MHS Boilers TUDOR NHRE Series User guide

TUDOR NHRE
L 147
TUDOR NHRE RANGE OF DIRECT GAS FIRED
WATER HEATERS
INSTRUCTIONS FOR INSTALLATION,
SERVICING & OPERATION FOR MODELS
NHRE 18,26,36,60 & 90.

1
TUDOR NHRETUDOR NHRE
contents
page section
2
. . . . . . . . . . . 1.0 General Notes
2.0 Water Byelaws
3.0 Building Regulations
4.0 Product Approvals
5.0 Product Description
3 . . . . . . . . . . . 6.0 Key Points
4 . . . . . . . . . . . 7.0 Specification For Tudor NHRE
5 . . . . . . . . . . . 8.0 Delivery Consignment
8.1 Handling & Storage
9.0 Optional Extras
6 . . . . . . . . . . 10.0 Single Water Heater Dimensional Data
7 . . . . . . . . . . 11.0 Technical Data
12.0 Installation Requirements
8 . . . . . . . . . . 13.0 Ventilation Requirements
14.0 Appliance Location
15.0 Gas Connection
9 . . . . . . . . . . 16.0 Flue Connection Draught Divertor Assembly
17.0 Electrical Connection
10 . . . . . . . . . 18.0 Water Systems
18.1 Water Connections General
18.2 Vented Systems
11-12 . . . . . . . 18.3 Unvented or Boosted Feed Systems
12-13 . . . . . . . 18.4 Unvented Installation Component Check List
14-15 . . . . . . . 18.5 Unvented Systems-Terminating Safety Discharge Pipes
16 . . . . . . . . . 18.6 Secondary Circulation
18.7 Anti Stratification System
17 . . . . . . . . . 18.8 Filling The Water Heater /
Commissioning the Water System
18 . . . . . . . . . 19.0 Detail of Burner Assemblies
19 19.1 Burners, Injectors, Burner Pressure &
Gas Consumption Data
20 . . . . . . . . . 20.0 Setting The Appliance To Work
20.1 NHRE 18 Initial Start-Up
22 . . . . . . . . . 21.0 To Turn Off The Appliance
21.1 NHRE 18
21.2 NHRE 26-90
21.3 Extended Shutdown Periods
22.0 Maintenance & Cleaning
22.1 Tank Flushing
23 . . . . . . . . . 22.2 Descaling The Tank
22.3 Burner Maintenance
22.4 Flueway Maintenance
24 . . . . . . . . . 23.0 Notes On Water Quality
24.0 Fault Finding
25.0 Trip Of Flue Spillage Detection Safety Device
25 . . . . . . . . . 26.0 Guarantee
25 . . . . . . . . . 27.0 Exploded Diagrams
26 . . . . . . . . . 28.0 Parts List

2
TUDOR NHRE
1.0 general
notes
These instructions are intended to assist the installer, commissioning engineer and maintenance
engineer with the installation and maintenance of Tudor NHRE Direct Gas Fired Water Heaters.
Please read this manual fully before commencing installation of the appliance. Tudor NHRE Water
Heaters must only be installed and maintained by persons deemed to be competent IE: Corgi Registered.
This manual must be handed to the appliance user following completion of the installation.
The water byelaws ensure a good supply of wholesome water, and that only approved materials, pipes
and fittings are used to convey water.
2.0 water
byelaws
Building regulations are statutory and take precedence over all other regulations and recommendations.
The installation of a water heater into an unvented system must meet the requirements of Building
Regulation G3 and may only be installed by a competent person. All installations of unvented hot water
storage systems having a capacity of more than 15 litres should be notified to the relevant Local Authority
by means of building notice or by the submission of full plans. Note, it is an offence to install an unvented
hot water storage system without notifying the Local Authority.
3.0 building
regulations
Tudor NHRE Water Heaters are approved in accordance with EN89 and are CE marked. C E 0049AR
1050. Tudor NHRE Water Heaters are listed in the water byelaws schemes water fittings and materials
directory, the schemes fitting assessment panel finds that the use of Tudor Water Heater fittings or units,
when correctly installed, will not contravene the requirements of the water byelaws or regulations (NI).
4.0 product
approvals
The Tudor NHRE range of open flued direct gas fired, high performance hot water heaters consists of
five models with outputs between 320 and 1443 litres/hr of continuous secondary delivery at 50ºc ∆t.
The range utilises high quality steel bodies with best quality enamel lining, a combination that assures
longevity and reliability.
Tudor NHRE water heaters are the perfect solution for hot water provision in a variety of commercial,
industrial and domestic applications with a range of storage capacities and heat input to suit.
Each Tudor NHRE appliance is equipped with multi atmospheric burners and standing pilot ignition for
simplicity and reliability. Safety is provided via thermoelectric flame failure protection, manual reset, high
limit thermostat and flue spillage detection device.
5.0 product
description

3
TUDOR NHRE
6.0 key
points
CE marked - 0049 AR 10 50
Each Tudor NHRE water heater has been tested and approved to meet the
specified requirements of European Standards on performance, efficiency, safety
and quality.
high grade materials
A heavy gauge, welded steel body with a Class "A" enamel coated interior, provides exceptional
corrosion and temperature resistance, ensuring long life and durability.
non-metallic outer jacket
The Tudor NHRE is supplied with a durable padded vinyl jacket over dense thermal insulation which
combines an attractive appearance with resistance to accidental impact. Should serious damage to the
jacket occur it can be simply removed and replaced.
low NOx emission
Each appliance meets the requirements of EN497 for NOx emissions.
functional simplicity
Provision of hot water is paramount in most applications. Reliability and ease of maintenance are
designed into the Tudor NHRE range through the specification of industry standard components such as
atmospheric burners, standing pilot and thermoelectric flame failure protection.
protech system
As standard, each Tudor NHRE water heater includes a powered active anode system which ensures
best possible protection from waterside corrossion in all water supply areas and avoids the need for anode
inspection & replacement.
ease of maintenance
Each water heater is equipped with a large bore drain port at the base of the tank to ensure rapid and
full drainage, facilitating internal inspection and cleaning via a generous access port. Internal protection is via
multiple sacrificial magnesium anodes.
open vented or vented water supply options
The Tudor NHRE has the option of being connected to a traditional hot water supply system via an
open cold water cistern or alternatively (with the use of additional controls) be fed from mains or boosted
cold water supplies.
anti-cycling
The use of standing pilot ignition provides a constant heat source which makes a useful contribution to
frost avoidance and main burner cycling prevention in periods of low hot water usage.
inbuilt time control option
For premises where comprehensive building controls are not installed, the Tudor water heater can be
supplied with an optional on-board time switch which facilitates timed hot water production (not Model
18). In addition all models may be time controlled from a remote point.
guarantee
Each Tudor NHRE water heater carries a conditional three year tank guarantee.
0049AR 10 50

4
TUDOR NHRETUDOR NHRE
7.0 specification
for Tudor NHRE
All Tudor NHRE water heaters are manufactured at a facility that is certified to ISO 9001. Each
appliance is thoroughly inspected and tested at each stage of production to ensure that the finished product
is of the highest quality.
tank
Manufactured from boiler quality ST-37 carbon steel internally coated with Class A enamel. During
production each tank is 100% video inspected, electrical resistance tested and pressure tested. Certified for
use on service pressures up to 7 bar.
outer jacket/insulation
Light impact resistant removable/replaceable foam padded vinyl with zipped closure finished in white.
Rockwool mineral fibre blanket of 35mm thickness plus 12mm thickness micro closed cell foam.
burner assembly/ignition system
Frame mounted multi stainless steel atmospheric burners with factory fixed primary aeration control.
Low energy standing pilot with piezo spark ignition.
flame failure protection
Thermoelectric system with safety interlocking to over-temperature limit thermostat and flue draught
anomaly (flue spillage) detection device.
control panel
Full appliance height stove enamelled, hinged, fabricated steel enclosure including full prewiring and
double pole on/off switch, user adjustable control thermostat, flue spillage detection device, burner on
indicator lamp and knock out for optional built in time control.
Note: Model 18 includes self energising/mechanical controls, but requires an electrical supply to
support the powered anode system.
cathodic protection
Non sacrificial powered active anode system with status indication lamps.
inspection/cleaning access
Flanged access with insulated moulded cover.
draught divertor
Spun brushed aluminium vertical discharge type with cradle for flue draught anomaly sensor. As an
option the Model 90 may be supplied with a fabricated steel draught divertor with an overhung draught
break and 45°flue off take.

5
TUDOR NHRETUDOR NHRE
8.0 delivery consignment
Each Tudor NHRE water heater is supplied within a protective polythene envelope, firmly attached to
a sturdy crated pallet.
Plus: Carton containing Flue Downdraught Divertor Assembly.
Carton/s containing any optional extra accessories.
8.1 handling &
storage
Tudor NHRE series water heaters must be stored upright in their original packaging in a dry and clean
environment to avoid any damage or deterioration to the product prior to installation.
The installers attention is drawn to the weight of the appliance - (see section 11) and sufficient persons
must be employed ( if being manually handled) to avoid injury to persons and damage to the product during
moving and handling operations.
It is advised that the product should remain in it’s original packaging during moving and handling.
The appliance should not be laid down during transit or moving and handling.
9.0 optional extras
●Model 90: 45°flue connection draught divertor.
●All models: pilot gas pressure proving switch to indicate pilot outage to a remote point
(volt free contact).
●Models 26, 36, 60 & 90: 7 day single channel time switch.
●Model 18: main burner gas supply solenoid kit to allow remote on/off control of main burner.
●All Models: matched WRc approved unvented hot water installation controls pack.

6
TUDOR NHRE
10.0 single water heater
dimensional data
Insulating
Jacket
Combustion
Chamber
Burners
Burner
View Point
Insulating
Jacket
Combustion
Chamber
Burners
Burner
View Point
Draught
Divertor
1" Connections
Flueways
Flueway
Baffles
Pilot
Assembly
Tray
1" Connections
Flueways
Flueway
Baffles
Flueways
Flueway
Baffles
Insulating
Jacket
Pilot
Assembly Pilot
Assembly
Enamelled
Tank
Cold Feed
11/2"
Combustion
Chamber
Burners
Gas Valve
Burner
View Point
Draught
Divertor
Drawoff
11/2"
650 1162
Draught
Divertor
2170
A
635 100
D
432
781
352
352373
G 3/4" F
All dimensions in mm (25.4mm = 1") M = Male Thread F = Female Thread L Centre Line
390
D
172432
781
G 1/2" F
Draw Off Cold Feed
390
D
172432
781
G 3/4" F
Draw Off Cold Feed
Cold Feed
Models 18-60
Hot Drawoff
Models 18-60
Control
Panel
Inspection/
Cleaning Port
Information
Label
ØE
D
C
A
G 290
B
Drain 3/4"
& Recirc 1"
F
275 (Model 18)
156 (Models 26-90)
NHRE 18
side view section
NHRE 26, 36, 60
side view section
NHRE 90
side view section
all models
front view
NHRE 18
plan
NHRE 26, 36, 60
plan
NHRE 90
plan Optional Draught
Divertor Model 90
Model
A - Height Less Flue Divertor
B - Height to Cold/Hot Water Conns
C - Overall Height
D - ØFlue
E - ØDiameter
F - Height to L Gas Connection
G - Height to L Drain Connection
ØCold Water Inlet BSP
ØHot Water Outlets BSP
ØGas BSPF
NHRE 18
1215
1245
1525
125
700
275
290
1" m
1" m
1/2"
NHRE 26
1530
1560
1840
139.8
700
156
290
1" m
1" m
3/4"
NHRE 36
1530
1560
1840
167.8
700
156
290
1" m
1" m
3/4"
NHRE 60
1890
1920
2200
181.2
700
156
290
1" m
1" m
3/4"
NHRE 90
2000
N/A
2285
230
700
156
290
11/2" F
11/2" F
3/4"
c
c
c

7
TUDOR NHRE
11.0 technical
data
Model
Water Capacity L
Net Heat Input kW
Output to Water kW
Gas Input Nat Gas G20 m3/h
Gas Input LPG G31 Kg/h
Peak 10min Output ∆t 44°CL
1st Hour Continuous Output ∆t 44°C L/h
Continuous Output ∆t 44°C L/h
Peak 10min Output ∆t 50°CL
1st Hour Continuous Output ∆t 50°C L/h
Continuous Output ∆t 50°C L/h
Recovery Time 10-60°C min
Max Operating Temp °C
Max Operating Pressure bar
Weight Empty/Full Kg
NOx Emission Class (G20)
Nominal Gas Inlet Pressure Nat Gas (G20) mbar
Nominal Gas Inlet Pressure LPG (31) mbar
Electrical Supply 230V 1ph 50Hz 3A
Electrical Consumption W
NHRE 18
185
22
18.7
2.33
1.71
245
549
364
238
505
320
35
85
7
143/328
2
20.0
37.0
NA
NA
NHRE 26
275
34
28.9
3.60
2.64
368
837
562
357
770
495
34
85
7
171/446
2
20.0
37.0
✓
5
NHRE 36
275
44
37.4
4.65
3.42
396
1003
728
381
916
641
26
85
7
171/446
2
20.0
37.0
✓
5
NHRE 60
350
67
57
7.08
5.20
535
1460
1110
512
1327
977
22
85
7
247/597
2
20.0
37.0
✓
5
NHRE 90
285
99
84.2
10.47
7.68
558
1925
1640
525
1728
1443
12
85
7
270/555
1
20.0
37.0
✓
5
Performance indication of largest model in the range - NHRE 90 :-
During tests, it was found that the water heater took 15 minutes to raise the contents of the appliance
from 15ºC to 78ºC (thermostat cut out) and took 11 minutes to reheat 70 % of the contents of the
appliance back to 78ºC.
Tudor NHRE series water heaters must be installed as appropriate with the relevant requirements of:
●Water Supply (Water Fittings) Regulations ●CP 342: Part 2: 1974
●Building Regulations ●BS 6644: 1991
●Gas Safety (Installation & Use) Regulations ●BS 5440: Part 1: 2000
●IEE Regulations ●BS 5440: Part 2: 2000
●BS 6700: 1997 ●BS 6891: 1998
●BS 5482 Parts1,2,3:1979 ●IGE/UP/2
●IGE/UP/10
The appliance should be positioned on a level fire proof base capable of supporting the weight of the
appliance when filled with water.
12.0 installation
requirements

It is important to ensure that an adequate supply of fresh air for combustion and general plant room
ventilation is provided.
The following requirements for ventilation must be met:
Or alternatively, the ventilation requirement may be met by the provision of mechanically supplied and
mechanically extracted air (interlocked to the appliance to prevent appliance operation in the event of
mechanical system failure) or mechanically supplied air (interlocked) and natural extract at the rate of:
Supply air at 1.1m 3/Sper 1000 kW of gross appliance input and extract air at 0.45m 3/Sper 1000 kW of
gross heat input.
Model
NHRE 18
NHRE 26
NHRE 36
NHRE 60
NHRE 90
High Level Free Area cm2
N/A
N/A
N/A
N/A
388
Low Level Free Area cm2
75
135
185
300
775
Natural Ventilation Direct to Outside Air
13.0 ventilation
requirements
14.0 appliance
location
The location chosen for the appliance must permit adequate space for maintenance and inspection and
must be capable of supporting the weight of the appliance when full of water.
Some chemicals produce vapours which can cause rapid failure of thermocouples, burners and the
water heater tank walls, if they are drawn into the combustion air supply. Therefore if this water heater
will be used to supply hot water to:
●Hairdressers
●Dry cleaners
●Industrial degreasing processes
●Or any other area where halogens or oxidising agents (such as swimming pools) are used or stored
then care should be taken to ensure that the combustion and ventilation air supply to the space where
the water heater is installed is communicated directly to outside air and free of any chemical vapour
contaminants.
15.0 Gas
connection
The gas supply to this appliance must be installed in accordance with either: BS 6891, BS5482 or
IGE/UP/2, as appropriate and the pipe used to supply the appliance must not permit a pressure drop of
more than 1 mbar from the meter to the appliance inlet connection.
Nominal inlet pressures (working) required are as follows:
Natural Gas G20 - 20 mbar
LPG G31 - 37 mbar.
The supplied gas isolation valve must be installed into the gas supply pipework adjacent to the appliance and
a method of disconnection must be included between the valve and the gas inlet connection to the appliance.
TUDOR NHRETUDOR NHRE
8

9
TUDOR NHRETUDOR NHRE
17.0 electrical
connection
A single phase 230V 50Hz 3Amp supply is required for all models.
The model NHRE 18 has self energising controls and only requires an electrical supply to support the
active anode.
Electrical connection
Slacken upper and lower control panel securing bolts and hinge open control panel. Make electrical
connection to supply terminal rail. Electrical works must be carried out in accordance with the current
edition IEE Regulations. Close and secure control panel.
16.0 flue connection
draught divertor assembly
The draught divertor supplied with the appliance must be installed following carefully the instructions
supplied in the carton with the specific draught divertor. The flue spillage detection safety device must also
be correctly installed following the instructions supplied with the draught divertor.
The flue pipe and fittings used must be of appropriate corrosion resistant material. The diameter of the
flue used must not be smaller than the flue connection on the appliance draught divertor and must be
installed in accordance with the requirements of BS 5440: Part 1, BS 6644 or British Gas IMII as appropriate.
The flue pipe should rise for at least 500mm vertically before any change in direction. Any horizontal runs
should include a rise of 60mm per 1000mm run.
A method of disconnection should be included in the flue immediately above the draught divertor
removal for servicing purposes. The flue must be adequately supported and the draught divertor must not
be used to support the flue.
wiring diagram models Tudor NHRE 26-90
manual reset
high limit
thermostat
manual reset
flue safety
thermostat
Supply
230v
50hz
3amp
Neutral
Earth
Phase
Control
Thermostat
On / Off Switch
Anode
Blue
Thermocouple
burner gas valve
Brown
Brown
Brown
Brown
Black
Brown
Blue
Blue
programmer
(option) external
control
option
{
wiring diagram model Tudor NHRE 18
manual reset
high limit
thermostat
manual reset
flue safety
thermostat
Supply
230v
50hz
3amp {
Protech
Unit
Protech
Unit
Stat
Anode
Thermocouple
Gas Valve with
Control Thermostat
L
E
N

10
TUDOR NHRETUDOR NHRE
18.0 water
systems
Tudor NHRE Water Heaters are suitable for connection to vented, unvented or boosted water supply systems.
In each case, appropriate valves and fittings should be used to ensure compliance with the requirements of
the water byelaws and as appropriate, the Building Regulations.
18.1 water Connections
general
Connections to the water heater should be made using only appropriate Water Byelaws scheme
approved fittings for use with tube and pipe and in conjunction with similarly approved jointing materials.
Connections should be made to the tappings on the appliance as shown in section 10.
The drain valve must be installed as low as possible and must not be positioned above the level of the
drain tapping on the appliance. The drain tapping is positioned at the lowest point of the vessel and is
capable of draining at least 80% of the total capacity of the vessel.
18.2 vented
systems
If the water heater is to be connected to a gravity feed cold water tank or cistern then the hot water
supply pipe must include an open vent pipe which discharges over the cold feed cistern. The cold feed
cistern must have an actual capacity of greater volume than the hourly recovery rate of the water heater
which it supplies.
typical installation schematic
single Tudor water heater in
open vented system
Non
Return
Valve
Drain Cock
Temperature
& Pressure
Relief Valve
Isolation Valve
Secondary
Circulation
Pump
Isolation
Valve Isolation Valve
fig.1

11
typical installation schematic
two Tudor water heaters in
open vented system
Secondary Circulation Pump
Isolation
Valve Isolation Valve
Temperature
& Pressure
Relief Valve
Non Return Valve
Drain Cock
Isolation ValveIsolation Valve
Isolation Valve
Non Return Valve
Drain Cock
Isolation Valve
T Port
Vent Valve
T Port
Vent Valve Temperature
& Pressure
Relief Valve
fig.2
18.3 unvented or boosted
feed systems
typical installation schematic
single Tudor water heater in unvented application
Balanced Pressure Cold Water Supply Boosted or
Mains Feed
Temperature &
Pressure Relief Valve
Set 7.0 bar & 90-95ºC
Secondary
Circulation
Pump
Isolation
Valve Isolation Valve
Tee piece
provided
Non
Return
Valve
Drain Cock
Tundish
Expansion
Vessel with
air charge
set 3.5 bar
Isolation ValveIsolation Valve
Pressure Limiting Valve
with Integral Strainer
Set 3.5 bar
Core Assembly with
Integral Non Return Valve
Expansion Relief Valve
Set 6.0 bar
fig.3
To install a Tudor NHRE Water Heater as an unvented hot water storage package, then a Water
Byelaws scheme approved kit of safety devices, valves and fittings complying with BS7206:1990 and
satisfying the requirements of Building Regulation G3, available from MHS Boilers Ltd must be installed to
protect the system and prevent water temperature from exceeding 100ºC. The kit of parts includes as a
minimum (see check list of components 18.4), a suitably sized expansion vessel with air change preset at
3.5 bar, a pressure limiting valve preset at 3.5 bar, an expansion relief valve set at 6.0 bar, a temperature
and pressure safety relief valve set 7.0 bar and 90 - 95ºC, a core manifold assembly with integral non return
valve and a tundish.
The components must be installed as shown in fig. 3.
There must be no valves installed between the water heater and the connection to the expansion relief valve.
The connections provided for the connection of the temperature and pressure safety relief valve and
the expansion relief valve must not be used for any other purpose.
The mains water supply pressure must not exceed 12.0 bar.
TUDOR NHRE

12
TUDOR NHRE
typical installation schematic
two Tudor water heaters serving unvented hot water system
Unvented application detail of
core Manifold Assembly
Balanced Pressure Cold Water Supply Boosted or
Mains Feed
Secondary Circulation Pump
Isolation
Valve Isolation Valve
Non Return Valve
Drain Cock
Isolation Valve
Non Return Valve
Drain Cock
Isolation Valve
Temperature
& Pressure
Relief Valve
Expansion
Vessel
Isolation Valve
Isolation Valve Isolation Valve
Pressure Limiting Valve
with Integral Strainer
Core Assembly
with Integral
Non Return Valve
Expansion
Relief Valve
Expansion Relief
Valve Set 6 bar
Core Manifold Inc
Non Return Valve
Remove and Discard
Plug. Connect
Expansion Vessel To
This Port
Pressure Limiting Valve
Set 3-5 bar Inc Strainer Plugged Tapping For
The Take-Off of A
“Balanced Pressure”
Cold Supply if Req’d.
Expansion
Vessel
Isolation Valve
Pressure Limiting Valve
with Integral Strainer
Core Assembly
with Integral
Non Return Valve
Expansion
Relief Valve
Isolation Valve
Temperature
& Pressure
Relief Valve
Isolation Valve
fig.4
fig.5
18.4 Unvented Installation
Component Check List
Water Heater Models NHRE 18 & NHRE 26
Component Part No
1 22mm Pressure Limiting Valve with Strainer &
Balanced Pressure Cold Water offtake - set 3.5 bar PRED 510 008
2 22mm Expansion/Check Valve Assembly with
Integral Expansion vessel connection. Relief setting
6 bar. CORE 215 002
3. 25 litre expansion vessel - Precharge pressure 3.5
bar. XVES 603 041

13
TUDOR NHRE
4. Wall mounting bracket for 25 litre expansion vessel. BRKS 240 024
5. 3/4”BSP expansion vessel connection hose
x 1000mm HOSE 202 106
6. 3/4”MI BSP inlet/22mm relief connection temperature
& pressure safety relief valve with 230mm probe. Set
7.0 bar & 90-95ºC. PTEM 575 901
7. 22mm inlet/28mm outlet straight tundish. TUND 219 001
8. 1”FI BSP equal tee bronze for temperature & pressure
relief valve connection to water heater hot drawoff
connection. ZTEE 250 007
9. 1”x 3/4”BSP reducing bush DZR for temperature &
pressure relief valve connection to tee piece (as
listed above).
Water Heater Models NHRE 36, NHRE 60, NHRE 90
Component Part No
1. 1”MI BSP Union type pressure limiting valve with
strainer - set 3.5 bar. PRED 300 027
2. 1”FI BSP Check valve core assembly with integral
G1 balanced cold/G3/4 vessel/G3/4 expansion relief
valve connections. CORE 255 001
3. 3/4”MI BSP Inlet/22mm relief connection expansion
relief valve set 6 bar. PREL 102 027
4. 40 litre expansion vessel - precharge pressure
3.5 bar. XVES 603 046
5. 3/4”BSP Expansion vessel connection hose x 1000m HOSE 202 106
6. 1”MI BSP/28mm relief connection temperature
& pressure safety relief valve with 230mm probe
set 7.0 bar & 90-95ºC. PTEM 100 002
7. 22mm inlet/28mm outlet straight tundish (for use
with item 3 only). TUND 219 001
8. 1”FI BSP Equal tee bronze for temperature & pressure
relief valve connection to water heater hot water
outlet connection. ZTEE 250 007
9. 11/2”x 1”BSP reducing bush DZR for reduction of hot
water outlet connection on water heater.
10. 1”BSP Nipple DZR
For connection of temperature and pressure relief valve
connection tee piece to water heater hot water outlet
connection.

14
TUDOR NHRE
18.5 unvented systems-
terminating safety discharge pipes
suggested ways of terminating
discharging pipes safely
suggested ways of
terminating discharging
pipes safely
300 mm Min
500 mm Max
Tundish
Tundish
Metal discharge pipe (D1) from
temperature relief valve to Tundish
Metal discharge pipe (D2)
from tundish, with continuous
fall. See 18.5d i-iv.
safety device
(e.g. temperature
relief valve)
Observe detail as Fig.6 above
Discharge below
fixed grating (18.5d
gives alternative
points of discharge)
Discharge above
ground level
Fixed grating
Trapped gulley
Max. 100mm
fig.6
fig.7
Table 1. Sizing of copper discharge pipe "D2" for common temperature valve outlet sizes.
Worked Example
The example below is G 3/4 Temperature and Pressure Relief valve with a discharge pipe (D2) having
4 no. elbows and length of 7m from the Tundish to the point of discharge.
From Table 1
•Maximum resistance allowed for straight length of 28mm copper discharge pipe (D2) from G3/4 T&P
valve is 9m.
•Subtract the resistance for 4 no. 28mm elbows at 1.0m each = 4.0m.
•Therefore the maximum permitted length equates to 5.0m.
•As 5.0m is less than the actual length of 7m therfore calculate the next largest size.
G 3/4
G 1
22mm
28mm
28mm
35mm
42mm
35mm
42mm
54mm
up to 9m
up to 18m
up to 27m
up to 9m
up to 18m
up to 27m
1.0m
1.4m
1.7m
1.4m
1.7m
2.3m
Minimum size of
discharge D1*
Valve oulet size Minimum size of
discharge D2*
from tundish
Resistance created by
each elbow or bend
Minimum resistance
allowed, expressed as a
length of pipe
(i.e. no elbow or bends)

15
TUDOR NHRE
The tundish should be vertical, located in the same space as the unvented hot water storage system
and be fitted as close as possible and within 500mm of the safety device (eg. the temperature relief valve)
and must be away from any electrical device.
The discharge pipe (D2) from the tundish should terminate in a safe place where there is no risk to
persons in the vicinity of the discharge, be of metal and:
a) be at least one pipe size larger than the nominal outlet size of the safety device unless its total
equivalent hydraulic resistance exceeds that of a straight pipe 9m long ie: discharge pipes
between 9m and 18m equivalent resistance length should be at least two sizes larger than the
nominal outlet size of the safety device, between 18m and 27m at least 3 sizes larger, and so
on. Bends must be taken into account in calculating the flow resistance. Refer to diagram 1, Table
1 and the worked example.
An alternative approach for sizing discharge pipes would be to follow BS 6700: 1987 Specification
for design installation, testing and maintenance of services supplying water for domestic use
within buildings and their curtilages. Appendix E, section E2 table 21.
b) have a vertical section of pipe at least 300mm long, below the tundish before any elbows or
bends in the pipework.
c) be installed with a continuous fall.
d) have discharges visible at both the tundish and the final point of discharge but where this is not
possible or is practically difficult there should be clear visibility at one or other of these locations.
Examples of acceptable discharge arrangements are:
i. ideally below a fixed grating and above the water seal in trapped gully.
ii. downward discharges at low level, ie: up to 100mm above external surfaces such as car parks,
hard standings, grassed areas etc. are acceptable providing that where children may play and
otherwise come into contact with discharges a wire cage or similar guard is positioned to prevent
contact, whilst maintaining visibility.
iii. discharges at high level; eg: into a metal hopper and metal down pipe with the end of the
discharge pipe clearly visible (tundish visible or not) or onto a roof capable of withstanding high
temperature discharges of water and 3m from any plastics guttering system that would collect
such discharges (tundish visible).
iv. where a single pipe serves a number of discharges, such as in blocks of flats, the number served
should be limited to not more than 6 systems so that any installation discharging can be traced
reasonably easily. The single common discharge pipe should be at least one pipe size larger than
the last individual discharge pipe (D2) to be connected. If unvented hot water storage systems
are installed where discharges from safety devices may not be apparent ie: in dwellings occupied
by blind, infirm or disabled people, consideration should be given to the installation of an
electronically operated device to warn when discharge takes place.
Note:The discharge will consist of scalding water and steam. Asphalt, roofing felt and
non-metallic rain water goods may be damaged by such discharges. Where children may
play or otherwise come in contact with discharges, a wire cage or similar guard must be
positioned to prevent contact whilst maintaining visibility.
•Maximum resistance allowed fro a straight length of 35mm pipe (D2) from G 3/4 T&P valve
equates to: 18m.
•Subtract the resistance for 4 no. 35mm elbow at 1.4 each = 5.6m.
•Therefore the maximum permitted length equates to: 14.4m
•As the actual length is 7m, a 35mm (D2) copper pipe will be satisfactory.

16
TUDOR NHRE
18.6 secondary
circulation
It is recommended that long dead legs are avoided and that a secondary circulation system is installed
as shown in figures 1 - 4.
18.7 anti stratification
system
Where there is no, or poor secondary circulation it is highly recommended to install an anti-
stratification link utilising all components as would be installed in a secondary circulation system. This avoids
high temperature water from being generated at the top of the appliance under light load operating
conditions. Failure to properly prevent stratification may cause nuisance operation of the safety high
temperature cut out thermostat.
typical anti-stratification system
Drain Cock
IV
IV
NRV
Temperature
& Pressure
Relief Valve
Isolation Valve
Small
Bronze
Pump
HW
Draw offs
fig.8
If the installation is unvented then the following information regarding system water capacity is of the
utmost importance. If the specific installation has a water capacity greater than can be accommodated by
this (standard) expansion vessel supplied with the water heater, then additional expansion vessels must be
installed. Contact MHS Boilers Ltd for advice and guidance on selection of additional expansion vessel/s.
Water Heater Model
NHRE 18
NHRE 26
NHRE 36
NHRE 60
NHRE 90
Standard Expansion
Vessel Size
25 litre
25 litre
40 litre
40 litre
40 litre
Max allowable system
content with standard
expansion vessel
315 litre
315 litre
500 litre
500 litre
500 litre
Max allowable pipework
length with standard
expansion vessel
245m of 28mm Tube
75m of 28mm Tube
424m of 28mm Tube
283m of 28mm Tube
252m of 35mm Tube

17
TUDOR NHRE
It is important to ensure that all pipework is flushed to avoid the damage that foreign particles could
do to control valves, this is particularly important where installation is unvented.
1) Open all outlet taps.
2) Turn on water supply and allow the water heater to fill.
3) Close taps in turn after having purged the system of air.
4) Check for water leaks around the appliance and in particular around any valves or controls.
Check again when the appliance is hot.
5) Check that no water is passing to waste through any relief valves.
6) Test the operation of any temperature and pressure relief and expansion valves by lifting/turning
the manually operated test lever/cap and observing that water flows freely and safely to waste.
7) Check that the discharge pipe is installed so that it falls continuously and that no taps, valves or
other shut off devices are installed in the pipe.
8) Turn on the power supply & the appliance on/off switch - ensure protech system green
lamp illuminates.
9) The burner system should be commissioned by a competent Gas Engineer see section 20.
10) Demonstrate operation to the user including the purpose and operation of any temperature and
pressure relief valve or expansion valve and what to do if these valves should self operate.
11) Hand over this manual to the user for future reference and advise that periodic checks of the
equipment are essential for safety.
Advise that any expansion vessel in an unvented application may need to be recharged
periodically by the installer.
Unvented system controls periodic checks must include:
a) Check and clean the line strainer.
b) Check pressure in expansion vessel and top up as necessary. Must be set 3.5 bar. Check should
be carried out with expansion vessel drained of water to avoid that you cross-read system water
pressure.
c) Check manually by lifting the test lever on the temperature and pressure relief valve.
d) Check manually by turning the test knob on the expansion relief valve.
e) Check discharge pipes from both relief valves to ensure no obstructions.
18.8 filling the water heater/
commissioning the water system

18
TUDOR NHRE
19.0 detail of
burner assemblies
NHRE 90
NHRE 60
NHRE 18
NHRE 26/36
thermocouple pilot
burner
body ignition
electrode
pilot burner
assembly
all-gas
injectors
ignition
button stop
button piezoelectric
ignitor
burner
pressure tapping
restrictor
location
detail
restrictor
gas valve
outlet port
NHRE 18 gas regulation block detail
outlet restrictor
burner fastening
primary
air filter
pilot burner
fastening screw
pilot flame
injector
fig.10
fig.9
fig.11
ab c d e f g
bcde cde
f
NHRE 18 gas regulation block

19
TUDOR NHRE
19.1 burners, injectors, burner pressure &
gas consumption data
18
26
36
60
90
Listing
C - D
C - D - E
C - D - E
C - D - E
B - F
C - D - E
A -B - F -G
Number
2
3
3
3
2
3
4
Diameter
300
300
325
325
300
365
300
Pressure
mbar
9
8.8
11.4
10.3
9.3
Diameter
175
170
190
190
175
210
170
Pressure
mbar
28
35.5
32.9
35.6
35.2
CATEGORIE: II 2H + 3P ENGLAND
Main Injector
Diameter and listing
in 1/100 of mm
Assembly arrangement
according to page 13
burner drawings
Injectors
Nat Gas
group H - G20
34.02 MJ/m3
20
Propane
G31
46.34 MJ/m3
37
Current Designation
Reference
Net calorific value (15ºC/1013 mbar)
Nominal Supply Pressure (mbar)
Equipment Type:
NHRE
Pilot Flame Injector (diameter 1/100 of mm)
Gas Type
27 22
18
26
36
60
90
Nat Gas
4 x 2,5
6.00
7.50
8.85
10.3
LPG
without
without
7.50
without
without
Nat Gas
2 x 2,8
26
without
28
32
LPG
without
without
without
without
without
in m3/h
2.33
3.60
4.65
7.08
10.47
in kg/h
1.71
2.64
3.42
5.20
7.68
Gas Valve Restrictor *
Diameter in mm
Draft Limiter
Diameter in mm Gas Flow Rates at 15ºC & 1013,25 mbar
*The restrictor is always at the outlet of the Gas Valve block.