Yes. No problem working at those two settings. A fellow windie has one and it works fine. His doesn't kick on at 1 or 2.Spruce would they ignite with the normal rate used when cleaning windows?? I use a brodex machine so the flow rate is from 1 to 9 and I would use it at 3 or4.
Working with warm water is an interesting experience. The viscosity of water changes with the rising water temperature, so you will get a higher flow at 4 than you do using cold as the pump has less work to do.
You can use this to your advantage as you will be able to wash and rinse windows quicker. Again it becomes another learning curve which will take a while to adjust to.