hydro air duct question

Bob Forand

Yes, it is a problem to have the supply and return located right next to one another. There will be very little air movement throughout the room, the coil will see cold return air and possibly have freezing issues. Not a good scenario at all.

The air conditioning system will work just fine as you described. It won't be oversized for either if only one zone calls. The noise may or may not be an issue. There are a lot of variables such as size of returns, length of return back to air handler, distance of supply trunk from the air handler etc. If noise is an issue you can add a bypass damper to it. I usually wait to add the damper until after I have run the blower. If I consider the system to be loud I add the damper. I haven't had any issues so far.

Good luck....

shawn laverty

This is a 2 part question.
First i have a job where our designer has put a supply vent and the main return vent both mounted on the wall. They are located right next to each other. Does anyone see any problems with this.
2nd question we have a 2 zone system on 1 unit. It feeds the third floor which is about 400 sq ft and the 2nd floor which is about 700 sq ft. The designer is using a 1 and half ton unit for heating and Ac. So my theory is when the third floor calls wont the unit be to large and could cycle or be very noisy. Same thing for the 2nd floor if that is the only zone calling. These handlers are not variable speed either and there is no sprd speced out on this job. We are using wheatherking condensors and first company handlers.

hvacfreak

if this is residential sidewall...

you might get away with something like a Lima series 100 register to redirect the supply air off to the side. It's the best you can do if this stuff has to be where it is.

tim smith

quite common in commercial systems

Concentric supply/returns have been done for years. As long as the return air grill is substantially larger than the supply register. The velocity will cary the air out in the room based on throw of register and then it will return back to Grill. It can work if you don't do bonehead moves. Tim

Unknown

What I do...

(although it sounds like it's too late for this one) is oversize my supply ducts one step and leave the off damper partially open so the excess pressure can be lost in the off side supply duct. Rather than dump or recirc.

don_185

I agree

I agree with Tim.I also would have skip the bypass all together and let either zone take all the air.

At only 600 cfm and, if you design for velocity and throw
you would be better off then just letting it dump the air where its needed.Down or up.Hot air rises and cool air falls.I would take advantage of that fact.