Question for the HVAC guys

[GT26]

I'm designing a house with radiant floors and a heat pump for back up and AC.
Can / should you plumb the returns to the ceilings of the rooms?

 

[btuser]

I'm designing a house with radiant floors and a heat pump for back up and AC.
Can / should you plumb the returns to the ceilings of the rooms?

Sure.

 

[Clarkbug]

What kind/size of house? Single or multiple story? I guess I would ask what would be gained by going to the ceiling with the return? I would assume more piping, and not a large amount of benefit, since you want the heat at the floor level with radiant anyway.

EDIT: Ignore my comments... I was thinking the hot water return, not the cold/hot air return. I needed more coffee....

 

[begreen]

Considering this system is going to be used primarily for cooling, a central ceiling return may work better. Are the supply vents in the ceiling? The downside of this is that it will be a poor winter heating performer, where the opposite setup is desirable (low vents and returns).

I am curious why the need for backup? Also, depending on the home design, sometimes a good mini-split system can be more efficient and may cost less. Something to investigate at least.

 

[btuser]

Big fan of the mini-splits myself, especially in a retro situation. Brand new I'd put all my ducts on the inside walls, with supply down low and return up high. This gives you the option of reversing the fan in the Winter for heating. I'd also look at a hydro-air setup (more expensive no doubt) so I'd have the flexibility to use any source I choose, be it oil, gas, geo or an electric water heater.

I'd spend the $500 to have someone who does forced air design. When it works it works, and when it suck it sucks. Its not like running 100' of baseboard. The velocity of air, turbulence in the ducts, duct material, fan speed, air temp, and FOR THE LOVE OF GOD BALANCING! Everything feeds/effects the other and will determine if after all your hard work you still end up with a dank, mold-breeding, clammy mess.

 

[flyingcow]

Used to tinknock for a living. I'll agree with above post. Have a system designed and balanced. If not, good chance it night not perform like you want it to. I also like the mini split systems. A lot of ways to do this. Keep looking. But, do have it designed and balanced. A good designer is priceless. BTW, I was a decent installer, but i saw alot of horrendous installs. By guys i thought were good. Also, do not use flex duct. Maybe a 6 inch hook up, but not longer. If anything looks like it will choke the air flow, than it is.

 

[begreen]

+ 1 on a good design and installation. I too have seen some really sloppy work. Our next door neighbor's ductwork was appalling. There was one run that had fallen apart and was just blowing air into the crawlspace. Out here we also still have a lot of converted coal (gravity) systems where the ducting is backwards from a proper forced-air design. It is rare to see a single joint on these systems sealed.

However, I don't follow the concern on flex ducting. Properly sized, supported and installed, it works well. When we renovated the house and crawlspace and installed the heat pump I redid the ducting as well. For most of the runs off the plenums I used flex-duct. They have been dong quite well for several years now. Properly supported I don't think they restrict airflow. Our system has a nice balance with good airflow even from the farthest run.

 

[GT26]

Thanks for the ideas guys!
I will look into having a system designed.
Tim