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Central Heating

Re:du145 honeywell auto bypass valve

I have a potterton profile boiler 60e with a megaflow tank in the loft,the system is plumbed with grundos alpha 2L pump with 2 motorised valve,one for heating and one for hotwater.I have trv valves on all radiator except bathroom which is a tower rail.If i was to install a DU145 honeywell auto bypass valve between the flow and return 22mm what would be the optimum setting of the valve be
Many thanks for your help

2 Answers from MyBuilder Heating Engineers

Best Answer


Have it set to 2 for your system.

All the best,



Answered 23rd Apr 2019

This is a fairly technical procedure. You will need to know the minimum flow requirement for the boiler which can usually be obtained from the manufacturers instructions, if not you may need to phone the manufacturer. Also you will need a graph from the pump manufacturer displaying the pump curves. You can then compare both of these to the bypass valves setting chart which will tell you which setting to use.
Here is a link which guides you through the process:


Answered 16th Apr 2015

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