Heater core & heater valve - which comes first?

[simonvolvo]

Does it depend on the car model? Does it matter?

In a related thread:
http://www.volvoforums.org.uk/showthread.php?t=262208
Ron posted a diagram which showed that the heater core comes first and then the valve. I and someone else questioned this. In my car (1970, B20) the heater valve comes first. However, my heater hoses are no longer original. Stock, by-the-meter, heater hose has been used. So I couldn’t be sure. The drawings in the GCP catalog (both B18 and B20) correspond to Ron’s arrangement.

Doubt set in. Must I change my hoses? Not exactly a 5 minute job.

I have since looked at some engine bays for 1970 Amazons on the Amazonpictures website:

http://www.volvoamazonpictures.se/Vo...php?start=2361

Working back from the latest chassis number, all of them seemed to have the heater valve first and then the core, like in my car. But none of the pics were very clear ... until I got to chassis 349287 (pic copied hereunder) which leaves no doubt.

According to CVI’s parts list the heater hoses for the B18 and B20 do differ - for the B18 there seems to be only one shaped hose whereas, for the B20, all three the hoses are shaped.

So, was the order changed when Volvo changed from B18 to the B20?