Strebel S-CB Px 120, Installation Operating & Maintenance Manual

Page: 20 / 118

S-CB Px 120 Manual 20
6.10. Water quality
The pH value of the water must be within the following limits: 7,5 < pH < 9,5. This pH value is reached with the
steady conditions. These steady conditions will occur, when after filling the heating system (pH around 7) with
fresh water, the water will lose its air because of the air bleeding operation and heating up (dead water condi-
tions).
Water hardness must be within the following limits:
3,5° Clark (50 ppm CaCO
3
) < total hardness < 10,5° Clark (150 ppm CaCO
3
)
When the water might contain aluminium particles, this should be of a maximum of 8.5 ppm. If there is any risk of
contamination of the water by any kind of debris/chemicals in the period after installing, a plate heat exchanger
should be used to separate the boiler circuit from the heating circuit (see drawing below).
It is advised to prevent the possible air intake and water leakage of the central heating system. Fresh oxygenated
water might damage the heat exchanger of the boiler and should therefore be prevented. Usual spots where air is
most likely to seep in are: suction gaskets, pumps, air valve working as a venting pipe, O-rings / gaskets in stuf-
fing box, under floor heating pipes.
6.11. Plastic piping in the heating system
When plastic pipes are used in the central heating system, these should be separated from the boiler system by
using a plate heat exchanger. Diffusion (of plastic) can cause air to enter the heating system. Be aware that plas-
tic piping is often used in under floor heating systems. When no measures have been taken to prevent the en-
trance of air into the boiler system, the warranty of the boiler and any boiler part may be deemed invalid.
6.12. Automatic air vent
This automatic air vent is only used for bleeding the air from the heat exchanger of the boiler, while filling the sys-
tem. Externally measures must be taken to bleed air from the heating system, using air separators in combination
with automatic air vents.
DE-AERATION PROGRAM. When the unit is fired for the first time the unit starts a de-aeration program. One
cycle is 5 seconds pump running and 5 seconds pump off. A complete de-aeration program consists out of
THREE cycles. The de-aeration program can be interrupted/stopped by briefly pressing the service button.
6.13. Automatic water filling systems
When using an automatic water refill system some precautions should be taken (fresh water is bringing fresh oxy-
gen into the system), like installing a water meter to measure and evaluate the total water volume that is added to
the system. Some form of logging should take place, so that continuously filling of the system with large amounts
of oxygen rich fresh water, indicating leakage, is detected in time.
boiler boiler boiler boiler
heating
zone
plate heat
exchanger
plate
heat exchanger
heating
zone