MHS Boilers 318 Installation and operation manual

Ultramax Floor Standing Condensing Boiler
Operating & Maintenance Manual
For Models 318 - 1018
MHS Boilers Ltd
3 Juniper West
Fenton Way
Basildon Essex
SS15 6SJ
01268 546700 Telephone [phone] Fax
WWW.MHSBOILERS.COM
L263

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Contents
Ultramax Technical data
Ultramax Dimensions
1 Introduction
1.1 General
1.2 Supplier
1.3 This document
1.4 Service
1.5 General restrictions
2 Description
2.1 General
2.2 Main components
2.2.1 Description of principal components
2.3 Boiler control
2.4 Safety aspects
3 Safety
4 Delivery and transport
4.1 Delivery
4 .2 Packaging
4.3 Transport
5 Installation
5.1 Regulations
5.2 Boiler room
5.2.1 General
5.2.2 Set up
5.2.3 Ventilation
5.3 Connections
5.3.1 Gas connection
5.3.2 Electrical connection
5.3.3 Water connections
5.3.4 Combustion air supply
5.3.4.1 General
5.3.4.2 Air supply pipe
5.3.5 The flue system
5.3.5.1 General
5.3.5.2 Chimney
5.3.6 Condensate discharge

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5.4 Hydraulic system
5.4.1 General
5.4.2 Water flow
5.4.2.1 Flow rate and resistance
5.4.2.2 Pump characteristics
5.4.2.3 Isolating valves
5.4.2.4 Valves
5.4.2.5 Water flow protection
5.4.3 Water pressure
5.4.3.1 Operating pressure
5.4.3.2 Boiler expansion tank
5.4.3.3 System expansion tank
5.4.3.4 Water pressure protection
5.4.4 Water temperature
5.4.5 Water quality
5.4.6 Examples of hydraulic systems
6 Operating instructions
6.1 Function
6.2 Regulation
6.3 Control module
6.4 Fault indications
6.5 Start-up
6.6 Shut-down
6 .7 Warnings
7 Commissioning
7.1 General
7 .2 Commissioning
8 Maintenance
8.1 Safety
8.2 General
8.3 Procedure
8.4 Cleaning the burner and heat exchangers
8.5 Cleaning the filter/screen in the gas combination block
8.6 Ionisation measurement
8.7 Replacing the frequency Inverter
8.8 Service
9 Conversion formulae and factors

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Ultramax Technical data
Type 318 378 443 508 559 624 730 826 923 1018
Nominal heat output
Nominal heat input (nett.)
Minimum heat output
kW
kW
kW
315
333
83
374
396
100
438
464
112
502
532
133
553
585
146
613
653
187
717
764
218
811
865
247
906
966
276
1000
1066
305
Pilot Burner kW 30 30 30 30 30
Gas consumption
Nat Gas H (10,9kWh/m3)
Propane (12,8 kWh/kg)
m3/h
kg/h
30.5
26.0
36.3
30.9
42.6
36.2
48.8
41.5
53.7
45.7
59.9
51.0
70.1
59.7
79.4
67.6
88.6
75.5
97.8
83.3
Gas inlet pressure
Nat Gas(min.)
Nat Gas(max.)
Propane (min./max.)
mbar
mbar
mbar
18
100
30/50
18
100
30/50
18
100
30/50
18
100
30/50
18
100
30/50
18
25
100
18
25
100
18
25
100
18
25
100
18
25
100
Water capacity
Max. working pressure
dm3
bar
38
6
41
6
44
6
47
6
50
6
53
6
70
6
75
6
80
6
85
6
Gas connection
G1
G2
G
R11⁄2"
-
-
Rp11⁄2
-
Rp2"
-
Rp2"
-
Rp2"
Rp2" Rp2" Rp2"
DN65
PN6
DN65
PN6
Water connections WDN65
PN6
DN65
PN6
DN65
PN6
DN65
PN6
DN65
PN6
DN65
PN6
DN80
PN6
DN80
PN6
DN80
PN6
DN80
PN6
Flue connection D mm 250 250 300 300 300 300 350 350 400 400
Safety valve
Boiler connection
Relief connection
Standard setting
bar
1"
11⁄4"
3
1"
11⁄4"
3
11⁄4"
11⁄2"
3
11⁄4"
11⁄2"
3
11⁄4"
11⁄2"
3
11⁄4"
11⁄2"
3
11⁄4"
11⁄2"
3
11⁄2"
2"
3
11⁄2"
2"
3
11⁄2"
2"
3
Power supply
Frequency
Fuse
V
Hz
A
400
50
10
400
50
10
400
50
10
400
50
10
400
50
10
400
50
16
400
50
16
400
50
20
400
50
20
400
50
20
Max. electrical power
consumption unit pump
maximum total
kW
kW
kW
0.42
0.46
0.88
0.67
0.72
1.39
0.71
0.72
1.43
0.71
0.72
1.43
0.73
1.15
1.88
0.90
1.15
2.05
0.90
1.15
2.05
1.27
1.15
2.42
1.27
1.50
2.77
1.27
1.50
2.77
Boiler weight, empty, ±5% kg 525 560 615 645 675 740 840 950 1070 1200
Dimensions height H
width B
length incl. connections L
mm
mm
mm
1355
830
1918
1355
930
1908
1355
1130
1908
1355
1130
1908
1355
1230
1958
1355
1330
2265
1355
1130
2653
1355
1130
2653
1355
1330
2658
1355
1330
2658

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Ultramax 318 – 559 Dimensions

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Ultramax 318 – 559 Dimensions
Type 318 376 443 508 559
B* mm 830 930 1130 1130 1230
B1 mm 710 810 960 1010 1110
B2 mm 120 120 170 120 120
B3 mm 646 746 946 946 1046
D mm 250 250 300 300 300
G1 R 11⁄2" - - - -
G2 - Rp 11⁄2" Rp 2" Rp 2" Rp 2"
H1 mm 1115 1205 1205 1205 1120
L mm 1918 1908 1908 1908 1958
L1 mm 555 545 545 545 595
L2 mm 1362 1362 1362 1362 1362
L3 mm 231 231 231 231 231
L4 mm 108 108 108 108 108
W DN65 PN6 DN65 PN6 DN65 PN6 DN65 PN6 DN65 PN6
B = Dimensions with external casing (panels) in place
* = To obtain the dimensions without the external casing, subtract 64 mm from dimension eBi.
(Changes may be introduced without notice)
As a result of manufacturing tolerances, there may be small variations in the dimensions.
Conditions applicable to above table:
- Nominal capacity measured at: 60 - 80°C.
- Gas consumption at: 1013 mbar, 15°C, dry
- Gas categ o ry: 22H3P
- Gas pressure: The unit is adjusted during manufacture for a
gas supply pressure of 25 mbar.
- Appliance categ o ry: B 23, C53, C33 or C63
- Protection deg r ee: I P20
Types R318 to 559 are suitable for nominal distribution pressures of both 20 and 100 mbar for natural
gas. For higher gas pressures, a separate gas pressure regulator must be
installed in consultation with the local gas supplier. The dynamic supply pressure must never fall
below 18 mbar (see para. 5.3.1).

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Ultramax 624 – 1018 Dimensions

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Ultramax 624 – 1018 Dimensions
Type 624 730 826 923 1018
B mm 1330 1130 1130 1330 1330
B1 mm 1210 1003 1053 1203 1253
B2 mm 665 565 565 665 665
B3 mm 120 127 77 127 77
B4 mm 1146 946 946 1146 1146
B5 mm 65 115 65 115 65
D mm 300 350 350 400 400
G Rp2" Rp2" Rp2" DN65 PN6 DN65 PN6
H mm 1355 1355 1355 1355 1355
H1 mm 1125 1400 1400 1155 1155
L mm 2265 2653 2653 2658 2658
L1 mm 595 610 610 615 615
L2 mm 700 1166 1166 1166 1166
L3 mm 108 88 88 88 88
W DN65 PN6 DN80 PN6 DN80 PN6 DN80 PN6 DN80 PN6
(Changes may be introduced without notice)
As a result of manufacturing tolerances, there may be small variations in the dimensions.
Conditions applicable to the above table:
- Nominal capacity measured at: 60 - 80°C.
- Gas consumption at: 1013 mbar, 15°C, dry
- Gas category: 22H3P
- Appliance category: B23, C53, C33 of C63
- Protection degree: IP20

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1 Introduction
1.1 General
Through their unique construction, the Ultramax range of central heating units are renowned for their:
- high thermal efficiency
- environmental friendliness
- light weight and small dimensions
- durability
- low noise production
- large regulating range
- available with many different options.
Active and market required research enables MHS Boilers Ltd to offer solutions for the most
provocative heating demands.
1.2 Supplier
MHS Boilers Ltd are proud to supply and technically support the Ultramax Range of boilers throughout
the United Kingdom.
For advice or more information please contact your local sales representative or our head office via
01268 591010.
1.3 This document
This documentation has been written to aid the following target groups:
- the consulting engineer
- the heating installer
- the service engineer
- the user.
Because these target groups require mostly similar information and also specific information, our
technical documentation has been integrated to provide these target groups with the necessary
general and specific information to install, service and operate this product.
If additional information is required please contact your local representative or our head office via
01268 591010.
The following aspects will be explained:
- general description
- technical specifications
- necessary services for system design and unit installation
- example systems
- maintenance instructions.
Operating instructions for the user can be found on the unit. See also chapter 6.
1.4 Service
For commissioning and assistance in maintenance matters, please contact the Technical Services
Department via 01268 591010.

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1.5 General restrictions
The application, installation and maintenance of MHS products must always be carried out
in accordance with the requirements (legal or otherwise), specifications and standards applicable
to such installations.
All data, information and suggestions provided by MHS Boilers Ltd. in relation to its products are
based on careful investigation. Nevertheless, neither MHS Boilers Ltd. nor any other organisation
connected with MHS Boilers Ltd. accepts any liability for application, installation or exploitation
that occurs outside its sphere of influence.
Changes may be incorporated without prior notice. MHS Boilers Ltd. accepts no obligation to
adapt previously delivered products to incorporate such changes.
2 Description
2.1 General
The Ultramax series are environmentally friendly modulating gas fired heating boilers that can vary its
output from 25% to 100% of its maximum capacity.
The Ultramax series consists of 10 models in a range from 318 to 1018 kW.
The units have an extremely low emission of NOx and CO, so that this boiler satisfies the most
stringent European requirements.
The R2700/R2800/R2900 series have CE approval for all relevant European countries.
The series are registered under the product identification numbers 0063AQ6600. (318 - 559) &
0063AR3514. (624 - 1018)
The boilers can be supplied either as a standard (category B23) or a room sealed (categories C53,
C33 or C63) appliance.
Working principle and construction
Air is blown into the appliance, as required, by a speed-controlled fan and thoroughly mixed with
gas in the correct proportions.
A temperature controller compares the desired water temperature with the temperature of the water
flow and sends a signal to the frequency converter to maintain the correct heating capacity.
The gas/air mixture so formed is passed through a cooled premix burner and ignited. The premix
burner is constructed of finned bimetallic pipes (internally from stainless steel and externally
from aluminium) with cast iron water headers.
Heat transfer takes place in two or three heat exchangers. The first heat exchanger is constructed
from smooth stainless steel pipes, while the second heat exchanger is fitted with laser welded,
stainless steel finned pipes. Both heat exchangers are fitted with cast iron profiled water distribution
components (headers) which guarantee an optimum water flow through the appliance.
The burner and the heat exchangers are connected in series.
The boiler pump ensures the correct water flow quantity.

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The Ultramax units have a small water capacity so that it can rapidly adjust to changing
conditions. It can be installed without any restrictions to the return water temperature. The
necessary water flow rate is ensured by the standard pump delivered with the appliance.
Application possibilities
Because of its construction, the Ultramax unit is suitable for use in heating systems:
- With a constant supply temperature
- With a weather dependent heating demand
- With low temperature condenser systems
- With optimised condensation
- With control by means of building optimizer/compensator system (0 – 10 Vdc = +2°C – +90°C),
see 5.3.2 connection terminals).

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2.2 Ultramax 318-559 Main components
1 Return connection 19 Flue gas collection chamber
2 Flue gas discharge attenuator 20 Combustion chamber
3 Water flow switch 21 Electrical cable duct
4 Safety valve 22 Condensate discharge
5 Inlet connection 23 Inspection opening
6 Filling / drainage valve 24 Gas valve unit
7 Cover 25 Fan
8 Distribution plate 26 Connection box
9 Burner 27 Control panel
10 First heat exchanger 28 Casing
11 Gas filter 29 Air inlet damper
12 Second heat exchanger 30 Butterfly valve
13 Gas train 31 Mixing chamber
14 Frame 32 Boiler pump
15 Water circulation piping A Air
16 Flue gas discharge B Gas
17 Third heat exchanger (Special Order Appliances Only) C Flue gas
18 Condensate collection tank D Condensate

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2.2 Ultramax 623-1018 Main components
1 Return connection 18 Condensate collection tank
2 Flue gas discharge attenuator 19 Flue gas collection chamber
20 Combustion chamber
3 Water flow switch 21 Electrical cable duct
4 Safety valve 22 Condensate discharge
5 Flow connection 23 Gas valve unit
6 Filling/drainage valve 24 Fan
7 Cover 25 Connection box
8 Distribution plate 26 Control panel
9 Burner 27 Casing
10 First heat exchanger 28 Air inlet damper
11 Gas filter 29 Main mixing chamber
12 Second heat exchanger 30 Pilot gas valve
13 Gas train 31 Pilot mixing chamber
14 Frame 32 Boiler pump
15 Water circulation piping A Air
16 Flue gas discharge B Gas
17 Third heat exchanger (Special Order Appliances Only) C Flue gas
D Condensate

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2.2.1 Description of principal components
The boiler is constructed from the following principal components:
Fan
This consists of a fan casing, a fan impeller and an electric motor. The fan sucks in combustion air
and increases the air pressure.
Air inlet damper
A specially developed air inlet damper ensures a low noise level. As an option, this can be provided
with an air filter or with an air inlet opening so that the appliance can function as a room sealed
appliance.
Gas train
The principal component of the gas train is the main gas valve/proportional pressure regulator. The
quantity of gas is adjusted in proportion to the quantity of air being supplied. The quantity
of air depends on the speed of the fan. The unit is fitted with a gas filter as standard.
Mixing chamber
This area is used for the thorough mixing of the gas and the combustion air.
Burner
After the gas/air mixture has been distributed over the burner with the aid of a distribution plate, the
mixture is burned on the surface of the burner in such a way that the flame is directed
downward. The burner is air and water cooled. The water distribution components are made from
cast iron and have a profile that ensures that an optimum distribution and flow are obtained.
Heat exchangers
The primary heat exchanger is constructed from smooth stainless steel tubes. These transfer
most of the heat energy to the system water. The secondary heat exchanger, which consists
of laser welded stainless steel finned tubes, transfers the remaining heat from the flue gasses to
the system water. All the water distribution components are constructed from cast iron and have
a profile that ensures that optimum distribution and flow are obtained. The space between the
burner and the secondary heat exchanger forms the combustion chamber.
Special order appliances only have a third heat exchanger is attached which consists of one or more
stainless steel fin tube(s), switched in series, in form of a spiral. It is arranged on the back of the boiler
on the flue gas collection chamber.
The boiler pump ensures the water flow quantity.
The third heat exchanger is switched parallel to the boiler and has a flow of 5 - 10% of the entire water
flow.
Water circulation pipes
These pipes connect the burner to the heat exchangers.
Water connections
These consist of a flow connection and a return connection. Both of these connections are

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provided with a filling/drain valve. The flow connection is also provided with a safety valve,
a flow switch and a temperature sensor.
Boiler pump
The boiler pump is mounted on the return connection to the unit and is directly connected electrically
to the appropriate terminals in the connection box. The capacity and the working head of the
pump is sufficient to overcome both the resistance of the boiler and some system resistance.
Flue gas collection chamber
The stainless steel flue gas collection chamber is mounted under the heat exchanger. This chamber
is provided with a flue gas exhaust connection, a condensate drain connection and an
inspection opening.
Frame
The frame is constructed from steel profile sections. Vibration absorption dampers are supplied
separately and must be fitted after the unit has been placed in position.
The casing
The casing consists of panels that can be removed easily without the aid of tools.
The electrical section
This includes the control and safety circuits for the unit.
Connection box
The electrical power supply for the boiler, the terminals, the pump connections and the pump
relay are mounted in an easily accessible connection box. The supply cables can easily be fed to
the connection box via the cable duct inside the boiler.
2.3 Boiler control
The principle employed for the Boiler Management Unit is as follows:
The boiler begins operating on receipt of a heating demand. This heating demand is generated either:
A. If the measured supply temperature is lower than the desired temperature.
B. As a result of a manual operation mode having been selected,
C. In standby mode, when the water temperature falls below the frost protection temperature.
After the boiler has started up, the PID controller sends a signal to the frequency converter. This
converter controls the speed of the fan. Depending on the quantity of air moved by the fan, the
proportional pressure regulator ensures that the corresponding quantity of gas is added.
In this way the boiler capacity is continually adjusted and the boiler can accurately follow the
heating demand. If the boiler is operating at minimum capacity and the temperature of the supply
water rises above the desired value, the boiler will be shut down. As soon as the temperature of
the supply water falls below the set value, the boiler will be re-started.

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2.4 Safety aspects
The boiler contains the following safety components:
- Flame protection with 1x re-start (ionisation)
- Water flow protection
- Maximum water temperature protection
- Gas valve test
- Gas valve leak test (option)
- Minimum air pressure protection
- Boiler pump motor over-heating protection (Clixon).
If one of these components operates, this results in a lockout fault. Lockout faults can only be
cancelled by resetting the unit.
The unit is fitted with a safety valve that opens at 3 bar.
3 Safety
Installation instructions
Read through these instructions carefully before starting the installation.
The appliance must be installed by a recognised installer in accordance with the applicable national
and local regulations.
The installation may only be used for heating systems up to a maximum water temperature of
90°C.
It is expressly stated that these installation instructions must be seen as a supplement to the
above mentioned standards and regulations and that these standards and regulations must take
precedence over any information included in this technical manual.
Maintenance
Work on the electrical installation may only be carried out by an authorised installer in accordance
with the applicable electrical regulations.
Work on the gas and hydraulic installations may only be undertaken by properly trained personnel
in accordance with the safety regulations for gas installations.
Keep unauthorised persons away from the installation. Do not place any objects on the unit.
Remain out of the area of the hot water connection and the chimney to avoid burns.
Before starting any maintenance or service activities, disconnect the electrical power supply and
close the gas supply valve.
After completing any maintenance or service activity, check the whole installation.
As a supplement to the information provided in this technical manual, all applicable safety regulations
must be consulted to avoid accidents.
All panels forming part of the casing must be mounted. Panels may only be removed for maintenance
or service purposes. After performing maintenance or service activities, ensure that all
panels are replaced.

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Safety provisions
The installation may never be switched on if any of the panels have been removed or if any of the
safety devices have been disabled.
Instruction and warning stickers
None of the instruction and warning stickers attached to the installation may be removed or covered
and during the whole of the lifetime of the installation they must remain legible.
Replace any damaged or unreadable instruction and warning stickers immediately.
Modification
Modifications to the installation may only be carried out with the written approval of the manufacturer.
Danger of explosion
When activities are being undertaken in the boiler room, always follow the applicable instructions
“Working in an area where there is a danger of explosion”.
Installation
The appliance must be installed by an authorised installer in accordance with the applicable national
and local specifications and regulations. Carefully follow all the safety instructions.
Operation
In the event of a gas leak, switch off the unit and close the gas supply valve. Open doors and windows
and warn the appropriate authorities.
When the installation is re-commissioned, always follow the instructions for use.
Technical specifications
The specifications listed in this technical manual cannot be ignored.
4 Delivery and transport
4.1 Delivery
The appliances are completely assembled, tested and covered in a “heat-shrink” protective covering.
After delivery and removal of the protective covering, check the appliance for damage.
Check that the equipment delivered is in accordance with the order and the delivery note.
On delivery, check the data plate for the correct boiler type and gas supply pressure.
4.2 Packaging
For transport purposes, the unit is mounted on wooden blocks, fitted with protective bumpers
and covered in a “heat-shrink” protective covering.
4.3 Transport
For transport, consult the technical details for dimensions and weight.
Remove the covering preferably after transportation and positioning in the boiler room or remove
the panels before transporting the appliance. This is to prevent damage to the casing panels.

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Moving the appliance
A pallet truck or fork lift truck with a minimum fork length of 1 m can be used at the side of the
unit.
Rollers
After the wooden blocks have been removed, it is possible to move the appliance by rolling it over
tubes.
Lifting
The figure below shows how a unit can be safely lifted. To avoid damage to the panels, these
should first be removed. The wooden bars between the straps ensure that the unit will not be
damaged during lifting.

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Caution:
- Ensure that the lifting straps are of the correct quality!
- Never move the units over the heads of persons!
Dismantling and reassembly
When the unit cannot be placed in position because of its dimensions or weight, the boiler may be
partially dismantled.
When it is necessary to perform extensive dismantling, we advise you to make early contact with
your supplier. The unit can be delivered in parts, each of which has been pre-tested. We strongly
advise you to have dismantling and reassembly activities carried out by the MHS Technical Service
Department trained staff.
Dimensions and weights of Burner and Heat exchangers

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Burner
Type Length mm Breadth mm Height mm Weight kg
318 1010 760 400 105
376 1010 860 410 115
443 1010 960 410 120
508 1010 1050 420 130
559 1010 1150 420 135
624 1010 1310 500 140
730 1420 1010 500 210
826 1420 1110 500 215
923 1420 1210 500 220
1018 1420 1310 500 225
Heat Exchanger One
Type Length mm Breadth mm Height mm Weight kg
318 1030 760 150 90
376 1030 860 150 95
443 1030 960 150 110
508 1030 1050 150 115
559 1030 1150 150 120
624 1010 1310 160 135
730 1420 1010 160 180
826 1420 1110 160 185
923 1420 1210 160 190
1018 1420 1310 160 195
Heat Exchanger Two
Type Length mm Breadth mm Height mm Weight kg
318 1030 760 150 100
376 1030 860 150 110
443 1030 960 150 120
508 1030 1050 150 130
559 1030 1150 150 135
624 1010 1310 160 150
730 1420 1010 160 200
826 1420 1110 160 200
923 1420 1210 160 210
1018 1420 1310 160 210