I have a central heating system with two zone valves, one for the hot water circuit and the other for the radiator circuit. I have a bypass valve installed between the flow after the pump and the return to the boiler. In case it helps, the bypass valve is a Taconova AV23 SETTER Inline with a scale (measuring range) of 8.0 - 30.0 litres/minute. The valve has a window through which you can view the float (attached to a spring) which measures the flow rate through the valve. The valve also has a screw adjustment.
Question1:
I was always under the impression that the bypass valve remained fully closed until the system enters bypass mode – that is, until both zone valves close, the heat exchanger in the boiler stops, but the pump carries on running for a certain period of time in order to dissipate the residual heat in the heat exchanger. However, recently, I noticed that when I switch on either the hot water, or the central heating, or both, the float in the bypass valve moves from its rest position and measures a small flow through the bypass valve. In other words, there appears to be a flow through the bypass valve even when the system is not in bypass mode. Is this to be expected? Or is it symptomatic of a badly adjusted bypass valve?
Question2:
When you adjust the bypass valve by setting the pump speed to 1, placing the system in bypass mode, and turning the adjustment screw with a screwdriver so that the float is set to the boiler minimum flow rate, what exactly are you doing? Are you setting the flow rate at which the bypass valve will open? Or are you ensuring that, no matter what the pump speed is subsequently, the flow through the bypass valve when the system is in bypass mode will always be at least at the boiler minimum flow rate? Or what?
Question1:
I was always under the impression that the bypass valve remained fully closed until the system enters bypass mode – that is, until both zone valves close, the heat exchanger in the boiler stops, but the pump carries on running for a certain period of time in order to dissipate the residual heat in the heat exchanger. However, recently, I noticed that when I switch on either the hot water, or the central heating, or both, the float in the bypass valve moves from its rest position and measures a small flow through the bypass valve. In other words, there appears to be a flow through the bypass valve even when the system is not in bypass mode. Is this to be expected? Or is it symptomatic of a badly adjusted bypass valve?
Question2:
When you adjust the bypass valve by setting the pump speed to 1, placing the system in bypass mode, and turning the adjustment screw with a screwdriver so that the float is set to the boiler minimum flow rate, what exactly are you doing? Are you setting the flow rate at which the bypass valve will open? Or are you ensuring that, no matter what the pump speed is subsequently, the flow through the bypass valve when the system is in bypass mode will always be at least at the boiler minimum flow rate? Or what?