Pre-heat

[culzean]

My Civic is garaged and I run a descicant dehumidifier to keep the garage at about 70% max humidity. Nice not to have to defrost the glass.

Even an open carport used to stop our cars screens frosting or icing up

[TnTkr]

Just as an example, this is the 1700 W electric interior heater mounted on the passanger side of the center console in my Jazz.

[sparky Paul]

Even an open carport used to stop our cars screens frosting or icing up

It may do on an estate, but not always in the countryside with a NE wind whistling up it.

When it was clear, I sometimes found that everything was so cold, I could get a few hundreds yards down the road and the windscreen fogged up, forcing you to stop anyway.

[TnTkr]

Even an open carport used to stop our cars screens frosting or icing up

It may do on an estate, but not always in the countryside with a NE wind whistling up it.

When it was clear, I sometimes found that everything was so cold, I could get a few hundreds yards down the road and the windscreen fogged up, forcing you to stop anyway.

In certain weather the moisture in the air condensates in the heater, and when the coolant starts to warm up, the moisture gets inside the windows. This gets worse by time, when some dust sticks inside the heater and holds more moisture. Really annoying.

[culzean]

I was referring to the carport stopping the frost forming on the car, not subsequently when you have driven away ( the moisture that forms frost drops down vertically from atmosphere as the air cools and can not hold as much moisture ) the frost forms on the roof of carport, not the car. Obviously having the car under the open sided carport will not really keep car any warmer.

Even in the nasty winter 1982/3 where the recorded for coldest temp in England at -26.1 deg C was set in Newport Shropshire only a few miles from where we lived our windscreens were clear of frost, snow and ice and if you warmed the car up a bit the inside would not mist up. I had to use a hairdryer to warm carburettor  up before car would start,  but never had a problem with frost on car.

[Westy36]

I still swear by a 2 litre bottle of tepid water. Clears the screen and stops it misting up inside. Been doing so for 20+yrs. Tepid is the key though.

To stop it misting overnight, get the car as cold as you can before you park it up at the end of the journey. Last 3 miles, set the temperature inside to cold, last 1/2 mile, open the windows. I only learnt this a couple of years ago, but parking your car up with the interior as close as possible to ambient temperature to stop it steamng up really does work.

[jazzaro]

Just as an example, this is the 1700 W electric interior heater mounted on the passanger side of the center console in my Jazz.

Ahaaaa
It's the same heater mounted in some ambulances I drive.

[jazzaro]

Yes, a pre-heater can be installed.

https://www.defa.com/electrical-preheating/engine-heaters/find-engine-heater/
http://old.defa.com/vfp/eh/412232.pdf

This is an electric heater, used to warm the coolant inside the engine block, so the whole engine. The car must be plugged to the 220v grid, then a timer or an app controlled switch will power the heater.

I was toying with the idea of fitting one of these Defa block heaters a few years ago, but the cost put me off a bit. At the time, I had a big MPV, and it took an age to warm up in winter, clobbering the fuel economy on the short school runs.

As usual, the Chinese are now churning out universal units that can be plumbed in for a fraction of the price. They look like a rip-off of the Kenlowe Hotstart idea.

https://www.ebay.co.uk/itm/220V-240V-3000W-Car-Engine-Heater-Coolant-Heating-Air-Parking-Pre-Heater-1pcs/363222865403

You can get them much cheaper on Aliexpress.

Yep, cheaper but less functional: this device must be put in one of the two hoses between the engine and the radiator, it will heat the coolant inside the hose hoping that it will start circulating itself by convective motion.
The aftermarket 220v Defa heater  (and the OEM 115v Honda heater, very similar to the Defa) will heat only the coolant inside the engine, heating the block, the head and  warming the lubricant.
Defa also sells that kind of heaters (same of the chinese you posted), but only when every other kind of heater cannot be mounted.

[sparky Paul]

Yep, cheaper but less functional: this device must be put in one of the two hoses between the engine and the radiator, it will heat the coolant inside the hose hoping that it will start circulating itself by convective motion.
The aftermarket 220v Defa heater  (and the OEM 115v Honda heater, very similar to the Defa) will heat only the coolant inside the engine, heating the block, the head and  warming the lubricant.
Defa also sells that kind of heaters (same of the chinese you posted), but only when every other kind of heater cannot be mounted.

The Chinese units are fitted in the existing heater circuit, not the radiator, so heating the engine block and heat exchanger circuit, same as the Defa. Any heater in the radiator circuit won't work, that's the wrong side of the thermostat. These heaters also have an electric pump built in, so are every bit as effective as the Defa unit.

Yes, the Defa units are a neater idea, using a heater element that fits into bottom hose connection of your specific engine, but they are ten times the price of the Chinese effort here in the UK.

[John Ratsey]

Electric pre-heating is OK (subject to having a convenient socket) for the start of a trip from home but will do nothing to help a trip back home after the car has been parked away from home all day although, I acknowledge, days tend to be a bit warmer than nights.

Getting back to the Mk. 4 Jazz, my concern is retention of such heat that the engine generates while it is running. In urban conditions it may only be needing to run to provide power for the vehicle for one minute every three or four minutes. When it isn't running it is cooling down either because of the cabin heating or due to natural ventilation of the engine compartment (a much grater problem when the vehicle is moving).

I've seen a comment somewhere that the basic Mk. 4 Jazz does warm up quite well but I'm unimpressed by the cold weather behaviour of my Crosstar. I have to wonder whether the basic Jazz's more solid face (which some say is ugly) combined with the undertray combine to keep the engine compartment warmer. Crosstar's extra vents on the front plus the lack of the undertray (not needed, we are told, as there's no aerodynamic improvement) substantially increase the amount of natural draught around the engine and cause the hybrid system to operate less efficiently. I wouldn't be at all surprised if the design engineers assumed that the Crosstar would have the undertray and the bean counters then left it off.

I wonder how Toyota have addressed this problem in the new Yaris - the advertising says that the engine only needs to run for one minute in five in urban driving.

[Kremmen]

At the moment I have my climate control set to 22 and the interior gets quite toastie in about 4 or 5 miles.

From what you're saying the Crosstar takes considerably longer, if at all, because the engine keeps cutting out ?

[John Ratsey]

From what you're saying the Crosstar takes considerably longer, if at all, because the engine keeps cutting out ?

What happens depends on the driving conditions. First there's the warm-up problem. Initially the engine has some load until the battery is fully charged (turning on the heated seats will slow that charge rate down slightly) but once the battery is charged and the engine is running only to heat the cabin then all the extra efficiency due to the hybrid system is lost. If the vehicle is moving then there's a cold breeze through the engine compartment delaying the engine reaching the optimum operating temperature so it's below the potential best efficiency. At low to moderate speeds the engine should keep cutting out for the hybrid system to run efficiently but if the engine cuts out then it starts to cool down and the greater the ventilation through the engine compartment then the faster that happens. At higher speeds the engine is likely to be running continuously with more load on it so it's likely to warm up faster but until it's hot the mixture will be richer with more fuel going down the exhaust pipe. 

Honda put grille shutters on the CR-V https://hondanews.eu/gb/en/cars/media/pressreleases/159200/2019-honda-cr-v-hybrid56 . They know there's a problem needing to be addressed:
"Air inlets at the front, beneath the chrome Honda badge on the nose, feature Honda’s Active Shutter Grille system to improve fuel efficiency. By default, the system keeps the grille shutters closed as much as possible, even in city driving, to improve the aerodynamic performance. However, when required, the system operates an electronic step motor to open the grille shutters as much as necessary to allow airflow into the engine bay. A central processor tracks major temperature parameters for engine coolant, transmission oil and air-conditioning requirements, to determine the ideal state for the shutters."

[Expatman]

At the moment I have my climate control set to 22 and the interior gets quite toastie in about 4 or 5 miles.

From what you're saying the Crosstar takes considerably longer, if at all, because the engine keeps cutting out ?

Is your Crosstar kept in a garage or open on a drive? Also does the engine keep running until the cabin set temperature is reached? I would expect  Honda to program the climate control to keep the engine running until the set temperature is achieved.

[Kremmen]

I've currently got a 2013 9G Civic but I have the Crosstar as my No1 for a change later this year so I'm here 'taking notes'

[jazzaro]

From what you're saying the Crosstar takes considerably longer, if at all, because the engine keeps cutting out ?

What happens depends on the driving conditions. First there's the warm-up problem. Initially the engine has some load until the battery is fully charged (turning on the heated seats will slow that charge rate down slightly) but once the battery is charged and the engine is running only to heat the cabin then all the extra efficiency due to the hybrid system is lost. If the vehicle is moving then there's a cold breeze through the engine compartment delaying the engine reaching the optimum operating temperature so it's below the potential best efficiency. At low to moderate speeds the engine should keep cutting out for the hybrid system to run efficiently but if the engine cuts out then it starts to cool down and the greater the ventilation through the engine compartment then the faster that happens. At higher speeds the engine is likely to be running continuously with more load on it so it's likely to warm up faster but until it's hot the mixture will be richer with more fuel going down the exhaust pipe. 

Honda put grille shutters on the CR-V https://hondanews.eu/gb/en/cars/media/pressreleases/159200/2019-honda-cr-v-hybrid56 . They know there's a problem needing to be addressed:
"Air inlets at the front, beneath the chrome Honda badge on the nose, feature Honda’s Active Shutter Grille system to improve fuel efficiency. By default, the system keeps the grille shutters closed as much as possible, even in city driving, to improve the aerodynamic performance. However, when required, the system operates an electronic step motor to open the grille shutters as much as necessary to allow airflow into the engine bay. A central processor tracks major temperature parameters for engine coolant, transmission oil and air-conditioning requirements, to determine the ideal state for the shutters."

That's sure, but there is another problem, cost cutting, that affects Honda while it builds cars, especially small cars like Jazz. A stepper motor operating front grill shtters could be put also on the Jazz, increasing its price list because it would become "a small CRV". Other features are not used in these cars because of the cost: we already talked about the heat pump, but the same would be for a other devices used for heat recovering and heat storaging. Also windows... now they only have one simple glass layer (apart from the windshield with two layers and a safety plastic foil between), but they could be more complex and heat insulating. During warmup, CRV has an heat exchanger to recover heat from exhaust gas,  shortening warmup  and recovering heat for the cabin, but it does not have a bowl to store heat and use it when the engine is off. Our cars could be much better in efficiency, but they would be much heavy and much expensive.