SOLARFOCUS octoplus, Руководство по установке

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Technical requirements
8 Installation manual octo
plus
and maintenance of the heating system. A constant
input of oxygen should be avoided.
Important in this regard:
- Expansion tank (ADG): Air must be prevented
from being drawn in when the heating system is
cooling down. Ensure:
- Correct planning and implementation of the
expansion tank.
- Regular check of the system pressure, expan-
sion tank pre-pressure.
- Immediate repair of leaks in the heating system.
- In the case of older underfloor heating, ensure
pipes are diffusion resistant.
Check the pH of the fill-up water
- The pH value must be between 8.2 and 9.5.
- If this pH value does not self adjust after a week
of operation, it must be raised by adding 10 g/m³
trisodium phosphate (Na3PO4) or 5 g/m³ sodium
hydroxide (NaOH). Allow 2 to 4 weeks of opera-
tion before further corrections.
- Exception: If aluminium materials are used in the
heating system, a pH from 8.2 to 8.5 must be met
(pH> 8.5 increased corrosion tendency).
Electrical conductivity
The probability of corrosion usually decreases
with decreasing electrical conductivity of the heating
water.
Low salt operation - filling with demineralised
water
, see VDI 2035 sheet 2.
Electrical conductivity at 25°C < 100 μS/cm
In the case of low-salt operation, feeding with non-
demineralised water can have a significant effect on
the pH value and push it into a critical range.
Check the pH value regularly.
3.8 Information about the hydraulic
connection
Return flow boosting (RFB)
- Functioning: If cold heating water (temperature <
55°C) flows from the heating circuit or the buffer
tank into the hot boiler, the steam contained in the
flue gas condenses on the "cool" boiler heat ex-
changer surfaces. In the long term this leads to
corrosion and damage in the boiler. To avoid this,
hot water from the boiler flow is added to the
boiler return.
- Return booster modules with a motor-controlled
mixer perform this task more accurately and relia-
bly than thermally controlled modules.
- In addition, they allow the use of residual heat: If
the boiler temperature rises again after the burner
has stopped, then the charging pump starts, the
mixer opens, and the residual heat from the boiler
is transferred to the buffer tank.

Due to the integrated design of the octo
plus
,
return flow boosting is not required.
Provide shut-off options in the lines
- Position shut-off valves for each section (in buffer
tank, etc.) in order to minimise the quantity of wa-
ter that needs to be replaced in the event of re-
pairs or system extensions (see: preventing the
ingress of oxygen, heating system's fill-up/make-
up water

7
).
Pressure equalisation through expansion tank
- The expansion tank prevents air from being drawn
in when the system cools down (issue: oxygen in-
put, heating system's fill-up water

7
)
- Dimension the expansion tank with a capacity of
12% of the total hydraulic system volume.
- Secure the expansion tank against shut-off. To do
this, either use the shut-off options on the way to
the expansion tank as cap valves, or unscrew the
hand lever (handwheel) and attach it to the ex-
pansion tank with the wire in a clearly visible posi-
tion.
- Installation of an expansion tank or a pressure
maintenance system is essential. Use of open ex-
pansion tanks is not permitted.
- The pressure in the heating system (can be
viewed on pressure gauge) and the set pre-pres-
sure in the expansion tank must be checked regu-
larly.
Caution with (older) diffusion-open plastic pipes,
e.g. existing underfloor heating
- In the case of older underfloor heating, the diffu-
sion-open plastic pipes can result in increased ox-
ygen input in the heating system. This has a cor-
rosion-inducing effect on the heating system com-
ponents (see:
Avoiding water-side corrosion 
7
).
- In this case, the system must be separated
(through installation of a heat exchanger).
- Newer plastic pipes (since around the mid 1980s)
are diffusion resistant in line with DIN 4726.
Hydraulic switch
- A hydraulic switch separates the flows in the
boiler and heating circuits.
- If the heating system is operated without a buffer
tank, a hydraulic switch must be installed between
flow and return.