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In-floor Radiant Heating Systems
Frequently Asked Questions

Here are some commonly asked questions, and answers about
Aqua-Therm  In-floor Radiant Heating Systems.

Please click on the questions below for the corresponding answer.

If you need any further information,   Click here  to contact us.


  1.  What parts do I need to do the job?
  2.  Can I install the tubing on upper floors?
  3.  How do I test for leaks in tubing before the concrete is poured?
  4.  How do I finish the transition between floor and foundation?
  5.  How does radiant floor compare with overhead convectors?
  6.  How about heat loss when I open my overhead doors?
  7.  Do I need to insulate under the slab?
  8.  How does Pex-Al-Pex™ compare with other tubing on the market?
  9.  How can I get a bid on my project?
  9.  What can Aqua-Therm do to help me with my project?
1. What parts do I need to do the job?

  • Tubing - Normally in 250 or 300 foot lengths.
  • Protective Sleeves - These slip over tubing and provide protection as it comes out of concrete.
  • Manifolds - These are the distribution points from the heat source. Ideally, they are centrally located in your building. Return manifolds have built-in balancing valves.
  • Adapters - These are used to connect the tubing to the manifold.
  • Manifold Mounting Bracket - Use to mount manifolds to the wall.
  • Pump - Aqua-Therm handles Taco™ and Grundfos™ brand pumps. We have several different models and sizes. The most common pump for radiant floor applications is a zone circulator, which has a low voltage relay built in. It can be wired directly to your wall thermostat.
  • Isolation Pump Flanges - These flanges have built in ball valves, so that you can remove the pump without draining the system.
  • Air Pressurizing Assembly - This attaches to the return manifold. It will allow you to put pressure into the tubing before you pour concrete. It also helps to bleed air out of the system when it is being filled.
  • House Wall Thermostats - This unit will connect directly to your zone circulating pumps.
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2. Can I install the tubing on upper floors?

Of course. There are many different methods of installing tubing on subfloors. It is very important to have the right amount of tubing and proper layout for these types of installations.

Tubing is attached to the top of the wood subfloor. Lightweight gypsum concrete is poured over it. Finish flooring or carpeting is installed over concrete. Tubing is attached to joists underneath the subfloor. By installing the tubing on the sides of the joists, tubing damage can be avoided from nails or screws placed in the floor.

Installing the tubing between the joists is the least desirable method of installation. There is no mass to hold the heat and radiate from. The R-Value of the floor covering becomes very critical with this method. It's also more difficult to install.

Aluminum heat emission plates can be installed under the subfloor. These are usually 4" - 6" wide and come in 24" sections. Tubing can be snapped into place. The track will securely hold tubing. The aluminum gives extra heat transfer; however, it adds to the cost of the project. With this method, you also need to install insulation below the tubing.

Back to Top 3. How do I test for leaks in tubing before the concrete is poured?

Pressure test any portion of the system that will be embedded in the floors, walls or ceilings of the building to 1 1/2 times the operating pressure, whichever is greater, for at least 30 minutes or for a sufficient period of time to determine if any leaks exist in the system, and as consistent with local and mechanical codes.

A 30 - 40 PSI pressure test should remain during phases of construction to monitor system integrity.

Back to Top 4. How do I finish the transition between floor and foundation?

You can install the insulation about an inch below the surface so the concrete will float over it or you can cut the edge on a 45° angle.

Back to Top 5. How does radiant floor compare with overhead convectors?

Radiant floor has many advantages over convectors. Back to Top 6. How about heat loss when I open my overhead doors?

Since the heat is in the floor, it is affected less by overhead doors than hot air unit heaters would be. Your entire slab plus the objects in your building are warm, so when the door is closed these objects are immediately radiating heat.

With a hot air system most of the air is lost and the system has to basically start over.

Back to Top 7. Do I need to insulate under the slab?

Yes, definitely. Radiant heat, unlike hot air which rises, goes in all directions. You should have a minimum of 2" perimeter insulation as well as a minimum of 1" under the slab.

Back to Top 8. How does Pex-Al-Pex™ compare with other tubing on the market?

Most other tubing sold for radiant floor is a straight PEX (crosslinked polyethylene).  The chart below shows the differences in the basic characteristics.

Pex-Al-Pex™ Tubing Comparison
Feature Pex™ Tubing Aqua-Therm Pex-Al-Pex™ Tubing
100% Oxygen Barrier No Yes
In-floor Detection ? Metal detector
Tools required to fix a kink High temperature heat gun Pliers
Temperature & Pressure Rating 180°F @ 100 psi 200°F @ 100 psi
Flow rate compared to copper tubing Decreased flow $37.22
Easy to lay out and install? No Yes


Back to Top 9. How can I get a bid on my project?

Call, mail, fax, or email your information to us. We can work off your blueprint or a sketch and required technical information concerning your project.  We will provide you with a detailed list of recommended components and the price delivered to your door.

Click here  to submit the details of your project and receive a quote.
Back to Top 10. What can Aqua-Therm do to help me with my project?

Our customers tell us that service is as important as the quality of our product. We will provide you with:

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Click here  for a product quote or to contact us for more information.