Diesel Parking Heater- Control

[WelshGas]

This is aimed at SE and Ocean owners. The Beach has a different Control Panel so I don’t know if it works in the same way.
I’m interested in how the Internal vehicle temperature is controlled. Having read the Handbook and California Suppliment , very informative NOT, I’m none the wiser.
The Parking Heater Temperature Selection has 10 levels to choose from Level 1-10. What do these Mean?

My theory.
I believe each Level selection determines How Long the period of maximum heat output lasts before entering Maintenance Mode.
The actual temperature within the vehicle is determined by the difference between Heat Output and Heat Loss via Bellows, windows and body panels.
Selecting a higher Level means the vehicle warms up more quickly and then it enters the Maintenance Mode which may vary in heat output depending on the Temperature Level selected.
There is a Temperature Sensor behind the grill in the Front footwell which, I believe, is set to switch off the heater when a certain maximum temperature is reached. I don’t believe this cut off temperature varies with the Temperature Level selected, it is fixed. The Temperature Sensor is behind the footwell grill because it is one of the lowest points in the vehicle interior and cold air will sink to the lowest point as it is denser and warm air will rise. If this sensor is triggered the Heater is switched Off and only comes back on when the temperature sensor drops to the low temperature trigger point. Something like Low 10c and High 20c or something like that.
So, for example if you select Level 3, the Heater fires up, warms the vehicle quickly and enters maintenance mode. Because it’s Cold outside Heat Input - Heat Loss produces a Temperature in the Vehicle of 15c and the Heater keeps functioning.
If the external temperature rises then the Heat Loss will decrease and the internal temperature rises triggering the High Temperature setting off the Footwell Sensor and the Heater switches Off until the Sensor Temperature drops to 10c and it is fired up again.

Does anyone know if that theory rings true or does know exactly how things are controlled.
All suggestions/theories welcomed.

 

[Loz]

don't over think it.. they use 1 to 10 as an arbitrary level; just like the volume on your stereo neither are calibrated.
The unit heats up at the same rate but as it reaches the level it slows down the fan, and idles and watches the temperature drop. Once a differential is passed it fires up again. This will say be 5-10 degrees difference for example.
We monitor kit that behaves like this and the developer has to strike the right balance between maintaining the exact temperature by running the heater more often and allowing a bigger swing before starting up again.
If it's cold outside then you will drop to the lower value quicker and the heater will run more often.
It is the same with air conditioning just cooling instead of heating. Look at this graph to see the effect in practice.


If you want a smoother graph you need to run the heater/cooler constantly but this uses more power.
The Webasto engineers will have calculated a balance to achieve the best use of power.

 

[MartG]

I think you're right. I looked at the Eberspacher / Webasto interface to Ocean control panel, the control panel setting is (I think) just a setpoint sent to the heater control electronics. The heater electronics has the temp sensor in the air inlet and cuts in / out according to it's setpoint, derived from the VW control signal - in other words, I think the VW level setting is a specific heat setpoint signal 'sent' to the heater, not a heat run time. My reasoning is that once temp is reached, the heater modulates by temp sensed rather than run time. I wouldn't think the level setting would affect a quicker heat-up rate, I think it's flat out until it approaches the setpoint, backs off, then enters 'maintenance mode'. I don't think the control panel has an internal temperature sensor or any control within itself. This is just my quick observation when I was trying to help out a T5 owner a couple of months back...

 

[WelshGas]

That’s what I’m trying to fathom out. Selecting Level 10 doesn’t seem to produce hotter air coming out of the vents but does seem to run for longer at full blast before entering maintenance mode compared to Level 1.
Or does the different Levels alter the High/Low trigger points of the Temperature Sensor?

 

[MartG]

Exactly, not hotter (out of the vent), just a higher temp setpoint, which causes the heater to cut out later at the higher temp sensed.

 

[Hotel California]

I don’t bother...when starting up i usual set on 5 , then lower to 3 .
Nighttime 1-2.
When extreme cold we set higher offcoarse .
And once a while i set it on 10 to have a good burn , but not while i’m in the Cali doh...way to hot !
When on hook-up , i’ll be using my small silent electric heater.

 

[ArunAlec]

Bit of a Spinal Tap scenario!

 

[sidepod]

I started to feel my eyelids gaining weight part way through so forgive me if this has been pointed out, doesn’t the heat setting regulate the pump ie higher heat setting more fuel pumped in?

 

[WelshGas]

I started to feel my eyelids gaining weight part way through so forgive me if this has been pointed out, doesn’t the heat setting regulate the pump ie higher heat setting more fuel pumped in?

Doesn’t seem to, apart from the initial startup when it seems to tick along at the same rate no matter what level is set until it slows to maintenance mode.

 

[ArunAlec]

Exactly, not hotter (out of the vent), just a higher temp setpoint, which causes the heater to cut out later at the higher temp sensed.

So similar function as a basic central heating room stat?

 

[Amarillo]

I started to feel my eyelids gaining weight part way through so forgive me if this has been pointed out, doesn’t the heat setting regulate the pump ie higher heat setting more fuel pumped in?

Does it tick faster on a higher setting? Or maybe each tick lasts for longer...

 

[sidepod]

Once up and running on a hi-ish temp mine ticks quickly. After 10-15 mins the fan speed and "tick" frequency slow.

 

[WelshGas]

On Level 1 the Low Temperature setting to re-start the Parking Heater seems to be about 15c and the High Temperature setting to switch it Off about 25c.

 

[MartG]

So similar function as a basic central heating room stat?

Yes, but it does throttle back once setpoint is neared, fan and pump slows .

 

[Loz]

I wonder if the pump works like an old solex fuel pump , once the pressure is reached it stops, so the more fuel the heater burns the faster it clicks.

 

[Nick Stubbs]

No it doesnt build pressure, its basically a open end to the burner, it drips a metered amount of fuel onto a stainless steel mesh that once running glows and burns the fuel dripping on it.

 

[sidepod]

No it doesnt build pressure, its basically a open end to the burner, it drips a metered amount of fuel onto a stainless steel mesh that once running glows and burns the fuel dripping on it.

Just like my garage heater when I was a kid. Used old sump oil.

 

[rod_vw]

The frequency of the pump pulsing is controlled by the heater ECU and is controlled in conjunction with the fan(s) speed. I say fans because there are two on the same motor shaft one supplying the combustion air and another the air that you feel blowing into the cabin.
There is a reasonable description of the operation here pages 29 onward. My understanding is that the heater as installed in the California is controlled in the basic fashion using monitoring of 'room' temperature in the in-going air (that taken into the heater from the right front footwell) and does not have a cold air circulation mode.

There are modulators (control units) available to those of us building our own campers that use room temperature monitoring at the location of the modulator and offer temperature settings in degrees centigrade just like a domestic central heating thermostat.
I use the simple 801 modulator which also provides cold air circulation and diagnostics display. There are a number of more advanced modulators providing timed control and remote radio switching options just like those that you have in a Cali.

Rod

 

[westfalia]

I asked Jürgen and he said "10 is hot and 1 is not too hot"

 

[WelshGas]

Based on @rod_vw 's document he posted. If the Heater works between 10 to 30c and the Control Panel Temperature Selection is Level 1 to 10c then I'm going to work on the premise that each level Counts for a 2c addition or therabouts. Level 1 = 12c.
I know it may be simplistic but it will do for me.

 

[Sp0_0k]

Sounds great in theory but one of winter nights I set it to 1 and wokeup up to heater blowing like crazy and too hot inside.
I suspect it was caught in a cycle of start ups and lowest temp overshoots too fast, resulting in numerous restarts (temp in a van drops in seconds with -15 outside) and battery almost dead, because each start takes 10 amps for couple minutes or so.
I am so desparate to make that thing simply work at one of set levels. Even single lowest will be enough.
So far it has been voodoo magic to predict heaters mood setting it to 3-4 when we need it at lowest just to prevent restarts.
Won't be surprised I will have to throw vw's Heater away and order Eberspacher directly just to fix this nonsense.

 

[clarinetbcn]

I think the problem is that the thermostat is near the air intake in the front footwell, which is the last place to heat up and the first to cool down. I have read on the forum that some who have installed aftermarket heaters on Beaches have an option to install the thermostat higher up in the rear cabin, which works much better, but I don't know if this can be done with the OEM heater system.

 

[TripleBee]

It is the same as the fridge. You can set it on 1 - 7, where 1 doesn't do much, and 7 is a freezer.
It is like putting the fridge on 10°C. up to 0°C. Where 1 = 10°C and 7 = 2°C. But we can't see what temperature it is set at.

If you put your heater on Stufe 1, then it will warm up to a certain degree. If you put it on Stufe 10, it will heat up to, let's say 30°C., and all inbetween. The problem is, we can't set a temperature, we can only trial and error what is the right temperature. I find Stufe 3 as a good (sometimes even too hot) setting, and Stufe 2 is not warm enough.
The only difference is the time the heater will run.
Another problem is that there is no modulation of temperature. The heater doesn't keep the temperature. Once reached it stops heating. When the temperature drops below a minimum for that Stufe, it restarts, like an old home heater.
Modern heaters regulate the temperature more precisely, having lower thresholds, meaning less gass (diesel) consumption.

Can everyone follow what I am typing?

 

[rod_vw]

I fit Eberspacher heaters in my conversions with their 801 modulator (digital control) with internal temperature sensor installed. The controller is situated two thirds of the way back down the habitation area.
This controller can be set to a specific temperature (in degrees C). This maintains the internal temperature within 4 degrees. There is a 4 degree overshoot which I suspect is to ensure that the heater always has the chance to get up to full running temperature before switching off. When running in this mode the heater will shut down to very low output to maintain the set temperature and does not require a full cold start.

 

[Sp0_0k]

all the temperature settings are useless in this van as soon as you cam below -10'c Because with no insulation you go from +20 inside to 0'c in minutes and heater goes crazy.
Same reaching hot temperatures is almost instant in such a small space.
I would only accept fixed heating level and adjust temperatute inside with windows.

Restarting the heater takes same diesel amount as running on low like half an hour. And burns the battery, so ecological factor is bs imho. Add smell alone on restarts.