2002 san heater connections

What are these connections for? Why are they tied together with the valve being open? Are they the connections for the heater that I couldn't locate? One is on the water pump, one is on the lower part of the block starboard side.

quinner wrote: Typically a heater will tap in 2 spots with 1.5-2" hose, the water pump and the manifold.

I think you mean 5/8".

I guess I didn'T give enough info, this is a gm 350 apex. The heater is factory but the coil was busted when I bought it and the lines are there but just laying under the motor. On your picture, the line connected to the manifold on yours, my manifold has a temp sensor in that location, and to turn a 90 elbow into this location can't be done because it would hit the fuel rail. So could this be why the other locations where used? Also is the manifold the supply side to the heater and the pump connection the return? Which would the connection I have at the lower side of the block be? Supply or return? On your picture what is the blue line tee'd into that line in the background?

Deleting post that is being mysteriously edited

Deleting post that is being mysteriously edited

You two are both clowns!

No one is asking which is supply and return on the heater core side... of course it doesnt matter which way the water flows through the core.

Not sure why it was implied that pulling the feed from the block would provide inadequate heat. Block and intake manifold are the 2 most common places Ive seen the feed tied to. Intake might be better since its last in the cooling loop, but block should be fine too.

Return can be plumbed to the rwp or circ pump, seems the OP's set up uses the latter. Nothing wrong with that.

mike32 wrote: What are these connections for? Why are they tied together with the valve being open? Are they the connections for the heater that I couldn't locate?

The answer to your question is yes, those are the heater connections. Theyre probably tied together in order to bypass the broken core. Putting a hose between them would be the easiest way to do that... way easier than removing the barbs and replacing with plugs. I suspect it doesnt matter much whether that valve is open or closed.

Hollywood wrote: And then there were 3 clowns. Both of those ports have positive pressure. Which ever one is higher pressure will be the supply. I can't say for sure which one that actually is.

Bingo. Return before the RWP.

Anyone with factory installed heaters please chime in. Year/model/engine

So let me get this straight, the block and the intake manifold are both positive pressure. So the other side needs to go to the small connection on the water pump referred to as RWP. The pic that I posted shows the line connected at the water pump, isn't this the return side of the pump? The only discharge off the pump goes to the testator housing, right?

Tstat housing.   Well which part is incorrect?

Well I guess I will. I can't test it until spring and I wanted to make sure that it was correct while I had time to do it.