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Sill Gap Problem

Revotec Fan

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I apologise as I may be revisiting an old subject, being a bt new to the Register I hope you will humour me.  I have purchased a Revotec electric fan, it looks pretty straightforward to fit, but I wondering as to where to install the controller.  There is space in the top hose and it looks easy to fit there.  The bottom hose appears to have a length of steel, to fit it there it looks like I would have to cut a section of the steel out, add some hose and then fit the controller between.

HELP...

Thanks

 

Iain

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Hi Iain

Put mine in the top hose, mine is a 'push' fan

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10 minutes ago, Mike C said:

Wouldn't the top hose be a better position to sense engine & cooling load ?

I was  told that if you put the stat in the bottom hose the fan only cuts in if the radiator has been unable to cool the water sufficiently before it goes back to the engine, in the top hose it runs immediately hot water from the engine hits it. Having said that I ran a very early Kenlow with the sensor in the top hose for 20+ years with no drama BEFORE I was told the stat might be in the wrong place. 

 

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22 minutes ago, Graham said:

I was  told that if you put the stat in the bottom hose the fan only cuts in if the radiator has been unable to cool the water sufficiently before it goes back to the engine, in the top hose it runs immediately hot water from the engine hits it. Having said that I ran a very early Kenlow with the sensor in the top hose for 20+ years with no drama BEFORE I was told the stat might be in the wrong place. 

 

I did the same with a Datsun 260Z in the late 1970's -sensor in the top hose and it ran fine. My idea back in those days was this was where engine temperature was sensed by the thermostat and temperature gauge therefore it was the correct place to sense the fan control temperature.

Looking back now I agree with the idea that the fan should only come on if the radiator by itself can't handle the cooling load- hence a sensor in the bottom return pipe is the way to go.

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I agree with Mike.

When located in the flow to the engine, so in the bottom hose, the engine water inlet temperature is controlled, regardless of how well the radiator cools.

When in the top hose, the water in rhe engine can be too cold if the radiator cools very well, like on cold days.

Waldi

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It’s quite an easy job to solder a M22 brass boss onto the bottom tank of the radiator. 
They are widely available. 

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4 hours ago, Waldi said:

I agree with Mike.

When located in the flow to the engine, so in the bottom hose, the engine water inlet temperature is controlled, regardless of how well the radiator cools.

When in the top hose, the water in rhe engine can be too cold if the radiator cools very well, like on cold days.

Waldi

+1

Peter W

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18 minutes ago, BlueTR3A-5EKT said:

When in the top hose, the water in rhe engine can be too cold if the radiator cools very well, like on cold days.

Waldi

I don't think so Waldi. That is what the thermostat is there to prevent, by cutting down flow if the exit water is too cold and so keep the engine temperature up. 

 

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So long as the fan stat is higher than the water thermostat it is fine in the top hose but also needs to be set to cut out at a temp higher than the water stat or it won't switch the fan off.

Modern cars vary in terms of location.

The temp range if sited in the bottom hose would be lower.

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4 hours ago, RobH said:

I don't think so Waldi. That is what the thermostat is there to prevent, by cutting down flow if the exit water is too cold and so keep the engine temperature up. 

 

Hi Rob,

yes, you are correct,

I forgot the thermostat.

So the reason for the temperature sender (which switches the electric fan) being in the bottom of the radiator is to cool the water further back if the radiator alone does not have sufficient capacity to achieve a more stable engine water temperature?? 

Waldi

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In practice I doubt it makes any difference which hose the sensor is in.  As Andy said, you just set the switching temperature accordingly - after all there is no point having the fan switch on until the excess water temperature exceeds the cooling capacity of the radiator and whether you sense that by seeing the rise at the engine output or at the radiator output is pretty much immaterial. 

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8 minutes ago, RobH said:

In practice I doubt it makes any difference which hose the sensor is in.  As Andy said, you just set the switching temperature accordingly - after all there is no point having the fan switch on until the excess water temperature exceeds the cooling capacity of the radiator and whether you sense that by seeing the rise at the engine output or at the radiator output is pretty much immaterial. 

My Kenlow sensor has been in the top hose for over 40 years as per Kenlow's instructions and I have never had any problems with cooling even in in traffic jams!

Bruce.

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I installed two Revotec switches. One in the top hose and one in the bottom.

The bottom (83° )regulates the fan at 50% (inkl. after engine is shut) and the top (95°) kicks in at a 12 degrees higher temperature turning the fan at 100%.

This is possible, since the temperature difference between top and bottom is about 6 degrees.

Ofcourse both switches are set slightly higher than the thermostat (82°) itself.

Works fine.

jochem

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It depends on how well you trust the Revotec switches.

Worth checking they both work because in my experience they do fail relatively easily.

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