Yes it's still important to remove hose reels poles etc and put them somewhere above freezing like a garage etc and then make sure all your pipe work in the van is lagged as best as possible, also best to lagg Di vessels and use an electric green house heater or similar for over night, weekend etc.
I have the PF 9KW heater and the frost stat only really protects the heater on my system as the pumps draw the cold water out of the tank and through the Di vessels it then passes through the heater and the hot water is returned to the tank, because the tank holds 650 L of cold water I have never found that the returned water is hot enough to make much difference to the water temperature in the tank.
Also worth remembering that the frost stat kicking in during the night will put quite a drain on your batteries if your planning on working the next day with the heater you will need to make sure those batteries are fully charged up.
With an anti freeze mix of -20 deg in the PF heater I shouldn't think that there is much to worry about with regards to frost damage to the heat exchanger, but I guess this depends on which part of the UK you live and how cold each winter becomes.
Well done for pointing this out though Trevor
Hi Simon
Good point re the battery use. It is not an exact science as to how much power the Frost stat will use. Please see a detailed answer below I hope it helps.
Firstly it is worth saying we are not experts on how the Webasto works as what we do with the control is provide a way to switch it on and off together with monitoring the temperature. So I am going to break down the advice as we can be pretty sure about how the pump and control will behave in most circumstances.
Please be aware there are some factors beyond our control which may effect individual systems differently to others for example. The ambient temperature of the air/water the quality of insulation/lagging also the efficiency of the pump and current water temperature will effect the draw the Webasto takes.
When the control is switched off at the end of the day the display goes blank and the control enters a sleep mode. This is because the processor is still operating and running occasional tests to check for operation. In sleep mode the control is drawing 50 milliamps or less.
In normal operation even running flat out the pump would draw between 3 - 5 amps. During frost protect mode the pump is turning at a minimum level perhaps 5 - 10 psi and would draw about 0.5 amps. creating a flow means the water has to be heated less and reduces the chance of freezing through the rest of the system other than the tank.
So during the frost protect cycle current is less than 1 amp
Now the Webasto is a bit more difficult for us to predict so I have sourced some information on the Thermo 90 S heater looking at points 3.1 Technical data. The data says while running on boost, so the heater is producing hot water for cleaning the draw is up to 7.5amps. Once heated the Webasto will draw between 3 and 6.9 amps to maintain operation.
It is worth pointing out we are only taking the water Temperature up to approx 4C and generating a water flow for a maximum of 13 minutes. This means the Webasto is likely to draw between 5 and 7 amps on start up this draw is for a couple of seconds then current draw will fall back nearer to the 3 amp range. So In practice the high draw may occur during initial start up of the Pump and Webasto but quickly fall.
Initial current draw might reach 8amps from the battery for a very short period then fall back to 3.5amp or less dependant on the factors mentioned above.
The pre set timing cycle in frost protect is based on the experience of a number of cleaners and speaking to some of the other WFP suppliers it was felt that less would not warm the water sufficiently, longer would be over kill and heat the water more than was needed. It is a difficult balance to strike heat the water to little and you have the webasto constantly powering up. To high and the principle of hot water freezing quicker than cold applies.
I am always happy to provide information on our Controls
Cheers
Ian