Sunday, January 13, 2008

Let there be heat.. someday

We lagged a little bit on making a decision about whether we wanted to put radiant heat in the slab downstairs, so we're currently holding everything up. These guys would've been ready to pour concrete last week, but we had some problems getting a permit (I know.. shocking, isn't it?!)

Dan knows a guy from an online newsgroup that works for a radiant heat place on the east coast. He designed the whole system and shipped us all the parts and plans. That, plus a weekend or so of manual labor is at a savings of about $8k from the quote we got for someone else to install the tubing!

<-- Don't these plans look beautiful?! Well, the city didn't think so.. at least not the section on the left where the garage and workshop have heat. Turns out, heating a garage is prohibeted in Alameda, along with even insulating one! Dan spent 2 days at the permit office, and talked to everyone on up to the head of the building department, but the answer was still no. We either have to build a wall to make a completely separate garage and then heat only the workshop, or no heat at all on that side of the bearing wall. Well, after all the effort to get a beam engineered to hold up the house so we could have a wide-open workshop, there's no way we're going to split it back up! Plus, we'd have to make it about 3 times bigger than the original garage was, because now that the wall is gone, we'd have to fulfill modern parking requirements. Needless to say, our workshop is not going to be as warm as we'd planned on.

So the plans were resubmitted with only the back part of the house having heat, and those were approved.

Everything we needed to install the tubing arrived within a week!

Dan assemled the manifold ->>

.. and then it was just a matter of zip-tying several hundred feet of half inch pex tubing to the rebar.. We rigged up a little spool on some sawhorses so the tubing wouldn't get all twisted up, and then pulled out enough for a loop at a time.
The only places we had problems were around some of the edges that were a bit too high.. the pex needs to be under at least an inch of concrete or the slab could crack. I ran the tubing under the rebar in those areas, and it's closer than I'd like in some spots, but according to the specs it should be good.

Check out my awesome blister! Someday I'll learn to wear my work gloves..

And voila!

Doesn't it look just like the plans?!

This is the bedroom, and it's on one circuit..

And this is the hallway leading to the back door, and the bathroom (in the yellow rectangle at the bottom right of the pic), and our spiral staircase (yellow square at the top right. The mounting points on the center column are market out so we don't hit tubing when we drill and epoxy in the bolts)

And here's the moment of truth.. the pressure test.

All the tubing is plumbed into the manifold, and then the system is filled with air. It leaked from a bunch of places at first, but with a little effort it seemed to be all good! Except that it's not holding pressure.. At 80 psi in about an hour it dropped down to 65 psi with no obvious leaks.

(handy tip for anyone looking to test for air leaks: get a bowl of soapy water and a brush. Brush the water onto all the connections and anywhere that's leaking will bubble up.)

Hopefully there's just a very slow leak from the manifold that's going unnoticed in the soapy water test.. because if it's leaking from any of the lines it'll be a looooong process to track it down.

We were hoping to get that inspected tommorow, and then the slab could be poured next week, but we need to figure out where it's leaking from and who knows how long that'll take.. Better that it leaks now than a year from now when most of it's embedded in concrete and it's impossible to fix.. but it sure would've been nice to have it be perfect the first time.

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