3
Grant Vortex Oil Boilers
During the combustion process, hydrogen and oxygen
combine to produce heat and water vapour. The water
vapour produced is in the form of superheated steam in
the heat exchanger. This superheated steam contains
sensible heat (available heat) and latent heat (heat
locked up in the flue gas). A conventional boiler
cannot recover any of the latent heat and this energy is
lost to the atmosphere through the flue.
The Grant Vortex condensing boiler contains an extra
heat exchanger which is designed to recover the latent
heat normally lost by a conventional boiler. It does this
by cooling the flue gases to below 90° C, thus
extracting more sensible heat and some of the latent
heat. This is achieved by cooling the flue gases to their
dew point (approximately 55° C).
To ensure maximum efficiency, the boiler return
temperature should be 55° C or less, this will enable
the latent heat to be condensed out of the flue gases.
The boiler will achieve nett thermal efficiencies of
100%.
To achieve maximum performance from the Grant
Vortex boiler, it is recommended that the heating
system is designed so that a temperature differential of
20° C between the flow and return is maintained. The
use of modulating circulating pumps (now widely
available) and effective control systems should be
considered.
The Grant Vortex boiler will however still operate at
extremely high efficiencies even when it is not in
condensing mode and therefore is suitable for fitting to
an existing heating system without alteration to the
radiator sizes. The boiler is capable of a maximum
flow temperature of 75° C.
How a condensing boiler works
1.1
Heating system design considerations
1.2
To achieve the maximum efficiencies possible from
the Grant Vortex boiler, the heating system should be
designed to the following parameters:
Radiators:-
Flow temperature
70° C
Return temperature
50° C
Differential
20° C
Underfloor:-
Flow temperature
50° C
Return temperature
40° C
Differential
10° C
1
Size radiators with a mean water temperature of
60° C.
2
Design system controls with programmable room
thermostats or use weather compensating controls
to maintain return temperatures below 55° C.
The boiler should not be allowed to operate with
return temperatures of less than 40° C when the
system is up to operating temperature.
3
The use of a pipe stat is recommended to control
the return temperature when using weather
compensating controls.
1 - INTRODUCTION
