We headed down to the hardware store to grab yet another stick o' pex tubing, some additional crimp rings, and to rent the crimping tool for what I declared to be "the last time, finally," barring any future repairs of course.
Way back when, about 1 or 2 days before we moved in, we plumbed the hot and cold water lines to the water heater in the basement. We had added a spur to the hot water line because we assumed we'd be needing that option for when we would splice in the furnace as a domestic hot water source. As it turned out, the furnace should splice into the cold lines. So, we had some plumbin' to do.
It was pretty exciting, cutting into live pipe. Cold water sprayed us down more than once, even though we had shut the valves. You see, we're pretty good with this simple material now. It didn't take long and there weren't any significant missteps. We connected the two remaining 3/4" pipes coming into the house from the furnace - ran them along the wall underneath the electric panel, up the wall, and over to the cold water line at the water heater. Each new pipe passed through a ball valve before T-ing into the vertical pipe and into the heater.
The idea is that in the winter time, when the fire's heating our house it will also be heating our domestic water. So when we turn that shower to hot, the water we're using will have run through a copper coil in the furnace before making its way to the bathroom. Efficient!
I rushed the crimping tool back down the road to the hardware store and declared "done!" Hoorah!
Next: the floor probe.
Given the thickness of our floors and the uninsulated state of our walls, we will be using a temperature probe under the floor rather than a thermostat to set our temperature. This is because with radiant heating, you're not really heating the air as much as you are the objects in the room and the house itself. Without boring you with the details (email me if you need the details), using a floor probe will result in less temperature swings and a more even and efficient performance.
To install the probe, I cut a small square of rigid insulation, dug a little notch out of it to stick the bullet-like sensor into, then screwed it up underneath the floor, using wooden shims as washers. Simply connected the two leads to some 18 gauge wire and ran the wires to the set point controller and voila.
Next: fill the radiant system!
That's right. Time to put some water in these tubes. First, we had to remove the Schrader valve and replace it with the expansion tank. This should have been smooth, but wasn't. It was the wrong size. But, we happened to have the right brass adapters to make it work. Second, you hook a garden hose up to the drain valve and another hose up to the fill valve and to a water source. We tied the hose from the drain valve off to one of the piers under the deck outside so that we could observe the water flow (looking for air pockets) and direct the water away from the house as it purged the system of debris and air. We made one more run down the checklist for the operation and then turned on the water. Erika opened the first circuit and I opened the valve to allow the water into the return manifold and out the drain valve.
With a woosh and a bang! Water was flowing through circuit one. There'd be a few sputters when an air pocket was pushed out and then the stream of water would be fairly consistent. The pressure would build to around 30psi until the air was pushed out, then it would drop back to around 17. Then we'd open up a second circuit and the water pounded through - pressure would drop, pressure would build, you'd hear the gurgling coming through, the hose would sputter, the pressure would drop, and then we'd open the next circuit.
Speaking of circus, Erika had her hands full outside trying to save all the water that we were using to flush the system. We're in a drought. To let 50 gallons or so of water go to waste is not something to be taken lightly. So, she was constantly getting buckets under the hose and scrambling around to find more containers...coolers, pots, big tupperware vats that we stored wedding food in... Meanwhile, the leaky garden hose in the basement was making a mess, but I was ignoring it. No other choice, really.
After we were pretty certain that the air had been purged from the system, I closed the drain valve and brought the pressure up to where we needed it (only about 14psi) and cut the fill. And there you have it.
I powered up the setpoint controller and pump. The probe was reading a floor temp of 68 degrees and the controller was set for 75 and click, on came the pump and circulated the water through the system. Awesome. But, it's cold water right now.
We've only got a night or two of work to finish the furnace hook ups. We plan to actually build a fire in that thing on Friday. We ate dinner Sunday night thinking, "by this time next week, we'll have a finished heat system and a warm house."