Monday, June 18, 2012

Faux Manifold

June 13
Wednesday morning, Mark and Emily met us at the lot to help us finish up the last four zones.  We had to reconfigure the last zone in the family room area a bit so we didn't run out of PEX tubing.  In the guest bedroom we tried to deviate from my design, but realized that it needed to go down exactly as planned.  Rob and I actually got out our Sharpie and measuring tape and drew out several quick lines and arrows so we'd know where to lay the tube.  We were surprised at how much more quickly we were able to finish the layout doing it that way.  Too bad we waited to figure that out until we only had one and a half zones left to finish.

Mark and I went back over the whole floor with the stapler to make sure there were staples about every two feet.  There were some stretches of tubing where the staples were close to five feet apart and because the tube is full of air it would have floated to the top of the concrete while it was curing.

While we did that, Rob and Emily finished up the details on the manifold.  The sub who is going to create the real manifold and connect all our tubing to the boiler asked us to make sure the tubes were labeled with the zone and the loop.  Emily colored the supply side of the loop red to indicate that it was the hotter water.  The return side of the loop was colored blue to indicate cooler water.  The water doesn't really change temperature that significantly but it does make it easier to tell the tubes that belong together in the loop.  If I'd been able to create a "perfect" design the tubes would have gone red blue red blue red blue and so on. 
We needed to fit all the tubing into a two foot space.  Unfortunately, part of that space was right on top of a monolithic footing so that gave Rob about a foot and a half to work in.  He could have started the first loop an inch or two closer to the footing but as it turned out he ended the last loop at exactly the two foot mark.  He used the conduit to line the tubing up in order and hold them in place for the concrete pour.

This is the back side of Rob's design.  Dad suggested that we run the loop for the little bedroom straight back through the manifold and under the wall.  Doing this kept the two tubes out of the mechanical room, out of the doorway (that was already crowded) and out of the hallway that was already going to be super warm due to all the other loops running through there.  It also gave the tubing a straight shot from the boiler to the room instead of turning three corners before it started heating the room.  Our builder said if we wanted to do that we should run the tube through a metal conduit to offer protection from any nails that might go through the stud wall into the concrete floor.

Here is Rob standing proudly next to his creation.  The outer pieces of rebar hold up the 2"x4"s.  The bottom 2"x4" has holes drilled through it for the tubing to run through which keeps it from flopping around and ending up in the concrete.  The top piece of wood is for stability.  There are two short pieces of rebar holding the conduit tightly together and the rebar tied crosswise behind the conduit helps everything stay up.  I was impressed!

Mark and Emily were standing next to the manifold while we were starting to clean up.  For fun, Mark blew into one tube to see if he could blow on Emily.  The air came through (just as it should have).  Rob decided this was a good way to do a basic pressure test so he capped off one end with his thumb and blew into the other end.  He had done about three loops when he realized we were paying the heating contractor to do this and he didn't need to become lightheaded trying to prove we did a good job.

The next day the heating contractor capped off one end of all the tubes, hooked the other ends together and installed a pressure valve.  Basically, this will stay on until the boiler is installed.  We can watch this valve as the basement is finished to make sure none of the tubes are damaged.  It's reassuring to know that we will be able to see immediately if there is any damage that will need to be repaired so our heating will work as it is meant to.

Next up, Concrete!

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