Product description
3
Logano GE515 - We reserve the right to make any changes due to technical modifications.
9
3.1
Operating conditions for Buderus G and GE cast iron boilers
Thermostream technology is a unique feature of Buderus cast iron boilers. Return water is preheated and mixed within
the boiler before it comes in contact with the heated surface of the combustion chamber. The Thermostream technology
ensures there is an even temperature distribution in the boiler and avoids condensate forming within the combustion
chamber. This reduces thermal stress, the main cause of failure of normal cast iron boilers. The benefit of this
technology is that if the minimum boiler operating temperature of the boiler is maintained (
Æ
table below), there is no
need for a conventional shunt pump to be installed, saving the cost of a pump, the electricity it consumes and the
breakdown it can cause. The minimum boiler operating temperature as shown in the table below must be reached within
10 minutes and then be maintained while the burner is running.
3.2
Operating conditions GE 515
1) This temperature has to be reached within ten minutes of the burner starting and has to be maintained whilst the burner is firing.
This operating condition can be easily achieved by the controls monitoring the boiler temperature and reducing the flow
rate through the boiler until the required temperature is reached. This is then maintained by continuing to control flow
based on the boiler temperature. The controls can reduce the flow rate by closing the valves on the mixed heating
circuits or by modulating the boiler primary pumps or by closing the motorised butterfly valves or by having a motorised
valve in the boiler return on a single boiler installation. The Buderus 4000 series controls can manage this process or
it can be done by the BMS.
If it is not possible for the controls to regulate the flow sufficiently to meet this operating condition then a shunt pump
circuit must be fitted to avoid the type of thermal stress that all boilers would experience in these conditions. This shunt
pump circuit can be controlled either with a Buderus 4000 control or with a Buderus 4212 fitted with a ZM427 module.
Failure to ensure that the operating condition is maintained may lead to thermal stress in the boiler and eventual failure
of the sections which would be outside the scope of the warranty.
Boiler controls
Minimum flow
rate through the
boiler
Minimum return
water
temperature
Minimum boiler
operating
temperature for
oil
Minimum boiler
operating
temperature for
gas
Other conditions
Buderus 4000 with
control over all
heating circuits
none
none
50 degrees
1)
50 degrees
1)
none
Where the
Buderus control is
not controlling the
heating circuits ie
External control
(BMS) or
Constant
temperature
control with
Buderus 4212 with
ZM427
none
none
50 degrees
1)
60 degrees
1)
none
