You cannot use a downdraft behind a range unless you use a Dacor DD behind a Dacor range. The guts of the system leave it up to 10 or 12" behind the range, depending on internal or external blower and the vent. Check any brands installation specs and you will see.

And they are all about the same anyway.

Dacor

AVOID DACOR AT ALL COSTS.

Not sure if it's the same issue as with a range, but we will be pairing a 36" Miele gas cooktop with a Thermador downdraft. I had heard from folks here, and from our appliance dealer that Thermador was the best for this. Also, Thermador's buttons are on the unit itself. Others would require an additional cutout for the controls.

Um, Dacor's controls are on the unit itself.

Woops. Meant to add this link.

Here is a link that might be useful: Dacor downdraft

Any opinions on Broan? I am planning to use the 36 inch Broan (9 inch pop-up) witn a 36 inch Monogram cooktop. I like the idea of putting the Broan filters in the dishwasher but would welcome some feed back from anyone experienced with Broan.

I agree with lindy1991. Avoid Dacor if possible. We have been fighting with Dacor since end of August for them to make good on our brand new defective REMP16. I had to hire a HVAC specialist for $350 to provide Dacor a diagram of my existing ductwork because Dacor insisted that their REMP 16 could not be at fault and it was my ductwork. However the REMP16 was clearly defective-- the specialist said the ducts are ok but that the RPM's of the REMP16 are not right. Dacor has FINALLY agreed TODAY to ship out new motor for REMP16. However Dacor said they WILL NOT pay to install it. We have been dealing with Melissa at Dacor. She has poor customer service skills. Matthew was better at the customer service skills, but knew nothing about ventilation. It was not unusual for us to spend 45 minutes at a time on the phone with them and resolve absolutely nothing. It has proven extremely frustrating to work with them. In our area, A&E handles Dacor's warranty issues.

The OP asked about downdrafts and RANGES. For this Dacor is the only game in town. With a cooktop, it doesn't really matter which brands you mate together, but for a Pro range Dacor is the only company that allows theirs to be used with a downdraft, the others do not recommend or allow this configuration.

And since Dacor is the only game anywhere for dd and range combo, that's enough of a reason to switch to ct or rangetop and dd plus separate oven. If you want more negative Dacor dd experiences (mine included), do a search on this forum.

I'm hoping I don't have a problem with my Dacor downdraft. Fingers crossed, it's been OK so far. Here's the funny thing - I chose it because I didn't want to deal with Thermador's customer service. I'd spent too much time talking to their clueless yet arrogant customer service people. I guess in this case the devil I didn't know was preferable to the devil I did.

Slightly OT: It's just amazing how much money we spend on these appliances only to be treated poorly after the sale. In my experience this seems to be mainly the case with American companies. For instance, I've had much better service when I've needed to call Miele and F&P vs. GE, Thermador, Whirpool . . . I wonder why that is.

Wolf does make a rangetop that goes w/ a downdraft. It is a sealed burner range only and I believe 36" is the max range top size. There are 2 sets of specs out there for the wolf downdraft--one states you cannot use w/ rangetop but there is a new version and plan that allows for a downdraft w/ a particular rangetop.
We also HAD to go w/ a downdraft and chose the dacor over the wolf due to large burner size on the dacor range. I hope things go well for us w/ dacor...