Beware of Thermex brand front heater core

[DanHoug]

thanks, Dave. looks way better!

on another observation on that core... there was very little flow restriction that i could detect via backpressure on the inlet. it'll be interesting to see how it heats.

-dan

[dobryan]

Dan, It would be great if someone had a Thermex brand one that they could send you to IR test.
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[DanHoug]

i'd love to do that! anyone have a new bad core they removed due to no heat they want to send me? it'd be very interesting to see if there are anomalies in the water flow.

-dan

[MsTaboo]

Anyone have an idea of how much water is passing through the heater core while driving?
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[DanHoug]

on an '85 i had, i wanted to increase the front heater output so i added a 12v hot water circulating pump in the line to the front heater. made a dramatic difference in heat. so my short answer would be, "Not Enough".

mind you, this was for a van being driven year round with -30F winter temps.

-dan

[Slimvest]

[dobryan]

[Slimvest]

[DanHoug]

as Dobryan says, all i have is just one Apple. no other Apple or Orange to compare with.

that said, the test proved what i wanted it to... namely that there wasn't short circuiting in the core. it distributed incoming hot water nicely over the entire surface, and that is flow rate independent. what we DON'T know is:

- does a proven bad Thermex have the same heat distribution?

- does the reduced fining of this core compared to the stock one reduce heat transfer? (there's more flattened tubes however which increase the Delta T onto the fins)

- does it bleed air as easily as the stock?

i think i have time to start the R&R this weekend. as always, the proof of the pudding is in the tasting. my current heat output sucks... bad foam, old heater core, frickin' mouse nest present observed (and pulled out) thru Mullendore port, locked up fan.

aaaand just to throw another variable in this equation, i'm pulling out my perforated restrictor plate and going to figure out some sort of fresh air flap. or maybe duct tape.

-dan

[cmayna]

Lots of good info here. Thinking of dropping my dash to reseal the heater box to the front cross member and will be replacing the heater core "while I'm at it".
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Craig

[boat_builder]

I'm having the exact same problem over here in Ireland with a new thermex heater matrix.
Blowing cold air and I can't get any more air out or coolant into the system. I've revved it pretty hard and driven about 40 miles and its still stone cold.
Looks like the dash has to come out for a third time!!

[VeeDubDaySpa]

This is all very interesting. So does anyone know why GoWesty stopped selling their "new" model???
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[djkeev]

[gbrandt]

[photogdave]

I think there is some confusion here. About two years ago GW started selling an in-house designed core made from brass and aluminum. I have this unit and it seems to work fine. I don't get as much heat as I used to but I also failed to get the heater valve hooked up to the wires correctly and cant open it all the way.
GW stopped selling this particular unit and now sells an off-the-shelf core that is supposed to be better than OEM.
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[VeeDubDaySpa]

[crazyvwvanman]

The 2 heater hoses that go from engine to the dash are easily access under the middle of the van. You could simply cut them there and splice in your replacement heater core for a stationary test.

Or hook it up in place of the rear heater if that is easier in your vehicle.


Mark

[boat_builder]

I cut my Thermex one open to see why it wouldn't heat up.
I reckon the gap under the scalloped edge of the divider lets all of the coolant flow in one pipe and directly out the other without being forced through the small passageways at all.
Hence why the pipes feel hot but the core doesn't produce heat.
Foursome vehicle heaters in the UK make a really good heater core. It works great.

[DanHoug]

that's so crazy bad. thanks for cutting one open.
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-dan
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[dhaavers]

Ridiculous. You could do better than that with a piece of window screen & a pack of drinking straws...



- Dave
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