STIEBEL ELTRON SOL 25 PLUS - Manual (Page 63)

WWW.STIEBEL-ELTRON-USA.COM SOL 25 PLUS | 63
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drain valve.
8. Open the air vent valve at the highest point, until only solar
medium is expelled.
9. Shut off the circulating pump.
10. Open the valve to the expansion tank to connect it to the solar
loop. The system pressure will drop slightly.
11. Use the charging pump to raise the system pressure (in a
cold state) to its operating pressure of 50 psi (or other target
pressure). (As there is sometimes still a little air remaining in
the system, which will eventually be purged via the Purg-O-Mat,
it is recommended that this pressure be a few psi higher than the
target.)
12. Use a permanent marker to record the pressure and the date/
time on the expansion tank.
13. It is further recommended that the installer measure
and record the glycol/water mixture using a refractometer or
hydrometer. It is critically important that the mixture be correct
before turning the system over to the final customer.
14. Set the red dial on the pressure gauge to the expansion tank’s
precharge pressure. This should be the lowest pressure that the
system ever reaches in normal operation.
15. Let the solar heating system rest overnight and vent again in
the morning, via the air vent valve, before solar radiation warms
the collectors. Close the air vent valve again.
16. Turn check valves in the pumping station to their normal 90°
position to allow one-way flow.
17. Make sure the controller and pumping station are energized
and that the proper settings for the controller have been entered.
18. Cover both fill & drain valves with the caps supplied.
19. If the system does not start automatically, there may still be
air in the system. Repeat the venting process, if required.
8.5 Start-up
Re-tighten all fittings prior to start-up.
Complete the Start-up report (Section 8.6) after the first Start-up.
Set the integral controller to “manual” mode to check whether all
required relays of the solar control unit are connected, according to
the controller’s operating instructions. Then set the control unit back
to “automatic” mode. The system should then start automatically,
subject to all starting conditions being met. If that is not the case,
check in Section 10.0, Troubleshooting, for a possible cause for this
fault. See that the solar system places no excessive temperature or
pressure on auxiliary system.
Have owner check the system daily to observe pressure,
temperature, and flow rate while the pump is on, and to look for
evidence of overflows from pressure relief valves. It is also wise to
continue checking for leaks periodically. Any deviation from normal
should prompt immediate corrective action by the installer.
The following procedure makes use of a charging pump, screen,
filter, and large pail or trough to circulate fluid through the system.
The sump can have a coarse-mesh screen to prevent large particles
from entering the pump. The outlet of the pump should be fitted
with 5-micron sediment filter. The intake sump should be set near
the bottom of the pail.
1. Connect the charging pump’s outlet to the to fill & drain valve
in the pumping station.
2. Connect a hose to the boiler drain at the bottom of the loop
(bottom fill & drain valve), at the outlet side of the storage tank’s
heat exchanger.
3. Use a clean, dry pail or catch basin and fill it with sufficient
Dowfrost medium (propylene glycol mixture) to fill the entire
system’s volume, plus some extra.
4. Keep all other vents and valves closed during the flushing
operation.
5. Close the flow meter adjusting screw at the pump assembly
(horizontal position).
6. Start charging the system and observe the loop fluid draining
back into the pail. Make sure that the fluid level in the container
always remains higher than the intake hose.
7. The flushing process should continue until the fluid draining
back appears clean and free of contaminants. The screens/filters
may require cleaning during this process.
8. When the system is fully flushed, proceed to the final charging
phase, described below.
8.4 Final Charging and Venting The System
The solar heating system must be filled exclusively with the
premixed propylene glycol heat transfer medium. The bottles
have been premixed and require no further treatment. Never
admix water or alternative process media: otherwise the essential
characteristics and corrosion protection can no longer be
guaranteed. For this reason, the system must not be topped off with
water.
Follow these steps to complete the final charging and venting
(purging of air) of the system:
1. Energize the pump station to activate the electric pump to
circulate the solar medium through the system.
2. Open the air vent valves and Purg-O-Mat at the highest point of
the system and open the ball valve for the flow meter.
3. To purge air from the system, the size of the air bubbles can
be reduced (as the system loop pressure increases), by slowly
constricting the return flow to the drain bucket via partially closing
the lower drain & fill valve while the pump is operating. Also
open the bleed screw on the circulator pump.
4. Continue purging the system until no more bubbles are
expelled from the drain hose. Allow system pressure to build up
to approx. 20-44 psi. This process usually takes 20-30 minutes.
Continue looking for leaks.
5. Tighten the anti-steaming valve fully and then back off 1/4-
turn.
6. Close the bottom fill & drain valve after completing this
ventilation step, but before shutting off the pump.
7. Keep the circulator pump running and then close the top fill &