On 30 Mar, 23:51, LaserMark wrote:
Hi

I just bought a new Siemens/Landis 3 port diverter valve to replace
the Switchmaster valve in our heating system that has finally expired
after 20 years.

I thought I would check it works OK before installing it, so after
wiring it in I observed the position of the valve ( its like a rubber
wedge) while changing the demand for heating and hot water.

With CH demand but no HW demand the CH port is fully open. With HW
demand but no CH demand the HW port is fully open. So far so good. But
with CH demand AND HW demand the valve does not go to exactly mid
point. I would estimate the valve goes to a position that is 60% CH
and 40% HW. Is this how these vlves are set up normally or is the
valve faulty?

Should not be a problem - it means the heating circuit will have a
bigger share of the available flow from the pump.


I can imagine that it would be an advantage to operate like this
because the CH loop will require greater flow than the HW loop. But is
this how it should be?

I believe the 'mid' position is set by microswitches, are these
adjustable?

No