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Heater valve, is it vital?
tegwin - 23/6/07 at 09:21 AM

I have just finished fitting my polo heater matrix and blower...

However, im wondering how important it is that I have a valve on the flow pipe to the heater matrix....do many people bother fitting one or do they just let the heater get hot all the time and only use the fan when they want hot to come into the car?....

BenB - 23/6/07 at 09:48 AM

You only need a heater valve if you want the facility to blow cold air in....

Theoretically because you're not cooling that water (when the heater fan isn't on) your coolant will run hotter than if you had 100% going through the radiator...
In practice the % flow through the heater matrix isn't that huge (unless you've got a stupidly over spec'd system) so it's not really a problem!!!!

britishtrident - 23/6/07 at 09:59 AM

quote:
Originally posted by BenB
You only need a heater valve if you want the facility to blow cold air in....

Theoretically because you're not cooling that water (when the heater fan isn't on) your coolant will run hotter than if you had 100% going through the radiator...
In practice the % flow through the heater matrix isn't that huge (unless you've got a stupidly over spec'd system) so it's not really a problem!!!!


You never have 100% flow through the rad a bypass connection is always required otherwise the bottom end of the engine will be over cooled.

A lot of cars (for example the Cortina) run the heatmatrix hot all the time the heater air output temperature is controlled by air blending.

tegwin - 23/6/07 at 11:35 AM

How does the sierra heater work?....Is that run on a bypass system or is that peminantly on?

RazMan - 23/6/07 at 11:38 AM

I used a Focus electric heater valve (built in solenoid) and it is interesting to note that when the heater was switched to the 'off' position, a small amount of water is let through the matrix, presumably to stop airlocks.