Does car heater use gas to generate heat?

I thought that the heat generated by the engine is passed?

The heater in your car operates off hot engine coolant which is circulated through a heater core. The core is basically a small radiator.
Most older cars used a heater valve to shut off the flow of hot coolant when heat was not desired.
Most modern era cars circulate hot coolant all the time and airflow is diverted by small doors in the A/C/heater ductwork.

There was a gasoline fueled heater option for the old air cooled VW buses. Not a very good option but when there’s little heat available one grasps at straws.

And for the very old Beetles… like my '61, for example. {:slight_smile:

The heat you’re using in the cabin heater is being generated whether you have the heater on or not. If the heater isn’t on, it simply gets dissipated by the car’s radiator along with the rest of the heat your engine generates instead of diverted for cabin use.

It could be argued technically that the heater fan uses a tiny bit of gas to generate the electricity to operate it, but you couldn’t measure the amount even if you tried without very sophisticated equipment and laboratory conditions. It’s that small.

Didn’t the Corvair also have a gas heater option? In response to the OP’s question, as others have said, this is just heat being wasted by the engine anyway. The only difference is instead of it being dissipated into the outside air by the car’s radiator, it’s being dissipated into the cabin through a smaller radiator called the heater core.

I wonder if this question is more properly stated: “Does the cold weather cause worse fuel economy because you have to heat the car?” - and the answer to that question is, Yes! - as there is more fuel consumed in order to bring everything up to operating temperature.

I keep the heater off when the engine is cold just so the engine warms up as fast as possible, once the engine reaches operating temperature, I use the heater. The waste heat has to be dissipated anyway so it might as well heat the car.
Using the defrost or defog setting will turn on the AC and the heat at the same time to de-humidify the air and this will use a little extra fuel, but even here, the compressor’s head pressure is not that high when the condenser is being cooled by ice cold air instead of 100 degree summer air. You might say that the air conditioner (a heat pump) does not have to pump the heat up a high hill so it does not take as much energy to drive the compressor.

Of course the heater uses gas. Just in a sort of round about way. The heater uses hot coolant flowing through the heater core. To do this it is required that the engine be running which requires gas/fuel. With out a running engine the would be no heat generated to make the hot coolant and the water pump would not be spinning to provide the flow.

The heat for the cabin in modern cars is the coolant heated by the engine. This heat is free in that otherwise thrown away into the atmosphere through the radiator. There were, in past years, car heaters that used gasoline. A heater used to be an option. Stewart-Warner made a gasoline heater that was an aftermarket accessory in the 1930s and 1940s and was called a Southwind heater
The heater on the first Corvairs, the 1960 model, was a gasoline heater. The 1961 and later Corvairs used a,heater that used air heated by the exhaust manifold. It seems to me that some late 1950s Chrysler cars,may have offered a gasoline heater as an option to the hot water heater.

The amount of extra gas used by the heater is negligible. During warm up, the coolant goes to the heater first, so theoretically, it takes longer to warm up the engine and get off the rich setting on the fuel supply.

My bet is that it would be nearly impossible to actually measure it.

Not sure just which useage of gas the op has in mind.
As others have said , the heater is not a gasoline powered unit in any way…it’s hot water aka coolant.
or –
Does it use ‘‘additional’’ gas to run it ?.
NO, never has, the coolant just flows the same.
These days , most vehicles do not even have a shutoff valve at all. The coolant is in continual flow through the heater core and NO energy difference occurs …NONE …with the heater on or off.
It’s just a flapper door that closes off , or opens, the air flow.

( unlike the air conditioning which draws energy when in use. The added resistance of the belt driven compressor causes the engine the need to use a tad more gas. )

Quoting oblivion

“Didn’t the Corvair also have a gas heater option?”
I think the gas heater was only available for the first year of Corvair production, 1960. In fact I THINK it was the only system available that year. I had one in the late '60s. The gas heater was much better than the later oil soaked heat generated by the heat exchangers in the exhaust. Those were a very bad idea.
Does it use ''additional'' gas to run it ?. NO, never has, the coolant just flows the same.

Actually yes it does. It will not be a measurable amount with the instruments on your vehicle, it would take scientific instruments to measure that small of a difference.

The reason it does is that the increased surface area for radiating the excess heat will tend to reduce the temperature of the coolant. In order to keep the coolant up to proper operating temperature, the thermostat will close down some. This creates additional drag for coolant flow that the water pump has to overcome, and that in turn uses more fuel.

It won’t be much more fuel, but it will be some. Seeing the difference at the pump would be almost unnoticeable, probably well within the normal statistical variation each time you fill up.

@MG_McAnick‌ You are correct. The gasoline heater was the only heater offered on the 1960 Corvairs. On the 1961and later, the only heaters available were hot air heaters that used exhaust manifold heat. The complaint about the gasoline heaters was that the heater really reduced the gas mileage. The hot air heaters were dangerous if there was an exhaust leak. I have, always thought Ralph Nader missed the really unsafe feature of the Corvairs.

Mostly free heat in modern cars. We should be careful not to give the OP an excuse to freeze his family in the winter by thinking it will save gas, though. A gust of wind could cause more of a MPG fluctuation than using the heater.

My 59 VW had the gas heater which would use gas from the tank to run it. But you’d never have to use it full time or while on the highway. The normal vent heaters worked good enough for that and the vent was right by your feet so kept your feet warm.

I had a 61 Corvair and didn’t have a gas heater with that one. Unsure if and when they were available, but again the exhaust heaters worked fine in Minnesota except for the smell. The wife complained about the smell on her clothes. Never did get that fixed.

Come to think of it, I had a 1980 VW Vanagon about 30 years ago that had a gas heater. It could be turned on without the car running so it was it warmed up when I got into it.

Don’t let Chrysler tell you they invented the minivan.

I had the same problem with the heater in my 1961 Corvair. My wife didn’t complain about the smell on her clothes. She just used it as an excuse to buy more clothes.

“…the thermostat will close down some. This creates additional drag for coolant flow that the water pump has to overcome…”

The water pump is a simple centrifugal pump. A centrifugal pump at a given rpm uses less power with less flow (as would result from increased drag).

A few luxury cars have supplemental electric ceramic heaters that kick in until the engine is warm. This will reduce your fuel economy a bit, but I’d say comfort is more important than that trivial amount of gas.

In the contrived oil shortage of the 1970s, a battery powered car was marketed called Citicar. For heat, the Citicar offered an optional propane heater.

The water pump is a simple centrifugal pump. A centrifugal pump at a given rpm uses less power with less flow (as would result from increased drag).

I would agree with you if the thermostat is restricting flow into the pump but not if it is restricting flow out of the pump. A restriction on the intake would lower the water pressure, on the output it would raise it.

But I do believe that some cars have the thermostat on the intake side of the pump now so that is a good point.