Remote hydronic manifolds

davidtennessee

I’m utilizing a Cross 8 zone manifold on a 6000 sq ft slab.  To keep my 1/2 loops to 300ft, I’m utilizing 8 remote manifolds fed by 3/4 in lines from the Cross zoning system.   Is this advisable?   

EBEBRATT-Ed

There is no reason that the manifolds have to be near the boiler. They can be remote and on commercial jobs frequently are. As long as the piping to feed the manifolds is the correct size and with the right circulators your fine

davidtennessee

Should I run the feed lines to the manifolds under the slab, or over the top? I’m guessing that I’d reduce length, and heat loss by running it all in slab. 

davidtennessee

Also due to having only electric, we will be heating with 2 150 gallon commercial hot water tanks. 

GroundUp

No reason why not, but with 6000 sq ft I'd be a little hesitant to say the manifold tube itself would have enough capacity to carry that many BTU.

davidtennessee

The longest feed line to a manifold is less than 50 ft 

davidtennessee

Should I insulate the feed lines to the manifolds? 

Paul Pollets

Manifold piping underneath the slab should be insulated with 3/4" wall neoprene. If the manifold has more than 4 ports, it should be piped in 3/4"

davidtennessee

Thanks Paul.   There is very little information on running remote manifolds.  Trying to run 24 lines into my utility room seemed a little crazy.  I figured I’d use access panels throughout the house to the zone manifolds. 

Paul Pollets

Most radiant courses teach how to do this. It's the first thing I look at when designing a system...where to put the manifolds in a central location to minimize loop lenghts. Closets work best.

hot_rod

What is the load on that 6000, slab? At 22 btu/ sq ft the load would be 132,000 btu/ hr

If you are going with Pex, consider 1” or larger.

davidtennessee

I apologize, the slab is 4300 on the first floor. All 10ft ceilings except for the garage at 18.  

A single upstairs bedroom that will be on a separate HVAC system.  

Putting remotes in closets and other hidden locations.   

hot_rod

3/4 Pex is good for 4 gpm.  you might be wise to use 1” for a 94,000 or so load