Mailing List flyrotary@lancaironline.net Message #41307
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] Re: Water Return in Radiator
Date: Sun, 27 Jan 2008 17:37:04 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
I agree, Wendell, the angle of the heater return into the return side of the radiator does seem a bit strange.  You would certainly think they would want it pointed toward the water pump inlet in the direction of the flow.  Sometimes production considerations override engineering considerations -  it looks like it might be a bit more difficult to produce if the top of heater tube was oriented toward the radiator rather than away as they have apparently done it.  But, still hard to believe they couldn't have found a better angle. 
 
Ed
----- Original Message -----
Sent: Sunday, January 27, 2008 3:51 PM
Subject: [FlyRotary] Re: Water Return in Radiator

 
----- Original Message -----
Sent: Sunday, January 27, 2008 8:56 AM
Subject: [FlyRotary] Re: Water Return in Radiator

Wendell, while the heater return does return to the radiator hose, it is not the hose connected to the output side of the pump (thermostat housing) , but instead the heater return is routed to  the hose from the radiator to the inlet side of the pump.  At least it is in the both the 1986 and 1991 shop manuals I have.  This is a low pressure area whereas the hose from outlet of waterpump (thermostat housing) to the radiator is in a higher pressure area.
 
Ed
I stand corrected (sort of), just had the radiator upside down when first looked at it.  The angle of the heater return connection is not 90 degrees and angles toward the radiator, and would be against the flow going back to the engine and IMHO would restrict coolant flow to the heater. This is presuming that the heater flow is going from the outlet on the rear housing, to the heater and then back to the engine. The additional cooling by passing the heater coolant through the radiator would be minor and when the heater is needed, it is cold and no extra engine cooling would be necessary.  For max heater flow, one would want the Y facing the engine. 
 
Wendell
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