We do not have a lot of radiant heat in this part of New Jersey. Very few new homes are being built in our area, it’s mostly older homes that we retrofit. The same holds true on commercial jobs — very little are fitted with radiant heat. As a matter of fact, most of the new construction in my area is in the form of apartment houses, hundreds of them. Most of these new apartments appear to be heated with warm air.

Oddly, we were asked to bid on two pretty good-sized radiant projects last week.

The first job we looked at was for a 5,000-square-foot home in a nearby town. A builder heard about us through another builder we have worked with in the past. The first builder did a job that had some heating issues that others couldn’t resolve. Thankfully, we were able to identify the problems and come up with a solution.

This new project involved a Victorian house that was built around the turn of the 20th century (funny how we must mention which century). The home has been gutted from the basement floor to the ceiling of the second floor. Oddly, the homeowner wanted to keep the third floor all original. The third floor has four original 100-year-old steam radiators, hardwood floors and plaster walls (with no insulation). Besides the third floor, the original steam heating system had been removed by others. The builder was not concerned about the third floor at this time, so I did not spend a lot of time on it.

There are 14 pages of plans with no mention of the heating system. In other words, I would call this one a “design-build.” We were told that the homeowner wants the entire basement, the first floor and the second floor to be heated with radiant heat. Based on the preliminary heat load calculations, I think we can meet his demands. For this project, we chose to use radiant panels that would be fastened to the top of the existing wood subfloor. We would install all the required radiant manifolds along with the home runs of PEX tubing first. Then we would assist the carpenters with the installation and layout of the 5/8-inch thick wood (MDF) radiant panels. Once the panels are installed, we would be responsible for installing the radiant tubing and testing. The carpenter agreed to protect the tubing/panels once installed.

Besides the five bathrooms that will have tile floors, the rest of the house will be quarter-sawn oak floors. The basement would be heated with radiant tubing that will be in the cement slab.

What stood out to me was how much time I spent on getting quotes for all the materials and calculating the labor on this job. To date, I have approximately 10 hours into this job. Once I quoted the rough numbers to the builder over the phone, he asked if he could buy the materials. I balked and mentioned that I would likely get much better pricing on the materials as I do a lot of volume with my suppliers and have a good track record for paying on time. I have not heard back from him; I think I may stop by the job today to check on the progress.

On the second radiant job, a private school is completely gutting two large classrooms. The classrooms are to become science labs. A plumber that I’ve known for many years asked us to bid on the radiant heat aspect of the job, including the new boiler room. These classrooms will have state-of-the-art heating and cooling (sort of) and massive amounts of ventilation. I assume the huge ventilation system is needed for future science projects that go bad.

The system was designed and specified by a licensed architect, mechanical engineer and professional engineer whose names are on the prints. Oddly, the first thing I noticed on the 22 pages of plans was the boiler they chose was the least expensive 110,000 Btu input combi-boiler money can buy. The plans call for two 2-inch copper supplies (one for each classroom) and one common 2.5-inch copper return. The circulator pumps that were specified are most efficient at 60gpm (each). Yet we are supposed to install circuit setters and set them to 12 gpm, maximum on the outlet of the pumps. I did my own heat load calculations on the two classrooms and came up with approximately 50,000 Btu. Not sure why we are asked to install 2-inch and 2.5-inch copper supply and returns with large commercial pumps for such a small load. As a matter of fact, I looked up the NPSH for the pumps specified and noticed there will be a problem. Ironically, that combi-boiler I mentioned earlier is about the right size for the job as it also provides DHW.

On this job, the professional design team recommended 1-inch foam radiant panels for the radiant tubing below the concrete on grade. I would have suggested foam panels at least 2 inches thick. A total of 2,500 feet of 5/8-inch radiant tubing was specified with two 1.5-inch radiant manifolds.

I am fearful that they used the cut-and-paste method and performed very few actual calculations for this job. I struggle with these types of jobs as I want the system to perform well, but not cost an arm and a leg.

Based on the brands of the equipment specified, I suspect the manufacturer’s representative may have done the design and specifications for the actual bill of materials. Oddly, the pumps, tubing, boiler and manifolds are all carried by one nearby representative. I am fearful that they used the cut-and-paste method and performed very few actual calculations for this job. I struggle with these types of jobs as I want the system to perform well, but not cost an arm and a leg. The hair on the back of my neck starts to stand up when we need as little as 3 gallons per minute and that 1hp three-phase pump might start to self-destruct.

I have always struggled to bid on both types of these jobs.

• The builder on the Victorian house likely budgeted about $20,000 for the new heating system (boiler, indirect DHW tank, radiant panels, radiant tubing, thermostats, etc.). Our material cost alone is more than double that amount.
• At the school job, the business administrator was likely given a target price before this project went out to bid. However, the cost of the radiant heat aspect could have easily been cut in half for a better-performing system that was properly sized.

In the end. I think I may have wasted my time bidding on both projects...