Gulfstream GS A-Class 12/OV Design, Installation & Servicing Instructions Download

Page: 4 / 44

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Page 4

INTRODUCTION

GulfStream

A-CLASS

is a room sealed gas ﬁred fan ﬂued condensing boiler

with an integrated store for space heating and domestic hot water. The
appliance incorporates a primary store for producing mains pressure
hot water. All models meet the essential requirements of the European
Gas Appliance Directive 90/396/EEC and are WRAS listed.

All models in the GulfStream

A-CLASS

range are supplied with an integrated

9kW electric boiler for space heating and domestic hot water in the
event of a failure on the gas side.

The operation is automatic and the fully modulating pre-mixed
burner ensures that the gas is burned efﬁciently and cleanly (< 17ppm
NO

Class 5) within the condensing heat exchanger. The advanced

integrated control system includes monitoring of all safety features
and diagnostics.

An important feature of this design is that domestic hot water can be
supplied directly from the mains without the need for additional safety
controls in the domestic hot water (DHW) supply. This is achieved by
passing the mains water through a plate heat exchanger which is heated
instantaneously by the preheated primary water from the store. The
domestic hot water outlet temperature is maintained at about 52

by the appliance controller which regulates the speed of the pump
circulating the primary hot water from the thermal store through the
primary side of the plate heat exchanger.

Because of the innovative method of hot water production no in-line
scale reducer is required on the cold water supply to the appliance,
provided hardness is below 250ppm.  In extreme conditions (ie above
this ﬁgure) a Gledhill scale reducer can be ﬁtted within the appliance.
This then does not require a fused spur in the cupboard.  If scale should
become  a  problem,  the  plate  heat  exchanger  is  easily  isolated  and
replaced with a service exchange unit.

The ‘-OV’ models (ﬁgure 1.1) are suitable for open vented heating
systems only and the ‘-SS’ models (ﬁgure 1.2) are suitable for sealed
heating systems only.

1.1 OPERATION
The  appliance  control  works  on  the  principle  of “hot  water  priority”
and  the  hot  water  store  is  directly  heated. Therefore  although  the
central  heating  output  may  be  temporarily  interrupted  if  the  store
temperature falls below the pre-set value, the heating off-period will
be very short (usually less than 6 minutes). The hydraulic and component
arrangements of the open vented and the sealed system models are
shown schematically in ﬁgures 1.3 and 1.4 respectively.

To suit conventional radiator based central heating systems, the
appliance will normally provide ﬂow temperature of about 82

C. The

appliance controls will automatically responds to lower central heating
and hot water demands by modulating the burner i.e. reducing the
heat output which also decreases wasteful on-off cycling. For low
temperature heating systems (e.g. under ﬂoor heating), a lower heating
ﬂow temperature can be factory set or can be programmed by the
Gledhill Area Technical Support Manager (ATSM).

Fig 1.1 Open Vented GulfStream

A-CLASS

Fig 1.1 Sealed System GulfStream

A-CLASS

INTRODUCTION

Burner
assembly

Fan

Relays

Hot water

outlet sensor

Condensate
trap

pump