Technical data

21
Water Systems
Purewell VariHeat boilers are suitable for both open vented or sealed
pressurised systems. Sealed systems must comply with Health and Safety
Document PM5 requirements for fuel supply cut off in the event of low and
high pressure conditions. To ensure compliance, consider using a proprietary
pressurisation unit with correctly sized expansion vessels.
In multiple boiler installations, the flow and return headers should be connected
in a “reverse return” arrangement (i.e. the water flow in each header follows
the same direction) thus providing equal flow through each boiler. This also
ensures that the pressure loss across any number of boilers will never be
greater than the head loss across one boilers plus local pipework losses.
System Feed Water Quality
If the boiler feed water has a high degree of hardness, it is recommended that
the water be treated to prevent precipitation of scale or sludge in the boiler
water passageways. Details of additives can be obtained from any reliable
manufacturer of water treatment products or the local water authority.
Open Vent Pipe and Cold Feed Pipe Data
Boiler Open Vent Size Cold Feed Size
<60kW 25mm (1 in) 19mm (
3
/4 in)
60kW - 150kW 32mm (1
1
/4 in) 25mm (1 in)
150kW - 300kW 38mm (1
1
/2 in) 32mm (1
1
/4 in)
300kW - 600kW 50mm (2 in) 38mm (1
1
/2 in)
Pressure Relief Valve
Each boiler, or in the case of a modular installation, each bank of boilers,
must be fitted with a pressure relief valve to BS EN ISO 4126-1,
and sized as shown in BS 6644.
Hamworthy can supply Purewell VariHeat pipe kits which have isolation valves
for each boiler, to enable individual boilers to be shut down from the system.
The pipe kit includes a three-port valve on the flow connection for each boiler,
enabling a single safety valve to be fitted to the connection on the header
pipework. Safety valves are not included.
Where these pipe kits are not used, each boiler must be fitted with a safety
valve in the flow pipework, positioned before any other valve in the system.
BS 6644 provides comprehensive information for the selection and location
of safety valves and attention is drawn to the higher capacity requirements
of safety valves for pressurised hot water systems.
Delivery
Each boiler is despatched fully assembled
and factory tested with the casing and
control panel fitted. The boiler base has been
designed to accept a pallet truck allowing
easy manoeuvrability. The assembly is
protected with cardboard edging and
shrink wrapped for transportation.
The primary flue pipe is supplied
separately for fitting on site.
All Hamworthy products are delivered
to site on a tail-lift vehicle, and deliveries
are closely co-ordinated with the customer,
to suit the site construction programme.
Standard delivery is to ground level from
the tail-lift of the vehicle. To enquire about
special delivery services, please contact
our customer services team.
Commissioning
Hamworthy Heating strongly recommend that
all boilers are commissioned by our service
department. On completion, Hamworthy will
issue a boiler log book which will provide
details of the initial operating settings.
The log book should be used to record any
future maintenance and service work.
For more information on commissioning
contact Hamworthy Heating Service
Department: Tel [phone].
Warranty
Products from Hamworthy carry a standard
two-year warranty on parts, and where
the product is commissioned by Hamworthy
service engineers, then the warranty covers
parts and labour. In offering flexible solutions
for after sales support, Hamworthy can
tailor packages to suit individual customer
requirements, many of which include
extended warranty benefits.