Remodeling With Radiant
As a Bostonian living in temporary exile in Minnesota, it's amazing to see the amount of new construction here in the land of Jesse "The Governing Body" Ventura. Drive through towns such as Lakeville, Savage or Prior Lake, and you can see thousands of new homes sprouting out of the ground like cornstalks - not to mention the ever-present "My Governor Can Beat Up Your Governor" bumper sticker on the pickup truck in front of you.
In many other parts of the country, new construction continues to be strong. Maybe not like Minnesota - but certainly strong enough to keep plenty busy. Not surprisingly, the growth in radiant floor heating has gone hand-in-glove with the ongoing new construction boom. Also not surprisingly, most contractors use floor heating almost exclusively for new work.
However, the forecasters are predicting that the remodel and retrofit market is going to go kablooey in the next several years - if it hasn't already. This prediction represents one hell of an interesting opportunity for the smart radiant heating contractor.
Why look at the remodel/retrofit market? Lots of reasons. First and foremost, the remodel/retrofit market offers a place where quality and service can easily outshine price. Got some solid sales skills to go along with the quality products you install? You can thrive here.
Second, and no less important, remodel/retrofit jobs can be very, shall we say, challenging. You've seen the crawlspaces, and you know what it's like trying to weave pipe through an 80-year-old house. It requires more than a little independent thinking. Your own creativity, plus a healthy dose of courage, can weed out lots of competitors and provide you with some healthy profits.
Finally, the remodel/retrofit is where the growth is. Here are some numbers to chew on: Remodeling was a $118 billion market in 1997, and was expected to hit nearly $122 billion in 1998. The myth that people move every five to seven years is fading like the Red Sox in a pennant race. America is aging. Baby-boomers are pushing and passing 50 and simply aren't bouncing around as they used to. Think of some of the biggest boom businesses of the 1990s - home computers, home entertainment systems, satellite dishes, home offices and home security systems. Who wants to be schlepping all that stuff around every five to seven years? Americans are staying put more, and they're spending more time at home. The emphasis on the quality of their home - and especially the comfort of their home - appears to be at an all-time high.
So, what are contractors asking about radiant floor heating in the remodel/retrofit market? At our Minnesota training sessions, the questions come faster than a flying scissors headlock from our governor. Here are some of the more common:
What installation method should I use for a retrofit/remodel job?Well, anyone who read my last PM article ("Radiant Wishes," February 1999) can probably guess the answer - it depends! In many cases, the most logical solution is joist heating, with tubing suspended below the subfloor, in between the floor joists, with or without plates, but always with insulation. Your heat loss and system design calculations (absolute musts with any floor heating job, but doubly essential with remodel/retrofit jobs) will help you determine the following:
- Whether you need plates.
- What water temperatures you need to run.
Depending upon the extent of the remodel job, you may have a few above-the-floor options. In a bathroom where the tile installer will be using a mud base that is at least 1-1/2 inches thick, tubing may certainly be clipped or stapled to the top of the subfloor, and then covered with the tile mud. However, watch for that sharp screen mesh they use. It won't cause any real problem with PEX tubing once the system is running, but you'll want to be careful during installation that no one steps on the mesh and drives it into the tubing.
But what if I can't get between the joists and there isn't any mud?Options, my friends, options. Radiant floor heating is first about comfort, but then about options. Everyone has his or her favorite installation method. But remember, the more bullets you have in your gun, the better your chances of winning the gunfight, so make sure to use all your options.
If joist heating or "mud" aren't options, do we bag radiant and instead look for kickspace heaters? Not if comfort is what we're after!
Let's take a look at a bathroom, for instance. It's a second floor gut job. Everything's coming out but the subfloor. There's no room for anything on or below the subfloor. Well, why not try radiant wall or radiant ceiling?
Yep, you heard right, radiant wall or radiant ceiling. Just take whatever you were planning to put in the floor, and stick it in either the wall or the ceiling. True, people won't actually be in contact with the radiant surface, but those walls or ceiling will still give off a glorious warmth that will make any bathroom toasty. And even though the tubing's not in the floor, the floor will actually warm up some - just not quite as much as if you heated the floor directly.
Here's how you do it: Radiant wall or ceiling is installed using single groove heat emission plates either stapled vertically to wall studs or to the bottom of floor joists, or stapled to firring strips installed perpendicular to studs or joist bottoms. The tubing is then snapped into the grooves, with either sheetrock or cement board (if the walls are to be tiled) installed over the plates. Insulation is installed behind the plates, in both instances, to ensure all the energy goes where you want it to go.
You can expect as many as 45 Btu per sq. ft. from radiant wall or radiant ceiling, while running 120 degrees F water. If the heatload of your bathroom is, say, 1,500 Btu, simply divide 1,500 by 45 to determine how many square feet of radiant wall or radiant ceiling area you'll need to heat the space. In this example, you'll need only 34 sq. ft. of radiant wall or ceiling panel!<
Should I put tubing under the tub or shower?By all means, yes! Especially if the tub is cast iron or the shower is tiled. Man, can you imagine how nice a warm tub or shower would be? Think you could get a homeowner excited about it? Also think about this - if a cast-iron tub is cold, how much of the hot water you run into it has to make the tub warm first?
Think about that shower for a minute - and think about a radiant wall in the shower. Simply take the same radiant wall construction method we discussed earlier and put it in the shower walls along with tubing under the shower base. Now, those cold tile walls and cold tile or stone shower floors will be deliciously warm, and your customers will be literally dripping with comfort.
A similar question is, should tubing be installed under the vanity? Generally speaking, no. It doesn't add much. However, you will have to take the area of the vanity into account when determining your Btu per square foot heat load. When you remove the vanity area from the available radiant floor size, you wind up with fewer square feet available to satisfy the heat load. You have, in fact, a smaller radiator with which to heat the room. The total Btu load of the bathroom won't change, but the actual Btu per square foot output required from the floor will increase slightly. Do the math.
How far should tubing be kept from the toilet's wax ring?This may or may not fall into the "urban legend" category, but it never hurts to be safe. I've heard lots of horror stories, but most involve, "I heard of a guy that happened to." Hercules says the wax in their closet seals will start to melt at around 135 degrees F. Keep in mind that radiant floors are designed for surface temperatures below 87.5 degrees F. Will the floors get warmer under a toilet?
Probably. Enough to melt a wax ring? Possibly. Should I keep the tubing away from the ring? Why not? Better safe than sorry, I suppose. Keep your tubing at least 8 inches or so from the wax ring. Or else use an alternate closet seal material.
Will radiant floor make the toilet seat warm?Yes, delightfully so.
Will the toilet tank sweat if the toilet gets too warm?