floor heat disappointments?

[Ohio Auto]

I want to build a 30X50 but the more I think about it think I'll just hang a modine or renzor heater and well insulate the place. As long as its 45-50F I am fine.

I just put heat in my 30 x 50 shop this year. I looked at all the options and talked to a lot of people. My biggest concern was fuel consumption. We live out in the country and heat with propane. I had four or five guys tell me they loved their radiant heat tubes on propane but that they seemed to **** a lot of fuel.

I ended up going with a top of the line Lennox furnace...98% efficient. Just ran the ductwork out the top of my compressor room and let it flow out like you would a Reznor.

I keep it at 45 degrees until I go out to work in it, then I bump it up to 55 degrees. Could not be any happier with my choice.

 

[chevelle64]

I think the reason a lot of people are having problems with their radiant heat is because of an improperly designed and/or built system. When I did mine I went to one of the experts, Radiantec, but there are others. They designed my system, sold me all of the parts and I installed it. There was no guesswork on my part. I keep mine at 60* and I wouldn't have any other type of heat. It seems a lot of people just throw a system together and hope for the best. I realize that it isn't "rocket science", but there is still a right way and a wrong way to do it. I am not yet retired, so I can only be out there minimally during the week. But a properly insulated garage along with a properly working system, will run extremely efficient and it won't matter if you're heating a space that isn't used 24/7. I am far from an expert, but there is something seriously wrong when someone says their radiant system is too expensive to operate. That's all I have to say about that.

 

[ctkid343w]

Located in Connecticut. Garage size is 24 x 24 x 10, Walls and ceiling are insulated r-13 & 5/8 sheetrock taped & painted. I only spend a few hours at a time in the garage. I heat with propane (burner hangs off the 20lb tank) for a couple of hours before I go out there. Keep the propane going while I work and turn it off about 30 minutes before I leave garage. Also have an electric heater hanging off ceiling that I use sparingly. Approach works unless it gets below 20 degrees outside. Then I have to run the propane heater longer before I go into garage. Less expensive then all electric heat, less work than wood stove. Works for my situation. My experience, hope it helps the next to read this.

 

[brianh]

I set up my floor for radiant the building is not finished yet but I worked in a shop with it and it was really nice.

I figured while pouring the slab it really was not much more to put in the pex I have 6 zones in a 40x60 it will have r 38 when done. The slab is insulated.

I will be using solar hot water panels so I figured the slab will be great for thermal mass storage. As long as I can keep it above freezing I will be happy, a woodstove and the toyo laser heater in my other shop will also be used when I am in it.

I have had the toyo heater in my smaller shop around ten years it works really well and is efficient.
http://www.toyotomiusa.com/products/laserventedheaters/L-73.php

 

[keweenawbee]

I am noticing in a lot of the photos in this forum not-so-tight spacing on the in-floor tubing layouts. I had used the one foot rule but one thing to keep in mind, especially if planning to use a modern condensing boiler design, is that the more pipe you can get into the slab the better heat transfer to the slab, thereby the best chance of condensing and recovering the heat. The magic number is 30 degrees between boiler supply and boiler return temperatures. Had I known what (I think I) know now I would have bought more pipe and tightened it up. A little more investment in the beginning will surely pay off in a short time.

 

[rlme36]

I am noticing in a lot of the photos in this forum not-so-tight spacing on the in-floor tubing layouts. I had used the one foot rule but one thing to keep in mind, especially if planning to use a modern condensing boiler design, is that the more pipe you can get into the slab the better heat transfer to the slab, thereby the best chance of condensing and recovering the heat. The magic number is 30 degrees between boiler supply and boiler return temperatures. Had I known what (I think I) know now I would have bought more pipe and tightened it up. A little more investment in the beginning will surely pay off in a short time.

I didn't know that fact but am glad that my system is within that spec, its closer to 25 Ithink. Your comment around proper design is a good one. I had my plan designed by pex supply regarding the # of feet of pipe and the # of runs and bought the boiler as a pre made kit with the proper #of pumps for my application already installed and warrantied.

 

[keweenawbee]

Very nice. Did you quit taking pictures last Jan? I don't see any photos of your boiler, manifolds, ect. Must be nice to have sub-contractors.

 

[rlme36]

Not quite I have a couple, of the heat set-up. I had a delay on the sheetrock in the garage due to a blown engine, its amazing the things you do "while you are in there".

 

[keweenawbee]

That looks like a pre-built Hydro-Smart panel. Do you utilize that blocking valve in the purge tee very often, either for purging air or changing it to a series flow through the boiler? I plan on using a couple of those in the 1 1/4" throat size. You are getting a 25° drop using it valve-open as a primary secondary configuration? That would mean that the flow & mix in the purge tee is working very well. I wanted to go up a size over my primary boiler piping to make sure that the internals present no interference. If I remember right from the Menards display yours is 3/4" from the boiler and a 1" out to the loops right? I know you pay a premium for that as a pre-built panel over the individual cost of the parts, but if you got it.................

 

[CARS]

I have my supply and return within 10 degrees... and I am still not happy with my systems efficiency.

 

[nate379]

Anyone want to explain supply and return temp and the difference?

Seems to me that the greater the difference the better as that would mean more heat pulled from the water and transferred into the slab?

The thing I don't like with the slab heat is the super slow reaction time. Sure it's nice to have a warm floor, but I'd also like to have warm air right there and then, not a few hours later.

 

[CARS]

Anyone want to explain supply and return temp and the difference?

Seems to me that the greater the difference the better as that would mean more heat pulled from the water and transferred into the slab?

Wouldn't a larger split mean that your slab is inefficient? I was actually proud to have a tight differential... maybe I am wrong??

The thing I don't like with the slab heat is the super slow reaction time. Sure it's nice to have a warm floor, but I'd also like to have warm air right there and then, not a few hours later.

It actually recovers pretty fast if you open the door, drive in, and shut the door. My problem is that I **** the air out of the shop by running my paint booth. I have installed a water to air exchanger (hanging hydronic heater) to help "catch up".

 

[BBQ&Love]

I have seen many people disappointed in their radiant floor heating systems. Every single time it was horrible design. Little or no insulation under the slab, poor layout, bad boiler room piping, or whatever.

Properly designed and installed, it is awesome! I did my own heat losses and designs. But I invested a ton of money, time, blood, sweat, and tears to learn what I was doing.

Radiant heating is the best way to heat but it's not always the best way to meet a particular heating need. Still, if radiant flooring isn't the best solution for your application, find another radiant heating method if possible.

 

[keweenawbee]

There are so many factors, type of boiler, piping configuration, pump speed, etc. Unless you have a gas fired, modulating, condensing boiler, I would say your ideal outgoing and returning temperatures would be a result of trial and error with your setup, observing your comfort and your heating bill. With a modcon you want 30° difference so you have condensation and heat recovery instead of heat loss up and out the flue.

 

[CARS]

Some good reading here: http://www.inspectapedia.com/heat/Radiant-Slab-Heat-Mistakes.htm

 

[keweenawbee]

A common tool used in the industry is the Wirsbo tubing stapler, designed to staple radiant tubing directly to the foam-board insulation at the bottom of the future poured slab. I saw Tommy and crew from TOH on tv actually use a rebar clip tool to attach tubing to the top of rebar. The tool was designed to attach plastic clips between rebar on top of rebar perpendicularly but worked elegantly for the radiant tubing. This resulted in a better controlled float of the tubing as the above article recommends.

 

[CARS]

My tubes are stapled to the foam insulation.... 6" down. I agree with that link I posted. Having the pex in the middle of the slab makes complete sense. Unfortunately my installer "has done all his installations that way".

With the tubes buried that deep the concrete guys were able to make the relief cuts and I have been able to anchor the paint booth and a few other items down without worrying about hitting a tube.

 

[rlme36]

That looks like a pre-built Hydro-Smart panel. Do you utilize that blocking valve in the purge tee very often, either for purging air or changing it to a series flow through the boiler? I plan on using a couple of those in the 1 1/4" throat size. You are getting a 25° drop using it valve-open as a primary secondary configuration? That would mean that the flow & mix in the purge tee is working very well. I wanted to go up a size over my primary boiler piping to make sure that the internals present no interference. If I remember right from the Menards display yours is 3/4" from the boiler and a 1" out to the loops right? I know you pay a premium for that as a pre-built panel over the individual cost of the parts, but if you got it.................

Yes it is a hydro smart system. The purge t was really helpful in filling the system and getting the majority of air out of the entire system. Yes I have the valve up to be a primary secondary type system. Yes I believe the out and in are 1" I used a threaded 1" connection to drop it down to 3/4 that has a very short run to a Wirsbo 4 loop distribution. Pretty happy with all the parts I have to say.

I did the math on the panel and getting the components it was very small difference all things considered, I want to say less than $200. I think I was at ~$1600ish for the panel with the boiler. 2 pumps, Boiler, expansion tank, it adds up quick and they use really nice sharkbite connections, so thats added expense on their side. I would have sweat the joints if I replicated. I don't have a Menards, but I did learn their price was higher than I could get from Dave at Hydrosmart by a decent margin.

 

[keweenawbee]

I have seen some very high prices on other sites but if you bought direct you probably did OK. Have you ever tried running it with the valve closed? Only problem there is both pumps would have to run. I am doing a bypass of one of the pumps so I can try it both ways.

 

[autosite]

Back in Sweden I had a nice garage with radiant heat. I ran the system from a heat pump and kept the temperature down to about 45 F. That is good enough for working there. But forget about the floor being warm and cozy to lie down on.
For people who only spend a couple of hours a day in the garage it is probably much better to heat the garage with something that blows hot air for the hours they work there, and keep the place from freezing with electric baseboards.
To have invested in radiant heat and then not using is REALLY expensive, as you will always carry the cost of the investment with no benefit to it.
The one great thing with radiant heat is that if you open the garage doors and let heat out, the garage is warm again almost instantly as you close the doors, as that concrete slab is very good storage for heat.
Oh - one more thing: If you have high a high ceiling to accomodate a lift, it is really nice to have the heat coming from under your feet. You can keep the temperature down and still be comfortable, as the heat doesn't disappear up to the ceiling the same way as with baseboards or air heating.
But you do have to be very careful to insulate under the concrete.

 

[Addrock]

I just received my second natural gas bill on my newly installed in-floor radiant floor in the Garage. The gas supplies the home (forced air) and the garage in floor. The two last bills were $160 or less. I think its a complete success, as well as well as proof of a well designed and implemented system.

 

[nate379]

Interesting because that is my primary complaint about floor heat. When the door is open for more than just a min or two it takes a LONG time for the garage to get warmed back up.

I don't even use the floor heat in my house, much cheaper to heat with wood. I have used about $400 of wood to hold the house at ~75* where with running the floor heat last year, keeping the house at 68* I spent close to $800 in the same time period. Outdoor temps between last year and this have been about the same.

The one great thing with radiant heat is that if you open the garage doors and let heat out, the garage is warm again almost instantly as you close the doors, as that concrete slab is very good storage for heat.

My system is setup correctly as far as I know. 2" foam under the slab, 2" foam on edges and also laid 3ft wide sheets laid flat on the perimeter "frost block". 6" slab, pex is spaced about every 12". 4 zones, one for living room/kitchen/front bath, 1 for 2 bedrooms, hallway and laundry, 1 for master bed and bath and 1 for garage.

 

[keweenawbee]

Nate379, how long is the $400/$800 period above that you speak of, and what type of boiler or water heater do you have? Also what is the total square footage of the area that you are heating? Sorry if you have already revealed all this in previous posts. I have the exact slab setup so I am very curious.

 

[nate379]

From Sept to today. $400 is what I have burned in wood vs $800 in natural gas that I paid last year for same time period.

Boiler is a Burnham direct vent, 90k BTU I believe.

Size... House is ~1400 and garage is ~625.

When it gets cold, like -20* my boiler will run darn near non stove, where the wood stove is cruising along on low without any trouble. The back rooms do get a bit colder then though. Like right now it's -8*, living room where the stove is is 68* right now (I just got home... this is from the wood I put in there about 12hrs ago) and back rooms are 63*

 

[keweenawbee]

Yeah my neighbor uses his propane boiler for his in-floor until it really starts to get cold outside, then he shunts in his wood boiler for the duration. Great setup, both boilers are in his all cinder-block garage with a short distance of underground insulated pex running to his house. BTW I think you can use some combination of keys with the 8 key to get the degree symbol. I am on a Mac and use the shift-alt and 8 keys to get the ° symbol. Haven't tried it with a PC yet though.

 

[Possum]

Hold Alt and punch 248 on the number pad for a degree symbol on a PC.

 

[nate379]

Yeah like I will remember that. I can hardly remember how to log on my damn emails.

 

[overdriv]

Yeah like I will remember that. I can hardly remember how to log on my damn emails.

Now that's funny......oops, I can relate to that

 

[groundloopdog]

anybody have trouble with the floor heat maintaining an even temperature ? ours at work swings 12 degrees if it 68 in the morning it will be 80 by quiting time. Any ideas where to start?

 

[CARS]

anybody have trouble with the floor heat maintaining an even temperature ? ours at work swings 12 degrees if it 68 in the morning it will be 80 by quiting time. Any ideas where to start?

Not that big of a temp swing. I would say during the day the shop temp goes up 4 or 5 degrees. Could be the lights? A sunny day?? Or I have always wondered if activity stiring up the air on the floor gets moved around and effects the air temp???

12 degrees would be a real issue. It must not call for heat for 16 hrs a day and allow the slab to cool down, then run for a steady 8 hour to catch back up. (those are just numbers thrown out for example) In MN, it's not uncommon to have a 40 degree outdoor temp difference from one sunny afternoon to a blizzard. On the sunny day the floor wont call for heat all day and allows it to cool down, then when the temp drops overnight that boiler runs for hours getting caught back up.

I should look into fancier controls but dang they are expensive and would require a complete re work I imagine

 

[Flathead Youngin']

man, this thread is making me seriously reconsider my plans for my basement slab and 1/2 my concrete in the 40x80 pole barn.....

 

[z28toz06]

I wouldn't pay attention to it. If the system was spec'd out correctly and the tubing runs etc were correct, there's no reason that system shouldnt be cheaper than any other system, save maybe a full blown solar system, which would cost aLOT more than the hydronic system. Runs can be too long, no insulation and or vapor barrier placed underneath, no insulation around the slab sides etc., are all issues that will make the system run non stop, causing fuel cost spikes. He nees to call hwomever spec'd the system out and deal with it, or keep using the stinky A$$ torpedos and live with it, which it sound slike what he's doing..

 

[sneezer41]

groundloop:

Several things or a combination are probably going on

Is someone turning the heat off at night? Not the prime way to run radiant

If one had the heat off at night, and then turned the water temp way up to speed the recovery time, I would anticipate a huge overshoot.

What is going on in there? Running a machine shop with lots of added heat would make it even worse

************

If you run a properly designed radiant system with a boiler the same efficiency as any other type, with a similar heating curve, it will cost the same to run. Anyone saying otherwise just doesn't understand the problem.

They work best in a well insulated building, as they cannot easily change temperature compared to firing a giant hot air furnace up.

 

[z28toz06]

Some say why heat the air? I say why heat the ground? Even with insulation the potential losses can be pretty great. Insulation in the slab is critical.
I guess to answer the question about cost. If he spend 60k on the shop, and it is costing him $600/month to heat it.....I guess I couldn't do that. There is a limit to everything.

heating the ground is what is so awesome about radiant hydronic heat. When you heat up that huge mass of concrete, you are storing energy that will stay warm for several days, when the heat is turned off. you want to design the system so the floor doesn't get above 85 degrees.

the other great thing about radiant heat is if designed adequately, it doesn't cause convection, which stops the warm air from rising. If the system is done right the temperature at the ceiling should be no more than 3 or 4 degrees warmer, and using a ceiling fan actually hurts more than helps.

 

[z28toz06]

another thing to do is make sure you have an ambient temperature control. this samples the outside air and makes the heat system react accordingly, saving fuel and preventing it from getting too warm inside. another fuel saver.

http://www.tekmarcontrols.com/prod/363.shtml

 

[swamp_donkey]

+100
This is one of the best posts I have read lately. I have tried to convince "wood heat nuts" for years that their heat is not free!!! It is an impossible task.

My first post here so i don't want to step on too many toes BUT: How can one person say whats right for them is right for every one. I understand that the guy from ND doesn't have the access to wood but has direct access to cheap natural gas. But what about the guy like me in the U.P. that can buy a loggers semi load of hardwood for around $650 delivered. Takes about 10 hours of "my time" (free) and maybe 5 gallons of gas and oil to cut and have ready for the wood boiler. And I can heat my 30 x 40 shop and home on about a semi load and a half every winter. I implore anyone on here to argue that their LP or natural gas bill for a comparable shop plus a 2400 sq ft home is only $1000 for a winter (November to at least April). Please, please, please tell me how cuz' I will switch immediately to whatever you are using and remove the "wood heat nut" bumper sticker from my bumper. For the record, no it's not free but it is simply much cheaper if done correctly.

Sorry for the rant on my first post, but it had to be said.

 

[jvitez]

Welcome Swamp Donkey. Your post demonstrates 2 things:

1. wood heating enthusiasts are passionate about their choice. Your bumper sticker serves you well.

2. Every post about heating must be taken with a grain of salt for exactly the reason you state. The devil is in the details. Local costs vary substantially across the nation(s). The "which is cheaper" thread can only be answered by the person himself knowing his own costs. And the right answer for which way to heat, has much personal opinion attached. Do you like or hate radiant heat warming your noggin from a ceiling mounted heater? Does fan noise make you crazy with a unit heater? Does melting snow give you the screaming meemies from a heated slab? There is no "one" right answer.

Personally, I'd love to have a well designed radiant floor heat system for the garage. But I need intermittent heat, so no go.

Anyway, welcome again. Post some information about your garage. Some pics of your wood heating system would be interesting.

 

[keweenawbee]

Ditto on that, me in U.P. too and would love to see your setup.

 

[3x9RT/SE]

Let me chime in here,I did radiant floor heat in my new garage,will have to find that "disappointment"thread to read.I love mine and is very,very efficient!
This is how I did mine,the larger the mass of concrete,the longer it will hold the heat,hence staying off and not calling for long periods of time.I setup my floor to be 6" thick,laid down 1/4" bubble wrap insulation right on the finished ground/grade(also served as the vapor barrier),4'x8' sheets of 10 ga. 6"x6" wire screen,TIED the 1/2" pex tubing every 2' and ran them on 1' centers,with no loop being longer than 250'(I have 5 loops),mounted a elect box during the pour to be finished at surface of concrete with the conduit running back to where my pump station is.This was for the radiant floor temp bulb sensor.Packed it with sand and set the bulb half way in the box and covered with more sand packing tightly.My walls are R19,garage doors are R16,no windows,and R38 in the ceiling.I send 80-85 degree water thru it,and have my slab set on 64 degrees.It calls roughly every 2-3 hours,and when does,it only runs for about 5-6 minutes,thats it!!!And off for another 2-3 hours,I can't tell you how happy I am with this system!!!!!
My boiler is a NG high eff that modulates from 26k BTU's up to 155 BTU's via return water temp,and outdoor reset monitoring whats going on outside,and will also automatically turn down the target water temp as to what the demand is.

And as for uniform temp,shoot the infrared thermometer on just about anything in the garage,its all pretty much 64 degrees!!!!

 

[Jackfre]

anybody have trouble with the floor heat maintaining an even temperature ? ours at work swings 12 degrees if it 68 in the morning it will be 80 by quiting time. Any ideas where to start?

As Z28 points out an "outdoor reset" control, and Tekmar is a major in that field, in conjunction with a slab sensor will...well it should, flatten out your temp swings. Without these controls you can have some giant swings due to the mass of the slab. What are you using to heat the slab and what controls do you have on the unit. It is not uncommon for reset controlled equipment to operate incorrectly due to improper set-up, so even if you have outdoor reset control equipped equipment I'd check its program.