Hydronic Heating question... need answer fairly soon.

[Doherty Plumbing]

Hey guys,

I am installing an in slab radiant system for a winery. The area of the room being heated is about 1600 sq feet.

Because of the size of the area I am using 3/4" pex to reduce the # of zones needed. However I am curious as to how far apart you would space the loops? I am thinking 12" but I am sort of thinking that may be a touch close. Maybe 14"?

The room will be quite tall as well @ 20' tall. However the building will be well insulated because most of the building will be under ground and insulated with 1.5" insulation below the slab and I am thinking R-40 all around. There are no windows either.

I have never ran an in-slab system for a building like this and unfortunately the guy at the whole-saler who's job it is to design system like this (they have all the fancy software) is away for the week and I need to start this install within 2 days.

Thanks to anyone who answers!

 

[NHmaster3015]

First off running 3/4 may or may not be the way to go. Less loops means less heat. You really need to do a heat loss and load calculation and then design for that. Loop spacing will change throughout the slab. Areas of hig loss ( near windows doors etc) generally get closer tube spacing than the middle of the slab. Try www.taco-hvac.com
they have load calculation software that's free. BTW, 12" is a close with 3/4" as you can get without deforming or kinking the tube. Remember also that 3/4 will give you higher volume and flow rate with a resulting lowering of the delta T, even with variable speed pumping.

 

[Sponsor]

 

[MACPLUMB]

YOU CAN ALSO POST YOUR QUESTIONS HERE ON THIS LINK HYDRONIC IS WHAT THEY DO ON FORUM !

http://www.heatinghelp.com/Forum

 

[hj]

Larger tubing means less surface area relative to the amount of water in the pipe, which can result in less heat.

 

[Doherty Plumbing]

Thank you for the responses.

Unfortunately I had to get the loops in today because the contractor is pouring the slab early this coming week.

Here is a picture of how it turned out. Is it perfect? Probably not... but it will work. Ended up with two 3/4" zones with spacing on the tubing of about 13.5". Roughly 900' in total for both loops.

 

[Jimbo]

Very nicely done. I would say that is quite large project to put in on a wing and a prayer...no heat loss calculations.

 

[Doherty Plumbing]

Very nicely done. I would say that is quite large project to put in on a wing and a prayer...no heat loss calculations.

Very true. But the heat loss is going to be pretty minimal. The building will be completely buried under ground with insulation all around. Plus the wine barrels that will be in the room will be covered with a special tarp to keep the heat in even more.

Lets just hope it all works out

 

[Doherty Plumbing]

Update

Well I talked to the Hydronics expert at the wholesaler and he quickly assured me that what I have there is more then adequete for what I need. So that was great to know that..... BUT about 3 hours later I get a call from the contractors office telling me that they had it wrong and according to the owner the heated portion of the slab is supposed to be on the other side of the slab!!!!!!

So needless to say I get paid to install the system AGAIN but on the other side.

 

[NHmaster3015]

Are those 2 loops evenly split at around 450' per loop? And, even if they are 450' is pushing it, you will need a circulator with very high head capability.

 

[Doherty Plumbing]

Yeah they're pretty close to around the same length (it just happened to work out that way).

And 450' is not pushing it... 500 is the max you can have and still have everything work just fine. 520' would be pushing it. 450' is perfectly safe. That's why I ran 3/4" after all. Plus the 3/4" will give me a little bit more heat output then 1/2" coils. And the 1/2" coils would have to be closer togeather making more piping, more time, and more zones to install it all.