In the Groove

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There is one last mechanical system that we aren't quite done with. And it is the only one that Mom could not possibly live without.

Heat. It is not a luxury or a convenience up here in Alaska. Heat is the only mechanical system that you must have to survive our extreme winter temperatures.

Because heat is so important up here in Alaska, especially the efficiency of the system, we've procrastinated on deciding how the Momplex should be heated. While the basement slab has radiant heat tubes poured right into the concrete, the upstairs main living area does not have a heat source.

We went back and forth on radiators or in floor radiant heat, and then all the different ways we could go about installing the different systems. What is the most efficient? Does it really work or are we just being marketed too? I wanted to hear from real people - what really works in your homes.

So a few weeks back, I wrote a blog post about our heated battle, asking for your advice on a heat system - and man did you ever come through for us! I want you to know that the decision we made was a direct result of your comments and suggestions. We are very appreciative of everyone who gave us advice - thank you.

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Step 1 Diagram: 
Step 1: 
We ultimately choose above the subfloor in floor heat. This is what the final install will look like. Over this heat system, we will place 1/8" thick underlayment plywood, followed by flooring. The heated tubes will be within 1/2" of the bottom of Mom's feet! We choose this method because it will allow us to run the boiler temperature much lower, resulting in lower heating bills. And because we are putting a heat system in so late in the game, this was actually one of the easiest methods. It's always easier to work on the floor as opposed to over your head on a ladder.
Step 2 Diagram: 
Step 2 Instructions: 
As you recommended, we worked with Radiantec to have a DIY kit sent up to us. We sent them a floor plan and they sent us a diagram of the tubing layout and the parts and pieces to hook it all up to a boiler system.
Step 3 Diagram: 
Step 3 Instructions: 
Because we have only about an inch to work with, we can't pour concrete or gypcrete on the floor, as some installations do. So we are filling the gaps between the pipes with 3/4" plywood. We've gotta rip 50 sheets into strips 10" and 4" wide. 50 sheets. Of 3/4" plywood. Each weighing oh about 60 pounds. We could run the 50 sheets each 5 times through the tablesaw. That's about 15,000 pounds of plywood being pushed through a tablesaw. Anyone eat their Wheaties today?
Step 4 Diagram: 
Step 4 Instructions: 
The Ram had a better idea. Why not run the 10 pound circular saw through multiple sheets of plywood at once? We have a <a href="" target="_blank">Kreg Rip Cut</a> (awesome tool BTW!) and we just set it to the width needed for ripping the plywood ...
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Step 5 Instructions: 
And started ripping!
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Step 6 Instructions: 
And kept on ripping. John and Junior are helping us out (something about making a Mother's Day moving date has us begging for help) and did most of the ripping. The plies of plywood strips piled up, and the sawdust had to be shoveled up at the end of the day. Most strips are ripped for 10" spacings (9 1/4" widths) but 4" strips are cut as well.
Step 7 Diagram: 
Step 7 Instructions: 
In the rooms, the 4" strips are used to picture frame the walls. This enables the heat transfer plates to sit off the wall.
Step 8 Diagram: 
Step 8 Instructions: 
Once the rooms are picture framed, we do a quick layout with chalk lines.
Step 9 Diagram: 
Step 9 Instructions: 
And then the 9 1/4" strips are cut down to length.
Step 10 Diagram: 
Step 10 Instructions: 
And layed in the room.
Step 11 Diagram: 
Step 11: 
Then you just load up with screws ...
Step 12 Diagram: 
Step 12: 
And start screwing the strips down to the subfloor.
Step 13 Diagram: 
Step 13: 
After we got into the groove of things - as in using plywood spacers in the grooves - things started going pretty fast.
Step 14 Diagram: 
Step 14: 
We found it was better to use the spacers to line up the strips than keeping in line with chalk lines. Our big worry is the spacing would be too tight to fit the pipe. Noticed the square ends that we leave open on every other row?
Step 15 Diagram: 
Step 15: 
<p>These are for the 180 degree bends where the pipes loop back around to the next row.</p><p></p><p>On some rows, we'll need to make a 90 at the ends, for transitioning between rooms or back to the main manifold.</p><p></p><img src="" style="width: 470px;" alt="" /><p><br /></p><p>We used a jigsaw to cut out a pattern of an arched 90 degree turn.</p><p><br /><p></p><p><img src="" alt="" /></p><p></p><p>And then screwed those down. &nbsp;We save the scrap piece for filling in the void on the end.</p><p></p><p><img src="" style="width: 470px;" alt="" /></p><p></p><p>You have to be careful with tubing to not bend too sharply or it will kink and eventually leak. &nbsp;So in a few spots, we did have to do some fancy cutting, like this sharp 90 near the stairs.</p><p></p><p>But for the most part, it's just long strips.</p><p></p><p><img src="" style="width: 470px;" alt="" /></p><p></p><p>Attaching the plywood spacers to the floors was actually pretty easy and went fast. &nbsp;Once one side was done, the other was a mirrored copy, so we could reference the finished side when doing the unfinished side.</p><p></p><p><img src="" alt="" /></p><p></p><p>Here's our first room done!</p><p></p><p><img src="" alt="" /></p><p></p><p>Once the plywood spacers are screwed down to the subfloor, we'll just need to add the heat transfer plates and piping, and then hook it all up to the boiler to be done with the heat system! &nbsp;We can't wait to see how this heat system performs.</p><p></p><p>So what do you think? &nbsp;Did we make the right decision with radiant heat above the floor? Have you installed radiant heat? &nbsp;Did you do anything different?</p><p></p><p>Thanks again for helping us out on this one!</p><p></p><p></p></p>


I will totally agree that radiant heat is wonderful! We installed it in our cabin just west of Yellowstone NP where temps (while not as cold as what you endure) can get down to 30 below. We installed ours above the floor (for the same reason as you) but then put a layer of cement over it (in both the basement and the main floor). We had to contend with the concrete cracking but solved that problem by sealing it with RedGard so that the cracks wouldn't transfer up to the tile we laid on top. I don't think we would change much about how or what we installed. We've only had one slight problem with losing pressure in one of the lines and one valve sticking open in the garage, both which were easily solved. I don't think your moms will be disappointed. Nothing like warmth radiating up between your toes or putting on warm shoes.

Ana- We are just a few steps behind you building our house in Oregon. I have enjoyed following your MomPlex blog so much along the way because you, and your online community, seem to be the only people who can relate and not think we are crazy for taking on such a project.

Currently we are attempting to wade through all of the conflicting information about hydronic installation methods. I would like to install the pex tubing above the subfloor for efficiency benefits, however, there are some concerns about the need to retrofit door heights and stair spacing. Our house is already framed and the windows and exterior doors are in, including some sliding glass doors. I'm wondering, did you take the extra (3/4" - 1.5"??) floor height into consideration before framing your doors and stairs? If not, do you have any plans on how you will account for the difference in height?

I'm looking forward to seeing how well this system works for you and your moms because we've been talking about doing this kind of heating system when we eventually build our dream house. We have wondered about how to do the main floor of the house since it is above a basement.
One question I have is do you have an alternate power source to run the pump the circulates the water if the power goes out? We have talked about having a wood/coal stove as an alternate source of heat so that we can survive off-the-grid if necessary.

This couldn't have come at a better time. We are relocating the kitchen from an exterior wall to an interior wall and to a different part of the house. This has caused also sorts of creative thinking in the household. Especially the heating system, since the old kitchen needs additional heating and the current system (hydronic baseboard) has come to its end of life. Copper just doesn't mix well with alkaline concrete (lime) and corrodes over time. Surprised it has lasted this long. So now's the time to do this.

We were going to retrofit a radiant floor heating system on top of existing 4-5" concrete slab (suspended over basement with steel I-beams) using rails, PEX-AL-PEX and lightweight concrete. We did the heat loss calcs and designed the system using LoopCad. Then our structural engineer told us that our slab cannot carry the added weight of a thin slab pour. The I-beams are just barely carrying the dead load of the existing concrete. I suggested to him that I'd call Santa Claus and see what he can come up with. ;)

We started going through the options. Since we have SlantFin fin tubes currently and in the basement we found extra ones hidden inside the walls in original packaging, it would have been the easiest option to use those and buy new covers. DH thinks they are butt ugly. But as tempting as that was, there is also Runtal radiators that look quite nice and have a low profile. Which DH found easier to swallow. However, this would have been between 3000-4000 in radiators only. Plus the added cost to reroute the copper tubing out of the concrete slab. So compared with DIY radiant floor heating, the price is not that far. But then there's the how?

I searched online and came up with a similar solution to yours. The reason why we didn't go with the plywood solution originally was the passive solar gain and thermal mass losses related to it. We have huge south facing windows in our 60's ranch. But all in all, it is a very nice system if you also amp up the insulation at the same time and then there's the potential savings of lowering the heating costs.

Anyhow, I just wanted to write about my experience with radiant and thank you for the well written post. It gave us a lot of optimism. :D

We absolutely love our radiant heat in our basement (where we are living right now while we finish the rest of our house). We plan to do something similar to what you've done on our upper floors. So cool to see you what you've done!