HVAC re-routing help

ajmckay · 08-28-2012, 05:39 PM

Hello,

In the process of my kitchen remodel I've run into some air balance issues. Prior to my starting, There was a single diffuser and a single return in the kitchen. The problem was that they were on the same wall about 3" off the floor, and they were located right next to each other. I'm guessing this is why the kitchen was always too hot/cold.

So with my remodel I removed the wall where the diffuser and return were. Now I need to add the HVAC back into the space. The dining room, now part of the kitchen (due to wall being removed) has a diffuser and a return (see picture, they're listed as "proposed new locations" but realistically they're already there).

Here's my question. I'm installing an island near where the initial diffuser and return were. Can I install a toe-kick diffuser and return in the proposed kitchen locations? I was thinking of building a simple plywood duct under each cabinet to channel the air to the register. I was going to use metal, but then I would have to deal with the potential for condensation under the wood cabinets.

I would appreciate your comments!

*EDIT* Picture removed, updated picture below.

**beenthere** · 08-28-2012, 06:35 PM

Gas and oil furnaces supply heated air at a temp of 120 or more. tends to dry out wood and be a fire potential when used as supply. Code also prohibits wood from being used as a supply duct where the air temp can exceed 120.

Doc Holliday · 08-28-2012, 08:30 PM

Usually there aren't return airs in the kitchen.

ajmckay · 08-28-2012, 11:25 PM

Thank you for the responses.

I can see why wood may be a poor choice in this scenario. I'm in Michigan so the heat gets pretty regular use as well.

The good news is that I found what I think may be a good solution. While at the hardware store today I found "oval" shaped ducts that are about 2.5" high and should fit under a cabinet. They look to be a similar volume to the 6" round ducting that I currently have.

I found an adapter which will connect the round to the oval, however, I didn't see an adapter from the oval shape to a square shape for the vent cover to attach to. No matter I'm sure this exists somewhere so I'll keep looking.

So back to the plan then. I will use the metal ducting for the supply air.

I did not realize that many kitchens did not have return airs. Is this to keep kitchen "smells" from permeating the house?

Slight change in the picture now... After re-tracing the ductwork I realized that the supply and return were flipped, and what I assumed was a return in the dining room is actually a supply. So the only return between the kitchen, dining room, and family room (family room is not in the picture, but you can see the entry way to it) is now going to be covered up by flooring (the purple squares were a return and supply).

From what I understand it's important that the system is balanced.

So if I set it up as it's shown in the new picture do you think it will be reasonably balanced? More or less so than not having a return in the kitchen?

**beenthere** · 08-29-2012, 05:14 AM

New return location should be ok.

They do make oval register boots.

Doc Holliday · 08-29-2012, 08:01 AM

As BT has said, you'll be good. The reason that returns are usually not positioned in the kitchen is the appliances put off an excessive amount of heat which in turn if sucked back up into the return has the potential to raise the supply air temp throughout the system. The system would be trying to extract the heat given off from the kitchen heat or rather that heat would be added to the regular conditioned space's heat and the system would, for lack of a better word, struggle. It would act as if there were a return air leak in a very hot attic.

That and the grease in the air (when cooking) is not good for your system.

ajmckay · 08-29-2012, 11:35 AM

Thanks to both of you for your replies. They have been very helpful.

I think I'll proceed with the plan then as drawn out. Of course now that I know why there usually aren't returns in kitchens the one I placed happens to be pretty close to an oven. The good thing is that it's a wall oven, so it's a few feet off the ground. also this is the very furthest return, thus I'm thinking that the long stretch of duct will help homogenize the temperature some before it reaches the blower unit.