Grant, it sounds like even though your control system is different the fan size and also your "pancake" heaters are exactly like those in the "SMC Era Beavers" like mine. For me the low fan speed simply didn't produce heat fast enough, and so I went with the high speed 140cfm (45db). Even though they are a little louder on the hi-speed than the stock fans, some of the noise is muffled by the installation itself, and when I turn the switch to low speed as Joel indicates it quiets down.
As I've examined these heater units, it seems to me that these fans will fight themselves as they pull air in and the angle means a lot of that air is bounced around inside these slim units rather than directly blowing over the hot coil. Therefore, the CFM rating is further cut down by this angle, so at the low CFM number you've mentioned, that CFM number will be further restricted.
I replaced mine because even on hi-speed of the stock units, I could barely feel air coming out. Now, true, some of that was the dirty units but I think most of it is the design of these pancake units. I don't know that they are even still available but wouldn't be surprised that they've been discontinued. I didn't find them in the Oasis Combi manual, but they are in the old Hurricane Manual.
Oh, just FYI for others - since I didn't need it I removed my Hurricane Reservoir Tank in the engine compartment and simply connected the two 5/8in pex hoses with a length of silicone heater hose (the Oasis Combi has this reservoir built into the unit with overflow tank as well). I guess these items don't go bad but does anyone need one of these tanks?
Mike
