Heat from gas engine
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Yes; when the coolant reaches a certain temperature it can open a valve connecting the cabin heater coolant to the engine coolant, so the heat from the engine warms up the cabin. The ICE warms up way faster in the Volt than any other car I've driven; you can usually get it to 160 *F in only a few minutes, which is plenty warm to heat up the cabin. Run in Hold mode until it reaches that and then switch to normal again; the coolant should stay warm for the rest of your drive without having to use a ton of battery power to heat it up.
Do you know what is the temperature point where this process takes place? There is coolant temperature indicator on the driver's screen which, then, should precisely determine when to switch back to normal from hold. Good information. Did not know about it.
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They even use the exhaust to warm up the coolant on the GEN 2 cars. Just after the catalytic converter there is a manifold that has coolant running through it to collect the extra heat.
It should open whenever the engine is running, or at least once it reaches "operating temperature" (~80-90 *F is when it starts putting load on the engine in Hold mode). If you let it run until about 160-170 you should get plenty of heat in the cabin.
Just FYI, the first time the engine starts on a cold day it always heats up, so even if you turn off hold mode the engine will still run for a couple minutes. At least that is what my 2012 does, don't think they have changed that behavior. I don't have Hold mode, but if I put it in mountain mode for example and turn it off right away it will run the engine until warm.
It does help preserve all electric range and is much hotter than what the electric heat can do, although the electric heat is generally fine, it does suck the range quickly.
It does help preserve all electric range and is much hotter than what the electric heat can do, although the electric heat is generally fine, it does suck the range quickly.
I'm not sure about gen 2, but my first generation Volt would first open the valve at about 150F coolant temperatures.
On my 2017 Volt I have experimented with the following sequence on cold mornings:
1) Precondition the Volt in my garage, two times for a total of 20 minutes. Settings: Climate:Auto, Climate Control:Max(electric heat), Temperature:Hi, Airflow:Recirculate
2) Start Volt, set Temperature to 74F, turn off the Climate control (deselect Max heat), and run with the just the fan on a medium low speed and the heated seats and steering wheel turned on. In my experience the residual heat from the preconditioning cycles will last about 15 to 20 minutes.
3a) When the air coming from the dashboard vents starts to feel cold to my bare hand I either start the gas engine or set the Climate control to Economy for about 5 minutes until the air coming from the vents starts to get warm. I continue to manually cycle the Economy mode on and off until I arrive at my destination, usually 1 to 2 on/off cycles of Economy electric heat.
3b) Else, if I start the gas engine by selecting Hold mode I can monitor the engine coolant temperature. Due to the preconditioning from Step 1 the engine coolant will usually start at 60F, as the gas engine runs after a few minutes the engine coolant will reach 140F. At this point I usually start to feel warm air from the dashboard vents. I have also experienced warm air not flowing from the vents until the coolant temperature reaches 160F so how quickly the engine coolant is mixed with the cabin coolant loop may depend on the outside temperature.
1) Precondition the Volt in my garage, two times for a total of 20 minutes. Settings: Climate:Auto, Climate Control:Max(electric heat), Temperature:Hi, Airflow:Recirculate
2) Start Volt, set Temperature to 74F, turn off the Climate control (deselect Max heat), and run with the just the fan on a medium low speed and the heated seats and steering wheel turned on. In my experience the residual heat from the preconditioning cycles will last about 15 to 20 minutes.
3a) When the air coming from the dashboard vents starts to feel cold to my bare hand I either start the gas engine or set the Climate control to Economy for about 5 minutes until the air coming from the vents starts to get warm. I continue to manually cycle the Economy mode on and off until I arrive at my destination, usually 1 to 2 on/off cycles of Economy electric heat.
3b) Else, if I start the gas engine by selecting Hold mode I can monitor the engine coolant temperature. Due to the preconditioning from Step 1 the engine coolant will usually start at 60F, as the gas engine runs after a few minutes the engine coolant will reach 140F. At this point I usually start to feel warm air from the dashboard vents. I have also experienced warm air not flowing from the vents until the coolant temperature reaches 160F so how quickly the engine coolant is mixed with the cabin coolant loop may depend on the outside temperature.
Why not just leave Economy on the whole time? Economy does a similar cycle by itself. And you'll have your eyes on the road for more of your trip.
Given more experience with driving in winter temperatures I probably would. It was my first winter driving a Volt and was trying to minimize the use of the electric heat. I precondition each morning, usually twice, before leaving home. I used to use just the preconditioning and the heated seats, steering wheel with no attempt to direct the residual heat from the preconditioning into the cabin. I eventually learned to use the fan to distribute the residual heat, that is good for about 15 minutes. My total drive time is about 35 minutes on a good day so I started cycling the electric heat on and off, not sure how my cycling the Economy setting on and off compares to just setting the climate control to Economy.Why not just leave Economy on the whole time? Economy does a similar cycle by itself. And you'll have your eyes on the road for more of your trip.
1) At night, before you turn off the Volt, set Climate Control System: Auto, Set Heat/AC: Max (for maximum electric heat), Set Temperature: HI, Set Airflow:Recirculate.
2) In the morning, 20 minutes before you want to drive the Volt, precondition it. If you precondition and use Level II EVSE you can recover most of the energy tapped from the battery that is being used to precondition while the Volt is still plugged in. While the Volt is still plugged in use the Remote Start feature (use the keyfob or the My Chevrolet phone App). You can use Remote Start twice for a total of 20 minutes.
3) Unplug the Volt, Get inside and start the Volt as you usually would. Set Temperature to 74F, Set Heat/AC to Economy instead of Max to conserve battery. I usually set the airflow to recirculate, that way there is less cold air from outside for the electric heat to overcome. If your windows start to fog use the front and rear defroster.
Note: Using the electric heat can reduce your EV range by 1/3 to 1/2. Dress warm, use the electrically heated seats and steering wheel (if equipped) as the Volt needs very little battery power to heat the seats and steering wheel as compared with heating the cabin using the electric heat.
Exhaust Gas Heat Recovery in a 2017 Volt? It would be great but I do not think 2017 Volt has it. To the best of my knowledge it is available on Malibu Hybrid only. Did I miss something?
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I agree...I don't believe there is any standalone HXR. However, the exhaust manifold is integrated into the head, so they can pull quite a bit of heat there compared to the average car.
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Much misinformation above!
The HVAC valve opens when the coolant is around 55C. It opens LONG before the engine reaches operating temperature if, by that, you mean when the thermostat opens to the front radiator (which it must have done to reach 'full operating temperature').
In the Gen 1 (I assume it will not be vastly different for Gen 2) you can run the engine in HOLD for 380cc of gas (or as little as 130cc in ERDTT) and you will start getting heat out, but that's way less than fully warmed up. 500cc and everything gets nicely warmed up but still not 'fully warm' and still no heat being rejected in the front radiator. You have to burn something like 1.2L to get the engine fully warm and the front rad doing some cooling.
In answer to the OP question, yes in the Volt the engine is configured to generate cabin heat. (It isn't in the i3 REx, for comparison.) For every kWh the gas engine generates for propulsion power it will ALSO deliver a kWh of heat into the cabin. About 10kWh (of each) from a gallon of gas. So in a way you get 20kWh out of a gallon of gas, so long as you need the heating and it replaces battery power.
The engine sucks up around 1kWh of that heating to 'warm' and 2kWh or so to 'fully hot', so if you start from cold you sort of get 10kWh of motive enegy and 8kWh of heat (but those figures are all approximations anyway, but I guess you get the point).
The HVAC valve opens when the coolant is around 55C. It opens LONG before the engine reaches operating temperature if, by that, you mean when the thermostat opens to the front radiator (which it must have done to reach 'full operating temperature').
In the Gen 1 (I assume it will not be vastly different for Gen 2) you can run the engine in HOLD for 380cc of gas (or as little as 130cc in ERDTT) and you will start getting heat out, but that's way less than fully warmed up. 500cc and everything gets nicely warmed up but still not 'fully warm' and still no heat being rejected in the front radiator. You have to burn something like 1.2L to get the engine fully warm and the front rad doing some cooling.
In answer to the OP question, yes in the Volt the engine is configured to generate cabin heat. (It isn't in the i3 REx, for comparison.) For every kWh the gas engine generates for propulsion power it will ALSO deliver a kWh of heat into the cabin. About 10kWh (of each) from a gallon of gas. So in a way you get 20kWh out of a gallon of gas, so long as you need the heating and it replaces battery power.
The engine sucks up around 1kWh of that heating to 'warm' and 2kWh or so to 'fully hot', so if you start from cold you sort of get 10kWh of motive enegy and 8kWh of heat (but those figures are all approximations anyway, but I guess you get the point).
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