39-40 hot water heater

[30-9]

Hey guys

The hoses going to the heater. Does it matter which way they go in?

Lower hose to lower connection on firewall & upper hose to upper connection or visa versa or no matter?

My heater is not putting out a lot of heat....

[petehoovie]

Hose from the head into the upper heater inlet....

[30-9]

Ok thanks. can anyone explain why it matters? I'm just seeking to learn.

[tubman]

As the coolant passes through the heater core, it loses some of it's latent heat, Cooler water is denser that warmer water so it wants to sink. Sort of like a thermo-sipho cooling system.

[petehoovie]

The water from the head is hotter than that from lower hose of the radiator....

[30-9]

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Thanks Gentlemen

[39topless]

Reverse in summer for AC.

[30-9]

Ok I went out to the garage (brrrrr cold out there) and it connected properly. Why would I only get cool air blowing out (with fan on)?

As for summer I have a shut off valve, but thanks

[petehoovie]

Do you have a valve at the cylinder head? Is it turned on? Did you let the engine warm up? Is the radiator topped off?

[40cpe]

Maybe the heater core is stopped up. Have you checked the flow through it?

[Brooks]

30-9 I sent you a P M about the diode wire.

[big job]

Old golden rule; bottom to top or top to bottom, which means bottom is water pump
that goes to top of heater and bottom of heater goes the top (head) ....

[30-9]

Guys yes valve is open and antifreeze is flowing through it as it should.

Am I reading "big job" post correctly he says hook up should be opposite of what everyone else described.

What am I missing too cold in MA need heat

[trainguy]

Thermostat?

[Terry,OH]

Follow the instructions that came with the heater.

[V8 Bob]

Originally Posted by big job

Old golden rule; bottom to top or top to bottom, which means bottom is water pump
that goes to top of heater and bottom of heater goes the top (head) ....

This ^ is how several vehicle illustrations show the connections, (like the ones below) and the layout I thought was correct for a '40 heater.
The one Terry OH provided isn't real clear, at least to my eyes.




Other diagrams show the exact opposite, like below.



I know the heater will perform better when connected properly, and cross vs vertical core flow may make a difference, so what's correct for a '40 heater?

[JSeery]

One way may be more efficient that the other, but the core is going to get hot either way and is going to provide heat. If the heater core is not getting hot then hot water is not flowing through it. Figure out the problem that is blocking the flow.

I would get it working and then experiment, try the hose connections with both arrangements and see how much difference it makes with the heating produced. Easy to check with a thermometer at the heater.

Looking at diagram Terry posted (which is difficult to see at the posted size) it looks like the lower hose goes to the top of the heater core and the head to the lower core connection. But again, this is NOT going to keep it from working or getting hot either way, just an issue of which is more efficient.

[hotcoupe]

Originally Posted by tubman

As the coolant passes through the heater core, it loses some of it's latent heat, Cooler water is denser that warmer water so it wants to sink. Sort of like a thermo-sipho cooling system.

i believe you should have said "sensible heat", 'latent heat" is a factor only when water as a liquid changes form either to a solid or a vapor.
tom

[JM 35 Sedan]

Originally Posted by JSeery

Looking at diagram Terry posted (which is difficult to see at the posted size) it looks like the lower hose goes to the top of the heater core and the head to the lower core connection. But again, this is NOT going to keep it from working or getting hot either way, just an issue of which is more efficient.

JSeery, when viewing those smaller pictures, click on them and hold the click in place until a drop down window appears. Then click on "open in new window" that enlarges the picture and even allows greated enlagment of that picture so you can see whatever you need to see. Much better than trying to view a small picture in some cases. At least this is how my computer and ipad work, not sure how your viewing system works.

Now, on the other hand, some folks here post pictures sooooo damn LARGE that they will not fit on the screen of my tablet, and are an even worse fit on my Droid (largest sceen available) smart phone. Sometimes these attached pictures are so large that I have to download them, and then downsize them, to be able view them properly. Not gonna mention any names here

[JSeery]

Yep, that is one method I have used. I normally save a photo to my desktop and enlarge them from there. This image does not enlarge that well for me to be sure of how the connections are made, are you able to enlarge it enough to tell of sure?

But it does look (to me) that the lower heater core hose goes to the head and the upper heater core hose goes to the lower radiator hose.