Hot-water Radiant Heating
Please see our Solar Hot Water and Hydronic Heating System Page for a detailed description of the Thermomax solar hot water collecting unit, circulating manifold, and special El-SID pumps which supply the hot water for the radiant floor systems for the straw bale house and mobile home.
INSTALLATION PROCEDURES FOR THE FLOOR OF A HOUSE
NOTE: Hot-water radiant heating can be installed in either a poured concrete floor or an adobe earthen floor. A concrete floor poured professionally would involve much less work labor for the owner-builder but is also much more expensive than a hand-made adobe floor. Also the manufacturing of Portland Cement involves a staggering amount of "embodied energy" and is therefore anything but friendly to our planet (see box below).
To save time, we opted for installing pre-manufactured adobe blocks on top of the hot-water radiant (PEX) tubing rather than purchasing high-clay content "dirt" and making our own floor. This was still considerably less expensive ($950 in materials) than a poured concrete floor where the lowest bid was $1800. We of course had to install the adobe blocks ourselves, but with the concrete floor we would have been responsible for leveling the floor and installing all the rebar prior to pouring -- approximately the same amount of labor.
The adobe blocks have the added advantage that if there were ever to be a leak in the PEX tubing, repair would only involve removing a few individual blocks rather than having to take a jack-hammer to the concrete floor to get to the problem! Continuous concrete slabs often crack as well; and fixing the cracks is never very satisfactory and always shows.
1 - Preparing the Remesh/Weld-wire: cut strips from the roll to cover the entire floor surface. These will be used as a framework for tying and holding the PEX hot-water tubing in place. Before taking the strips in to the house lay them out on the floor, you will need to HOP UP AND DOWN on them good and pound on them with a rubber mallet until they will lay flat.
2 - Preparing the PEX Tubing: run tubing off the big spool of tubing and straight out on the ground until the desired length is reached (usually about 250 feet for each loop). It must be laid out flat without kinks or twists in it or there will be a lot of trouble later. PEX has a mind of it's own...
3 - Preparing the Bare Dirt Floor: first use shovels and a pick to break up the surface. Then drag a long, heavy piece of angle-iron and/or a wooden 4x4 over the dirt to make it flat and level. Place a regular carpenters level on top of the 4x4 to check on the level (using a small laser level would be even better if you have one). (Finally, we also spread rock salt on the leveled surface as one way to - hopefully - keep termites under control.)
4 - Laying Down Polystyrene (EPS) Sheets for Insulation: completely cover the leveled dirt floor with 1-2 EPS sheets. Install the strips of remesh on top of the EPS to hold the PEX in place.
5 - Laying out the PEX Tubing: run the PEX tubing from the circulating manifold to the leveled floor area which has been prepared with EPS sheets and remesh/weld-wire. Though there are many possible configurations for laying out the PEX, lore has it that one works about a well as another. The most important thing is that there be two loops for each zone running in opposite directions. This ensures that as the hot water looses its heat in one loop by the time it reaches the other side of the zone that the second loop with fresh hot water from the manifold is there to compensate.
Bend the PEX around into the appropriate loops and tie the PEX in place to the remesh using strong twine or plastic electrical ties.
6 - Covering the PEX Tubing: cover the PEX loops with dirt until the tubing is completely buried but still very near the surface of the dirt if you will be using adobe blocks for your final floor. Level out the dirt as before, finally wetting down the dirt by sprinkling it with the spay attachment on your garden hose.
(OCCUPATIONAL HAZARD: - if you happen to have a cat,
this just might prove to be one of the finest litter boxes on the planet)
7 - Installing the Adobe Blocks: We used 16 x 4 x 16 blocks which are "stabilized" with cement. They are very heavy -- 47 pounds each -- and the perfect formula for a back injury. Lift the blocks straight up slowly using your knees (dont bend over).
Since these are the type of blocks most often used for building walls, they were quite rough and needed to be "sanded" to make them smoother and more level. We used a short piece of 2x4 wrapped with "1.75 expanded metal lath". The block in the left of the picture below has not been sanded while the block at the right has been smoothed with our "sanding block".
Also the rough edges on the sides of each block will need to knocked off or sanded and the backing paper removed. Place the blocks on the prepared level dirt surface -- spacing them approximately 1/8th inch apart. Finally, work sand down into the cracks with a push broom. (The blocks will have be leveled individually as no two are exactly the same.)
8 - Sealing the Blocks: After the blocks have been allowed to settle into place and re-leveled if necessary, they will need to be "sealed". Raw, unboiled linseed oil has traditionally been used for this purpose. Other oils used include tung oil, hemp oil, cottonseed oil, or even coconut oil. Usually three or four applications are used. Since linseed oil takes a week or two to dry, some people have used boiled linseed to cut down on the drying time. The solvents or "driers" used in this form of oil do outgas, however, and are to be avoided if you are at all chemically sensitive or just don't appreciate your floor smelling like turpentine. We have been told that allowing linseed oil to stand in a container out in the fresh air for a few days increases the "oxidation" of the oil and reduces the subsequent drying time once applied to the floor... For more information about this and about installing adobe floors in general, see "Earthen Floors" by Athena and Bill Steen: a Canelo Project Booklet, HC1 Box 324, Elgin, AZ 85611 - order from The Canelo Project.
INSTALLATION PROCEDURES FOR THE FLOOR OF A MOBILE HOME
We purchased 1000 feet of 1/2" Pex tubing, 800 feet to be run underneath the floor boards, the remainder to circulate water from our regular domestic hot water tank and the hot water heating unit on the roof of the greenhouse. We first removed the old insulation and threw it away. Messy job! It was badly compressed from its original thickness, torn in many places, and riddled with packrat poop. The tubing was attached to the floor boards with plastic "J" clips made for this purpose. About every three feet was sufficient to keep the tubing in contact with the floor boards. The tubing was kept at least two inches from the sides of the floor joist.
Holes were drilled at the end of each floor joist to thread the tubing from one floor joist cavity to the next. We got into some spectacular snarls. I thought keeping 25 feet of garden hose untangled was a pain, but...
The tubing was run in two loops for each of two separate zones. Thus the master bedroom and bath room which comprised Zone 1 consisted of two 200 foot loops. The first loop was threaded from left to right, the second loop from right to left. Thus each floor joist cavity had two Pex pipes in it, each to be fed with hot water from the opposite direction from the manifold. Zone 2 which comprised the living room and kitchen similarly had two 200 foot loops, strung in opposite directions from the manifold.
New R-13 fiberglass insulation was then fitted to the bottom of each floor joist cavity. This left about a 1"-2" air space between the insulation and the piping -- necessary for optimal functioning of the system. Reflective foil was stapled underneath the floor joists to hold in the insulation, provide a barrier against air seeping up through the sides of insulation, and further increase thermal efficiency.
Finally, 2' x 8' sheets of "Expanded Metal Lath" were attached to the floor joists. This serves not only to insure the insulation will stay up in place, but most importantly to keep our packrat friends from taking up residence in such a nice new soft and warm home. A packrat couldn't have it any better! They would of course chew on the rafters and on the pipes and wreak havoc in short order.
Solar Hot Water and Hydronic Heating Page / Construction Pictures - Page 4
Solar Haven Main Page
©2002-2013 by Jim Phypers