Its more resistive wire heaters versus resistive film. The film consumes less power and spreads the heat more evenly than a wire.
http://www.dew-not.com/kendrick-comparison.htm
As far as power consumption goes I the unit I was looking at was the 16 inch strap and as I recall it was rated to just under 5 amps which at 240V = 1200W which would make my generator rev rather than power everything at idle with less noise and less fuel consumption.
Kendrick also have brought out a film heater strap as well.
The Kendrick controller is more expensive. I am sure its fine. I was told they are a bit complex. I also want to keep my system as simple as possible as the tiring thing in this pursuit is something not working properly that night and chasing it down!
This is the review that alerted me to power usage which I wasn't even considering as an issue but could see it may well be using a generator:
http://www.astromart.com/articles/ar...article_id=105
Also bear in mind this is merely as a result of my internet research when looking at dew removal recently not from practical experience as I have never used a dew strap. So if your experience is otherwise I bow to your practical experience over internet reports as I would with anything. The internet is a source of data both good and bad. Like anything in life you have to be able to evaluate the data and match against your own observation and experience and decide if its valid or not. I am sure I don't have to tell you how much rubbish data there is on the internet with vested interest and personal bias.
Greg.
Quote:
Originally Posted by peter_4059
Greg,
I don't follow your rationale on the power consumption comment. Are you saying Dew-Not are capable of putting the same amount of heating into the OTA while using half the power of a Kendrick heater? The only way I can imagine that would be the case is if the insulation on the Dew-Not is twice as effective (which I doubt).
My EQ6 and Kendrick controller both running draws 0.47A whereas my heater strap for the SN10 is rated at 2A - ie the heater strap can use an order of magnitude more power than the controller. Although the strap is rated at 2A, it would only draw this current if you ran it at 100% output on the controller (which I never do).
I have a Kendrick controller that is capable of sensing ambient temperature, dew point and also the optics temperature. The controller keeps the optics a fixed delta above dew point. It switches the heat on and off to do this and never exceeds 50% output.
I suspect the Dew-Not strap is simply just rated at a lower power, so to keep the optic at a certain temperature, you will need to run a higher output on your controller and the actual power consumption will be pretty much the same - you just have less headroom in your system.
I've attempted a side by side comparison of the power ratings of the two systems.
Here's the data:
Kendrick http://www.kendrickastro.com/dew_premierheaters.html
Dew-Not http://www.dew-not.com/specifications.htm
Peter |