I was going air HP but over the weekend my money situation changed. I was ready to pour my bsement floor this week and now just putting in the gravel until I can get some quick bids. Any lessons learned or smart ways to go about soliciting bids? I want to have them break it down into areas as I can do my own excuvation and I guess tube laying (any smarts for this)? I am not sure if I can lay the radiant floor. I am not sure that contactors are keen on the home owner doing part and they the other. Just soliciting comments THX Lisa

     You have to be confident of your work if you mix and match.  Contractor will not accept total responsibility for the system if you do parts of it.  That is as it should be. He should not have to trouble shoot the system to find out you made a mistake.  Essentially you will have the warranty on the total system. Contractor will only guarantee the portion he installed.  So when something goes wrong, call yourself, not him.   That beign said, if you do the work right, and save enough monies, then it may still pencil out.  As always an honest contractor that will work with you is a key.  Your proposed method can work but  you need to do your work correctly and you need the right contractor (difficult to find).

I found that in my area, Central Arkansas, no one wanted to install a horizontal loop system due to 9' or greater loop depth. So vertical loop wells were necessary. With vertical loops there was very little I could do myself. I called a couple of local installers and received very similar bids.

I don't agree that conditions in Arkansas necessarily demand a 9' depth for horizontal loops.

Lisa, Laying radiant tubing for a basement floor is not rocket science, but it is a lot of work. Most contractors in our area want to do all the concrete work, but they won't touch the pex. You have to hire someone else to do that part. The pex is the easiest part of the whole floor. Getting the gravel level is the hardest part. You need to compact it with a vibratory compactor also. Make sure you lay a 6 mil plastic sheet over the top of it for a vapor barrier. Tape all the seams. On top of that, be sure to put 2" of foam high density insulation. It comes in 4x8 sheets from the local home store. Then you need to think about your pex layout. Put the 1/2" pex on 12" centers and make no runs longer than 300 feet. Try to keep them all as close to the same length as possible. Pex is an easy product to work with. You will need either rebar or mesh to tie the pex to. Make sure that the pex is tied down well so that it does not float to the top during the pour. Some people staple it to the foam, but some believe that if it is in the middle of the slab you will get better performance. I put mine in the middle of the slab, but I have not seen any scientific evidence that supports that theory. Also, you do realize that you will need a more expensive geothermal system if you are going to do a radiant floor AND use it for A/C. In other words, it has to heat water and cool air.

We usually recommend less than 12" centers.  Ideally if we can get 6" it provides better thermal property with less heat, fluid in floor around 85-90 deg F and the COP of the heat pump is better.

There's software out there that designs radiant floor systems based on room load, floor R values, tube diameter, supply water temp. It gives options on tube spacing, loop lengths. It also handles pressure drops, computes pump power, etc.

In this day and age, why guess or go by rules of thumb?

Thanks guys for the detailed info --really great stuff. If by some chance I don't go radiant (husband not to keen has had it before and was still cold) What should I consider for heatin? I have 2 wood burning stoves (up and down) and hope to not have to use auxiliary heating like electric unless very little. Propane is $2.37 and electric 11 cents. We are putting propane in for stove top and for Back/up generator that we already have and will move to new house. I will make sure my return upstais is far enough away from stove so will not provide false reading but want to keep heating $$ down. What are these heat srips and what should I look for for the heating part of the package? I assume I will go electric vice propane. Lisa