metal
hoses for flexible connections.
Never equip the system on the primary side with
■
zinc-plated heat exchangers, containers or pipes as
zinc can be corroded by glycol/water mixtures.
24
(cont.)
To avoid the risk of corrosion, ensure that there is no
■
difference in electrical potential between system
components that are in contact with antifreeze.
■ Route all pipes in such a way that circulation cannot
be interrupted by gas cushions or deposits.
The water circuit must always be filled up to the high-
■
est point with the heat transfer medium.
After filling, ensure there are no more air cushions in
■
the system. When the temperature falls, gas cush-
ions form negative pressure and this can draw air
into the system.
■ After initial filling and commissioning, but after 14
days at the latest, clean the integral dirt trap so the
heat transfer medium can flow freely.
■ Following any losses through leaks or drawing off,
top up the antifreeze solution according to the con-
centration already in place. Establish the volume of
antifreeze as a check.