25
TopGas Cascade
60 - 720 kW
4215256-00 - 11/16
4. Installation Requirements
4.3. Water Quality
The heating water must be treated in the TopGas Cascade to the
correct standard. Specific information can be found in the TopGas
Technical information Installation instructions document:
TopGas 35-120, document: 4214 783
The system heating water must be tested anually as a minimum
but Hoval recommend this to be done twice a year or after
every drain down and re-fill. If the water treatment specialist
recommends that this needs to be done more frequently please
follow their advice.
On account of the danger of spot corrosion the chloride, nitrate
and sulphate contents of the heating water must not exceed
200mg/l in total.
The pH value of the heating water should lie between 8,0 and 8,5
after 6 - 12 weeks of heating operation.
The boilers have aluminium heat exchangers which are in contact
with the heating water: Any inhibitors used must take account
of this and specialist advice should be sought prior to filling the
system based on local water quality conditions.
4.4. Gas Connection
The gas installation must fully conform with IGE/UP/2 and all re-
lated regulations.
The incoming natural gas supply to the TopGas Cascade must be
between 18-50 mbar with all connected appliances at full output.
For LPG this must be between 37-50 mbar.
All gas pipework must be tested and purged in accordance with
IGE/UP/1 or IGE/UP/1A.
Any gas work performed must be done by competent persons
holding a valid qualification.
4.1. Hydraulic Installation
Water from each safety valve discharge can cause severe burns.
Install the safety valve to ensure that there is no danger to other
persons. Route the safety valve discharge pipe to a tundish and
pipe to drain (not supplied by Hoval).
Flush the heating installation thoroughly prior to installation as
any foregin bodies or contaminants in the pipework may damage
the boiler.
If oxygen ingress is possible ensure that de-aeration equipment
is installed. If the plant is topped up with raw water ensure the
overall water quality still meets the required specification.
The
total amount of filling and replacement heating system water
which is used throughout the total service life of the boiler
must not exceed three times the service capacity of the
plant.
4.2. Recommendations
It is recommended that each system should be filled and refilled
with treated water and specialist companies will be able to advise
in this respect. Before filling check the following:
•
All connections are made and tightened
•
Sensor and instrument pockets are fitted and water tight
•
Spare sockets are fitted with plugs and are water tight
•
All valves in the heating circuit are open
•
The installation is completely vented
•
if a pressurisation unit is installed reference should be made
to the manufacturers filling instructions and applied
•
The installation is fully flushed
•
A suitable strainer and air/dirt separator are fitted to protect
the equipment supplied.
For connection to the system a hydraulic header has to be used.
Hoval offer an optional low loss header kit or an air and dirt
separator that can act as a hydraulic header between the boiler
cascade and the heating system. These options should be
installed adjacent to the boiler cascade and advice should be
sought from Hoval technical if an alternative method is to be
adopted.
The pump set supplied with each boiler in the cascade is sized
to provide a ΔT of 20 K across each boiler flow and return. An
electrical flying lead is provided for the installer to connect each
pump to it’s respective TopGas boiler. A minimum flow must be
maintained through a boiler that is firing or being called to fire. As
standard the TopGas boilers have a pump over-run feature that
maintains water flow through the boilers for five minutes after it
has completed its firing sequence.
To allow the boiler to operate correctly it must have a minimum
water pressure of 1 bar. If this is not present an error code P27
will be displayed on each individual boiler control panel and the
boiler will not operate.
IMPORTANT NOTE:
Following assembly of the TopGas
Cascade arrangement it is the installer’s
responsibility to carry out suitable
water-side and gas-side pressure tests
and a flue system tightness test. These
tests are to be carried out by suitably
qualified personnel.
