pellet furnace options

I would have to concerns with doing that.

1) The temperature of the air coming out of the new furnace will be hot and may cause overheating issues or melt things in the blower compartment that aren't rated to handle that hot of an air temperature.
2) the furnace you are installing is designed to work at at certain static pressure and cfm so if you have a second blower pulling air off of it you will mess with the dynamics of the furnace design usually resulting in less than stellar performance. It will also cause your air temperature to be lower coming out of the registers and make it feel cold instead of warm and toasty.

 

I know that I'm not supposed to install it into the cold air return, but since a HVAC (but not pellet) pro suggested installing it that way I thought I would throw that out there just for the experts to comment on. I understand that the manual was written for a reason as well. I had considered the concerns, and here are my thoughts. I'm probably totally wrong here, but just wanted to throw these out here.

1. I don't know what output temps are going to be on the furnace yet, as I've only done a test burn in the garage. It's a 45k btu unit, with a 600/800 cfm blower. I'm thinking I'm going to be somewhere near 200-225 output temp, just as a wild guess. Theoretically I'd be hooking into the cold air return approx 10-12 feet away from where the return enters the furnace. If the furnace blower is running, I'm thinking that I'm pulling at least 1200-1500 CFM through the cold air return. So, I'm mixing 800 cfm of 200 degree air with 1500 CFM of 70 degree air. By the time it actually hits the furnace, the air is probably reasonably mixed up and approx 110-120 degrees, right? That can't be that much hotter than the interior of the LP furnace when it's running, right?

2. I'm not sure how the proposed installation would affect static pressure. I know that I'll have lower temps coming out of the registers, and that's ok, as long as the house stays warm. If it's not warm enough, I'll fire the CPM.

I know it would void the warranty to hook it up that way, but (un)fortunately, the nearest St. Croix dealers are too far away for a service call, so I at least won't get busted for an improper installation. Unless I do it wrong, and then post about it!

Thanks for the thoughts.