From memory, the connection to the HBV goes into the nose of the pump and the feed to the heater matrix (bulk head connection, top) is from the side due to the fact its an impeller pump
Your drawing suggests that the t-piece pipe connects to the HBV, heater matrix return pipe and the pump, is that correct?
Usually its to the HBV (lower from memory) connection, heater matrix return (lower connection) and the coolant return pipe from rad (stainless pipe to the rear of block).
The nose of the pump goes to heater matrix, I have double checked that now.
Yes the drawing is right, it goes to lower connection of the heater matrix but it just goes trough the pump.
So I think that the electric pump is going to be removed or then put under manual switch because:
In situation where the HBV is vacuumed it doesn't matter which way the pump is pumping it's either creating a pressure or then underperssure to the heater matrix and HBV. . Am I right?
When the HBV is not vacuumed then there could be the pump pumping but only pumping out of the heater matrix because if it would pump against the heater matrix there would be two ways going in.... Am I right?
Also the pre heater that I'm going to install will work just fine pumping into the heater matrix because then the HBV is not vacuumed and the water can go to engine trough HBV... I am right, am I?