Dc heater experiments

Late last fall I bumped my alt up to a 95 amps, when it died. I had already made a dc electic blow gun. for it. as a defroster.
Also In preperation to upgrade the beetle I got a road worty back seat heater kit. It is a off the shelf 1100 btu heater that draws 12 amps.
My home made unit is not only hotter but also quieter. How can I check how much its current draw is. If 2 don't exceed 30 amps it should be alright.

Looks like Id be better of making 3 more and shoehorning 2 of them into both cars heater channels for heat almost as good as a beetle was new.

It does look very promising ,but I also need to upgrade the power cables even 10 gauge wires get warm after about ten minutes and I am going to upgrage it with 2 ABS 70 amp relays per car.

I also have a working BN-2 eberspacher but i still don't trust it just yeat sometimes it spits and sputers when I start it Im guesing air in the line. is this normal for a Bn-2.

barry,

do you have the original heater boxes (on the engine)? Also if you do, are they the "heavy" weight variety? (with the internal fins)?. I'd highly doubt that any electric form of heat would match a properlly installed stock vw system. Mine works amazing with the stock shroud (not 36hp style) and proper good quality heater boxes. Also you said you have a gas heater, those things put out like 8000+ BTU, there's no way you'd even get close to 500BTU from any electric system you could install in your car, it just won't work. Get that gas heater up and running, they are quite simple, i actually have the entire factory service manual for all the B-serries gas heaters on my computer. Contrary to "myths" the gas heater is VERY safe, and in proper working order they put out retarded amounts of heat. Not to shoot you down, but i think your wasting time and $ trying to put together a electric system that would really never preform as well as the stock vw heat system.

martin

Barry-

Do a site search on electric heat. It's a bad idea.

Do gas heaters have a "smell" to them?

I have not installed the bn-2 So can't tell you about smells. BUT show me a bug that doesn't have a little smell from the exchangers.

Plus I want to open up the exhaust.

Im guessing my single blow gun is at least 1500 BTUs A pair would be 3,000.BTUs In a small beetle cab thats quite a bit.

My VS has new everything and new old stock exchanger and its very poor heat.

I have a good question what is the BN-2s BTU rating ? They say it is very good even in a bug.

barry,

i just bought heavy Dansk heater boxes for my speedy, and they work great, excellent heat, they don't smell, the same heater boxes in my 74 beetle work amazing, i've driven my beetle in -10 DEG Celcus and i had to open the window cause i was hot with just the heat exchangers. I have 4 mint BN2 heaters, i planned on putting one in my beetle, but i could'nt bring myself to cut big holes in my mint arizona totally virgin body on my 74 bug, so i went the heat exchanger route and it's surpassed my expectations.

Just to add, gas heaters do not smell at all, neither do stock vw heat exchangers. And i doubt you'd get that btu rating from electric heat source, the gas heater has about 8000-9000 BTU, and that's ALOT. You would have to wear shorts in winter with a gas heater, they work better than ANY possible system you could make, even better than a modern water-cooled car. Electric heat will allways be just about as good as a warm fart, espically in a speedster.

barry, do you have a thermostat on you engine? what are your oil temps?

martin

The reason for poor heat is the distance the hot air has to travel to reach the interior.
The pvc pipe set up is a large mass that conducts the ambient cold hence, cools the hot air by the time it reaches your cold fingers and toes...

Heating systems are what I do to support this hobby. I'm not an engineer, nor do I play one on TV. But I'm from a cold climate, and I've thought a LOT about this.

Most of the problem with heat in a speedster isn't the the capacity of the heating system-- it's the intensity of the air infiltration into the car. The difference between various builders in terms of sealing air leaks cannot be overstated-- there is a HUGE difference. Pan based cars have built-in air leaks that require a lot of care in construction to seal up. I'm sure Alan M takes the time to do what needs done-- neither of the builders of my pan cars did.

Good Dansk (or Asian equivalent) heater boxes on a small engine produce (barely) enough heat for a speedster down to about 20 deg or so, assuming the air leaks can be sealed up. I'd say that sealing the air leaks is impossible, but Barry has proved with his Vintage Speedster "D" conversion that (with enough work) anything is possible. Suffice it to say that it is no small undertaking.

The problems come in with larger engines, or with Type 4 conversions, where good heater boxes haven't been available. Engines bigger that 1776 or so, really need bigger exhausts- the 1-1/2" flanged heater boxes out there don't have heat sincs. With REALLY big engines (bigger than 2L), a 1-5/8" exhaust is a good idea, but until recently there wasn't any 1-5/8" heat exchangers of any kind available. A1 makes one now, and Berg has always had one (if you'd buy the entire ugly, overpriced exhaust)-- but neither of them have heat sincs. W/ Type 4s, you're still on your own.

If you want to be comfortable in a speedster below 20 deg or so, then the fact that the normal heating system draws in outdoor (less than 20 deg) air becomes a limiting factor-- no matter how good the heater boxes, or how well insulated the ducting. Air needs to be at least 110 deg discharge to feel even remotely warm-- at 10 deg o/a temperature, that little box needs to create a 100 deg temperature rise. That is a lot to ask of 16" of pipe with a lot of air from the engine cooling fan whipping through it.

If a fan is connected to the heating system (ala Intermeccanica), then at least the airflow can be regulated and the boxes can have a chance at heating the air. If the inlet to the heat exchanger could be directed back to the cabin, then you'd have a really decent system-- pulling 50 deg cabin air into the heat exchanger, rather than 10 deg outdoor air. This would work-- but it assumes an airtight cabin, and a lot of ugly ducting.

Continued...

Continued from above...

I looked at mounting a 96 plate EMPI oil cooler (with fan) in the cabin, and directing hot oil into the cooler to provide heat-- but this requires some sort of solenoid to keep from doing the same thing in the summer. I get nervous about pumping oil all over the car as well-- long lines equal pressure drop.

I looked at a 924 oil/water heat exchanger to heat a closed glycol loop with oil. A heater coil could be mounted in the cabin, and an electric pump used to circulate the solution on a call for heat. Problems? The price of the parts got pretty high-- the system requires a reliable 12v pump, an expensive heat exchanger, a surge tank, and a lot of piping.

If you run the numbers on an electric heater, you'll find that they are pathetic from a BTU/hr standpoint, and can easily use up all the available current from even the most heavy duty alternators (which are not cheap). A much better use of the available electricity is heated seats, or a heated vest like motorcyclists wear. For 90% of the guys out there heated seats with an Intermeccanica-style heater-box fan set-up would be quite satisfactory.

But for the rest of us (who live in the Midwest or even higher latitudes)... in the end-- nothing produces heat like a fire. And a gasoline heater is like a bonfire in your lap. It's the best solution for BIG heat, without any complexity in the engine compartment. I've got a new Espar heater in my car, and I feel like it is worth whatever it costs to have. I can use any header I want with any engine I want. I'm not playing games with the oil system. The heat comes on-- right now!-- when I push the button. It smells a bit on start-up, but it is powerful enough to overcome the small air leaks that even the best constructed speedster will suffer.

Good luck.

Mike,
Mine is a early VS and they are still plummed in the chassey rails down the sides . even with the booster fans iI added .I barely feel anything

I have the rails well insulated. I have determended its got to many turns before the rails. I would realy like to keep it on the outer rails if I could pipe the rear ends of them somehow and get good air pressure. I be a happy camper. AND these are the better heat exchangers

MIke I know you like to run the heat down the tunnel but that is not where it is on a real porsche. I Know you Dont have to lecture me this is not a porsche. But im pushing it in that direction anyway.

Stan/ when I added the boosters they pull air from the cabin. But like you said if your top has any air cracks anywhere your fighting a loseing battle . it will have to have a hotter heat source thats not restricted. I'd like to see some of the tricks you do to stop air from comeing in.

I will say ,I feel the lower half of the car is tight enough it would problaley float. Mind? I don't want to find that one out.But the doors do seal up pretty good . if I leave the top down a lot the back window seals give trouble But if I heat them with a heat gun they come back fine. They are Softseal

That leaves the rear nonzipper window . It could be a big part of my problem. I need to add some velcro. and figure out a neat way to seal the rear cab deck.

My beetle does have decent heat but the motor is very old. and yes it smells BAADDDDD I avoid using the heat because of how clean the car is.

I have the eberspacher plumming kit for a superbeetle .

But like I asked, is it common for the heater to spit and stumble when first lit and is there a way to pre prime the lines or re cirulate the fuel like fuel injection does to keep air out of the lines? If I could cure that I'd be much happer with it.

Some time ago I addressed this .
I've done speedsters and other air-cooled heated replicas using the center tunnel as the most direct delivery of hot air with the heat ports on the left and right forward areas of the tunnel.
It works so well the shifter and e'brake handles gets damn hot. This allows for forced air as well as radiant tunnel heat.

I've always loved Alan's tunnel method-- it takes a problem area, prone to leaking in cold air, and makes it the source of heat. It's an elegant upgrade for a heater box system.

I got a email with my answer. A BN-2 is rated a little under 8,000 BTUs. That is a real big difference.

I have my electric heater that I bought some time ago for sale if anyone is interested. I believe its 900 watts or so and requires a 60 amp fuse and wiring to handle it. I recall it was only recommended for a 60 amp gen or better.

All self contained with fan, thermostat and on/off switch. Paid $220 US in the mid-80's for the unit and used it just sporadically to supplement the heater in my diesel Benz as the diesel would only heat up under load and not around town.

Brian