who do you know with a 5kw heater thats happy with the heat it produces?(nigels heater doesnt count as his is a DIY model)
A few on the old farcebook groups, and someone called Stuart on another forum. All have grippa 5kw fitted in the last year and are happy. 
What I don’t get, is on the grippa site the 5kw is capable of 76 degrees. That’s hot!
The problems seem to come from the streamline or pure freedom 5kw, grippa may have done something different with how they rigged it up. Still waiting on Oliver’s response.
Its capable of that because that's the maxium heat it will achieve before it goes into shutdown mode.
Remember, its designed as an engine preheater. It will circulate and reheat the water in the vehicles engine until it reaches this temperature. It would be a waste of time heating it to a higher temperature and this is when the thermostat in the engine will open to allow hot water through the radiator to be cooled.
What the concern is not what temperature it will reach, but can it supply enough heat to the heat exchanger to keep the water to the brush head at the required temperature?
It requires more heat to heat a flow of 5 liters of water per minute than it does 1 liter of water per minute.
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That makes sense spruce. Thanks for your input as always.
What you can achieve at the brush head heating on demand also depends on the base temperature. So if the water in your tank is 5 degrees then the resulting temperature at the brush head would be lower than if the water in your tank was 20 degrees.
In the test I did with my 5kw Webasto I only manged to raise the temperture at the brush head to 35 degrees with the water in the tank at 9 degrees. My flow was cold 1.5lpm at the brush, but at 35 degrees it was more with the same controller setting.
According to the calorific calculator, raising that flow of water by 26 degrees used 2.65kw of energy. That heater was giving everything it had as the water was cold after it had left the water to water plate heat exchanger - it had every bit of heat zapped from it.
Before I started this experiment on the test bench, the maths indicated to me that a 5kw heater would just manage to supply the heat requirements of 2 operators. This was in conflict with the reality as others experience was that it would just supply 1 operator.
So my next question was where the other 2.5kw was going? The exhaust got very hot so my only conclusion was that the vast majority of this 2.5kw is wasted and is lost to the atmosphere. So for every liter of diesel at £1.20 about 0.59p is not used but wasted. This is a sobering thought.
There is a windie in Andover who uses a Thermo Top C to heat the water in his tank. He has enclosed the heater's silencer in an alloy box with a fan inside the van. (Silencers are normally fitted outside the van.) He uses that heat to warm the back of the van.
Another thing we don't see is any insulation inside these steel heater box containers. (PF are the only ones who do I believe.) So they act as radiators. The van keeps warm but lots of heat is lost in the process.
In its designed application as an engine preheater heat loss isn't terribly important as the sales pitch to fit one is that its a labour saving device, saves energy when compared to letting an engine idle to warm up so is more environmentally friendly, increased comfort getting into a warm, defrosted vehicle, no frozen windscreen to scrape, etc, etc. So if the preheater is set for 30 minutes its only going to cost you about 40p to save all that bother. 4 mornings use for the cost of a cup of coffee at McDonalds and 7 mornings worth for a Costa Coffee, so of course you can afford to run that. (A 5kw Webasto uses less than a liter of diesel an hour 0.61l on full throttle.)
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