Do-it-yourself hydronic installations are not good for our industry.

It was about 8 o’clock Sunday evening. I was out in the office getting ready for the Monday morning rush. The phone rang, and when I picked it up, a man - we’ll call him Jack - asked how he could get in touch with John Siegenthaler. “You got him,” I answered.

He explained how a Fine Homebuilding article I had written more than 10 years ago convinced him to install radiant floor heating in a new post-and-beam-style house he was building. “Great,” I responded, pleased that the article had influenced his decision.

Sensing my approval, Jack went on to tell me how he purchased the PEX tubing and other hardware from a Web-based supplier, and that he and his wife would be doing the entire installation. To that end he was calling for a few “pointers” on some details. My initial zeal began fading, but Jack’s enthusiasm, combined with my curiosity, kept the conversation going.


A Few Minor Details

Jack’s specific questions dealt with installing a concrete thin-slab radiant floor. His plan was to pour a stained concrete thin slab over tubing stapled to the tongue-and-groove floor planks and use the concrete surface as the finish floor.
Here are some of the issues we discussed:

1. Lack of underside insulation. The underside of the tongue-and-groove planks in Jack’s new home would be the exposed ceiling for the rooms below. Because of this, he didn’t plan to install any underside insulation. When I told him this was a mistake, he asked if it would be OK to lay some “bubble/foil” product on top of the planks before placing the tubing and concrete. I told him the R-value of such a product installed in this manner is minimal and far below a nominal R-11 that we recommend for underside insulation when the space below the floor is heated.

He then asked if transparent acrylic panels could be installed under the exposed ceiling to trap air between the exposed beams to act as insulation but still allow the wood ceiling to be seen. Expensive - you bet. Sufficient R-value - absolutely not. The problem remained unresolved.

2. Equal circuit lengths. Jack was planning to run tubing from one room to the next through holes in the lower wall plate. This was based on advice from the tubing supplier that all the floor circuits should be the same length. He understood that equal circuit lengths would yield approximately equal flow rates. I explained that equal flow rates was not the goal, but delivering the proper rate of heat input to each room. I went on to describe how we arrange circuits on a room-by-room basis, and use balancing valves on the manifold to adjust flows through circuits of different length. This was probably the first time he had heard that concept.

3. Concrete mixtures. Jack asked what type of concrete should be used for the thin slab. I explained that the concrete we specify for these systems contains an additive called Fibermesh. A cubic yard of this concrete contains millions of tiny fiberglass filaments that form a three-dimensional reinforcing system within the concrete and eliminate the need for wire reinforcing. Inevitably a few of these filaments end up at the top of the slab.

Remember; Jack planned to use the top of the slab as the finish floor, and would probably not enjoy a floor that was both warm and fuzzy (e.g., having exposed fiberglass filaments projecting from the surface). Upon thinking this through, he realized that a stained finish floor (without Fibermesh) was going to compromise the strength of the slab, and probably lead to unwanted cracks.

As the conversation wound on, the tone of Jack’s voice grew more concerned. Reality was setting in, and many of the concepts he had envisioned were starting to appear problematic.

I could tell Jack was an intelligent man. Based on the home he was building, he had obviously been successful in his chosen career. But that career wasn’t in hydronics, and he was quickly discovering there’s more to installing a radiant heating system than stapling tubing to a subfloor and covering it with colored concrete.


Good Intentions

Years ago I was an enthusiastic supporter of DIY projects. I based this on being raised in a family that did things for themselves. My father, who started out as a dairy farmer before being trained as a carpenter and electrician, was always learning about other trades so he could be a “general practitioner” when it came to work on our house. I grew up thinking this was normal, and that just about anyone could do most of the work on their own house if they put their mind to it. I even encouraged DIY undertakings for clients when I starting designing homes and heating systems.

As the years rolled on, and the SOS calls kept coming in, I finally realized that most people are far from sufficiently committed to learning the finer points of hydronic heating design before reaching for their tools.

Sure, the average homeowner wandering the isles at Lowe’s or Home Depot can handle a paint brush, change a door knob, caulk a window or install a screen door. Likewise, most of us can remove a sliver from our thumb and “install” a Band-Aid, but that doesn’t make us surgeons, does it?

The vast majority of DIYers are way beyond their knowledge and experience base when attempting to install a hydronic heating system. The results can be costly, dangerous and highly unlikely to perform as expected. DIY hydronic heating is a bad idea, and something I now go out of my way to discourage.

Figure 1. Photo courtesy of Harvey Youker.


Dealing With DIYers

Take a look at Figure 1. This scene recently greeted a hydronic heating professional called in to smooth out a few wrinkles in a DIY installation. It took this pro about 0.5 seconds to realize the situation went way beyond a few wrinkles. This collection of hardware was quite possibly the worse anomaly he had seen in 25 years of installing hydronic systems. Believe it or not, this is supposed to be a floor heating system!

What would you do when facing such a mess?

Here are a few thoughts:

  • First, don’t criticize the person who did the installation. The fact that you, a professional, are now standing in his basement suggests he probably already knows his attempted install was a flop. Although it’s human nature to criticize, especially in our areas of expertise, this only widens the “us-vs.-them” gap between DIYers and professionals.

  • Second, inspect the installation in a calm and professional manner. Don’t indulge your ego by pointing out what you consider “stupid” mistakes while simultaneously chuckling and shaking your head. Instead, look for safety as well as performance-related issues. Ask the occupants about what they’ve experienced with the installation, and listen carefully. Convey your interest in getting the system to perform correctly, rather than just offering to work on it without assurance of success.

Keep in mind that you’re being sized up by someone who may not yet be convinced that hiring a pro is the way to go.

  • Third, be aware that most DIYers in this predicament will be watching and listening to you closely. They’ll catch every facial expression you offer, every written note you make, and every photo you snap. For each DIYer who’s ready to hand his work-in-progress over to a pro, another is hoping that pro generously points out mistakes and describes how to fix them.

    The latter type might even ask the pro to prepare an estimate for what it takes to correct the installation - the next step being to decline the proposal and get back in the DIY game now that they've been enlightened. Some people never learn, so be careful about what information you offer.

  • Finally, never compromise your professionalism when it comes to making alterations. Although it may be possible to reuse some of the existing hardware, don’t be swayed in your design decisions by material or assemblies that you wouldn’t otherwise use for a new installation.

    If you don’t feel you can rework the current installation to provide the same performance as one you designed and built from scratch, my advice is to politely decline further involvement. This is not easy for many hydronic pros, who by nature are problem-solvers and want to “make it all better” when it comes to under-performing pipes, pumps and boilers. But such a decision is absolutely necessary from a business standpoint to prevent saddling your company to a pile of perpetual problems.

    Availability of hardware has never been a problem in the North American hydronics market. This is truer now than ever, given the numerous Web-based hardware vendors. Instead, our biggest problem is under-trained installers, including weekend warriors convinced they can staple down (or staple up) PEX as good as any pro.

    Every level of our industry, from manufacturer to installation professional, must remain diligent about keeping hydronics within the realm of professionals. The future of the industry depends on it.

(For a detailed list of what went wrong with this installation, visit and view the August 2007 “The Glitch & The Fix.”)