DORCHESTER DR-FC 25 Guide

1
DORCHESTER MODELS: DR-FC 25, 30, 45, 60
Condensing, Closed Combustion, Direct Gas Fired Hot Water Storage Heaters
with Automatic Ignition for
Domestic Hot Water Installations
NOTE: THESE INSTRUCTIONS MUST BE READ AND UNDERSTOOD BEFORE
INSTALLING, COMMISSIONING, OPERATING OR SERVICING EQUIPMENT.
THIS WATER HEATER IS FOR USE ON GROUP H NATURAL GAS (2ND FAMILY) I2H OR
LPG (3RD FAMILY) I3+. PLEASE ENSURE RELEVANT INFORMATION REQUIRED WITHIN
DOCUMENT IS FOUND RELATING TO SPECIFIC GAS TO BE FIRED BEFORE FIRING
HEATER.
THIS WATER HEATER COMPLIES WITH ALL RELEVANT EUROPEAN DIRECTIVES.
PUBLICATION NO. 500001153
ISSUE ‘A’
FEBRUARY 2006
DORCHESTER
DR-FC 25 to DR-FC 60
HOT WATER
STORAGE HEATERS
Installation, Commissioning
and Maintenance Instructions

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Table of contents
1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
1.1 About the water heater - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
1.2 What to do if you smell gas- - - - - - - - - - - - - - - - - - - - - - - - - 7
1.3 Regulations and documents - - - - - - - - - - - - - - - - - - - - - - - - 7
1.4 Target groups - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8
1.5 Maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.6 Forms of notation - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9
1.7 Overview of this document - - - - - - - - - - - - - - - - - - - - - - - - 10
2 Functioning of the water heater - - - - - - - - - - - - - - - - 11
2.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 11
2.2 Functional description of the water heater - - - - - - - - - - - - - - - - 11
2.3 The water heater’s heating cycle - - - - - - - - - - - - - - - - - - - - - 12
2.4 Protection for the water heater - - - - - - - - - - - - - - - - - - - - - - 12
2.4.1 Water temperature protection - - - - - - - - - - - - - - - - - 13
2.4.2 Gas control - - - - - - - - - - - - - - - - - - - - - - - - - - 13
2.4.3 Fan - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 13
2.4.4 Pressure switch - - - - - - - - - - - - - - - - - - - - - - - - 13
2.4.5 Flame probe - - - - - - - - - - - - - - - - - - - - - - - - - 14
2.5 Safety of the installation - - - - - - - - - - - - - - - - - - - - - - - - - 14
2.5.1 Unvented installation - - - - - - - - - - - - - - - - - - - - - 14
2.5.2 Vented installation- - - - - - - - - - - - - - - - - - - - - - - 14
2.5.3 T&P valve - - - - - - - - - - - - - - - - - - - - - - - - - - - 14
2.6 Options - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 15
2.6.1 LPG- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 15
2.6.2 Unvented Supply - - - - - - - - - - - - - - - - - - - - - - - 15
2.6.3 Top to Bottom Circulation - - - - - - - - - - - - - - - - - - - 15
3 Installation - - - - - - - - - - - - - - - - - - - - - - - - - - - 17
3.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 17
3.2 Packaging - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 17
3.3 Environmental conditions- - - - - - - - - - - - - - - - - - - - - - - - - 17
3.3.1 Humidity and ambient temperature- - - - - - - - - - - - - - - 18
3.3.2 Maximum floor loading - - - - - - - - - - - - - - - - - - - - 18
3.3.3 Working clearances - - - - - - - - - - - - - - - - - - - - - - 18
3.4 Technical specifications - - - - - - - - - - - - - - - - - - - - - - - - - 20
3.5 Installation diagram - - - - - - - - - - - - - - - - - - - - - - - - - - - 22
3.6 Water connections, Unvented - - - - - - - - - - - - - - - - - - - - - - 24
3.6.1 Cold water side - - - - - - - - - - - - - - - - - - - - - - - - 24
3.6.2 Top to bottom recirculating pump - - - - - - - - - - - - - - - 24
3.6.3 Hot water side- - - - - - - - - - - - - - - - - - - - - - - - - 24
3.6.4 Circulation pipe - - - - - - - - - - - - - - - - - - - - - - - - 24
3.6.5 Condensation drainage - - - - - - - - - - - - - - - - - - - - 24
3.7 Water connections, Vented- - - - - - - - - - - - - - - - - - - - - - - - 25
3.7.1 Cold water side - - - - - - - - - - - - - - - - - - - - - - - - 25
3.7.2 Top to bottom recirculating pump - - - - - - - - - - - - - - - 25
3.7.3 Hot water side- - - - - - - - - - - - - - - - - - - - - - - - - 25
3.7.4 Circulation pipe - - - - - - - - - - - - - - - - - - - - - - - - 25
3.7.5 Condensation drainage - - - - - - - - - - - - - - - - - - - - 25
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4Instruction Manual DR-FC
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3.8 Gas connection - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 25
3.9 Air supply and flue gas discharge - - - - - - - - - - - - - - - - - - - - - 26
3.9.1 Concentric wall flue terminal - - - - - - - - - - - - - - - - - - 28
3.9.2 Concentric roof flue terminal - - - - - - - - - - - - - - - - - - 29
3.10 Electrical connection - - - - - - - - - - - - - - - - - - - - - - - - - - - 29
3.10.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 29
3.10.2 Preparation- - - - - - - - - - - - - - - - - - - - - - - - - - - 30
3.10.3 Mains voltage - - - - - - - - - - - - - - - - - - - - - - - - - 31
3.10.4 Isolating Transformer - - - - - - - - - - - - - - - - - - - - - - 31
3.10.5 Continuous pump- - - - - - - - - - - - - - - - - - - - - - - - 32
3.10.6 program-controlled pump - - - - - - - - - - - - - - - - - - - - 32
3.10.7 Extra ON mode switch (“Heater ON”) - - - - - - - - - - - - - - 32
3.10.8 Connecting extra error signal (“Alarm OUT”) - - - - - - - - - - 32
3.11 Checking the supply pressure and burner pressure - - - - - - - - - - - - 33
3.12 Conversion to a different gas category - - - - - - - - - - - - - - - - - - - 35
4 Filling and draining - - - - - - - - - - - - - - - - - - - - - - - 39
4.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 39
4.2 Filling the water heater - - - - - - - - - - - - - - - - - - - - - - - - - - 39
4.2.1 Filling unvented installations - - - - - - - - - - - - - - - - - - 39
4.2.2 Filling vented installations- - - - - - - - - - - - - - - - - - - - 39
4.3 Draining the water heater - - - - - - - - - - - - - - - - - - - - - - - - - 41
4.3.1 Draining unvented installations - - - - - - - - - - - - - - - - - 41
4.3.2 Draining vented installations - - - - - - - - - - - - - - - - - - 41
5 The control panel - - - - - - - - - - - - - - - - - - - - - - - - 43
5.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 43
5.2 Operating - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 43
5.3 Explanation of the icons - - - - - - - - - - - - - - - - - - - - - - - - - - 44
5.4 ON/OFF switch of control panel - - - - - - - - - - - - - - - - - - - - - - 44
5.5 Navigation buttons - - - - - - - - - - - - - - - - - - - - - - - - - - - - 44
5.6 PC connection. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 45
6 Status of the water heater - - - - - - - - - - - - - - - - - - - 47
6.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 47
6.2 Operating modes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 47
6.3 Error conditions - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 48
6.4 Service condition - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 49
7 Starting up and shutting down - - - - - - - - - - - - - - - - - 51
7.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 51
7.2 Starting up - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 51
7.3 Shutting down- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 52
7.3.1 Shut the water heater down for a brief period (“OFF mode”) - - - 52
7.3.2 Isolate the water heater from the power supply - - - - - - - - - 52
7.3.3 Shut the water heater down for a longer period - - - - - - - - - 53
7.4 The water heater’s heating cycle - - - - - - - - - - - - - - - - - - - - - 53
8 Main menu - - - - - - - - - - - - - - - - - - - - - - - - - - - 57
8.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 57
8.2 Notational convention for menu-related instructions - - - - - - - - - - - - 57
8.3 Switching into “ON mode” - - - - - - - - - - - - - - - - - - - - - - - - - 58

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8.4 Setting the water temperature - - - - - - - - - - - - - - - - - - - - - - 58
8.4.1 Setting the water temperature via SETPOINT MENU - - - - - - 58
8.4.2 Setting water temperature during ON mode - - - - - - - - - - 58
8.5 Week programme - - - - - - - - - - - - - - - - - - - - - - - - - - - - 59
8.5.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 59
8.5.2 Starting up and shutting down the week program- - - - - - - - 59
8.5.3 Changing the water heater’s standard week program- - - - - - 59
8.5.4 Adding times to a week program - - - - - - - - - - - - - - - - 61
8.5.5 Deleting times from a week program - - - - - - - - - - - - - - 62
8.6 Extra period - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 64
8.6.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 64
8.6.2 Programming an extra period - - - - - - - - - - - - - - - - - 64
8.7 Settings - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 65
8.7.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 65
8.7.2 Setting menu language - - - - - - - - - - - - - - - - - - - - 65
8.7.3 Setting day and time- - - - - - - - - - - - - - - - - - - - - - 66
8.7.4 Displaying water heater specifications - - - - - - - - - - - - - 66
9 Service program - - - - - - - - - - - - - - - - - - - - - - - - 69
9.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 69
9.2 Setting the hysteresis - - - - - - - - - - - - - - - - - - - - - - - - - - 69
9.3 Displaying the error history - - - - - - - - - - - - - - - - - - - - - - - - 69
9.4 Displaying the water heater history - - - - - - - - - - - - - - - - - - - - 70
9.5 Display the selected water heater - - - - - - - - - - - - - - - - - - - - 70
9.6 Setting the pump on/off - - - - - - - - - - - - - - - - - - - - - - - - - 70
9.7 Setting the service interval - - - - - - - - - - - - - - - - - - - - - - - - 70
9.8 Setting the display contrast- - - - - - - - - - - - - - - - - - - - - - - - 71
9.9 Setting the backlight time- - - - - - - - - - - - - - - - - - - - - - - - - 71
9.10 Setting the display scroll speed- - - - - - - - - - - - - - - - - - - - - - 71
10 Troubleshooting - - - - - - - - - - - - - - - - - - - - - - - - 73
10.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 73
11 Maintenance frequency - - - - - - - - - - - - - - - - - - - - 89
11.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 89
11.2 Determining service interval - - - - - - - - - - - - - - - - - - - - - - - 89
12 Maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - 91
12.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 91
12.2 Preparation for maintenance - - - - - - - - - - - - - - - - - - - - - - - 91
12.3 Water-side maintenance - - - - - - - - - - - - - - - - - - - - - - - - - 93
12.3.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 93
12.3.2 Checking the anodes - - - - - - - - - - - - - - - - - - - - - 93
12.3.3 Descaling and cleaning the heater - - - - - - - - - - - - - - - 93
12.3.4 Cleaning condensate discharge - - - - - - - - - - - - - - - - 93
12.4 Gas-side maintenance - - - - - - - - - - - - - - - - - - - - - - - - - - 93
12.4.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - 93
12.4.2 Cleaning the burner - - - - - - - - - - - - - - - - - - - - - - 93
12.4.3 Cleaning the orifice - - - - - - - - - - - - - - - - - - - - - - 93
12.4.4 Cleaning heat exchanger - - - - - - - - - - - - - - - - - - - 94
12.5 Finalising maintenance- - - - - - - - - - - - - - - - - - - - - - - - - - 94

6Instruction Manual DR-FC
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A Appendices - - - - - - - - - - - - - - - - - - - - - - - - - - - 95
A.1 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 95
A.2 Electrical diagram DR-FC - - - - - - - - - - - - - - - - - - - - - - - - - 96

About the water heater
Instruction Manual DR-FC 7
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1 Introduction
1.1 About the water
heater
This manual describes how to install, service and use the DR-FC water heater.
The DR-FC water heater is a condensing room-sealed water heater with a fan
in the air intake. A concentric chimney connector is fitted standard to the water
heater. Alternatively, the water heater can be connected using a parallel system.
Installation types possible with this water heater are B23, C13, C33, C43, C53
and C63. The information in this manual is applicable to types: DR-FC 25, DR-
FC 30, DR-FC 45 and DR-FC 60.
The manner of construction and features of the water heater are in conformance
with the European standard for gas-fired storage water heaters for the
production of domestic hot water (EN 89). The water heaters are compliant with
the European Directive for Gas Water heaters, and have the right to bear the
CE mark.
Warning
Read this manual carefully before starting up the water heater. Failure to
read the manual and to follow the printed instructions may lead to personal
injury and damage to the water heater.
1.2 What to do if you
smell gas Warning
Whenever there is a smell of gas:
No naked flames! No smoking!
Avoid causing sparks! Do not use any electrical equipment or switch, i.e. no
telephones, plugs or bells!
Shut off the mains gas supply!
Open windows and doors!
Warn occupants and leave the building!
After leaving the building, alert the gas distribution company or installer.
1.3 Regulations and
documents
Gas Safety Installations and Use Regulations 1998, (As amended). It is law
that all gas appliances are installed by competent persons, in accordance with
the above regulations. Failure to install appliances correctly could lead to
prosecution. It is in your own interest, and that of safety, to ensure that this law
is complied with.
The installation of the boiler MUST be in accordance with the relevant
requirements of the Gas Safety Regulations, Building Regulations, IEE
Regulations and the Water Supply (water fittings) Regulations.
The installation should also be in accordance with any relevant requirements of
the HSE, local gas region and local authority and the relevant recommendations
of the following documents:
0063
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Introduction
8Instruction Manual DR-FC
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British Standards
•BS 6891: Specification for installation of low pressure gas pipework of up to
28 mm (R1) in domestic premises (2nd family gas). For larger installations
see IGE/UP/2 below.
•BS 6798: Specification for installation of gas-fired boilers of rated input not
exceeding 70 kW net.
•BS 6644: Specification for installation of gas-fired hot water boilers of rated
inputs between 60 kW and 2 MW (2nd and 3rd family gases).
•BS 6700: Specification for design, installation, testing and maintenance of
services supplying water for domestic use within buildings and their
curtilages.
•BS EN 806-2: Specification for installations inside buildings conveying water
for human consumption. Part 2: Design.
•BS 5546: Specification for installation of hot water supplies for domestic
purposes, using gas-fired appliances of rated input not exceeding 70 kW.
•BS 5440: Installation and maintenance of flues and ventilation for gas
appliances of rated input not exceeding 70 kW net (1st, 2nd and 3rd family
gases). Part 1: Flues. Part 2: Ventilation.
Institute of Gas Engineers and Managers Publications
• IGE/UP/1 Soundness testing and purging of industrial and commercial gas
installations.
• IGE/UP/1A Soundness testing and direct purging of small low pressure
industrial and commercial natural gas installations.
• IGE/UP/2 Gas installation pipework, boosters and compressors on industrial
and commercial premises.
• IGE/UP/10 Installation of gas appliances in industrial and commercial
premises. Part 1: flued appliances.
CIBSE Publications:- "CIBSE Guide"
Section B4 : Water Service Systems.
1.4 Target groups The three target groups for this manual are:
• (end) users;
•installers;
• service and maintenance engineers.
Symbols on each page indicate the target groups for whom the information is
intended. See Tabel 1.1.
Tabel 1.1 Target group symbols
Symbol Target group
g(End) user
iinstaller
sService and maintenance engineer

Maintenance
Instruction Manual DR-FC 9
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1.5 Maintenance A service should be carried out at least once a year, both on the water side and
on the gas side. Maintenance frequency depends, among other things, on the
water quality, the average burning time per day and the set water temperature.
nRemark
To determine the correct maintenance frequency, it is recommended to
arrange for the service and maintenance engineer to check the water heater
on both the water and gas side, three months after installation. Based on this
check, the best maintenance frequency can be determined.
nRemark
Regular maintenance extends the service life of the water heater.
1.6 Forms of notation The following notation is used in this manual:
nRemark
Important information
cNote
Ignoring this information can lead to the water heater being damaged.
Warning
Failure to carefully read this information may lead to danger of personal
injury, and serious damage to the water heater.

Introduction
10 Instruction Manual DR-FC
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1.7 Overview of this
document
Tabel 1.2 provides an overview of the contents of this document.
Tabel 1.2 Contents of document
Chapter Target groups Description
2 Functioning of the water
heater gis This chapter describes how the water heater functions.
3Installation is This chapter describes the installation activity to be completed
before you actually start up the water heater.
4 Filling and draining gis This chapter describes how to fill and drain the water heater.
5 The control panel gis This chapter describes the general control of the water heater
using the display.
6 Status of the water heater gis This chapter describes the status (mode or condition) that the
water heater may have, and possible actions to take.
7 Starting up and shutting
down
This chapter describes how to start up the water heater, and
how to shut it down for a brief or long period of time. The
general heating cycle of the water heater is also described.
8 Main menu gis Describes the main menu of the display. This is the actual
menu for the user, however the installer and service and
maintenance engineers will also need to use this menu.
9 Service program is Describes the service menu. It is mainly intended for the
installer and service and maintenance engineers. End users
may also refer to this chapter for additional information about
the water heater.
10 Troubleshooting gis This chapter is mainly intended for the installer and the service
and maintenance engineer. It describes water heater errors.
These errors are indicated on the display. A troubleshooting
table of possible causes and solutions is provided. End users
may also refer to this chapter for additional information about
the water heater.
11 Maintenance frequency gs This chapter describes how to determine the optimum
frequency at which to carry out maintenance. Both the end
user and the service and maintenance engineer are
responsible for regular maintenance. They need to reach clear
agreement on this.
nRemark
If the water heater is not regularly maintained, the warranty
will become void.
12 Maintenance sThis chapter sets out the maintenance tasks to be carried out
during a service.

Introduction
Instruction Manual DR-FC 11
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2 Functioning of the
water heater
2.1 Introduction Topics covered in this chapter:
•Functional description of the water heater;
•The water heater’s heating cycle;
•Protection for the water heater;
•Safety of the installation.
2.2 Functional
description of the
water heater
Figure 2.1 shows a cut-away view of the water heater.
Legend
atop cover
bhot water outlet
celectrical connection block
dcontrol panel
epressure switch
fcontrol panel
gtemperature sensor T1
hcombustion chamber
ianode
jheater
kheat exchanger
linspection and cleaning
opening
mtemperature sensor T2
ncold water inlet
odrain valve
pgas control
qburner
rfan
sair supply hose
thot surface igniter
uflame probe
vchimney pipe
wsiphon
xPU insulation layer
IMD-0393
Figure 2.1 Cut-away view of the water heater
k
i
a
p
c
e
u
b
o
r
x
q
h
f
d
j
n
t
v
w
s
g
l
m
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Functioning of the water heater
12 Instruction Manual DR-FC
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In this water heater the cold water enters the bottom of the heater via the cold
water inlet n. The tap water, heated by the combustion chamber hand heat
exchanger k, leaves the heater through the hot water outlet b. Once the water
heater is completely filled with water, it remains constantly under water supply
pressure. As hot water is drawn from the water heater, cold water is immediately
added.
The air required for combustion is forcibly delivered to the burner qby the
fan r. The gas is fed to the burner qvia the gas control p. Thanks to the
modulated supply of gas and air, the optimum gas/air mixture is always
achieved. The special construction of the burner causes the mixture to form a
vortex (the cyclone effect), before it becomes ignited. Because of this vorticity,
ignition at the hot surface igniter tis improved, and the combustion efficiency
is also optimised. Through the special design of the heat exchanger k, the flue
gases are first led downwards via the combustion chamber, then upwards again
via the heat exchanger, then once more downwards beside the water in the
heater. In this process, the flue gases gradually become cooler. Because the
cooled flue gases flow alongside the cold water below in the heater, they start
to condense. This condensation causes latent heat energy to be released,
which is transferred to the cooler water, and thereby increases the performance
of the unit. The condensate yielded by this process is discharged via the
siphon w.
The PU insulation layer xprevents heat loss. The inside of the heater is
enamelled to protect against corrosion. The magnesium anodes iprovide
extra protection against corrosion.
For use during maintenance, the water heater has a inspection and cleaning
opening l.
2.3 The water heater’s
heating cycle
The water heater is controlled (and monitored) by the control panel d. The
temperature sensor T1g(in the top of the heater j) and the temperature
sensor T2m(in the bottom of the heater) measure the water temperature.
These temperatures are sent to the control panel. Based on these two
observations, the control panel calculates a net water temperature: Tnet. The
value of Tnet lies between the temperatures measured at the top and bottom of
the heater. As soon as Tnet falls below the set water temperature (Tset), the
control panel registers a ‘heat demand’. The gas control pis opened, and the
gas is mixed with air. This mixture is ignited by the hot surface igniter tand the
water becomes heated. As soon as Tnet rises above Tset, the heat demand
ends, and the control panel stops the heating cycle.
Both when registering and ending the heat demand, the control panel assumes
a certain margin. We refer to this margin as the hysteresis (see paragraph
’9.2 Setting the hysteresis’).
2.4 Protection for the
water heater
The control panel monitors the water temperature and ensures safe
combustion. This is achieved by:
• the Water temperature protection;
• the Gas control;
• the Fan;
• the Pressure switch;
• the Flame probe.

Protection for the water heater
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2.4.1 Water temperature protection
With temperature sensor T1gand temperature sensor T2m, the control panel
monitors three temperatures which are important for safety. Tab e l 2 . 1 explains
the functioning of the temperature sensors.
2.4.2 Gas control
The control panel opens the gas control so that gas can be supplied to the
burner. As a safety measure, the gas control has two valves. Both valves shut
off the gas supply.
Smooth ignition is achieved by opening the gas control with a delay (‘softlite’).
2.4.3 Fan
The fan provides an optimum air supply when there is a heat demand. A safety
aspect is that the fan ensures that any gases present in the combustion
chamber get removed, both before and after combustion. We refer to this as
pre- and post-purge.
The fan speed is continuously monitored by the control panel. The control panel
takes control if the speed of rotation varies too much from the value set.
2.4.4 Pressure switch
The pressure switch ensures the discharge of flue gases and the supply of
incoming air during the pre-purge and normal running of the water heater. The
standard position of the pressure switch is open. When sufficient pressure
differential is reached, the pressure switch closes. However, in the event of a
fault, the pressure switch will be tripped open, and the heating cycle will be
interrupted.
Tabel 2.1 Temperature protection
Protection Description
Against frost
(T1< 5°C or T2< 5°C)
The frost protection cuts in. The water is heated to 20°C.
For maximum water temperature
(T1> 85°C or T2> 85°C)
The high-limit safeguard serves to prevent overheating and/or excessive
formation of scale in the water heater. Should the high-limit safeguard be
activated, the heating is halted. This causes the water in the heater to cool
down. Once the water has cooled sufficiently (T1< 78 °C), the control panel
resets the water heater.
For extra safety
(T1> 93°C or T2> 93°C)
A lockout error of the water heater controller takes place. The controller must
be manually reset before the water heater can resume operation (see
paragraph ’6.3 Error conditions’). The reset may only be performed once T1<
78°C.

Functioning of the water heater
14 Instruction Manual DR-FC
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Tabel 2.2 shows the trip point per water heater.
nRemark
The trip point of the pressure switch is not adjustable.
2.4.5 Flame probe
To ensure that no gas will flow when there is no combustion, an flame probe has
been fitted. The control panel uses this rod for flame detection, by means of
ionisation detection. The control panel cuts in, the instant it detects that there is
a gas flow but no flame.
2.5 Safety of the instal-
lation
2.5.1 Unvented installation
With an unvented installation, a expansion valve and expansion vessel prevent
excessive pressure in the heater. This prevents damage being caused to the
enamelled coating (in the water heater) or to the heater. A non-return valve
prevents excessive pressure in the water supply system. This valve also
prevents water from flowing backwards from the heater into the cold water
supply system. The pressure reducing valve protects the installation against an
excessively high water supply pressure. These components are fitted to the cold
water pipe. See paragraph ’3.6.1 Cold water side’.
2.5.2 Vented installation
With a vented installation, excess pressure is taken up by the open water tank.
The level of the water tank determines the maximum working pressure in the
heater, which may not exceed 8 bar. The installation must also be fitted with an
open vent from the hot water pipe. Ideally the vent pipe should be linked to a
separate tundish/drain or else to the cold water storage tank. A safety valve
should also be fitted to the water heater. See paragraph ’3.6.3 Hot water side’.
2.5.3 T&P valve
A T&P valve is mandatory in an ’unvented’ installation.
A T&P valve monitors the water pressure in the water heater and the water
temperature at the top of it. If the pressure in the water heater becomes
excessive (> 7 bar) or the water temperature is too high (>97°C), the valve will
open. The hot water will immediately flow out of the heater. Because the water
Tabel 2.2 Pressure switch trip points
Water
heater
Pressure differential [Pa]
Closing Opening
DR-FC
25
>635 < 605
DR-FC
30
>855 < 825
DR-FC
45
>885 < 855
DR-FC
60
>1085 < 1055

Options
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heater is under water supply pressure, cold water will automatically flow into it.
The valve remains open until the unsafe situation has been averted. A
connecting point for a T&P valve is standard on the water heater. See paragraph
’3.6.3 Hot water side’.
2.6 Options The heaters can be supplied with the following additional variations, either
ready fitted or for site fitting:
2.6.1 LPG
The heaters can be supplied adjusted for use on propane or butane, see section
3.12. It is most important that the heater is correctly adjusted for the gas to be
fired.
2.6.2 Unvented Supply
The heaters can be supplied with a purpose designed and sized unvented kit
comprising pressure reducing valve, non-return valve, expansion vessel,
expansion relief valve and pressure/temperature relief valve, to enable the
heater to be coupled directly to the mains water. For details see 2.5.1, 2.5.3 and
3.6.
2.6.3 Top to Bottom Circulation
In order to give enhanced temperature control to aid compliance with the HSE
guidance and the DHss Code of Practice for 'The Control of Legionellae in
Health Care Premises', a pump circulation kit can be supplied comprising 230
volt single phase pump, non-return valve, pipe work and sufficient fittings to
contact between the hot water flow and the bottom connection. For details see
section 3.5 of this manual.

Functioning of the water heater
16 Instruction Manual DR-FC
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Introduction
Instruction Manual DR-FC 17
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3 Installation
Warning
The installation should be carried out by an approved installer in compliance
with the general and local regulations imposed by the gas, water and power
supply companies and the fire service.
The water heater may only be installed in a room which complies with the
requirements stated in national and local ventilation regulations.
Refer also to paragraph ’1.3 Regulations and documents’.
3.1 Introduction This chapter describes the installation activities to be carried out before the
water heater may be started up, namely:
•Packaging;
•Environmental conditions;
•Technical specifications;
•Water connections, Unvented;
•Water connections, Vented;
•Gas connection;
•Air supply and flue gas discharge;
•Electrical connection;
•Checking the supply pressure and burner pressure;
•Conversion to a different gas category.
nRemark
Starting up the water heater is described in chapter ’7 Starting up and
shutting down’.
3.2 Packaging To avoid damaging the water heater, remove the packaging carefully. We
recommend unpacking the water heater at or near its intended location.
cNote
The water heater may only be manoeuvred in an upright position. Take care
that the water heater is not damaged after unpacking.
3.3 Environmental
conditions The DR-FC water heater is a room-sealed water heater. Installation types
possible with this water heater are B23, C13, C33, C43, C53 and C63. This
makes it possible to install the water heater in either a closed or an open boiler
room.
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Installation
18 Instruction Manual DR-FC
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3.3.1 Humidity and ambient temperature
The boiler room must be frost-free, or be protected against frost. Table 3.1
shows the environmental conditions that must be adhered to, for correct
functioning of the electronics present in the water heater to be guaranteed.
3.3.2 Maximum floor loading
In connection with the water heater’s weight, take account of the maximum floor
loading, see Ta b le 3.2.
3.3.3 Working clearances
For access to the water heater it is recommended that the following
clearances are observed (see Figure 3.2):
• AA: around the water heater’s control column and cleaning openings: 100
cm.
• BB: around the water heater itself: 50 cm.
• Above the water heater (room to replace the anodes):
- 100 cm if using fixed anodes, or
- 50 cm if using flexible anodes.
Table 3.1 Humidity and ambient temperature specifications
Humidity and ambient temperature
Humidity max. 93% RH at +25°C
Ambient temperature Functional: 0 ≤t ≤60°C
Table 3.2 Weight specifications related to maximum floor loading
Weight of the water heater filled with water
DR-FC 25 402 kg
DR-FC 30, DR-FC 45, DR-
FC 60
606 kg

Environmental conditions
Instruction Manual DR-FC 19
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If the available clearance is less than 100 cm, flexible magnesium anodes
may be ordered from Hamworthy, the installer / supplier.
nRemark
When installing the water heater, be aware that any leakage from the heater
and/or connections can cause damage to the immediate environment or
floors below the level of the boiler room. If this is the case, then the water
heater should be installed above a wastewater drain or in a suitable metal
leak tray.
The leak tray must have an appropriate wastewater drain and must be at
least 5cm deep with a length and width at least 5cm greater than the
diameter of the water heater.
Figure 3.1 Working clearances
IMD-0073
a

Installation
20 Instruction Manual DR-FC
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3.4 Technical
specifications
The water heater is supplied without accessories. Check the dimensions and
other specifications for the accessories to be used, based on Figure 3.2 and
Tabel 3.5.
Figure 3.2 Plan and elevation of the water heater
IMD-0394
Table 3.3 Dimensions
Dime
nsion
Description DR-FC 25 DR-FC 30 DR-FC 45 DR-FC 60
A Total height (mm) 1370 1900 1900 1900
D Diameter of the water heater (mm) 705 705 705 705
G Diameter of air supply/flue gas discharge (mm) 80/125 100/150 100/150 100/150
K Height of the gas connection (mm) 1270 1810 1810 1810
M Height of cold water supply connection (mm) 160 160 160 160
N Height of hot water outlet connection (mm) 1405 1920 1920 1920
P Height of cleaning and inspection opening (mm) 200 200 200 200