20
6.9
Installing a strainer and/or dirt separator
Always install a strainer (water filter) and/or
a dirt separator on the system side after a
low loss header / Strebel boiler guard / plate
heat exchanger on the return pipe pipework
– not on the boiler side (primary)! This will
ensure that the water going to the boiler is
free of any flow restrictions. When using a
water filter always check a week after instal-
lation to determine the strainer cleaning in-
terval. Advice is to mount valves before and
after the strainer, including an air bleed
valve, so the strainer can be isolated from
the heating circuit for service operations.
Clean water is very important, blocked
and/or polluted heat exchangers,
including failures and/or damages caused by
this blockage are not covered by the war-
ranty.
Clean water is important, blocked and/or
polluted heat exchangers, including fail-
ures and/or damages caused by this
blockage are not covered by the war-
ranty.
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 conditions).
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 0,2 mg/litres. If there is the 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 next section).
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 stuffing
box, under floor heating pipes.
SYSTEM WITH DIRT SEPARATOR
SYSTEM WITH STRAINER
SYSTEM WITH STRAINER AND DIRT SEPARATOR
DIRT SEPARATOR
DIRT SE-
PARATOR
WATER RETURN
FROM SYSTEM
WATER
RETURN
FROM
SYSTEM
WATER
RETURN
FROM
SYSTEM
WATER FLOW TO LLH /
BOILER GUARD / PHE
)
WATER FLOW TO LLH
/ BOILER GUARD / PHE
WATER FLOW
TO LLH /
BOILER
GUARD / PHE
DIRT
BLEED
VALVE
DIRT
BLEED
VALVE
AIR
BLEED
VALVE
AIR
BLEED
VALVE
VALVE
VALVE
VALVE
VALVE
STRAINER
(WATER FILTER)
STRAINER
(WATER FILTER)
