14
Limitations
The Andrews water heater should not be used in any of the following instances:
Solid fuel boilers or any other boiler in which the energy input is not under effective thermostatic control unless
additional and appropriate safety measures are installed.
Gravity circulation primaries.
Steam heating plant unless additional and appropriate safety devices are installed.
Ascending spray type bidets or any other class 5 back syphonage risk requiring that a Type AA, AB, AD or AG air gap
be employed.
Water supplies that have either inadequate pressure or where the supply may be intermittent.
Situations where it is not possible to safely pipe away any discharge from the safety valves.
Areas where the water consistently contains a high proportion of solids, eg. suspended matter that could block the
strainer, unless adequate filtration can be ensured.
The installation must be carried out in accordance with the relevant requirements of:
The appropriate building regulations: either The building regulations (England), The building regulations (Scotland) or
building regulations (Northern Ireland). The water fittings regulations (England and Wales) or water byelaws Scotland).
Water supply
The mains water supply to the property will be supplying both the hot and cold water requirements simultaneously. It
is recommended that the maximum water demand be assessed and the water supply checked to ensure this demand
can be met.
NOTE: A high mains water pressure will not always guarantee high flow rates.
The main supply pipe should be in 28mm minimum. This sizing will need to increase accordingly to the size of the cylinder
inlet. The minimum mains water supply requirements should be 0.15 MPa (1.5 bar) working pressure and 100 litres per
minute flow rate. At these values outlet flow rates may be poor, the higher the available pressure and flow rate the
better the system performance will be.
The water supply must be of wholesome water quality (Fluid Category 1 as defined by the Water Supply Regulations
1999). The Andrews Water Heaters - STXL cylinder is to be used for the storage of wholesome water (max. 250mg/l
chloride).
IMPORTANT INSTALLATION NOTE:
WHERE THE INLET SUPPLY TO THE PRESSURE REDUCING VALVE (PRV) IS ROUTED THROUGH A HEATED
SPACE AND IS FITTED WITH A CHECK VALVE OR OTHER FITTING THAT WOULD PREVENT BACK FLOW, HIGH
PRESSURES CAN BE EXPERIENCED IN THE INLET PIPE DUE TO WARMING THAT CAN CAUSE DAMAGE TO THE
PRV OR OTHER FITTINGS ON THE INLET SUPPLY.
IN THESE CIRCUMSTANCES, THE INSTALLATION OF A MEANS TO ACCOMMODATE EXPANSION AND THUS
LIMIT THE PRESSURE RISE IN THE INLET PIPE IS RECOMMENDED. REFER TO THE INSTALLATION SECTION FOR
FURTHER DETAILS.
Water container:
Duplex stainless steel. 100% pressure tested to 2.25 MPa (22.5 bar).
