Radiant

Radiant Roger

I am installing radiant in a new house. A couple of questions??? Floor covering is critical for the calculations How do you deal with floor covering being changed while in the basement doing the work?? Also when I go and sell this house, how is the best way to explain the radiant floor so they can change floor covering without damaging the piping??? I can educate the first owner but what happens after the first sale??? Small powder rooms on an outside wall, is the floor area large enough to heat the room??? Insulating from the basement and getting a 2" air space/and also working around bridging--- What is the best way and material?? Two teenagers will be helping me with this?? Radiant Roger

Mike T., Swampeast MO

If you haven't made a thorough, accurate heat loss calculation, DO IT BEFORE YOU START! Without such your work amounts to nothing more than a hopeful guess!

Re: floor coverings. A few area rugs won't affect things drastically, but wall-to-wall carpet & pad can be disastrous. If you truly expect drastic changes in floor covering you have a few options. A very good one is to include TRV'd panel (or old/new iron) rads in the spaces where change is expected. The TRVs will keep the rads from overheating the space, and at the same time compensate for changing floor covering. In this regard, it would be best to size the radiant WITHOUT added floor covering. You can also size the radiant WITH the greatest insulating value you expect for the space and install two-way valves in the affected loops. Remember that these are strictly LIMITING devices, so you MUST size for the highest expected insulation value on top of the floor.

Re: powder room. Only the heat loss will tell. Most new homes are quite tight and unless the exposed wall is unusually long or there is a lot of glass, there will likely be enough floor. You can vary tube size/spacing somewhat or use supplemental radiation if necessary. Remember that you can safely (and comfortably) have a bathroom floor 5° or so higher than the rest.

Re: insulation. The Achilles heel of bare staple-up/suspended. While such systems seem very practical in theory, their reliance on inefficient convection makes insulation critical. Bridging, wiring, plumbing, etc. all make this MUCH more difficult to achieve than you expect. While such can and does work the aggravation of the insulation alone (rigid foil-faced is [likely] best) may well justify the use of heavy aluminum conduction plates. With these you insulate directly against the plates and less-than-perfect insulation (say around bridging) won't affect the overall result too greatly.

Tom Meyer

Proper documentation

We have a large developer with the same issues. We created a homeowner's guide to hydronics. The first page is "Things you should know about your radiant system." It included changing the flooring material.

We also made up a technical guide for the system including all equipment manuals, diagrams, specifications, flow charts, heat loss, AND pictures of the track systems and manifolds.

The best way to communicate with future owners and technicians servicing the system is DOCUMENTATION. The homeowner's manual was the bare bones information about things they should know and be able to control. We did not include things they shouldn't adjust. It was a 1/2" 3-ring binder. The tech manual was a 3" binder chock full. When you develop this manual, just think of what you would want to know if you came into this system without being the installer.

Heat loss is the only way to tell if you have enough going into the powder room. There are many ways to adjust the total BTU's going into the room, but you need to know how much wiggling you need to do first.

I would strongly urge you to get a copy of the Radiant Panel Association's Standard Guidelines. It goes into great detail about insulation. It's also available on their website: www.radiantpanelassociation.org

Senior Designer/Trainer
Precision Hydronics Corporation
www.precisionhydronics.com