DIY Hydronic Floor Heating

[cbearden]

Hi to all. I've been reading your forums over the past year with much enthusiasm I might add. And I've finally started on our new house in the past few weeks. I've decided to try to install a hydronic heated floor. And I thought I would share details on how this project is going. Our house will be two stories. The first is on a concrete slab that's above ground because of drainage issues on our property. And this is where I'm putting in my PEX for my heated floor. Here are some of the details of my installation. I'll try and post pics as soon as I have enough posts on here.
Slab: 4" concrete with 1" white styrofoam foil-backed insulation under entire slab.
2" XPS pink insulation around entire perimeter of house, but it's inside footings/concrete blocks.
our slab is roughly 900sq ft in size for our first floot.

hydronic floor - 1/2" pex throughout most all of the slab. spaced about 12" apart.
I have broken up the pex into 7 zones. The longest zone is about 260' I believe.
I used a trial program called LoopCAD to help design and layout my PEX. This was a big help to me.
I've also laid in separate pex tubes with temp sensors for each room,
with an additional temp sensor under the slab,
and more sensors planned inside and outside the house.
I'll be using a raspberry PI computer to measure all of the temps,
update a local webpage with data as needed,
and switch on relay circuits to control the pump for my floor loops.

walls - we upgraded to 2x6 walls to have extra insulation. I think our builder is putting in blown cellulose in the walls.

heating/cooling - our builder is putting in a standard heat pump system.

I'm also building a 24x24 shop nearby. on the side of this, I'm going to attempt to build solar collectors to heat water that will be pumped into a water storage tank in my shop. Then, I'm planning on running larger 1" pex pipe between my shop and house to serve as heat source for my floor loops.
At least this is my attempt at all of this. This will certainly be an interesting adventure to be sure. My goal is to hopefully save energy, while at the same time not spend too much money on this project and also to keep my wife from choking me over its cost. haha!

[randen]

Cbearden

Congrats on your new build. You will enjoy the heated floor so much. I have heated floors in both shop and home. The shop was done first to try it out as no-one was doing it around here. The office space of the shop has Kitec tube (no-longer avalible) 5/8 Id x 12" spacing. We had put 1" foam under. Should have been at least 2". The 6" slab losses heat alot quicker than the house which is 2" Otherwise its fabulous.

At home there is nothing like comming to the bottom of the steps in the morn. and your bare feet slapping down on warm tile floor.

We have as well 8 solar hot water panels. Another beautiful thing. A sunny day heats the house for 24 hrs. Hopefully you have a lot of sun in AR. Love the free heat. This winter has been overcast with only about 10 days of sun. I hate paying for it all. Geo thermal is our back-up source but still twice the electical cost as what we are normally use to with sun making up nearly half.

We have five controlled zones, really not nessisary. We could have done just one for the whole ground floor. 1700 sq ft. Make sure you can replace your in concrete sensors. Lightining strikes close to home take them out. I've replaced 5 in the 15 yrs we lived here. I think the temp. sensor outside is good for the anticipation of heat required as the lag time to heat the slab. Check with Mikesolar.

If I built again 2x6 construction with 3" or more rigid foam on the exterior. A rule of thumb for solar space heating for flat plate 10-30% of your floor area to panel area.

Again congrats on your new home.

Randen

[cbearden]

That is awesome hearing about your setup! I already know there are things I could have done better, more insulation, closer-spaced pex runs, more insulation. haha!
Since I only have one large manifold, all my pex runs go back to our laundry room at the corner of the house. I know this isn't the ideal way to do things either. But this was about the best place I could do with this, esp being my first time experiment.
All of the home runs go into the laundry room and this is kind of a hall-way type run roughly 25' worth. So, to help with this and heating losses, I went out to our site tonight and did a last-minute insulation addition. I put in 1/2" pipe wrap insulation around 20' of all 5 of my loop circuits to our main house. Our garage has two additional circuits, but we don't plan on using those right away.
Maybe the insulation will help with some of my losses and help keep this hall-way from overheating, compared to the rest of the house.

[randen]

Good call

Insulating the runs to their point of use. I was going to mention this as I didn`t think about it for my installation. Mine happen to run in a high heat loss area and actually help. I have one run like you to the garage that runs under a small bathroom and this one run causes the bathroom floor to warm just a little more than one would need but my wife likes it. Don't worry it isn't an experiment it will work well. The Laundry room is a great place for the utilities thats were I have mine. Have you both considered stained polished concrete.

I know your in all likelyhood your tired of the planning and little peskey details but trust me as someone that has done it. It will pay you in huge dividens. The concrete floor is actually a important integral part of the system. Think of it this way, if you where to shop around for the MOST efficient heating system eg high efficiency nat. gas or heat-pumps or instant hot water systems, and have to pay to have these installed the extra details for the solar heated concrete is money-time best spent.

If I may suggest, if you are planning on a larger solar hot water space heating system there is this detail. Now take this again as I've experience with this, I just didn't read about it. I have 280 sq ft of solar hot water flat panel that will heat my home for 24 hrs. with one full day of sun and -21 Deg.C. outside. It does work. and it makes a huge impact on the electric bill.

However the heat that is collected with my system is not all being absorbed by the concrete floor. Even though I have a huge heat-exchanger there is hot water returning to the panels on very sunny days. If I had to do it again knowing these details I would install in the floor a second dedicated loop for the solar hot water. This would eliminate the Heat exchanger and all the heat I could collect would be absorbed in the floor. Heat exchangers are not cheap and the tubing is relatively. Once you pour the concrete your committed. This being said it works very well but would work better.
I'm going to install another HX to reduce this inefficiency but thats another $500.00 however with one sunny winter it will pay for itself. Solar hot water space heating works well.

It may be hard to justify at first glance but whatever heating energy you will buy will always go up in price. But the solar will always be free. The solar heating is silent and automatic. With the concrete in floor heating you have THE best method of using this free heat.

Some numbers to help: 8 flat panels producing water/glycol temps 50-60 Deg.C. One full day sun equals one full days heating. Floor temp morn 23 deg C afternoon 28-30 Deg C. dropping thru the night to 23 Deg to repeat if there is sun the next day. Dollar value for electricity for the geo-thermal 6-$8 per day depending how cold and windy. Seasonal Reduction with good sun 1/2 to 1/3 is seen. We see approx $1200 dollar value reduction per year with in-floor heating and domestic hot water. We have from Mar to Nov. supplied domestic hot water with no electrical input with the exception of approx 5 days of extended overcast.

You and your wife will enjoy the warm floors and guilt free long hot showers, hot water for laundry and or jaccuzy tub. Solar hot water is worth the extra time and attention.

Randen

[cbearden]

That's great info to hear. I hope that it does work out. It sounds like our setups are similar for the most part. One thing that is different in my setup is that I plan on using plain water in my PEX. It doesn't get down to freezing that often down here in AR. And when it does, I plan on using a drain-down setup that I think I read about on the build it solar website.
I want to build as much of this as I can, not only for initial costs, but also for future modifications that I'll probably need to do. I know I can get higher performance from commercially built solar collectors, but there's something appealing to me with knowing that I've made it myself. And I certainly don't mind the extra work to put into it.

[randen]

If you can DIY by all means. My panels are all DIY but I,m in the tool & die business so its pretty much the same thing I do all day. When I do the DIY thing I spend money on the best materials so all my panels are copper & stainless with double the insulation.

Don't be to rash I've seen a few times on flea-bay a number of good panels for $250 ea. The glass is almost worth that. You have time. By the way don't plumb pex for your solar, copper only. Rough it in the walls with fiberglass insulation.

Get the photos going.

Randen

[cbearden]

I was thinking about using PEX for my panels, mainly because I'm familiar with it already and it would be less expensive than copper. Do you think that I wouldn't be able to get enough heat transfer via PEX in my panels?
Another reason I wanted to build these is that I wanted to use the entire side of my shop building. my plan is to build this 24x24, and since it'll be 8' high, just use the entire one side facing the sun as my collector mounting area.
that might give me close to 200 sq ft, and I think I could go a little higher than the top for more sq ft because of my roof pitch anyway.
Here are some pics that I took today of our house as it is.
They just poured the slab this morning.
I'm hoping this pics will show up since this will be my first attempt.
one of them shows before they poured, when I finished putting in my pipe wrap insulation. the way the pipes are grouped like they are, I'm a little disappointed. I was hoping for a more neat appearance. But I wasn't able to leave the manifold hooked up during the pour. And I wasn't able to be present during the pour to make sure this went better either. the other group of pipes with the blue wires hanging out are my sensors, soldered to cat5 networking cable. after the sensor, I filled the end of the pex with silicone to help seal moisture, and then duct-taped over that.
This kinda feels like getting your very first car. This is my first major attempt at energy saving. And while it feels awesome to try this, I know it's far from being perfect.

[Drake]

moved post to new thread.

[Mikesolar]

Open systems are a last resort or a cheap resort. First, the tubing is going to be in the cement longer than any of us will be alive so why not spend a few extra cents/ft for an O2 barrier. It doesn't make sense to be cheap about it.

Next is the health issue. Stagnant water in the tubing COULD promote bacteria growth and in some cases it has. Because of this, most building depts don't allow it, and they shouldn't allow it.

The only operational reason for an open system is ....no HX and one fewer pump.

You cannot move to a boiler with a non barrier tubing or have anything in the system which is steel/cast iron. This means your pumps must be brass or stainless, which is more expensive.

[cbearden]

Randen,
Why do you recommend copper and NOT PEX for solar panels?
On this site, they've done tests comparing the two, and they're claiming PEX collectors are 1/6th the price with only 15% loss in performance.
Comparing Solar Collector Performance -- Small Panel Tests