ANDREWS WATER HEATERS 7799195 Unvented System Kit Installation Guide
- June 9, 2024
- ANDREWS WATER HEATERS
Table of Contents
ANDREWS WATER HEATERS 7799195 Unvented System Kit
Product Information
7799195 – UNVENTED SYSTEM KIT for MAXXflo EVO Lite Water Heaters
The 7799195 – UNVENTED SYSTEM KIT is designed for use with MAXXflo EVO Lite
Water Heaters. It is a 3.5 Bar Unvented Kit that comes with a Through Flow
Valve. The kit comprises of three components, namely:
- B1 One-piece Inlet Control (pressure reducing valve 3.5 bar, check valve, pressure relief valve 6 bar)
- B2 Expansion Vessel (24 litre) c/w bracket
- B3 Through Flow Valve
The kit also includes a Tundish (B5) that is supplied with the SC15/SC25 or SC35/SC45 water heater, depending on the model purchased.
OVERVIEW
3.5 Bar Unvented Kit c/w Through Flow Valve. Part No. 7799195 (Comprising B1-B3)
| Components| Andrews| Size
---|---|---|---
| Part No.|
B1| One-piece Inlet Control (pressure reducing valve 3.5 bar, check valve,
pressure relief valve 6 bar)| 7705044| 28mm comp
B2| Expansion Vessel (24 litre) c/w bracket| 7727951| ¾” BSP
B3| Through Flow Valve| 7727953| ¾” BSP
B4| Temperature/Pressure Relief Valve 7 bar/95˚C (Factory fitted on
SC15/SC25)| G068| ¾” BSP
B4| Temperature/Pressure Relief Valve 7 bar/95˚C (Factory fitted on
SC35/SC45)| 7705045| 1” BSP
B5| Tundish (Supplied with the SC15/SC25 water heater)| 7807481| 22mm x 28mm
comp
B5| Tundish (Supplied with the SC35/SC45 water heater)| 5139811| 1” – 1¼” BSP
INSTALLATION INSTRUCTION
- This addendum is to be read in conjunction with the manufacturer’s technical data and installation instructions.
- Installation of unvented hot water systems must comply with Part G3 of the Building Regulations 2010.
- Flush supply pipework to remove all flux and debris prior to fitting inlet controls.
- Failure to do this may result in irreparable damage to the controls and will invalidate the warranty.
NB: Item B1 is not adjustable.
B1 One-piece Inlet Control Valve
The B1 One-piece Inlet Control Valve is a combination of a pressure
reducing valve, single check valve, pressure relief valve, and dedicated
connection for an expansion vessel and balanced cold water connections. The
pressure-reducing valve is set at 3.5 bar to control the operating pressure,
and includes a wire gauze line strainer. The check valve function prevents
back-flow and ingress of hot water into the cold supply. The inlet control
valve has 28mm female threaded inline ports, and the check valve housing
incorporates a 22mm comp cold water take off and the 3/4 connection for an
expansion vessel. An expansion relief valve is set to discharge at 6 bar, with
a 22mm comp outlet. This combination incorporates: pressure reducing valve,
single check valve, pressure relief valve and dedicated connection for an
expansion vessel and balanced cold water connections. The pressure reducing
valve is set at 3.5 bar to control the operating pressure, and includes a wire
gauze line strainer. The check valve function prevents back-flow and ingress
of hot water into the cold supply. In addition to the 28mm female threaded
inline ports, the check valve housing incorporates a 22mm comp cold water take
off and the 3/4”connection for an expansion vessel. The water pressure at this
point will be similar to that available at the hot water outlet of the heater.
If higher flow rates are required for the cold water services, a suitable
‘tee’ fitting should be incorporated upstream of B1. An expansion relief valve
is set to discharge at 6 bar, with a 22mm comp outlet. Not only does this
limit the maximum system pressure to 6 bar, it also helps to indicate a
malfunction in the system (eg expansion vessel fault, or cross-flow). The
expansion relief valve should be fitted with the discharge directed downwards
or horizontally; if fitted in an inverted position, debris may be deposited on
the seat of the valve and prevent full closure. The easing knob on the valve
should be operated periodically to ensure the valve is able to function. There
is a 1/4” gauge port to enable pressure gauge monitoring if required. If
unused, the port should be sealed with the plugs supplied.
B2 Expansion Vessel (24 litre)
The B2 Expansion Vessel is designed to accommodate the expansion resulting
from increased water temperature. The dry side of the diaphragm is charged to
a pressure of 3.5 bar. It is recommended that the dry side air pressure within
the expansion vessel is set to equal the dynamic water pressure of the system.
This may involve pumping up or reducing the air pressure within the expansion
vessel via the Schraeder-valve in the top of the expansion vessel. This
pressure should be checked periodically, via the Schraeder-type valve on the
top of the unit. This vessel is designed to accommodate the expansion
resulting from increased water temperature. The dry side of the diaphragm is
charged to a pressure of 3.5 bar. It is recommended that the dry side air
pressure within the expansion vessel is set to equal the dynamic water
pressure of the system. This may involve pumping up or reducing the air
pressure within the expansion vessel via the Schraeder-valve in the top of the
expansion vessel. This can be done by using a hand or foot pump and a tyre
gauge during the commissioning stage of the water heater and system. This
pressure should be checked periodically, via the Schraeder-type valve on the
top of the unit.
N.B: Water pressure must be relieved whilst checking and adjusting the
pressure.
B3 Through Flow Valve
The B3 Through Flow Valve is designed to divert a proportion of the water
that is flowing through a system into the vessel to cause turbulence and
encourage an exchange of water within it. This is designed to divert a
proportion of the water that is flowing through a system into the vessel to
cause turbulence and encourage an exchange of water within it.
B4 Combination Temperature/Pressure Relief Valve
This opens at 95˚C and/or 7 bar. Its principle function is to prevent the
water temperature from, at any time, exceeding 100˚C, in compliance with the
Requirement G3 of the Building Regulations 2010.
B5 Tundish
To comply with the requirement G3 of the Building Regulations 2010 this must
be installed within a distance of 500mm for the Temperature/Pressure relief
valve. When fitting B1 care must be taken to ensure that flow arrows, marked
on the components, are pointing in the direction of water flow: i.e. towards
the heater.
Size
- The UNVENTED SYSTEM KIT is compatible with MAXXflo EVO Lite Water Heaters.
- Please ensure that you read and understand these instructions before commencing installation and leave this manual with the customer for future reference. Andrews. Built to perform.
- This addendum is to be read in conjunction with the manufacturer’s technical data and installation instructions.
- Installation of unvented hot water systems must comply with Part G3 of the Building Regulations 2010. Flush supply pipework to remove all flux and debris prior to fitting inlet controls. Failure to do this may result in irreparable damage to the controls and will invalidate the warranty.
- NB: Tees, elbow, stop valve and pipework not supplied. NB: Item B1 is not adjustable.
Product Usage Instructions
- Before installing, flush supply pipework to remove all flux and debris to avoid irreparable damage to the controls.
- Install the UNVENTED SYSTEM KIT in accordance with the manufacturer’s technical data and installation instructions.
- Ensure that the water pressure is relieved whilst checking and adjusting the pressure of the B2 Expansion Vessel.
- Set the dry side air pressure within the expansion vessel to equal the dynamic water pressure of the system. This may involve pumping up or reducing the air pressure within the expansion vessel via the Schraeder-valve in the top of the expansion vessel.
- Periodically check the pressure of the expansion vessel using the Schraeder-type valve on the top of the unit.
- If higher flow rates are required for the cold water services, incorporate a suitable ‘tee’ fitting upstream of B1.
Adjustments
Important: Before beginning the installation it is necessary to make some adjustments to two of the supplied parts to allow correct fitting of anti legionella valve to the expansion vessel. Follow steps 1 to 3 below.
- Remove the parts supplied in the box marked ‘Anti Legionella valve’.
- Take out the white plastic tube measuring 19.5mm in length. 3mm will need to be cut off the smaller diameter end of the tube (A). To aid with the cut the plastic tube has an indented ridge to guide the knife (see photo below). This cut will allow the tube (B) to fit inside the expansion vessel end as required in the Anti legionella instructions (supplied separately in box).
- Take the anti legionella valve and identify the end with the female thread that screws onto the expansion vessel. Located here is a flat white plastic paddle (C) that will require cutting down by 3mm. The paddle already has a small crease at the desired break point and may break off without the need for a knife (D).
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