240 Heater valve. How does it work?

[hrforever]

The replacement tap is this one
http://cgi.ebay.com.au/16mm-5-8-Car-Hea ... 7C294%3A50

[vegasjetskier]

It looks like a rotary valve. IMO, this will give you flow at a progressively faster rate as the valve is opened, but then you won't get much more at the end due to the crossectional area of the opening. So in order to control the heat you'd need to feather the opening very finely near the beginning of the control travel (at the cold end).

[hrforever]

Ok. I spent a bit of time yesterday with a Volvo 240 heater valve and a hot air gun to see what the capillary was doing to effect the valve.

With the heater tap closed and the heat gun on the end of the capillary nothing changed. The valve stayed shut. With the valve tap fully open and the heat gun on, the valve partially shut (approx 1/3). When the heat gun was turned off the valve returned to the full on position.

Obviously this is a form of water flow regulator to keep the cars heater temp at a fairly constant temp. Now I'm wondering whether the fact the heater core has both the in and out outlets at the top of the core has necessitated the need for this kind of regulation. Anyway, I'm just going to put the replacement Volvo valve in to replace the after market unit and I'll see how it goes.

[sergitin32]

I know this is an old post but I believe the capillary does affect the flow of hot coolant in some way without affecting the position of the valve shaft itself. Maybe by some sort of intruding object that simply forces the flow to diminish or increase depending on the ambiance temp in the cabin. I do have a question, could we just remove this extra fixture and let the valve work just by the shaft mechanical mechanism? I am sure if doable someone else would have done it by now