During our kitchen remodel a little over 2 years ago, I purchased a Viking island hood off of Ebay that did not have the blower. All the literature said to use the Viking blower but I determined that was for warranty purposes. Since I was not getting a warranty anyway and what really needs to be warranted on the actual hood anyway, I purchased an inline Fantech blower and silencer that is mounted away from the hood. The same model as yours just 900 cfm. I had no problem hooking it up to the electrical switch box in the hood and the controls and light work as designed. The only problem is that I am not sure you can get a Viking supplier to sell a Viking hood without their blower as it may violate rules of distribution, that is why I started to look on Ebay. Do not rule out looking for it on Ebay as I remember there were quite a few models always available when I was looking. I was surprised to find the island hood I needed, but lucked out and saved quite a bit off both the hood and going with Fantech.

heartsurgeon and cpovey, Thanks for the info. In March, after reading hours (days?) of hood information on GardenWeb, I had decided to get a VAH 42", 600 cfm (VAH doesn't make anything higher than 600 cfm for a 42" hood and 48" was too big). I had made a cardboard hood of that size and mounted above the cooktop (no cooking allowed!) to get an idea of sightlines. 32" was best for viewing across the greatroom for me, but the cook in the house was fine with 30". The VAH rep insisted to never go above 30", so we were set to go with VAH at 30". But, since there was a delay in the BlueStar cooktop we wanted, we waited. The housing market got worse and a large appliance place folded and liquidated their inventory, and I got a deal on a Viking that I couldn't pass up. The hood didn't come with a blower, so that's why I have been asking the blower questions. Since higher CFM blowers were available on the Viking, I thought I could push the hood up to 32" with higher CFM and be OK. I figured the internal motor probably has twice the noise...the air noise through the baffles and then the air noise through the squirrel cage blower. So heartsurgeon, it wouldn't surprise me that it's noisy when on high at 600 cfm. Do you even hear the motor...or is it all air? The external probably does look like the best option, as I agree with cpovey that an in-line motor would be a hassle to maintain. Looking at the specs, I think the external would fit on the roof. Cpovey, I don't know if I could install the external upside down either...is there a damper that would be upside down? I had been only considering venting out of the bottom if I used the in-line. If I use external, it would go on the roof. Now today when I picked up my hood, I scrounged around the warehouse and found that they had a 600 cfm internal blower left for that hood, which I able to pick up for a good deal as well...so I couldn't pass that up either. So I"ll start with a 600 cfm internal, mounting the hood at 30". If it end's up too noisy, it's not that much of a loss and it would allow us to find out if we need more than 600 cfm. If we don't, but want to use an external for noise reasons, we will still come out ahead cost-wise. I think I'll still use 10" duct work in case I do want to go up in CFM if we go to an external...it's not that long of a run, so it shouldn't cost that much more. Also, I would think that a 10" elbow above the hood would make less noise than a 7" elbow. I plugged the 600 cfm fan in (not inside the hood) to an outlet to see how noisy it was. It does make some noise, but it seemed less noisy when I added some wind resistance, so I won't be able to tell much until it's fully installed. It sure could blow some air when unrestricted though! This got me a little concerned that if the vent exits on the top of the roof...it will be only about 8 feet away from the deck table, pointing right at it. Will this cause an unappealing breeze to the outside dinner guests? Maybe the baffles cause enough resistance that it really doesn't blow out that fast in the real application? I am still interested to hear if someone has put an external fan this close to an outdoor sitting area and what the noise level is like. I'm guessing that it may just be a white noise-type situation outside?

You might want to look in the Appliance forum. There are a lot of threads there about range hoods and make-up air. Modern-Aire and Vent-A-Hood are 2 brands that come up often. My wife and I looked at hoods last weekend. In the area where we live, Modern-Aire is only available through approved KDs and architects, so we weren't able to look at that. The first thing you should decide on is whether you want mesh filters, the VAH Magic lung or baffles. If you going to have a grill on your range, then you'll probably want to stay away from mesh. The VAH Magic lung uses squirrel-cage type blowers that use centrifugal force to remove all of the grease from the air and blow it into an enclosure. The enclosure is removed once a month or so and cleaned in the dishwasher. About once a year, the squirrel cages should be removed and cleaned as well (by hand, I think). VAH also claims that their 600 CFM fan is the equivalent to 900 CFM in other brands (because you're not pulling air through filters), but some people dispute that. As neither my wife nor I are very mechanically inclined, we found the process of removing the enclosure a bit clunky, and the prospect of cleaning the squirrel cages to be particularly daunting, so we passed on the VAH. That leaves baffle filters. The baffles have handles on them, and they simply snap out and go in the dishwasher. I've seen complaints in some forums about grease getting behind the baffles and needing to clean the inside of the hood under the baffles. The higher the air flow from the fan, the more grease that is trapped by the baffles, but it's likely that some amount of grease will always get through. Also a higher speed fan operating at a lower speed is quieter than a lower speed fan operating at capacity. So if you plan to do a lot of grilling or wok cooking, you might want to oversize the fan. You can get fans mounted inside the hood, in-line or roof-mounted. The farther away the fan is, the quieter the hood will be (although there will still be the noise of the air rushing over the baffles). With a remote fan you'll also need to oversize a bit to get the Required CFM down at the hood. Our salesman recommended the Best brand in a baffle hood, as they manufacture the hoods sold by Wolf and many others. It seems to have a reputation as a solid mid-range hood here on GW. The Best hoods have a bit of mesh between the baffles as well. I don't know if this is good or bad. We would have chosen the Best hood, but my wife and I couldn't agree on the hood style (she wanted a chimney style and I wanted a slanted pro-style). The only style we could agree on was a hood insert inside a cabinet enclosure. As it turns out, the cabinet company we're using, uses Modern-Aire for their hood inserts, so that's what we'll be getting. Now my wife and I just need to agree on the type of wood for the cabinets! Finally as others have mentioned, you should look into the issue of make-up air. If you're building a tight new house with little leakage, then it probably makes sense to install it now. Also check with your town to see if it's required (many jurisdictions don't require it in residential installations). My understanding is that a simple make-up air system isn't that expensive. Putting in a heated system (if you live in a cold climate) can be very expensive though. Some people, especially those with large hot commercial-style ranges (like Bluestar), simply run the make-up air duct under the range so the air coming in goes right back out the hood. Others (like me) simply rely on the open window approach and get a bit cold in the winter. The important thing to remember is that if you have a tight house and large CFM hood, then the air is going to come into your house from somewhere. If you don't allow for make-up air in some fashion, that air will come in from an undesirable location, like your chimney or furnace exhaust, and likely bring carbon monoxide into the house as well.

It is worth pointing out, I think, that the pressure differential across the blower, called pressure loss, is essentially the same whether the blower is in the hood, at the end of the duct outside, or in a door blowing into an otherwise sealed house. The pressure loss is the sum of all the losses due to friction and turbulence in the duct, duct cap where present, hood transitions, baffles, make-up air system restrictions, etc. Any slight differences in pressure loss with blower position will be due to local transitions where the blower is mounted versus the blower's air flow uniformity at the blower exit. The resulting flow rate will be that which applies to that pressure loss on the fan curve plot. Front of hood deposited grease is due to insufficient overlap and/or insufficient air velocity at the hood aperture. Hoods are generally poor at drawing air from the vicinity of the burners. Most plume capture depends on the plume's upward velocity, mainly driven by the buoyancy of hot grease and water vapor and air. The plume naturally expands as it rises, hence hood aperture overlap is desirable.