regulating of a hot water heating system can be carried out by adjusting a 3 or
4 way control valve. This allows maintaining the boiler at high temperature
under the control of its aquastat.
This is desirable or necessary for standards fuel boilers.
This « low quality » solution is un-adapted for « low temperature » and condensation boilers because we wish to keep them at the lowest temperature possible.
In general, we would recommend the fitting of a motorised valve piloted automatically depending on the inside or outside temperature. However, this fitting could, in certain cases, lead to an increase in energy consumption if the user initially sets his manual valve in a “Spartan” manner.
Operating principle of 3 way valves (in ‘mixing’ mode).
The temperature variation is carried out by mixing; mixing water from the boiler with water returning from the emitters.
a) It is very cold: the water temperature is at maximum in the radiators
b) It is warm: the water temperature is at minimum in the radiators
c) In mid-season: the 3 way valve is set at intermediary
Start the film below (switch on the sound) and watch the use of a 3 way valve on a boiler which must stay at operating temperature.
(Source : « Apprendre le chauffage à eau chaude sur Simulateur) :
Operating principle of 4 way valves:
a) It is very
cold: the 4 way valve is fully open and the water temperature is at maximum
in the radiators.
b) It is warm: the 4 way valve is “shut” and the water temperature is at minimum in the radiators.
To encourage circulation by thermosiphon, the valve should be fitted, if possible, one metre above the boiler and the valve to boiler return pipe should not be insulated (obviously not ideal).
c) In mid-season: the 4 way valve is set at intermediary