heat exchanger hot water using rear heat

[Flux]

I think with that solenoid valve, he can shut off flow of hot coolant to he exchanger.

[Glider]

Roger that--but I think we might be misunderstanding each other.

He has his bypass valve below the heater core. That means that coolant must run through the heater core before it can get to the bypass valve. My question is--is coolant always running through the heater core, or does it only run through the heater core when the heating system is on?

If coolant only runs through the core when the heating system is on, then coolant would only reach the bypass valve when the cab heat is on.

[Flux]

No worries. I have this bad habit of skimming things and usually miss something. Senility I think.

[Glider]

Originally Posted by Flux

No worries. I have this bad habit of skimming things and usually miss something. Senility I think.

Oh, good. That means I'm in good company. ;-)

[1der]

Glider - I am pretty sure, per previous threads, that hot coolant is ALWAYS circulating through the heater cores. This creates an undesirable effect of the dash vents being warmer than ambient air even when on cold. There is a solenoid valve solution by member JWA which will cut off the flow of hot water to the heater core. This is something I have on my list to do. 86Scotty's solution seems like it would be something similar with bypass capability to run the coolant through a heat exchanger.

[TeleSteve]

I can't speak for the ford vans as my system is on a Chevy, but mine circulates through the heater core all the time. From the few responses here it sounds like the Fords are the same.
The bypass valve I used is actually from GM vehicles that bypass flow to the heater core. So it is possible to add that bypass valve to cut off flow to the heater core.

[Glider]

1der and TeleSteve-
Thank you, that clarifies things.

TeleSteve, in your setup, if you were to cut off coolant flow to the heater core, you would also lose coolant flow to your flat plate system.

Would it be possible to add a bypass system that would not cut off coolant to the heater core, but would, instead, route coolant around the heater core so it would still hit the flat plate system? I'm attaching a quick sketch to illustrate my question.

[TeleSteve]

Originally Posted by Glider

1der and TeleSteve-
Thank you, that clarifies things.

TeleSteve, in your setup, if you were to cut off coolant flow to the heater core, you would also lose coolant flow to your flat plate system.

Would it be possible to add a bypass system that would not cut off coolant to the heater core, but would, instead, route coolant around the heater core so it would still hit the flat plate system? I'm attaching a quick sketch to illustrate my question.

Yes that would be possible, but instead of using the two single bypass valves for the heater core a single double bypass would do. Just run the stock heater hose loop through two of the bypass valves I used, one for the heater core, one for the heat exchanger. Hope that makes sense! I don't have time to make a sketch.
I have never had heat issues from my heater core so this isn't an issue in my van. I did add a mechanical bypass to my early bronco for this reason.

[Glider]

Originally Posted by TeleSteve

Yes that would be possible, but instead of using the two single bypass valves for the heater core a single double bypass would do. Just run the stock heater hose loop through two of the bypass valves I used, one for the heater core, one for the heat exchanger. Hope that makes sense! I don't have time to make a sketch.
I have never had heat issues from my heater core so this isn't an issue in my van. I did add a mechanical bypass to my early bronco for this reason.

That makes perfect sense.
Thank you!

[TeleSteve]

Went back and looked at some of my bookmarks from when I researched heat exchangers. A 20 plate double wall from the same manufacturer is $169. So about $100 more.
B3-14DW 20 Plate Double Wall Heat Exchanger [HX1420DW] | DudaDiesel Biodiesel Supplies