Mark MEGAFLEX, Technical Manual

Page: 37 / 58

EN
37
• Always mount air vents at the highest points in the installation.
• Install isolation/check valves near the boiler and on strategic locations (anticipating any future expansi-
ons of the system) to avoid fills, refills and topping up as much as possible.
• Install a water meter to check the amount of filled, refilled and topped up water.
• Install a filter (magnetite and dirt) in the return.
• Install an isolation heat-exchanger to separate the boiler from the installation to protect dirt or lime
in the secondary system from affecting the boiler.
• avoid leaks and if there is a leak, repair as soon as possible.
6.3.4 Water connection general
1. Water connections for flow and return are size DN125
2. The installation must have a pressure relief valve (with a capacity higher than the boiler output) and
an expansion vessel. The capacity of this vessel should be sufficient for the installation.
3. To avoid blocking and non volatile lock-out of the boiler control it is recommended to install a by-
pass in the installation to guarantee the minimum flow through the boiler. The by-pass valve should
be mounted as far away from the boiler as possible to have the biggest possible content of the by-
pass-circuit (also a big radiator without valves could be used).
4. Drain the condensate via a tundish and an U-trap to the sewer.
5. At the highest point of the installation a de-airing device should be mounted.
6.4 Gas connection
1. The gas connection must be done in accordance with all local and national codes, regulations and
standards, and in accordance with the directives of all relevant authorities.
2. The gaspipe of the boiler has a R 2” connection.
3. In order to avoid blockage of the gas valve, ensure that there is no dirt in the gas pipework prior to
commissioning.
4. The maximum allowable inlet pressure for the gas valve is 50 mbar.
5. Check the heat input of the boiler.The load as given on the type plate should be checked.
6.5 Air-supply and flue-gas connection
Air connection : All types have air connection ø 200 mm Flue gas connection : ø 250 mm for all types
Allowed Appliance types:
Possibilities for air / flue system ; B23, C33, C63
6.5.1 B23
As standard the boiler is delivered as type B23 where the supply air is taken from the room where the
boiler has been installed in.
If the inlet air contains dust or dirt one should install a filter or a leaf catcher in the air supply.
A vertical terminal is recommended.
Roof terminals and extensions and/or condensate trap/collector must be obtained by M&G. See page 40.
For pressure drop calculation of appliance type B23 use the table for pressure drop per component and
the table for total pressure drop calculation. See page 39.
For total available pressure drop see table on page 38.
6.5.2 C33
Roof terminals and extensions and/or condensate trap/collector must be obtained from M&G. See page
39.