Diesel heater left on all night

[mccp]

This raises an interesting question. If I set the heater control on 7, will the van warm up (to a comfortable temperature) more quickly than if I set it on 1?

It all depends on how the heater modulates its output. My guess (from casual observation) is that the heater turns on at full power until the cabin temperature reaches the thermostat set point. From that point on it will run at a lower output to maintain the temperature within a small range above and below the set point.

I guess that the effect would be that it seems to heat up more quickly on 7 because the heater will be running at full blast until you feel too hot, at which time you will turn the heater down.

 

[Borris]

This raises an interesting question. If I set the heater control on 7, will the van warm up (to a comfortable temperature) more quickly than if I set it on 1?

I ask this because Mrs VD has an extremely annoying habit spinning the climate dial in our Volvo up to about 30 degrees when she sets off on a cold day, as she believes the car will warm up more quickly than if she just leaves it on say 20 deg. My protestation that the set point does not change the rate of heat gain falls on deaf ears. Even though she has a degree in physics.

Vis-a-vis the Cali aux heater, can anyone save our marriage?

I can't answer your question and I don't know how the Volvo heater system works or pretend to know much about automobile heaters however on some of the cars that I've owned in the past I obtained quicker and more efficient results if I delayed using the heater until the engine had warmed up to full running temperature (I also understand that some cars have completely separate heater circuits). I have always thought that with the heater turned off, the engine coolant in the former type only circulated through the engine block, coolant pipework etc and radiator and that the use of the heater only delays the vehicle reaching full normal operating temperature. Am I correct?

As the Cali parking heater is an independant heater to the cabin engine coolant heater my theory wouldn't apply. I quite often take the grandchildren to school with both the engine cabin heater and the parking heater running. It warms up super quick.

 

[Velma's Dad]

Get a replacement car with dual temperature control. A small price for tranquillity??

Yes ours has two zones but Mrs VD gets to set both of them even when I'm driving.

Re Borris's theory about keeping the heater off until the engine's warm. Yes makes sense in terms of engine efficiency/fuel economy, and to some extent engine wear, as engine gets to optimum running temp quicker. But logically should not make interior warm-up quicker, as no heat energy at all can be transferred to cabin until heater circuit opened (okay, apart from a bit of conduction through the bulkhead).

BUT I guess we also need to allow for fact that cabin of 'cold' car may still be warmer than outside (and engine bay) temp due to solar gain or a bit of retained heat overnight. So, switching on the blower when engine still cold will force cold air into the (slightly warmer) cabin, so cooling it... In that case, better to wait until engine temp is at least equal to cabin temp. I wonder if smart climate systems on modern cars do that?

 

[Velma's Dad]

BUT I guess we also need to allow for fact that cabin of 'cold' car may still be warmer than outside (and engine bay) temp due to solar gain or a bit of retained heat overnight. So, switching on the blower when engine still cold will force cold air into the (slightly warmer) cabin, so cooling it... In that case, better to wait until engine temp is at least equal to cabin temp. I wonder if smart climate systems on modern cars do that?

Duh, after thunking about it... I guess the climate control initially sets the system to recirculate so it doesn't suck in colder outside air. Shoulda engaged brain, etc...

 

[larrylamb]

Yes ours has two zones but Mrs VD gets to set both of them even when I'm driving.

Re Borris's theory about keeping the heater off until the engine's warm. Yes makes sense in terms of engine efficiency/fuel economy, and to some extent engine wear, as engine gets to optimum running temp quicker. But logically should not make interior warm-up quicker, as no heat energy at all can be transferred to cabin until heater circuit opened (okay, apart from a bit of conduction through the bulkhead).

BUT I guess we also need to allow for fact that cabin of 'cold' car may still be warmer than outside (and engine bay) temp due to solar gain or a bit of retained heat overnight. So, switching on the blower when engine still cold will force cold air into the (slightly warmer) cabin, so cooling it... In that case, better to wait until engine temp is at least equal to cabin temp. I wonder if smart climate systems on modern cars do that?

Thank god for the heated seats, another winner on the Cali.

 

[mccp]

Thank god for the heated seats, another winner on the Cali.

Seconded. Especially as they go up to 3 (or 'wife' setting).

 

[Borris]

Yes ours has two zones but Mrs VD gets to set both of them even when I'm driving.

Re Borris's theory about keeping the heater off until the engine's warm. Yes makes sense in terms of as engine gets to optimum running temp quicker. But logically should not make interior warm-up quicker, as no heat energy at all can be transferred to cabin until heater circuit opened (okay, apart from a bit of conduction through the bulkhead).

BUT I guess we also need to allow for fact that cabin of 'cold' car may still be warmer than outside (and engine bay) temp due to solar gain or a bit of retained heat overnight. So, switching on the blower when engine still cold will force cold air into the (slightly warmer) cabin, so cooling it... In that case, better to wait until engine temp is at least equal to cabin temp. I wonder if smart climate systems on modern cars do that?

My point was really that by running the heater before the engine has reached full normal running temperature you will just prolong both the engine warm up process and its ability to produce full heat from the heater. So not good in either respect.
I agree that the engine efficiency/fuel economy and wear issues that you mentioned are also important reasons to hold off going for full heat until up to normal running temp but my point really only concerned getting warm quickly.

 

[WelshGas]

Are you sure that the MFD takes into account the amount of gas-oil going into the heating and not going through the motor feed pump flowmeter's ?

The MFD doesn't account for the fuel used in the Parking Heater, BUT might, via the " Distance to Drive " function on the MFD indicate volume changes due to expansion/contraction of fuel in the tank and/or fuel used by the Parking Heater.

 

[andyinluton]

The thermal expansion coefficient for gas-oil is about 1/1000.
For a tank containing 60 litrers, a variation of 20 ° C to 0 ° C will cause a decrease in volume of about 1,2 litres.
It's not nothing but will the gauge show 1 litre of difference?

The calorific content of the diesel in the fuel tank hasn't changed just the volume slightly, therefore the range available shouldn't have changed?

 

[Velma's Dad]

My point was really that by running the heater before the engine has reached full normal running temperature you will just prolong both the engine warm up process and its ability to produce full heat from the heater. So not good in either respect.

Yeah but I guess it's really a philosophical question around the merits of delayed gratification. Although I'm not inclined to suggest trying the Stanford marshmallow experiment on Mrs VD.

 

[Borris]

Yeah but I guess it's really a philosophical question around the merits of delayed gratification. Although I'm not inclined to suggest trying the Stanford marshmallow experiment on Mrs VD.

Absolutely.

Go on I'll buy it, what's the Stanford marshmallow experiment?

 

[Velma's Dad]

Go on I'll buy it, whats the Stanford marshmallow experiment?

It's a well-known experiment in developmental psychology, that also shows how being able to save up our pennies (for a Cali) is correlated with being an all round high achiever in life:
https://en.wikipedia.org/wiki/Stanford_marshmallow_experiment

 

[Borris]

It's a well-known experiment in developmental psychology, that also shows how being able to save up our pennies (for a Cali) is correlated with being an all round high achiever in life:
https://en.wikipedia.org/wiki/Stanford_marshmallow_experiment

Then it's a good job it wasn't called the Stanford winegum experiment. I'd be hopeless.

 

[WelshGas]

The calorific content of the diesel in the fuel tank hasn't changed just the volume slightly, therefore the range available shouldn't have changed?

But I don’t think the MFD calculation is based on the calorific value of the fuel remaining but rather the volume at the time of measurement which of course will depend on the temperature of the fuel. Of course that presumes that the MFD display/calculations are more accurate than the analogue fuel tank display.

 

[andyinluton]

If the change in temperature is enough to change the volume of fuel in the tank, it will also affect the volume of air in the tyres which in turn will affect the rolling radius of the wheels, also need to take into account if the weather is colder I will be wearing more clothes, will have eaten mince pies etc making me heavier.


On the other hand I will just leave it as I get about 550 miles to a tank in the summer, a bit less in winter due to the parking heater being used. Thats accurate enough for me....my last post on the subject.

 

[Azteccamper]

Can you use your parking heater whilst driving?

 

[larrylamb]

Can you use your parking heater whilst driving?

yep

 

[Azteccamper]

yep

Thank you Larry. Handy to know.