Heater core shutoff valve? - ZR-1 Net Registry Forums

VetteMed · 06-11-2011

My recent A/C issues have gotten me wondering about hot water flow through the heater core, which in these cars occurs regardless of A/C setting, from what I can tell. It seems like having 200+ degree coolant in the heater box, when trying to deliver cold air just inches away, is counterproductive and likely to reduce ultimate cabin cooling capacity. I know there's the blend door, which closes fully when the Temp is set to "60", but I would assume there's still some heat being radiated through that door and perhaps through the plastic heater box housing into the underdash space and into the cabin.

Has anyone installed a valve to block off coolant flow into the heater core in the summer months? Or does someone have a reason why this would be a bad idea? Or am I just making something out of nothing?

Thanks
Andrew

Paul Workman · 06-12-2011

Sounds like a candidate for a science experiment to test your hypothesis!

Easy enough to run the AC with at thermometer in the air stream: 1) with the heater core in normal config, and then 2) a simple "U" bypass installed in the heater circuit. Comparing the results would be interesting - to me at least (as I love science experiments - always have

)

P.

VetteMed · 06-12-2011

Quote:

Originally Posted by Paul Workman

Sounds like a candidate for a science experiment to test your hypothesis!

Easy enough to run the AC with at thermometer in the air stream: 1) with the heater core in normal config, and then 2) a simple "U" bypass installed in the heater circuit. Comparing the results would be interesting - to me at least (as I love science experiments - always have

)

P.

Paul, thanks for the reply. I think that will be the plan, to see if there's an appreciable difference. If so, I will probably try to install something semi-permanent to act as a switchable bypass.

VetteMed · 06-12-2011

I just got to thinking -- the heater bypass valves that are available, are 1-in, 2-out, where one of the outputs goes to the heater core, under heat demand, and when AC is needed, the other output is supposed to return coolant to the water pump or other suitable area in the cooling system return side. Trying to figure out where I'd route the bypassed coolant back to if I were to plumb in such a valve.

EDIT: Looks like 4-port valves exist, to form an "H" in the system, I think that would be the way to go here if needed..

QB93Z · 06-13-2011

I would suggest that you consider the effect of having stagnant coolant in the heater core. I suspect that you will eventually have issues with clogging of the heater core and possibly corrsion. You may want to have a small amount of flow to keep the heater core coolant from stagnating.

My comparison is the Throttle Body coolant cavity. That cavity has relatively stagnant coolant in it. Every throttle body plate that I have removed has had a "goopy" mess of deposited coolant in it and a lot of throttle bodies I have seen have external corrosion issues.

Jim

-=Jeff=- · 06-13-2011

84-87 used a heater control valve on the Heater core lines that accomplished what I think you want to do:

here is a post from CF

http://forums.*************.com/c4-t...-corvette.html

On thing I am unsure of is what vacuum line to use..

06-11-2011	#1
VetteMed Join Date: Mar 2009 Location: Orlando, FL Posts: 1,821	Heater core shutoff valve? My recent A/C issues have gotten me wondering about hot water flow through the heater core, which in these cars occurs regardless of A/C setting, from what I can tell. It seems like having 200+ degree coolant in the heater box, when trying to deliver cold air just inches away, is counterproductive and likely to reduce ultimate cabin cooling capacity. I know there's the blend door, which closes fully when the Temp is set to "60", but I would assume there's still some heat being radiated through that door and perhaps through the plastic heater box housing into the underdash space and into the cabin. Has anyone installed a valve to block off coolant flow into the heater core in the summer months? Or does someone have a reason why this would be a bad idea? Or am I just making something out of nothing? Thanks Andrew __________________ 2004 Z06/Z16 LeMans Commemorative Edition 1991 ZR-1 #302 White/Gray (sold) 1991 ZR-1 #1147 Red/Saddle (sold)

06-12-2011	#2
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,491	Re: Heater core shutoff valve? Sounds like a candidate for a science experiment to test your hypothesis! Easy enough to run the AC with at thermometer in the air stream: 1) with the heater core in normal config, and then 2) a simple "U" bypass installed in the heater circuit. Comparing the results would be interesting - to me at least (as I love science experiments - always have) P. __________________ Good carz, good food, good friendz = the best of timez! 90 #1202 "FBI" top end ported & relieved Cam timing by "Pete the Greek" Sans secondaries Chip & dyno tuning by Haibeck Automotive SW headers, X-pipe, MF muffs Former Secretary, ZR-1 Net Registry

06-12-2011	#4
VetteMed Join Date: Mar 2009 Location: Orlando, FL Posts: 1,821	Re: Heater core shutoff valve? I just got to thinking -- the heater bypass valves that are available, are 1-in, 2-out, where one of the outputs goes to the heater core, under heat demand, and when AC is needed, the other output is supposed to return coolant to the water pump or other suitable area in the cooling system return side. Trying to figure out where I'd route the bypassed coolant back to if I were to plumb in such a valve. EDIT: Looks like 4-port valves exist, to form an "H" in the system, I think that would be the way to go here if needed.. __________________ 2004 Z06/Z16 LeMans Commemorative Edition 1991 ZR-1 #302 White/Gray (sold) 1991 ZR-1 #1147 Red/Saddle (sold) Last edited by VetteMed; 06-12-2011 at 11:41 AM.

06-13-2011	#5
QB93Z Join Date: May 2007 Location: Westminster, Maryland Posts: 3,685	Re: Heater core shutoff valve? I would suggest that you consider the effect of having stagnant coolant in the heater core. I suspect that you will eventually have issues with clogging of the heater core and possibly corrsion. You may want to have a small amount of flow to keep the heater core coolant from stagnating. My comparison is the Throttle Body coolant cavity. That cavity has relatively stagnant coolant in it. Every throttle body plate that I have removed has had a "goopy" mess of deposited coolant in it and a lot of throttle bodies I have seen have external corrosion issues. Jim __________________ If it isn't fun, you aren't doing it right! 1990 Black ZR-1 - sold 1993 Quasar Blue ZR-1 1994 Competition Yellow ZR-1 1995 Dark Purple ZR-1 Maryland State Coordinator WAZOO Member

06-13-2011	#6
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,180	Re: Heater core shutoff valve? 84-87 used a heater control valve on the Heater core lines that accomplished what I think you want to do: here is a post from CF http://forums.************.com/c4-t...-corvette.html On thing I am unsure of is what vacuum line to use.. __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Shelby Series 1 - Wilwood Brakes Custom Interior NCM Lifetime Member #978 Last edited by -=Jeff=-; 06-13-2011 at 12:18 PM.*