You will need at least 500W which is over 40 amps at 12v. Feasible if you have a large enough charging circuit. Dont be fooled by ebay stuff that claims 850w from a cigar lighter socket.
You might consider heated seats. Don't know about amp draw but a roadster that comes to coffee on Saturday mornings has them and it runs a small tractor size alternator on a small block Chevy. Just a thought.
I used one in one of my 32's and it pulls a lot of power and the heat is minimal, driving down the road you will be lucky if the electric heater raises the cabin interior 5 to 8 degrees. I fought installing a heater because I didn't like the hoses exposed when the hood was open, I said screw it! After years of freezing my **** off, I installed a vintage heat & air and can ENJOY driving my hot rods in any type of weather in comfort! HRP
Yep, not a viable choice as noted above. These come up here every so often, outlandish claims as to how much heat they throw out. Do a BTU to watts conversion to get the real output or actual amp draw at advertised heat output. They don't compute.... If all you're after is enough heat to defog the windshield on a not-too-cold day they can handle that but actual cabin heat, no. A generator won't supply enough power, you'll need a larger alternator with the attendant large wire. Other alternatives are gasoline-powered heaters (semi-popular at one time) or heat exchanger types. The latter type is used in aircraft as well on air-cooled cars (VW comes to mind) so the tech is out there. These were also used in the early days as options on Model As and others. Tough to keep smells out of the cabin with the vintage units however. There are some nice aircraft heaters, but unit bulk and prices that will take your breath away generally rule those out.
My Roadster had a bolt on top and I made lexan snap in windows, had to snap them in after entering car. For some warmth I used a 12 volt electric blanket that with a jacket, gloves, hat made it pleasant/tolerable on those cool/cold evening rides home in Wisconsin Spring/Fall, when the top was off those were Very Cold rides home. After this fun for 7 years my next hobby ride was a 32 3 window and Like HRP I installed heat/defrost/ AC which made the season a longer and much more comfortable for me and then my wife would come along occasionally. I knew men that bought a small electric heater at the truckstop that they liked/used, today with the heated seat inserts that would be a big help, we all had alternators, not generators. IF you are having an old school traditional hot rod, a heater with hoses is your only option or no heat and freeze your **** off. For me the very best option for me early/late season was my OT ragtop that I bought new in the 80's, I still have it, now a very nice survivor car. Roadster and 32 3 window pics in my albums.
Yes, heater hoses on my roadster. Has a top and on cool days keeps me comfy with the fan on high. I will take comfort over aesthetics any day. KK
Some folks may disagree with this, but…. if you exhaust pipes run under you cab, you can build a “ box” around one and force air thorough it with a small blower and plumb an intake from and exhaust into the cab. How much blower? How big of box? But the heat( BTUs) are there to heat your cab! I know…fumes! But if done right , there should be no problem! Might work! Bones
A simple heat exchanger. These work if you have the room, but as Bones noted getting a good enough seal to keep fumes out is the main trick.
I have built an electric heater for the roadster, it works. I had to wire for it (6 gauge around the fuse panel with it's own breaker), use a big power gen and only use it when I have 2000 rpms or better. My buddy @Kim Strobeck rode in it one chilly night at the beach and it convinced him to install his own version of electric heater. It doesn't work at an idle but then again you only need it when you are stirring up the cold. No, would I do it again? No. Too expensive, too difficult and a water heater works better.
Someone asked on FB the other day and a 12V heater for a skid steer was suggested. One like this but they draw about 15 amps 12 Volt Cab Heater | Work In Comfort – SkidSteerCabs.com From talking to a couple of guys who have tried them those plug into the lighter 12 V heaters they advertise will almost defog a window but don't really put out any heat. I've got a 12V electric throw blanket that I carry in my OT car that will keep your legs fairly warm if you cover up with it. I bought it for back seat p***engers in that car but have only used it once or twice.
Many ways to route the heater hoses so they don't stick out as bad. I have seen them hardline down the back in front of the firewall, turn under the car and come up through the floorboards. I did like Danny, I bought a VA heat, def, AC behind the dash unit, all you see on mine are three vents under the dash, with the controls in the center vent housing. I'm using one of those square plates to go through the firewall, my heater hoses go to the right side, AC lines are going to the left.
Reasonably honest specs for a change, although I'll question that 15 amp rating. It takes 25 amps to produce 300 watts at 12V.
With the two 20 amp fuses in the circuit I was wondering if it drew more than 15 amps. That may be at the low setting.
I had an OT commuter, heater/defroster quit. I could deal with the temperature, but not the fog on the windshield. I used a 12v hair/blow dryer. Eventually it would defog the windshield, took forever so I just kept a towel in the car. Don’t recall the wattage it was rated at, but wouldn’t keep you warm a bit if needed for heat.
The people who try to sell these 'lectric 12v heaters never heard "you don't get nothing for nothing"?
And Model A Ford. Draws air from behind the rad and a heat exchanger on the exhaust manifold and heats it up before ducting it into the cab
If you don't like the look of hoses, metal pipes can be an option (except for short hoses to let the engine move). Stainless, chrome, br***, copper, lots of options for looks.
I guess one could sweat onto the heater som 90’s out of the firewall, keep them against the firewall, down low get over to the frame, run around and back up to the front of the engine. It wouldn’t hide it all, but could be a “cleaner” look. Or just keep the hood shut.
https://www.jalopyjournal.com/forum/threads/small-electric-roadster-heater.215409/#post-2292475 https://www.jalopyjournal.com/forum/threads/12-volt-electric-heater-experience.855119/ https://www.jalopyjournal.com/forum/threads/electric-heaters-for-cars.1118701/ https://www.jalopyjournal.com/forum/threads/12volt-heater-anybody-use-one.284645/ https://www.jalopyjournal.com/forum/threads/where-can-i-get-an-electric-car-heater-from.10265/ ETC...
I had a 32 roadster years ago, the previous owner put a louvered belly pan attached to the bottom of the ch***is rail. The exhausts ran between the pan and the floor. That car was always toasty warm even with the top down, only ever put it up if raining. Then you only need a fan for a demister.
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