advise about water heated floor for shop

[mweiman]

I am looking to put up a shop in the near future and am thinking of heating the floor. I have not been around that type of heat much and am looking for advise. I have a large outdoor wood furnace now for my house that I plan to hook onto. Shop will be about 60' by 80' pole barn from concrete pier system. I may add another boiler of some kind to supplement the wood furnace depending on how much wood it takes. I know the cost will be higher than other options but I am thinking the benefits will be worth it. Also with natural gas vehicles becoming more popular a flame free source of heat will be important.

Thanks for any input.

Matt

 

[Wayne M.]

Interesting topic. What's your climate? You don't list a location. Good luck and success.

 

[BIGNASTY]

Radiant heat flooring is what your talking about, We were thinking about it when we built our house in Montana. Its a nice even heat meaning that the room/house/ what ever you have it in will be warm top to bottom. We were thinking about it in just the bathrooms with tile floors and it could also be used in a towel warming rack if plumbed that way. The Problem ( to us anyway) was the amount of BTU's to make it worthwhile its not just a turn on and it gets warm in 3 min. type thing it pretty much has to be on all the time. It can be thermostacitly controlled but still must have a heat supply ALL THE TIME. You said that you run a wood fired boiler if your in a cold clime then this would be a nice addition but if your just going to fire up the boiler to heat the shop floor I WOULDNT THINK OF IT AS AN OPTION. There are also electric radiant heaters I HAVE NO IDEA about them they were out of the question for us because we are off grid and have to produce our own elect. Good luck its an interesting idea.



BIG

 

[p-Bar]

I'm working in a very large house in Rancho Sante Fe , North San Diego and he did the radiant heat route it is unbelievable how well it works 25' tall ceilings and you were warm . The engineers were there today as i had a long discussion with them they said the cheap part is the under the slab stuff so install that and you can wait on the rest. Not sure where you are at but in the colder parts of the country you will need to increase the thickness of the insulation under the concrete then it turns into one big heat sink. I will be back down there next week I will take a pic of the mechanical room.

 

[BIGNASTY]

Another option that was looked at, I had to find the info website but this was another option we found it a very costly one and a major project to install (FOR US ANYWAY)

http://www.consumerenergycenter.org/home/heating_cooling/geothermal.html

 

[ALSAN]

Well here is are some guide lines for the area I live Northern Wisconsin/2 hrs east of Saint Paul , with a post frame building you will need to ring the out side edge with 2 inch high density foam 2 feet deep puting it on edge-then approx 2 ft down on the out side you need to go out 4 ft at a sight pitch away from the building with 2 inch foam this keeps the frost from getting under the slab- now back to the inside, 4 feet in all the way around the inside of the building 2 inch foam then the rest of the area 1. 5 inch foam

When you lay out the tubing you will want to seperate the two ends (infeed and outfeed) what I do is attach a 2x6 to the wall and staple the ends to it and cover the ends with tape or if you can install the manifolds and cap the unit off with a presure gauge and air fill valve in the line and add some air pressure this will also alert you to any holes from damaged lines while pouring

I then figure out where I want the manifold and pump then lay out my loop of tubing one foot on centers with the max lenght of 250 feet ( I use a wersbo barrier pex tubing that I staple to the foam) also in a work shop I will over the foam/tubing I set it up for a layer of sand maybe 5 inchs thick with the crete on top of that . That way if you want to drill into the floor to anchor equipment down, less fear and worrys about putting a hole in the tubing

I have done this type of system for a friends shop 40 x 48 w /12 ft walls and his heat source was an outside wood stove that pumped hot water in to the house and his shop the only problem that he called me about in late January is while working on his trurk and laying on the floor he almost fell asleep

Your manifold set up will also have mixing valves, circulating pump, and it would be wise to install a thermostat wire/sensor in the crete while pouring

 

[mweiman]

Alsan,
That is similiar to how I have heard to set things up. Laying the foam on the outside also seems like a good idea. Also you are saying you put your lines below the sand, so about 10 or 11 inches below the surface? My wood furnace regulates water temp between 175-185 degrees which is higher than I have heard recomended to run through concrete so not sure if that will have to be regulated down somehow. Maybe not if the lines are laying in sand. Are you using a thermostat reading from the concrete to control shop temperature then?
I am located in west central IL so we have a winter but definately not as cold as some of you. I plan to just keep the temp around 45 or so in the building for now as I won't be working in it all day but might be in the future.
Matt

 

[HBarlow]

An in floor heating system in your building sounds like a system to dream for to me. It will be a wonderful way to heat your building if you can afford it.

My steel barn is insulated and on a thick concrete pad. It stays about 15° to 20° warmer than ambient temp in the coldest, windy winter weather. I don't heat it but our temps on the south plains of Texas are much warmer than in IL or other northern states. I don't even drain the water lines or water heater in my fiver which is stored inside.

 

[AClayton]

!80-190* is the what your boiler or WH is set at... . the water temperature going through your in floor tubing is around 140*. The boiler or WH you use needs to be set much higher to prevent condensation build up inside the heat exchanger. The 140* is achieved easily through mixing valves that simply mix supply and return piping with an adjustable setting to the outlet temperature..... which in turn is circulated through your system.

It is a lot slower to heat this way but it is so much better because the heat is where we are at working..... on the floor. Heat rises naturally so it fills the room with quiet radiant heat. What I have done with jobs in the past is to install a hydronic to air heater and operate it through a 2nd zone to heat up the space more quickly when you have a short job to complete. However, it has been proven that it is wiser to just set the garage temp very low to maintain the space..... IF, it is used daily. Regardless, you have to maintain a certain boiler or WH setting to prevent freezing of the appliance and its attributing zones. Maintaining 35* or even 40* is hardly a big deal as HB pointed out - provided your bldg is insulated. Let's face it: if you have the funding to install this type of heating system, you will have no issue with building a high quality structure for which to work in, that is insulated!

Radiant floor heat is the best and you get what you pay for. As an added bonus, publications and DIY TV programs have helped to get this type of system the recognition it has always deserved..... in turn, the manufacturing of different hydronic systems are mass produced. And made easier to install with detailed instructions on how to design, set-up and install yourself. Prep work before slab is key... ... the few posts above had it right and I won't bother repeating it, however, I need to stress the importance of the perimeter 2" foam blocking in the slab - very important! Also, when designing your loop in the slab, allow extra a few extra rounds on the outside walls and even the roll-up door... . especially the roll-up door! You will thank me later!

 

[mweiman]

We have a heatpump on our house that we use just for a few cool nights early and late in the winter but once I light the wood furnace it burns all winter so the hot water is always there. I am worried about keeping up feeding wood to heat the house and shop. We have had a fairly cold winter so far and I have not gone through that much wood on the house only. We remodeled the upstairs a couple years ago(old farmhouse) it was previously not heated and we didn't use the upstairs, it was sealed off. Added an additional coil to heat the upstairs and spray foam insulation and it seems that I am using a lot less wood. I am hoping with proper insulation in the shop and eventually foam on the lower level of the house heating with wood will be manageable. Not sure if I can afford to foam the whole shop but I think I will at least foam certain areas like around windows.
I think the radiant heat will be especially nice not being in the shop all day being able to keep the temp lower and be able to walk in and go to work comfortably.

 

[RobertHiltz]

I have a heating system like you are asking about. You will like it. Do some research on the various methods for below slab designs. Some use a deep layer of sand (several feet) without the insulation board in the center area of the slab, most systems are like described in the above post, my system is pex stapled to the foam board and 7. 5 inch concrete poured on it without a extra layer of sand. My outside wood boiler water tank is 150 gallon with hot outlets near the top of the tank and returns near the bottom, so I used a bottom outlet for the hot supply line to the garage. I run the stove water through a low output water to water heat exchanger to have cooler water in my slab system than my baseboard hot water system in my house. You can use mixing vaves to control your maximum temp slab heat water too. I felt it was better to control water max temp before the slab system. I do not see water temps above 160 degrees in my slab system. My house is 30 x 60 with a full walkout basement and the garage/woodshop is 32 x 44 with 12 foot walls. The boiler has heated my house for 40 years now, I built the garage 8 years ago. I used to fill the stove once a day, after adding the garage I have to wood it up twice or more per day. If you would like more info on my setup email me -- email address removed --.

 

[ALSAN]

One thing about radiant in floor heating is that EVERYTHING in the building if it has been in there for awhile will be close to the same temp as the floor
also if you live in Il there must be a Menards store close ,go in and look at the set ups on display this will explane alot of what is stated in the posts and if you have not worked with it a picture is worth a lot of words

I too have a outside (Taylor) wood furnace that heats my house thur a heat exchanger in the furnace . The stove is 185 feet from the house and 200 feet to the furnace I lose about 3 degrees water temp. My line is about 5 feet deep and insulated with reflective foil bubble wrap then installed in 4 inch pvc (this so the water can not get in then I put a 1. 5 inch foam box around this ( this is the way I did it the 2nd time, one of lifes lessons )

I have a friend that works on snowmobiles and his shop has infloor heat I think he sets the temp to 60 other wise it is to warm to work, he will bring in the units at night before he closes shop and the next morning they are thawed and dry, but one thing of note is the contractor ( not me ) that built the building set the building on frost walls and did not install any foam as a thermal break between the slab and wall so in the winter the grass outside is green heat loss you think?

I will be building a 36 x 48 shop this year and and will be doing the infloor heat using the set up as I outlined above with the exception mine will be built on frost walls using insulated concrete forms (ICFs) so I will not need the 4 ft of foam outside , Pm me and I will give you my phone number if there is any thing that I can help with Alan

 

[mwilson]

The largest downside to in floor radiant heat is the recovery time. What many up here do now is add some basboard units in a home or in the case of a shop some wall mounted registers with a fan. Put the extra baseboard or wall units on a separate zone with their own thermostat. Then if a short burst of recovery heat is needed turn that zone up for a short while, then turn them back down and let the radiant take over.

When you have kids swinging the doors open all day or repeated opening of large overhead doors the radiant simply takes forever to recover. Great if you have all night for the vehicle to absorb the heat but chilly if it occurs during the day.



Take this as sound advice if you are in a climate where winter temps average between 10 degrees and -20 below at night.



-8 below here last night with no wind for example.



JMHO.



Mike.

 

[fox]

4 years ago I had a local builder put up a 26 x 50 garage. 10 foot walls with in floor heat.
I love it. It is slow to change temps of course but i just keep it 55-60.
I use a 50 gallon water heater to run water thru it. Even last year when wee had a week of single digits and one element was bad, it maintained 55 or better.
I'd do it again, but it would be bigger!
Many heat and air guys said it was a joke and would not, could not work. I've had them here to see it and they are amazed.

 

[JJPage]

Make sure you use a water to water heat exchanger(brass), then the floor side water/glycol mix can be pressurized to about 12# and valved off(closed loop). Install a permanent gauge to monitor pressure, you will know if you acquire a leak. I have seen electric and gas water heaters used as a boiler source, work fine but are against most building codes.

 

[DGamelin]

I have heated floors and wouldn't even considered anything else. I'm in upper Michigan, about 2 miles from Lake Superior. The shop is 40'x50' with 16' cellings and 14' doors. I built this shop 11 years ago. My kids and I built everything but the pouring of the concrete, I wanted poured walls. I put a foot of sand down, then for an insulator you want at least a r10 rating under the floor. The shop is 6" thick and the office and store is 4". I used wire concrete reinforcement that had 6" squares. I ran my lines 12" apart, the reinforcement gave me something to zip tie to. Tried to pull it half way up in the concrete as they poured. During my research on it I found out on the east coast it was mandatory for less heat loss and to meet their codes. They actually had little stands to keep it there while you pour but I didn't learn about this until just before pouring. I really believe that suspending it in the center of the concrete helps for less heat loss. I have a Central 5648 wood stove, 385 gallons, the small shop size. My boiler runs 175-185 degrees. I have my mixing vavle set so that the lines in the floor are at 110. If the lines in the floor get to hot, they say it will make cracks in the floor following the line. It runs to the house then back to the shop. The house has baseboard registers with a gas boiler. I installed a heat exchanger, putting the house on a closed loop. The shop and office have their own heat exchangers also. The shop, office, and sidewalk have antifreeze in the system. When I built the valve banks I put valves on every line so I could shut off the sidewalk when not need or shut off a leaking line. The boiler in the house can be used as a backup to keep the lines to the stove from freezing. I'd like antifreeze in the loop the furnace makes, but 400 gallons is a little much to buy. The system came out really nice, I don't think I would do anything different and I'm sure I'm saving a lot of money in heating bills considering the house is so old you can't light a candle in it. The stove burns at least 7 months out of the year and runs hot water heaters. I have only replaced one pump since it was put in. We burn about 21 long cords a year. I will put some pictures on of the floor and the valve banks I built over the next couple of days. The two blank spots in the floor are for a lift. The office had not been added to the building yet. Good luck with your project. Do lots of research.











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[JJPage]

Nice looking job!

 

[HBarlow]

I'd love to have one like it.

 

[DGamelin]

Thanks, heres a couple of pictures of the valve banks I built. The first one is under the parts counter, the other is in the shop there is supposed to be under a stair staircase by now leading to the new addition but you know how that go's. I have some of my crew if I can find them.

 

[HBarlow]

That's a very professional looking installation. You did a great job.