• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Suggestion for improving Heater fan

Share this page

Hi Steve
PPS
10A FUSE is OVER SIZED x4- you can fuse the wire plastic cover, if a short occour- better a 5A fuse- the AMPERAGE of the NEW blower is about 2,5 A and I think that also the older have the same - so the the fuse have only the double capacity blowing after few seconds
 
andrea said:
Hi Steve
PPS
10A FUSE is OVER SIZED x4- you can fuse the wire plastic cover, if a short occour- better a 5A fuse- the AMPERAGE of the NEW blower is about 2,5 A and I think that also the older have the same - so the the fuse have only the double capacity blowing after few seconds
Click to expand...

Hi Andrea,
Thanks. Will take your advice and install a 5A inline fuse, re-routing the relay power line from the horn position on the fusebox to position "A" on the voltage regulator.
 
I finally finished the installation of the 4" bilge blower fan on the fresh air side. I used an Atwood 4000 Water proof blower ($22) with a
RioRand Upgraded 6V-90V 15A DC Motor Pump Speed Controller($11). Both purchased from Amazon. I chose to install the speed controller near the air vent.
The controller has several aluminum heat sinks which tells me there must be some heat generated when the speed is dialed down and having it mounted
in the air stream is probably a good idea. I made a simple mounting bracket for the control knob and mounted that to two of the bolts that fasten
the wiper motor to the mount. The blower generates a good stream of air both through the screen grill and out the bottom vent towards your feet.
It will still be a few months before I can try it out under road conditions, but it looks promising.
 

Attachments

  • IMG_5526.jpg
    IMG_5526.jpg
    75.9 KB · Views: 128
  • IMG_5531.jpg
    IMG_5531.jpg
    70.3 KB · Views: 127
  • IMG_5532.jpg
    IMG_5532.jpg
    46.9 KB · Views: 121
Rob - the install looks pretty cool. Is that a baffle where the rheostat is mounted?

PS - I removed the mesh from the opening and the airflow is greater that way. There's a mesh in the front to keep the buzzards out.
 
Hi Rob,

The installation looks great and will be definitely incognito. I hate to suggest additional work but I have found that the air stream created is directed up and toward the back of the dash and not down at your feet. To address the redirection of the cold air air stream, I created a deflector, mounted on the bottom of the windshield wiper motor and includes the speed control.

attachment.php
attachment.php


All the best,
Ray(64BJ8P1)
 

Attachments

  • Fig 5.jpg
    Fig 5.jpg
    69.3 KB · Views: 170
  • Fig 9.jpg
    Fig 9.jpg
    65.8 KB · Views: 173
Looks good, Rob. Good idea to put the controller in the air stream. I do have two thoughts:
  • I lined my fresh air duct with a 3" aluminum duct surrounded by 1/8" self-adhesive pipe wrap. It comes in 2" width about 15' long. You could even do two layers. That keeps the air cool coming through the engine compartment as it goes by the exhaust side of the engine.
  • The blower manufacturer recommends that the blower be mounted on some rubber isolators to cut down on the noise. Perhaps a set of wiper motor mounts would work.

I've installed a temporary, insulated fresh air duct on the passenger side by removing the duct to the heater blower (and taping up the blower inlet), and running a 4" insulated as above, aluminum duct to the blanked holes for the master cylinders on the right side. We tried it this last weekend and my wife said it was the first time her feet didn't roast. Progress! Now to do it up final with the bilge blower and the original duct material on the outside.
 
Hi John/Steve,

John, you had mentioned insulating the cold air duct before but I felt, at the time, the air was moving sufficiently fast that the amount of heat picked up during it short fast travel near the exhaust would not be much if any. I had later associated the hot air, emitted from the cold air duct when the car was stopped on a hot day, to be engine compartment air escaping through the steering box opening and being sucked into the cold air duct by the blower. Since installing the shield mentioned previously, I have noticed a definite difference but not as much as I would have expected. I am wondering if my initial perception was in error and an insulated duct, as you had originally suggested, is required. Are you using any shields to stop engine compartment air from being sucked into the cold air duct?

Steve, you have gone further toward sealing your radiator bulkhead then anyone I am aware of and, as I understand, this effort produced a significant cold air flow temperature drop. Did you also insulate your duct?

Thanks,
Ray(64BJ8P1)
 
Steve,

That's a good observation and maybe the air IS warming on its travel to the vent by exhaust pipe radiation. Since I will have to remove the fender to do a good job, I guess that will be a project for this winter.

Thanks for your valued input as always,
Ray (64BJ8P1)
 
RAC68 said:
Hi John/Steve,

.... Are you using any shields to stop engine compartment air from being sucked into the cold air duct?

Thanks,
Ray(64BJ8P1)
Click to expand...

No shields, but I do have the rally vents to let hot air out the sides. I will be installing my new coolant overflow tank in that area, so I'll have some opportunity to work on a shield, even if it's nothing more than the tank.

I haven't installed the blower yet, so how it works standing still is still in question.
 
Thanks John,

I thought you suggested to, and had, insulated your cold air duct against heat transfer from the exhaust pipes and manifold it passed. With the rally vents, your engine compartment would not be that vulnerable to engine compartment hot air recirculation.

All the best,
Ray(64BJ8P1)
 
I finally got around to using the new wind meter to test the air flow on the heater side to compare the original Smiths fan with the new Atwood 4" bilge blower. You know how you start down a path expecting one result and it turns out to be false. Well that's what I found. After fitting the Atwood blower to the fresh air side and feeling the good flow of air, I expected to see a vast improvement on the heater side. Well, that wasn't the case. I tested both the old fan and the new one under the same conditions. First with the 3" duct going into the heater removed and then with it hooked to the heater. I measured the air speed out of the open 3" duct and later out of both the floor vents and defroster vents.
The first test was with the old Smiths fan in place. The second test was with the 4" Atwood feeding the Smiths fan housing but with the old fan and motor removed and a blanking plate installed where the motor mounted. Both tests were done with the motors wired directly to the hot wire on the starter solenoid.
After taking multiple wind readings, I was surprised to find the the new bilge blower produced 70% to 82% less wind speed that the Smiths unit. I could get 19mph out of the 3" duct with the Smiths unit and only 16mph with the Atwood. Once I hooked everything back together, I could measure about 8 to 8.5mph at the foot vents with the old fan and only 6 to 7 mph with the new fan. Obviously there is quite a loss of speed passing through the heater core and ducting. For a point of reference, the Atwood fan running by itself will generate about 20 mph.
I was able to achieve 22.2 mph running both the old and new fans at the same time, but that is more motors working than I want.
So, bottom line is I am sticking with the old Smiths fan at this time. If someone comes up with some improved results using a newer motor attached to the Smith fan, then I may consider it.

Back to the fresh air side. Steve G. Thanks for the idea about removing the screen mesh. The air speed at the vent was 15-16mph with the screen in place and 19-20mph with it removed.
Also, Ray and John, I may try adding a baffle and duct insulation once I see how this set up works.
Thanks to everyone that offered suggestions and ideas.
 
Steve, I have tried that and saw less volume with the normal feed wire. The replacement wiring harness I purchased seems to be made with smaller gauge wire than the original. I plan on using a relay to power the heater fan.
 
Rob Glasgow said:
Steve, I have tried that and saw less volume with the normal feed wire. The replacement wiring harness I purchased seems to be made with smaller gauge wire than the original. I plan on using a relay to power the heater fan.
Click to expand...

My harness is original and the feed wire looks to be about 18 ga.

Relay with new 14 ga supply wire made a noticeable improvement in the airflow.
 
Rob,

I am wondering if the bilge blower is more susceptible to resistance than a squirrel cage fan. Since there is quite a number of flow-interfering elements within the path of the heater duct and air path, apposed to the straight forward cold air path, would require an air pump with more back-pressure resistance.

When modifying my Smiths blower so many years ago, my objective was to get a greater air flow and the motor acquired from the scrapped Olds convertible definitely produced greater air flow. In fact, with the vent door closed, my defoggers would (and still) whistle.

Ray (64BJ8P1)
 
Seems to me the whole ducting system was poorly thought out. The heater hose should be the one on the side with the exhaust manifold. That way, the engine can help heat the air you want heated instead of trying to insulate that hose. Anyone ever look at reconfiguring the heater box under the dash to have the hose from the left side feed it?
 
Hi Rob
I have all TWO motor working in tandem (my car have the alternator, so not exceeds in consumption)
for me this solution are the better for air flow inside my car in the foots compartments,
Windshield Defrost never have increase (that are my target)-in my car after this mod- probably for have good pressure at defrost I will close the opening (With adhesive aluminium ribbon) in the rear of the heather, but this mod is irreversible
 
Back
Top