heater hose re-route ?

[stan360]

I am adding a water heated inlet manifold to the car, because that seems to be the minispares option for a single HIF44 carb.  Here is a diagram of my old system hose routing when it was an exhaust heated manifold.

I drew up what I am thinking is the new route.  Is this correct ?  Add a two hole blanking plate and route both heater in and back out hoses through it to have a direct shot to the manifold and then out from manifold to the heater valve . And block off the old hose exit hole on the other side of the firewall. I also suppose I could leave the manifold without even connecting the hose to it and route things as they were... but it could be nice to use it as designed.   

This may be the first installment in a series of ...."what the hell am i doing."

[MiniDave]

Or, similar idea......using the holes on the right end of the firewall instead of the left - heater valve to heater in, heater out to manifold, manifold to lower rad hose..... that way the times you need manifold heat will probably be the times you need heat in the car too, and you can control both with the heater valve.

[John Gervais]

That's how I did mine - replaced the rubber grommets (Linked:  34G3651 (some minis use 5/8"heater hose and used 2 of CLP6235)) and the bulkhead blanking plate that the hoses pass through (Linked:  ALA7530) too while I was at it.

This is an older picture, but the hoses haven't changed:

[stan360]

OK, I understand why that makes more sense.... The more efficient routing as you describe Dave, seems to be  easier with John's LHD setup instead of my RHD. 

With the heater...is the top  "in" and the bottom is "out" ?     Does it matter?  ...the matrix wasn't directionally labeled.    Went from radiator into top of my heater and out bottom to heater valve.

[John Gervais]

"block off the old hose exit hole on the other side of the firewall"

Isn't that where the master cylinders sit?

ALA6505

[stan360]

Here is the right side of the firewall. 

[John Gervais]

Ah, I see - interesting - yeah, I'd put a blanking grommet in that hole.

Edit - re-thought this, maybe I'd drill another hole beside this one and run both hoses through similar to the LHD layout.  I must confess, I've never really looked at the RHD details before.

[stan360]

I am still thinking about this.   So if you ran the hoses either way as shown in drawings, it can work. One method runs warm coolant through the heater matrix then the manifold.... the other method through the manifold first , then the heater and and then on into radiator and back through system. 

Does the heater matrix generate that much additional heat, or is the coolant about as hot as it will get coming out of the cylinder head and the matrix merely traps it long enough for the fan to blow air through it.  If the matrix adds heat, I can see running it through there first then on to manifold....now if the coolant is  all about the same heated temp. , then either way could be about as equally efficient  and pulling the heater knob will still run the coolant through them both ?!?   I guess I am not clear on the heater matrix actual function.

[MPlayle]

The heater matrix is like a radiator: hot fluid goes in and the heat is radiated out - cooling the fluid some.  The blower pushes cool air through the matrix (which heats the air) and out into the cabin to provide heat for the passengers.

Fluid will be hottest coming out of the heater valve on the cylinder head.  Going through the manifold first will drop the temperature a bit before entering the heater matrix, which will drop the fluid temperature some more before sending it back into the lower radiator hose leading back into the water pump and engine.  This will mean a tad less heat into the cabin.

The other route (heater first, then manifold) will mean more heat into the cabin and less into the manifold.  It does not take much heat in the manifold to help prevent "carb icing".  The manifold will also get some radiant heat from the exhaust as well.

[stan360]

Yes, this does make sense.....thanks for clarifying.    Dave had talked about routing through the heater first as John's car shows..., which does seem to be the optimal method, most direct route from heater valve to heater provides most cabin heat... and while it made sense to me....I was just  lacking in my knowledge of the how and why all the components work.   The matrix then has no formal in and out like the radiator does....fluid just has to pass through it.