Interesting Link about Manifold Heaters

[marty in Ohio]

Shrew01, Thanks for this link. I had no trouble loading it.
As I looked thru the many different types I noticed the Red Head heater. My '30 town sedan has a hole (now covered by a piece of asbestos) smack in the middle of the firewall. This answers a big question. I've had the car for 30 years and never knew what the hole was for. Thank you, thank you!
Marty