STOKVIS ENERGY SYSTEMS REX F, Technical Manual, Page: 29 / 38

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Pressurisation values should be included in the range given in the table of technical specifications.
IMPORTANT
The delta T betw een flow and return must not exceed 30°C, in order to av oid thermal shocks in the
boiler. The boiler return temperature must be higher than 50°C on natural gas or LPG firing and
higher than 40°C on oil firing, in order to protect the boiler from corrosion due to acid flue gas con-
densation; the guarantee therefore does not cover damages due to condensation.
If the system return temperature does not fulfill the abov e requirements, it is necessary to increase
the return temperature by using a mixing valve and/or a recirculation pump.
It is necessary to keep the burner switch always switched on in order to maintain water temperature equal
approximately to the value set through the thermostat.
If the flue gas seal is poor in the fr ont par t of the boiler (m anhole and burner plate) or the back part
(smokebox), the closing tie rods of the indiv idual parts must be adjusted; if this is not sufficient, the seals
must be replaced.
CAUTION
Do not open the manhole and do not remov e the smokebox while the burner is working. Always wait
few minutes after the burner has been switched off until the insulating parts are cooler .
6.2 CLEANING AND SERVICING
Close fuel supply and disconnect the electrical mains before starting any cleaning and servicing operations.
As economic running depends on cleaning of the exchange surfaces and regulation of the burner, the follow-
ing operations should be performed:
- Clean the tube bundle and turbolators with the appropr iate tube-brush every month for heavy oil-fired
boilers, every three months for gas oil-fired boilers. Generally speaking with a proper use of natural gas
and/or LPG, the cleaning of fire tubes is not required. Cleaning schedule depends on plant features.
Quick cleaning can be performed by opening the front m anhole only, taking the turnolators out and cleaning
the tubes with a tube-brush. For more thorough cleani ng, the smokebox must be re moved to eliminated car-
bon deposits from the rear side.
- Have the burner calibration checked by professionally qualified personnel;
- Have the water circulating in the system analys ed and provide for adequate treatment to avoid the for-
mation of scale which initially reduces the efficienc y of the boiler and in the long term will permanently
damage it, making it unserviceable;
- Check that the refractory castings in contact with the flue gases ar e in perfect condition and if not, re-
place them;
- Periodically check the efficiency of the system regulation and safety instruments.