I find it very interesting that your water was cold when it came out the exchanger. That tells us that all the energy was removed to the pole hose. My exchanger output is still toasty using the 9kw.
It was because of one of your other posts explaining the 5kw heat issue for 2 people that made me splash out on the Thermo 90 😂😂 I'm glad that this experiment helped you as well.
Did you ever try it without the thermostatic valve to see if you could get more temperate?
What about running the hot input on the coolant loop to first mix with the output side of the heat exchanger?
I had thermostatic valves on 2 of the heat exchangers as you can see. No I didn't remove them. I had the temperature set to max on the thermostatic valve and the temperature wasn't reaching it.
As I mentioned earlier, this experiment wasn't scientific. It was to give me a sense of direction. The water coming out of the heat exchanger felt cold. I may have been 10 or 12 degrees but I didn't actually measure it.
Over the years since then there are a lot more diesel heaters about. Users are saying the a 5.2 Webasto based unit isn't powerful enough to run a single operator system successfully. I proved that to myself and learnt a lot in the process. The 9.1 works better and due to its being more powerful and having different programming (3 stage heating) is more suited to window cleaning application IMHO.
The Thermo Top C is perfect for what it was designed for - as a diesel engine preheater for vehicles used in countries that experience extreme cold conditions.
I have plans to put this Webasto Thermo Top C into my Peugeot Boxer and use it as it was intended for, to preheat the engine and defrost the windscreen in winter. Will I ever get around to doing it? I don't know. The mind is willing but the body isn't anymore I'm afraid.