gledhill BoilerMate CP 120 Design, Installation & Servicing Instructions page 4

DESIGN
The BoilerMate CP shown schematically above is designed to provide an improved
method of supplying mains pressure hot water when used with a central plant system.
An important feature of the concept is that hot water can be supplied directly from
the mains at conventional fl ow rates without the need for temperature and pressure
relief safety valves or expansion vessels. This is achieved by passing the mains water
through a plate heat exchanger. The outlet temperature of the domestic hot water
is maintained by a printed circuit control board, which controls the speed of the
pump circulating the primary water from the store through the plate heat exchanger.
The Domestic Building Services Compliance Guide (2013) provides more detailed
information on the guidance contained in Approval Documents L1A and L1B, guidance
to the Building Regulations. The recommended minimum standards specify that
"where the mains water hardness exceeds 200ppm provision should be made to treat
the feed water to water heaters and the hot water circuit of combination boilers to
reduce the rate of accumulation of lime scale".
To comply with this requirement the hardness of the mains water should be checked
by the installer and if necessary the optional factory fi tted in-line scale inhibitor should
be specifi ed at the time of order for hardness levels between 200 and 300 ppm (mg/l).
Where the water is very hard ie 300ppm (mg/l) and above the optional polyphosphate
type, inhibitor should be specifi ed at the time of order. However, this will need to
be fi tted by the installer at a suitable point in the cold water supply to the appliance.
INTRODUCTION
10
4
1
2
11
7
1. Boiler flow
2. Backup immersion heater
3. PHE pump
4. Cold Feed
5. CW inlet
6. HW outlet
7. Drain
8. Return from PHE to store
9. Flow from store to PHE
10. Feed and expansion tank
9
11. Boiler return
3
6
5
8
The printed circuit board incorporates the
facility to automatically run the D.H.W. Primary
pump for about 3 seconds every 30 hours to
help prevent it sticking. For this reason we
would recommend that once the appliance is
installed it should be commissioned and the
electricity left on to the appliance.
Because this product does not require a safety
discharge from a temperature and pressure
relief valve, any installations will be easy to
incorporate into the building and will not suff er
from the problems associated with using PVCu
soil stacks to take the discharge from unvented
cylinders.
The heat losses from thermal stores should not
be directly compared with heat losses from
unvented or vented cylinders because they are
treated diff erently in SAP. This is because the
unvented and vented cylinders are tested at
65°C and the thermal store at 75°C.
Page 4
Figure 1.1