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The mCHP BoilerMate A-Class shown schematically in figures 2.1 and 2.2 is primarily
designed for the new build market. The thermal store completely isolates the mCHP
unit from the space heating and hot water demands and functions.
The heat losses from thermal stores should not be directly compared with heat losses
from unvented or vented cylinders because they are treated differently in SAP. The
SAP calculator takes account of the type of store and various correction factors are
included to reflect the different ways that the hot water and heating operates.
For further information please request a copy of the SAP 2005 Data Sheet which
provides the information required to produce SAP calculations for all Gledhill Thermal
Storage products.
The Building Regulations L1A: New dwellings/L1B: Existing dwellings and the
requirements set out in the Domestic Heating Compliance Guide 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 fitted electronic in-line scale
inhibitor should be specified 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 specified at the time of order. However, this will need to be
fitted by the installer at a suitable point in the cold water supply to the appliance.
if scale should ever become a problem the plate heat exchanger is easily isolated and
quickly replaced with a service exchange unit which can be obtained at a nominal
cost from Gledhill.
Because this product does not require a safety discharge from a temperature and
pressure relief valve, any installations will not suffer from the problems associated
with using PVCu soil stacks to take the discharge from unvented cylinders.
The mCHP BoilerMate
A-CLASS
controls incorporate the following main functions:-
• They sense the demand for space heating and hot water from external user controls
and switch on the appropriate system components to satisfy these demands.
• The space heating and plate heat exchanger pumps operate for a few seconds every
36 hours when there is no demand for space heating and domestic hot water to
reduce the likelihood of the pumps and diverter valves sticking.
• They provide the mCHP pump overrun facility when necessary.
• Depending upon the store temperature and the energy demands, they provide
switch on and off control signals for running the mCHP unit in normal and boost
modes.
• Depending upon the store temperature and the energy demands, they also provide
switch on and off control signals for the built in 6kW electric boost heater to satisfy
short term peak space heating loads greater than the thermal rating of the mCHP
unit.
• in the event of failure of the mCHP unit they provide the opportunity to manually
energise the 'Switch' 6kW electric backup facility for hot water and central
heating.
SYSTEM DESCRIPTION 2.0
2.1 INTRODUCTION
Page 7
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