Can the heater core be turned off?

[YakkoWarner]

A lot of vehicles have a valve to control the flow of hot water through the heater core, whereas the the squarebody vintage trucks don't. I am wondering if that could be added because down here it gets way too hot in the summertime, and even with the controls set to vent I get air much hotter than ambient coming out of the vents.

I've considering disconnecting and coupling the hoses together to just bypass the core in the summertime - I'm wondering if putting a shutoff valve in the line would cause other problems. If the engine depends on the water flow through the heater loop, I don't want to block it off and risk damaging something else, but a valve would be easier than removing and coupling the hoses every summer.

 

[Radiohead]

You could put a shutoff on each outlet of the core and build a crossover out of flush tees and hose. But probably easier to just use a little tubing to clamp each hose to its friend and call it good. Just depends on how complicated you are willing to make the plumbing.

 

[Ricko1966]

I don't like blocking heater hoses like using a shut off valve. Some cars it creates hot spots in the cylinder head or block because that was factored in as a bypass when built. So I just play safe and don't do it. You could make a bypass with 2 ball valves and 2 tees. It would be simple,but as @ radiohead said just couple the 2 hoses for summer is simple. For a by pass find your supply line,remove it from the heater core,put a ball valve right at the heater core. Stick a tee into the old supply line and connect it to the ball valve. On the dog leg of the tee put another ball valve abd another tee. Splice that tee into your heater return line. Let's call heater core ball valve #1 with it shut and other ball valve open water follows path of least resistance from supply to return. With valve 1 open and ball valve 2 shut water has to flow through the heater core.

 

[YakkoWarner]

I don't like blocking heater hoses like using a shut off valve. Some cars it creates hot spots in the cylinder head or block because that circulation was factored in when built. So I just play safe and don't do it. You could make a bypass with 2 ball valves and 2 tees. It would be simple,but as @ radiohead said just couple the 2 hoses for summer is simple. For a by pass find your supply line,remove it from the heater core,put a ball valve right at the heater core. Stick a tee into the old supply line and connect it to the ball valve. On the dog leg of the tee put another ball valve abd another tee. Splice that tee into your heater return line. Let's call heater core ball valve #1 with it shut and other ball valve open water follows path of least resistance from supply to return. With valve 1 open and ball valve 2 shut water has to flow through the heater core.

Thats pretty much what I needed to know and thanks for the prompt responses. If it didn't have a control valve by design, probably not wise to install one. I'll just do the hose coupling trick for now and maybe try to do something more elaborate next year when I'm past heater season again (and cap the pipes for the core with something to keep unwanted debris and creatures out).

 

[justhorns]

Easy- Build a loop with both ends going to the engine. Just plug the heater core hoses, leaving coolant in them. And connect the two hoses coming off the engine. When winter comes next month, just put the hoses back as they were.
If you have the connectors before you do it, you could cut the hoses. So, have two plugs the size of heater hoses 4 clamps, and two connectors to place in the hoses.
The hard way, Me, I have customers that have complained about a hot heater in the cab as you, and have installed normal heater valves, and just manually shut off by reaching into the engine compartment. I have also put choke type cables to actuate the valve from inside. No problems. Below install in a 41 Chevy AK Pickup

 

[DoubleDingo]

....I've considering disconnecting and coupling the hoses together to just bypass the core in the summertime - I'm wondering if putting a shutoff valve in the line would cause other problems. If the engine depends on the water flow through the heater loop, I don't want to block it off and risk damaging something else, but a valve would be easier than removing and coupling the hoses every summer.

This is what I do. Summer, no coolant to the core, but I don't let it drain either. Winter, hook it back up and enjoy the heat.

 

[DoubleDingo]

I have two sets of couplers/unions. One set is 3/4 x 5/8. Second set is 3/4 x 3/4, and 5/8 x 5/8.

 

[Snoots]

There is a 4-port valve that you can use. It is vacuum controlled so you hook it up to a line that has vacuum when the A/C is on.

 

[ali_c20]

I run this from old air products. Its cable controled and works good.

https://www.oldairproducts.com/product/25-1018-bypass-heater-valve

 

[Bennyt]

A previous owner installed valves(3 total) and a bypass loop on my C30. I'm sure it makes a difference but I plan to remove it all pretty soon It looks messy and I like clean and simple.

 

[75gmck25]

I found a vacuum-controlled heater bypass valve, and set it up so when I put the A/C in Max recirculate mode it also bypassed the heater core. Bottom line - it didn’t really seem to make much difference.

 

[Bennyt]

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[90Supurban]

I found a vacuum-controlled heater bypass valve, and set it up so when I put the A/C in Max recirculate mode it also bypassed the heater core. Bottom line - it didn’t really seem to make much difference.

I found mention of this valve on this site recently, looks like the valve from a 95 c/k is the one. It has 3/4 and 5/8 inlets and outlets, about $25. No idea on how well it works but it is on my to do list.

 

[Radiohead]

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Exactly

 

[MikeB]

You can use one of these, properly sized for your hoses, and operate it manually instead of with a cable.

I used something similar on my 82 C10 that was operated by vacuum. Kinda crude, but I would connect the port to a vacuum hose in the winter, and then disconnect and plug the hose in summer. It made a big difference in the summer. Lots of them on Amazon. You just need to find one with the correct hose nipple size.

25-1019 - Heater Valve | Bypass Style, Cable Operated, Pull to Close

Old Air Products has the correct universal fit, cable operated bypass heater valve for your application. Built with Pull to Close action.

www.oldairproducts.com

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