FBH problem - opposite to usual

[Raistlin]

Originally Posted by moodybluezt

hee hee, he's already had the webasto manuals from me.
Im trying to become webasto guru, I like things that make noise and get hot. ! ( or not)

Steve

Steve - no I haven't

Juergen - the coolant is circulating as the car gets nice and warm when I use it to pre-heat the car

If the FBH runs on part throttle even when the coolant is upto temp, doesn't that use a heck of a lot of fuel?

Thanks again to all for your help

[black olive]

Hi Paul,

I did email them to you. they may take a while going through the external firewall at work. WRT to fuel consumption, bear in mind that the fuel burned in the heater is only to produce heat, which is transferred into the coolant via an efficient heat exchanger, and not used to move a lump of car around ( a by product of which is the waste heat transferred to the coolant, which in the case of a diesel engine isnt a lot, hence the webasto) Im sure someone with a degree in thermodynamics would be able to do the sums and work out how much fuel the webast uses (or it may be in the webast tech spec !!)
Ill send them again tomorrow

steve

[Simon]

From the UK Webasto website and looking at the specifications sheet for the Webasto Thermo Top E (the one best suited to the size of the Rover 75)...

Fuel consumption is 0.5 litres per hour for a 60-minute heating phase on full load (ie, cold to hot without any regulation from the thermostat)

0.5L/hour translates too 0.1 gallons per hour.

0.1 gallons per hour very very roughly means your mpg will drop by 1mpg... (of course, this is the FBH working at full whack for the entire time your engine is running, which in reality it isn't)

[Raistlin]

Steve

Thanks - I'll look out for them

It seems that I am just going to have to get used to hearing the Webasto running when I switch off the engine if ambient temperature is less than 5 degrees

[Lovel]

Originally Posted by Simon D

From the UK Webasto website and looking at the specifications sheet for the Webasto Thermo Top E (the one best suited to the size of the Rover 75)...

Fuel consumption is 0.5 litres per hour for a 60-minute heating phase on full load (ie, cold to hot without any regulation from the thermostat)

0.5L/hour translates too 0.1 gallons per hour.

0.1 gallons per hour very very roughly means your mpg will drop by 1mpg... (of course, this is the FBH working at full whack for the entire time your engine is running, which in reality it isn't)

Just before the end of 2006, locally we had a sustained cold snap for two weeks solid where the outside temp very rarely got above freezing even during the daytime. During this period I used the Parking heater 30 mins at a time every morning and night for commuting. I also carried out a fuel consumption check using the old top up method, and agree that the burner used up about 1-2 mpg, compared to my normal driving consumption of 42-43mpg. I'm sure it would have also came on at other times during that period too when the car was started the FBH would have kicked in due to lower temps.
As well as burning fuel the FBH would possibly save you fuel too during cold start up. Also helps engine oil life. I have been using parking heater probably every working day since beginning of October.

[Keith]

Interesting numbers there guys but unfortunately Paul has bigger issues to worry about now, see his thread in the main forum.

[Jürgen]

Originally Posted by Simon D

From the UK Webasto website and looking at the specifications sheet for the Webasto Thermo Top E (the one best suited to the size of the Rover 75)...

Fuel consumption is 0.5 litres per hour for a 60-minute heating phase on full load (ie, cold to hot without any regulation from the thermostat)

0.5L/hour translates too 0.1 gallons per hour.

0.1 gallons per hour very very roughly means your mpg will drop by 1mpg... (of course, this is the FBH working at full whack for the entire time your engine is running, which in reality it isn't)

It's a Webasto Thermo Top C on my 75.

The heat output is 5 kW at full load or 2.5 kW at partial load (I just wanted to throw out a few more numbers ).

The fuel consumption is measured in kilograms, not litres (who knows why?). It is 0.5 kg or 0.25 kg per hour. As fuel is lighter than water that means about 0.6 litres per hour.

Originally Posted by Lovel

As well as burning fuel the FBH would possibly save you fuel too during cold start up. Also helps engine oil life. I have been using parking heater probably every working day since beginning of October.

If you don't drive just a few miles after using the FBH you won't use significant more fuel, if at all. A warm engine will use less fuel than a cold one. Another big plus is less engine wear.