Radiant floor heat design service

[mruffatto]

Hello all,
I'm beginning construction on a new house that will have an attached garage and hangar. The garage is 1000sqft and the hangar is 3000sqft. 14' ceilings. I want to install radiant floor heat and have two zones. The more I research the more I realize there is way more to this than I anticipated. I had radiantec give me a quote for a system. They suggest 7/8" pex. I'm reading that 1/2 may be much more desirable. Their prices do not seem all that great either. I cant seem to find any other design options. Any suggestions on where to turn for layout, run sizing, boiler options etc..? I'm planning on installing myself before concrete. I have plenty of experience with pex but not in this application.
Thanks
Mike

 

[PoorUB]

7/8ths? never seen that large used and we did some big builds. A couple jobs had around 35,000 feet of tubing!
Larger tubing allows longer runs and less loops. Typically 1/2" is 300 feet, 5/8 is 400 feet and 3/4" is 500 feet. No matter what size you can figure one foot of tubing per square foot, so you will be running around 4,000 feet of tube.
it is pretty hard to screw up floor tubing. We always used poly vapor barrier and 2" foam and stapled down the tube. Just lay it one foot apart and run it back and foth until you get close to the length of tubing allowed for the diameter you are using, then run to the manifold. Some guys run a couple loops closer to the outside of the slab but I don't know if it makes a difference. I have laid thousands of feet of tube and no layout for most jobs.

For the 1000 sqft garage you probably just need one centrally located manifold. For the 3000 sqft you might want to use a couple so all the tubing doesn't run to one spot.

Another think we did was use unistrut. Pound two into the ground like stakes and bolt a third piece for a cross bar. Use PVC sweeps clamped to the cross strut. Every other tube is supply and return. It makes for a neat, clean install.

 

[Stuart in MN]

Where are you located? Assuming you're somewhere in the United States, Uponor is a big name in the radiant heat industry. They have some design assistance information on their website, and you can also locate a distributor or retailer near to you. https://www.uponor.com/en-us/residential-solutions

 

[Chris705]

Mike - if you use larger diameter pex be aware of possible floating of the pex during your floor pour….. a GJ member used 7/8” tube and it floated up during his pour…. Be cognizant of zip tie or staple spacing. I used 1/2” pex with about 16-20” spacing with no problems…. I did tighter spacing at the bends to keep it flat. Good luck! Califfe has great educational info available on line….

Education

www.caleffi.com

 

[jack stand]

Disclaimer;
I've only done this once, my current house-shop.
I paid for a design service by a couple of younger guys that are radiant nerds. In other words, fans of efficiency. They needed rough dimensioned drawings, an insulation schedule along with window and door efficiency ratings. They asked about my fuel preferences. I also informed them about my wood boiler.
There "deal" was that if I bought all the stuff (less the boiler(s)) that there would be no design fees.
They provided me with drawings of my project, complete with tube layout. This allowed me to do the complete installation myself, and I'm not a plumber or HVAC guy.
I'm thoroughly understanding of my system and how it works and man is that comforting.
They were always there for my questions (often stupid) and "held my hand" through the whole thing. Periodically, mostly out of curiosity I'd check their prices with "Supplyhouse.com" and they were right in line.
They were about an hour and a half away from us and never set foot on the job.
They included things that I would never have thought of like valve's on both sides of a circ pump for replacement and there are many others.
Unfortunately they closed and went back to design work for bigger local companies or I'd gladly give you their information.
There's got to be plenty of these type of business out there.
You might check out another forum "green building talk .com" this is where I found these guys, actually one of them. He was a very active participant in the radiant heat section of the forum and it was easy to see that this guy knew his chit! FWIW his name is Rob.
It's an interesting site that's basically efficiency/economical oriented but if you have efficiency and good insulation, you have "green" so don't let the title throw you off.
I highly recommend this approach, after all you only get one shot at the tubing. I have a 2 story section of the house that he had me space the tubing every 6", then I have 12" & 18" spacing in the shop and other areas (all 1/2") along with aluminium reflector plates in a ceiling where there's exposed ceiling/floor (think post and beam) so the floor was not available for radiant.
Good luck and keep up with your "homework"

 

[78SC4X4]

You can get a free 30 day trial of loop cad. It takes a little time to figure it all out but you will end up with a good pex layout, heat load and flow information. Then we can talk about types of boilers and the layout of the system. Take a look at threads like this one. https://www.garagejournal.com/forum/threads/picts-of-your-in-floor-heat-set-ups.49557/

 

[yeldogt]

What is the location ? fuel used? Radiant or hot water heat in home?

IMO it's easier to stick with 1/2 PEX ......

Location determines the heat load - that gives you the BTU's per square foot and the water temp.

If the hanger will just have the plane sitting there it can be done with simple layout .... if you will have a work area you can increase tubing in that area. In a very cold climate laying the tubing tighter in some areas can make for more comfort ...all depends on the use and location.

Same with the garage -- what's the use? Radiant likes to just run with the boiler providing (modulating) to provide just what the space needs.

Zoning is easy and again depends on use. The boiler can be set to whatever the warmer space will be using out door reset --- and the other space can have a Tstat w/ air and floor sensors.

The most important thing to do is think about how you are going to use the spaces .... It's as simple as getting the right boiler -- two manifolds -- two pumps and a few other items. You can also get a book primary/ secondary that will give you some overall knowledge --- worth the $25

 

[86turbodsl]

I'd never go larger than 1/2 pex in a floor that's the normal 4-5in thick. Rule of thumb is 300ft length/loop, 1 ft spacing, keep loop lengths as close to same length as possible. You'll need 1 ft of tubing for every square foot of building space. Shoot for a 20 degree deltaT over the inlet/outlet.

 

[fitter30]

House you don't want one zone. Bedrooms at the least should be separate.