Author Topic: Anybody ever spec or install radiant in floor heat?  (Read 6325 times)

_JT

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Anybody ever spec or install radiant in floor heat?
« on: November 25, 2013, 08:33:34 PM »
I'm almost done building the recording studio in my detached garage, and while I wait for drywall mud to dry I'm mentally moving on to the next project: redoing my master bedroom/bathroom. Thinking about installing some infloor heating, but it doesn't seem to be very DIY friendly unless you're doing electric in a really small space (which is a total possibility if I decide to only do it in the bathroom, which is 35sq-ft).

Anyone ever done radiant in floor hydroponic heating systems? What was the approximate cost/sq-ft, what brands did you have good luck with, and what else should I know about it? I don't have gas available at my house, so it'd be an electric mini boiler (less than 3kW should be fine -- talking about 150-175sq-ft here with forced air heat already installed). I'll be replacing the flooring, so it's easy to lay it over the subfloor, as well.

geekette

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #1 on: November 25, 2013, 08:54:39 PM »
We did electric in floor heat in our master bath about 8 years ago and went with Warmly Yours, with a programmable thermostat.  It's definitely easy enough for DIY, and they have a design tool that calculates how much you need and (at least at the time) included a schematic for cuts and turns. 

I'm not sure why you say it's only good for a really small space - run cost?  Purchase cost?  Our kit was about $750 back then, for about 50? sq ft.  I guess it is a bit pricey...

_JT

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #2 on: November 25, 2013, 09:08:34 PM »
Electric is generally considered ideal for spaces no more than 50-75sq-ft, for exactly as you say -- operating cost. Electric heat is accomplished by resistive heating strips, which use a TON of electricity. For small spaces and limited usage it's not an issue, but you'd never do electric in floor heating in an entire house.

Glad to hear it's easy to install -- it looked it (I actually was looking at Warmly Yours' website just a few days ago). It's the hydroponic in floor heating that is more difficult to install, since you need a boiler/pump/controller system instead of just power and a thermostat.

Have you guys been happy with your system?

Cinder

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #3 on: November 26, 2013, 06:21:58 AM »
I JUST finished doing a reno on my bathroom where we put in-floor electric heat.  I can look up more specific details for you later, I'm at work and just going off of what is in my gmail history (which actually covers quite a bit!)

We used a Honeywell  Aube TH115-AF-240S. This one is not a GFCI, and we probably should have gone with one.  You can install a GFCI at your fuse box.  We replaced a prior existing baseboard electric heat element that was running on 220, and tied into that circuit. 

http://www.warmingsystems.com/easy-installation/

Since my bathroom was an odd shape, we went with the 'coil' of wire instead of the mats.  It made it easy to fit into odd nooks and crannies. They do have a 'square foot' coverage listed for each one.  In PA, you don't need to be a licensed electrician, so our contractor did the install (I helped/watched and learned). 

To prep the floor, we removed everything down to the subfloor, and installed 'backerboard' over the plywood.  This reduces the flex in the floor, and also keeps most of the moisture from the cement/thinset from absorbing into the plywood subfloor.

To install the kit, we attached provided strips of metal to the floor, then snaked the coil back and forth, folding over the tabs on the strips to hold it down.  In the above link at warmingsystems, it looks like they use some sort of HVAC tap to hold down the coil.  Then we placed the in-floor sensors with enough length to reach back to the thermostat.  They recommend putting a second one in at this point, and running it up and taping it in your box incase the first thermostat fails for some reason - then you don't need to break up your floor, you can just hook up the second sensor.

After it is all down and in place, we pour a self leveling concrete over the element/coil.  If you are putting down a laminate floor it is really important for this step to be as flat/level as possible.  Since we were just tiling over it, we just let it cure and then put thinset directly ontop of it.  They recommend using a plastic float (or at least a non metal one) so you don't catch/nick the element.

 Thoughout the entire process, they have you check the resistance in both the element and the floor sensor.  If it is outside the recommend range, then the unit somehow became damaged.  It is easier to find it one or two steps in then to find out after you've laid all your flooring ontop of it! 

My wife loves the warm tile on her feet in the chilly mornings.  The thermostat is programmable so when we'd wake up it is ready, and when we go to work it shuts off.  The thermal mass of the tile holds heat well, so you can time it to shut off about an hour before you'll leave, and you'll still have plenty of warmth.

If you have any more questions let me know!

Greg

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #4 on: November 26, 2013, 10:17:23 AM »
I installed in-floor and under-floor hydronic heat in my home, using a Rinnai propane on-demand heater as the heat source, which also is used for the rest of our hot-water needs.   So my system is in the concrete floor on the lower level, and under the plywood subfloor on the upper level.

Cost DIY was about $1/sq.ft., not including the heater.  I used 1/2" pex tubing in both cases, with two Taco zone pumps, one for each floor.

For a retrofit application, you can do under floor using pex clips for the purpose, metal tracks, or you can go over the top with subfloor products that have channelling for pex built in, like WarmBoard.  You can also do a layer of concrete over your subfloor but it would need to be designed for the load.

For your heat source, electric can be expensive, but if it's your only option, an electric tank in the circuit would work depending on the size.   If you can get propane, that might be a better option.

_JT

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #5 on: November 26, 2013, 11:01:47 AM »
Thanks for the info, guys. Appreciate it!

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Greg, did you need any sort of controller for that system?

geekette

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #6 on: November 26, 2013, 11:16:45 AM »
We've certainly enjoyed ours for the last 8 winters.  It only runs a couple hours morning and evening, so I don't think it's terribly expensive for supplemental heating.  It sure is nice to step out of the shower onto a warm bath mat.  I see that now they have ones approved to go under the tile, which is new to me.  We went with a composite shower base so it's not cold like our old tile shower floor was, but if that under shower warmer had been available back then, we would have added it.

Greg

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #7 on: November 26, 2013, 01:19:24 PM »
Greg, did you need any sort of controller for that system?

Taco used to make 007 zone pumps that included a relay that could be operated from a standard low-voltage thermostat.  Not anymore, so now they sell a relay panel for that purpose.  It can be controlled by a battery-operated thermostat. 

The pumps themselves plug into an outlet.  Now you have to add the cord to plug them in.

The pumps typically can handle a loop of about 300' of 1/2" tubing.  More than that and you have to add a second loop.  Each of my pumps has 3 loops on it.

Hope that helps.

_JT

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #8 on: December 01, 2013, 04:31:56 PM »
Greg, did you need any sort of controller for that system?

Taco used to make 007 zone pumps that included a relay that could be operated from a standard low-voltage thermostat.  Not anymore, so now they sell a relay panel for that purpose.  It can be controlled by a battery-operated thermostat. 

The pumps themselves plug into an outlet.  Now you have to add the cord to plug them in.

The pumps typically can handle a loop of about 300' of 1/2" tubing.  More than that and you have to add a second loop.  Each of my pumps has 3 loops on it.

Hope that helps.

That would be awesome, bypassing the need for a controller altogether! I've also been kicking the idea around of using a small PLC, in case I wanted a more complicated multi-zone system. But if I can find a pump/relay setup that interfaces with the thermostat that'd work, too. Every online seller is trying to sell me a mini boiler, but I'll probably try it with my existing water heater at least at first and see what the costs/loading looks like.

MrsPete

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #9 on: December 01, 2013, 04:50:03 PM »
We're planning a retirement home right now, and I am planning to use radiant heat in the bathroom.  I just lost a dear, dear relative who was ancient-old, and I saw things that were difficult in her life; I'm trying to plan my house to make my own life easier when I reach that age -- two things that worked against her were that 1) she felt the cold something terrible, and 2) she had to get rid of all her throw rugs because they tripped her.  So, yes, I am planning this in my bathroom.  I think it'll be costly . . . but useful. 

I'm also planning to use a similar system to make a "heated island" in the kitchen.  This is less practical, but also not very expensive for such a small spot. 

Greg

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #10 on: December 01, 2013, 06:28:41 PM »
That would be awesome, bypassing the need for a controller altogether! I've also been kicking the idea around of using a small PLC, in case I wanted a more complicated multi-zone system. But if I can find a pump/relay setup that interfaces with the thermostat that'd work, too. Every online seller is trying to sell me a mini boiler, but I'll probably try it with my existing water heater at least at first and see what the costs/loading looks like.

Upunor makes (or used to, haven't looked in a while) manifolds that have adjustable valves for each loop.  The ones we used have 4 valves, so 4 loops, and an opening on the end where I installed a temp gauge.  Each valve allows you to manually adjust flow for that loop.  For instance we have our entry warmer and the kitchen cooler.  These adjustable valves can also be fitted with a thermostat- or other-controlled actuator, so that you can have 4 loops each with their own thermostat for instance. 

We found that simpler was better though, and never installed the loop valve controllers.  It's more of a set-it-and-forget-it system, though we have adjusted the times it's on and off with a fairly complex programmable (but still battery operated) thermostat.

We run ours off of the same on-demand water heater that heats the domestic hot water for our fixtures in what's referred to as an open system.  We thought we'd need to cool the water down from 120F to 110F but it works fine at 120F.  So the mixing valve is another part we didn't need.

I created a system for a 200 sq. ft. workshop using a 50 gal. electric water heater, seems to work fine but I don't pay their bills and so don't know how efficient it is.

I can say that having a warm floor means we feel warmer even at 67F.  It's just not very reactive, meaning you can't turn it on and off quickly.

_JT

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #11 on: December 01, 2013, 09:42:15 PM »
Temperature systems are always SLOW, so that doesn't bother me. Honestly, I think I'd do the bedroom/bathroom on one loop, and just put them on a timer to come on an hour before I get up in the morning, and probably not any other time. Simple is good by me, as well.

I appreciate all your input -- it's gotten me headed down some much more productive google paths. :)

Mr. Minsc

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #12 on: December 02, 2013, 06:00:46 AM »
Here's what I've picked up from working at various plumbing companies.

- Space 1/2 tubing on 12" centres about starting 6-9" from the wall.
- Feed outside walls first.
- I you have a high temp boiler you'll need a mixing valve to cool the water to 120 degrees F.  This valve takes the cooler return water and mixes it with the supply.
- Insulate any ground floor!  No point putting your heat into the ground.
- With 1/2 pex keep your loops a max of 300'.  It is my understanding that beyond that point the water will have cooled to a point it no longer provides adequate heating.
- If the area you want to heat is far away from the heating source you can run 3/4" (I don't see 1" being needed in most household applications) supply and return lines to a more convenient header location.

_JT

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #13 on: December 02, 2013, 09:23:51 AM »
Nice! Those coincide with most of the tips I've read online. One thing I haven't seen articulated well is feeding the outside walls first -- do you know the reason for that?

Greg

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #14 on: December 02, 2013, 09:47:16 AM »
Mr. Minsc brings up some good advice. 

The reason you heat the perimeter first with the beginning of the loop is that's where the floor is coldest, and the heat tubing the hottest.  This works well, and you can double up the spacing in front of doors as well.  This creates extra-warm areas right in front of doors which feels good, and dries shoes and floor more as well.

Another basic point is use continuous tubing anywhere you can't access it, like in a poured concrete floor or enclosed joist space.  No joints allowed.  Crawlspace retrofit applications are more forgiving, you can always get to it if there's a problem.

MrsPete

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #15 on: December 02, 2013, 09:51:19 AM »
Temperature systems are always SLOW, so that doesn't bother me. Honestly, I think I'd do the bedroom/bathroom on one loop, and just put them on a timer to come on an hour before I get up in the morning, and probably not any other time. Simple is good by me, as well.

I appreciate all your input -- it's gotten me headed down some much more productive google paths. :)
I've been wondering about this same topic, and here's what I want to know:  Assuming you're talking about a new build -- not an addition to a new house -- could you install a switch beside the bed so you could "turn on" the tiles, then lay in bed a while longer as it heats up? 

_JT

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #16 on: December 02, 2013, 10:22:59 AM »
Temperature systems are always SLOW, so that doesn't bother me. Honestly, I think I'd do the bedroom/bathroom on one loop, and just put them on a timer to come on an hour before I get up in the morning, and probably not any other time. Simple is good by me, as well.

I appreciate all your input -- it's gotten me headed down some much more productive google paths. :)
I've been wondering about this same topic, and here's what I want to know:  Assuming you're talking about a new build -- not an addition to a new house -- could you install a switch beside the bed so you could "turn on" the tiles, then lay in bed a while longer as it heats up?

Sure. You can locate the thermostat controls wherever you want. You can also get a thermostat that has timer functions, as far as I know (depending on which system you use).

Greg

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Re: Anybody ever spec or install radiant in floor heat?
« Reply #17 on: December 02, 2013, 02:47:09 PM »
JT, you may want to browse PexSupply.com, that's where I got a lot of my system.