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bennelson 11-11-16 08:19 AM

Hey Guys.

I'm driving a Mitsubishi iMiEV electric car. It's not fancy, but it's a VERY functional car, and in the 2012 model year, it was THE MOST EFFICIENT CAR in the United States, period. It was also affordable enough that I could simply write a check and be done with it.

I'm designing the radiant floor system right now. I was able to get a trial copy of the LoopCAD software. Unfortunately, I couldn't get it to work on my computer, so I had to install it somewhere else. Would be handier to have it at home, but oh well.

I did a few loop layouts, and it looks like 12" spacing on four circuits of half-inch Pex tubing would work fine, but there would be a fairly steep temperature gradient from the send to return lines. I also spoke with Daox, who said that in part of his house, he has some 12" spaced radiant heat, and that you can really feel the difference between the warmer and colder spots.
I don't know how different it will be with the heat coming up through four inches of concrete, but a little closer spacing seems like a good idea.

I also ran diagrams for 9 inch and 10 inch spacing. 9 inch starts to look a little complicated, and starts using longer runs of tubing. I think I'm going with the 10 inch spacing. The loops are still relatively short (only one going over 250 feet) and the labor to lay out the tubing should be a little easier.

Here's an image of the 12" layout. I forgot to save an image file version of the 10" layout when I was on that other computer.

All three of the layouts I ran COULD get my garage up to 70 degrees IF I wanted it to. I'm shooting for just being able to comfortably work in the garage in the winter, and 50 degrees is LUXURIOUS compared to not being heated, but I'd like the system designed so that I COULD heat it higher (for example, if I ever have to live out there, work on an extended project, etc.)

The masonry for the garage is done. Now I have to layout the Pex this weekend, and the mason will come back on Monday to pour the slab. We have 2 inches of foam under where the slab will go and around the foundation wall.

For solar power overall, the plan is to go with PV only. That will make a nice looking array on the roof. With PV, I can make electricity which can then charge a car, power my house, or make heat. I'd love some solar thermal as well, but I'm just very limited on space.

I do have a 4x10' hot water panel on the south-east corner of my house, which I do not have plumbed up yet. That should be good for domestic hot water in the summer, but probably not much help in the winter, and certainly not enough for any garage heat. (I've spoken to a guy locally with a very nice modern solar domestic hot water system. Says it's fantastic all summer, and does minimal good in the winter. That's just all based on cloud-cover and sun angle in my area in Wisconsin in the winter.)

I do have a wood-stove in my living room and would love to plan for future expansion. In theory, I could run some "outdoor wood boiler"-style hoses from my house to the garage, and at some point in the future, connect a heat exchanger to my wood-stove to be able to send some heat from the house to the garage. Likely, I would need to upgrade my stove to do that properly.

Here's some photos of the masonry in place with the insulation on top of it.

bennelson 11-11-16 08:36 AM


Originally Posted by dh1 (Post 52273)
You might want to rethink the shape of your garage, especially the south wall.
Something like this might work better for you. House heating Solar Shed -- homemade collectors

There are a number of limitations imposed on me by the size and shape of my property, as well as by the county in which I live.

The garage doors need to be on the south side, as that's where the driveway is. The corner of the garage was already on the property line, and I needed special permission (and permits, and stupid meetings, and $$$$) just to be able to rebuild the garage where it was. I was also limited by the county board on how tall I could build the garage.

So, yes, I certainly have considered different shapes. I also considered a gambrel roof and some other options, all of which had negatives as well.

Moving the man door to around the corner would have been a possibility, but I do like the look of where it is. Also, the main electric breaker panel will go right in that south-west corner. My parent's garage has the layout of a man door around the left corner, and it's NOT a great design, it ends up making the corner less usable. I don't think that door on their property has been opened in 20 years. Also, my property is on a bit of a slope. If the door was on the west side, it would be a BIG step down out of that door. At a bare minimum it would need a concrete stoop, and I'm already building to the west as far as the county will let me.

The big upsides of what I am able to do are:

1) Rotating the roof 90 degrees. The old roof faced east-west. The new one will face north-south. The south-face really does face nearly due south - perfect for solar.

2) The garage will have an upstairs. We will be using "storage trusses" which leave a space down the middle. It will be a little over 6'6" tall (which is good because I'm 6') and about 4' wide on the flat of the ceiling, with lower storage space on either side of that.

3) It's bigger. The new garage is 5 feet wider and 7 feet deeper than the old one. This gives me storage space, so that I can for example store my riding lawn mower indoors, instead of in my yard, and have space for workbenches and tools.

4) Heat and insulation
The old garage was completely uninsulated. I could literally see daylight through the siding. Simply insulating that structure wouldn't have made sense. It was falling down. I experimented with heating. What worked best was using some old TV Studio lights - 1,000 watts each, as radiant heaters. As long as they were pointed right at me, they worked pretty well. They really didn't heat the garage, but as long as they were pointed at me, I stayed somewhat warm. Still not ideal, especially depending on the outdoor winter temperatures.

Lastly, as far as solar-thermal goes, because the garage doors DO face south, I'm planning on building some glazing for one of the two doors, so that on a sunny winter day, I can open the garage door and use it as a giant picture window, letting the light in.

dh1 11-11-16 05:07 PM

I was just thinking that if you could change the angle of the roof so whatever collectors you put up there would be more efficient.
Rotating the roof to catch the sun from the south would do it. :thumbup:

bennelson 11-11-16 08:30 PM

Unfortunately, the pitch of the roof is determined by the maximum height of the building, which the county won't let me go as high as I want. I think a steeper roof would look nice! For one thing, it would match the pitch of the house.

It would also give me more space upstairs. I have a couple of neighbors who have very big garages, which look GREAT! Oh well.

I did purchase 1,000 feet of Pex tubing and a manifold this evening. Tomorrow, I'll install the tubing. I also rented a stapler for the plastic staples to hold down the tubing to the insulation.

I also finally had a chance to meet with the mason in person. (His schedule and mine have been opposite for this entire last week - the whole time he was here!)

I should be able to put a little insulation around the slab on the interior of the wall. The outside of the wall already has an inch of styrofoam on it. I want to put at least an inch on the interior as a thermal break. I'm not sure if I want to do 2 inches or not. For one thing, that's a big gap all the way around the outside of the floor when I'm all done. 2 inches is a LOT of space to try to cover with a piece of trim.

I've seen diagrams of doing perimeter insulation with a bevel cut in the top of the insulation in such a way that the very top of the concrete slab covers the top of the insulation all the way to the wall. It looks nice when it's done, the insulation is protected, and you get most of the benefit of the insulation. Looks like a lot more work and skill to do that though.

stevehull 11-12-16 09:18 AM

Have you considered some exterior slab closed cell insulation around the footing? Even an inch would prevent a tremendous amount of thermal "bleed" in your Wisconsin winter.

I know its a garage . . . .


bennelson 11-12-16 12:21 PM


Originally Posted by stevehull (Post 52387)
Have you considered some exterior slab closed cell nsulation around the footing? Even an inch...

There's an inch of foam around the exterior where it's exposed to air and two inches where it's below grade. Two inches exposed to air would be hard to do because then the foundation would stick out further than the wall.

I'm going to do two inches of foam with a bevel on it around the INSIDE between the wall and the slab.

jeff5may 11-12-16 01:08 PM

I'm with Steve on that one: it would be much easier to just pour your slab all the way out to the block on the inside. From the pic you posted, it looks like you went below grade along the footer with the xps board. The deeper underground you go with the foam, the harder it will be for heat to find its way in from below. In any case, I would definitely sheath the footer down below the frost line. Also remember not to make a moat around your footer: make sure it can drain and will not act as a wick that can hydrate your block.

I've been looking around on the web about air-to-water systems, and have found a couple of new things. They are much more popular in Eurasia than in America. In the last 5 to 10 years, the Chinese and Indian manufacturers have been conjuring up all kinds of inexpensive systems. A decent number of OEM's that sell complete systems also market "universal replacement control board" modules. These "brain in a box"packages can be used to replace defective controls in existing systems, or to modify or invent your own equipment. The offerings range from "standard window A/C controller" to "programmable commercial control box". Some of the air-to-water controls I happened across:

Qunda QD25a is commercial, QD26a is residential.

bennelson 11-13-16 06:36 PM

pinballlooking 11-13-16 09:45 PM

I liked your video. Thanks for sharing.

randen 11-14-16 05:36 AM


For my home here in Canada the perimeter of the slab inside the foundation is exactly like what you have in the illustration. We didn't bevel the top edge of the foam. The floor tile is covering the 2" of foam. So the thermal break is on the inside. I'm not sure if warming the block foundation would be in your best interest. With my experience here I would go with the inside perimeter foam thermal break.

I can hardly wait to hear your findings of floor heat in your man cave once you have it operational.

One final word of caution. DO NOT OPERATE WITHOUT AN ANTI-FREEZE in your system. One burp be it a power-outage or pump failure or a battery going flat in your thermostat your tubes will freeze and split. Rendering all your work useless and near impossible to repair.

Propylene Glycol is your friend. NON toxic and it will save your butt if something goes south in the depths of winter.


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