[Thermostream]

Thermostream is a Buderus patented technology which allows the boiler to be installed without a minimum return temperature and without a minimum flow rate.

A normal cast iron boiler has a minimum return temperature. If cold water, returning to the boiler, were to come in contract with the hot combustion chamber this would cause thermal stress, leading eventually to boiler failure. To prevent this from happening a normal cast iron boiler has to be installed with a shunt pump circuit which comprises of a sensor, a pump and a mixing valve. When the return temperature to the boiler is too low, hot water is pumped through the mixing valve and back into the boiler. These parts add cost, they make the installation more complicated and time consuming, they consume electricity and are the cause of costly maintenance visits.

Inside a Buderus Thermostream boiler, cold water returning to the boiler is directed through a central feed tube and is injected away from the combustion surface so that it mixes with hot water in the boiler before it comes in contact with the surface of the combustion chamber. There is no need to control the return temperature and therefore you do not need to install a shunt pump circuit.

Conventional Cast Iron Boiler

1. Sensor return flow 1
2. Mixing Pump
3. Actuator, return temperature increase
4. Actuator, heating circuit
5. Pump, heating circuit
6. Thermostatic radiator valve
7. Radiator
8. Flow circuit
9. Return circuit

Buderus Ecostream Cast Iron Boiler

1. Actuator, heating circuit
2. Pump, heating circuit
3. Thermostatic radiator valve
4. Radiator
5. Flow circuit
6. Return circuit

When the burner first fires, the Buderus 4000 Control Unit or the Building Management System (BMS) closes the mixing valves within the heating system to ensure that the boiler reaches 50^oC within 10 minutes. The Buderus 4000 Control Unit or the BMS then maintains the boiler temperature above 50^oC by controlling the heating circuits. There is no minimum return temperature and no minimum flow rates.

Thermostream requires that either a Buderus 4000 Control Unit or the BMS is controlling the boiler temperature, making sure 50^oC is reached quickly and maintained. If there are no mixing valves on each heating circuit, the same effect can be achieved by controlling the circulation pumps, although in this case an additional temperature sensor is required in the return. If the design of the existing heating system or the limitation of the BMS can not ensure these conditions are met, the boiler can still be installed like a normal boiler with a shunt pump circuit.

Once you have installed a Buderus Thermostream boiler, you will never want to install a normal cast iron boiler again.