Hot water heating systems

[odee]

Guys fixing to start working on the heating system for my new shop. I have given some thought to a heated concrete floor. When you do the hot water set-up would it be best to insulate with a foam,then the water system covered by the concrete? How does the foam stand up the the weight on it? How thick on the foam and concrete? I was thinking about a 2" foam and 4" of concrete? Anybody know of any plans on the net about building a outside wood fired boiler?

[The Adam Blaster]

There is a product that i used called "insultarp" that we laid down on top of the gravel, then the piping went down on top of that. It's easy to lay down, cuts easy, and you can wrap it up the sides of the rat wall to insulate it from the foundation wall. The foundation wall being made of cement can pull a lot of heat out of your floor. Think for 2 rolls of the stuff that was a little more than enough to cover the space of my 20x24 garage, was around 5-600 bucks.
The bubble-wrap stuff with the foil on it is useless, it totally compresses under the weight of the cement and might as well be a thin sheet of plastic.

The styrofoam stuff is supposeldy "ok" to take the weight, but for me it seemed kind of pricey. Especially since you are looking at the thicker stuff, price goes up with the thickness. I don't remember exactly how much the foam would have been to cover the gravel in my space, but i do remember it being a lot more expensive than the insultarp.

I'm using a boiler system that is gas-powered, and the installer said that with a well insulated building (2x6 walls) and properly set up floor, that it can be around 95% efficient. Sounded pretty good to me.
As well, with this boiler, it can provide up to 5 gallons/minute of hot potable water, so since i have a 2nd storey, and will eventually have an apartment up there, having a shower, washing dishes etc. will be no problem. As well, i will have a 2nd "zone" setup so that the floor upstairs is also heated, but i can adjust the temps. of the 1st floor, and 2nd floors indepently.

With a wood powered boiler, i can't imagine how well the heat would be regulated, no idea myself on that issue.

[The Adam Blaster]

Oh ya, with the price of everything above, i would not recommend doing this type of in-floor heating unless you are sure that you will own this property for at least 15 years.
All the piping that i used has 25 year guarantee, and was NOT cheap.

[TLCObsession]

What Boiler did you use?

[jeeplord]

I'm not sure about where you guys live, but here in the Northwoods we don't use water in the system, becasue if your boiler ever stops and the lines do freeze, you're hosed (pardon the pun). There are several non-freezing liquids designed for this purpose. Do a little research before you fill your lines.

[odee]

I can put my hands on some 1 or 2 inch foam pretty easy thru a friend at his work. I can also put my hands on a oil fired boiler set also. I was just giving the the wood fired thing because I have easy access to a good supply of firewood.

[pmurf1]

Why not just throw a gas fired furnace or Sterling style unit heater in the space? It seems to me it would take a lot of time to make up any energy benefits/ payback by doing a radiant setup over a simple gas forced air heater in the space. You can usually find used furnaces for less than $100, we throw them away all the time here in AZ when we do changeouts. Hell a new 80% is less than $400 new. A simple filter stand and a piece of supply ductwork is all you'd need. Hook up the gas and run a t-stat, plug it in and you've got heat. The cost of all that piping, zone valves, pumps, boiler, etc. will buy a lot of gas, kind of Adam Blasters arguement about payback. It's like the diesel vs. gas tow rig arguement.

[odee]

Well I guess I will be here for a long time. I have alot of the parts already for this type of set up that I have picked up over time from a couple of different jobs that I have been on when they had extra and new parts had gotten chucked in the scrap bins. I would like to get some first hand info from someone that has done the slab heat with the foam under the concrete.

[The Adam Blaster]

I actually don't have my boiler installed yet, so i can't say what brand it is.
I've got a nice place on the wall where i want it though. :D

Just trying to get ahold of the guy that's going to install it within the next week or so.... :rolleyes:

There is an additive that you can add to the water in the pipes, and it prevents the water from freezing. I think you can put this stuff in after everything else is done, and i'm also pretty sure that you can flush the system out as well to add new water, and the additive.

[jasonmt]

Why not just throw a gas fired furnace or Sterling style unit heater in the space? It seems to me it would take a lot of time to make up any energy benefits/ payback by doing a radiant setup over a simple gas forced air heater in the space. You can usually find used furnaces for less than $100, we throw them away all the time here in AZ when we do changeouts. Hell a new 80% is less than $400 new. A simple filter stand and a piece of supply ductwork is all you'd need. Hook up the gas and run a t-stat, plug it in and you've got heat. The cost of all that piping, zone valves, pumps, boiler, etc. will buy a lot of gas, kind of Adam Blasters arguement about payback. It's like the diesel vs. gas tow rig arguement.

Adam ends up with a 95% efficient system with a warm slab and evenly distributed heat which is something that an 80% furnace and a chunk of ductwork won’t do.

What is the average high/low in Phoenix in January - around 66/41? Where I am it is 16/-4 so if it costs an extra $500-$1000 to install slab heat so be it, a warm slab to work on it is well worth the money and the payback period is under 5 years compared to a 80% furnace.

[pmurf1]

Adam ends up with a 95% efficient system with a warm slab and evenly distributed heat which is something that an 80% furnace and a chunk of ductwork won’t do.

What is the average high/low in Phoenix in January - around 66/41? Where I am it is 16/-4 so if it costs an extra $500-$1000 to install slab heat so be it, a warm slab to work on it is well worth the money and the payback period is under 5 years compared to a 80% furnace.


How do you figure it will only cost $500-1000 more to install slab heat? Even if you did the work yourself, the piping, fittings and supports, insulation, pump, zone valves, manifolds, and source of heat are going to end up way more than that. And I hate to tell you that most affordable boilers/water heaters that guys use aren't exactly energy efficient. There is no way you're going to pay back this system over a cheap set-up period. If you're concerned about gas efficiency, get a 90 plus furnace with dual heat exchangers and you're still money ahead with the extra stuff you have to do to install it. You've been talking to too many salesmen to think you're going to heat any sort of shop efficiently and reasonably. Comfort costs money, period. It's like these salesmen they have at the Home Depot's out here that have a pretty 17-19 SEER Trane a/c set up that dupe people into installing. There is no way you can pay back a system like that, and if you did, it would then be obsolete.
I just threw away a 10 year old Trane 80% the other day, would have gladly given it away to anyone who wanted it for a shop, but like you said it's not really needed here in AZ. Build a simple angle iron stand for it in, slap in a filter, pick up a 18x18x24" box for the supply duct and cut in two registers. Install a $30 digital stat on the side of the unit, hook up the gas and 115 volts, run a flue outside and you've got heat for less than $150. If you're space challenged, hang it from the ceiling in a corner and do basicly the same thing. Hell change the orifice and run propane to it if it's cheaper than natural gas. You can buy a hell of a lot of gas for a simple setup like this compared to the slab setup. Simple maintenance and cheaper to repair if something goes wrong. Priced a tube bundle for a boiler lately? How about an underground water leak?

[pmurf1]

Adam, ask you installer to give you the energy info card on your new boiler. I'd be interested to see what the efficiency rating on it is. That must be one hell of a boiler if it'll do potable and a sealed source of hot water in one unit. What was the price on it?

[jasonmt]

In Adams case we are talking about a 20x24' garage so I have no problem with $500-$1000 more than a comparable forced air system, IE compare a NEW furnace to a NEW boiler. In our climate a slab above the frost line should be insulated whether or not the heat is forced or not. So $300 for 600' of 1/2" Alu-Pex, $300 for your PRV, BFPD, air vent, expansion tank and associated fittings. Circ pump and valve - $200. Boiler is going to be $650 (80% efficient) up depending on what you want for efficiency. So $1450 versus your $400 for a new 80% furnace. Add in the costs of the ductwork and venting and the price difference is not great.

Payback period is going to be entirely different when your gas bill is $200 a month versus $30, big difference in fuel usage between different climates.

As far as things breaking - The system I installed in my old house is 14 years old now and has never had a problem beyond replacing a pump and a few zone valves. My sisters system was 10 years old when she sold it again with only replacing a few zone valves. In both cases the costs were similar to a forced air system due to the fact that we had no problem installing everything ourselves versus needing a tin basher for a forced air system.

Once again having worked in shops with both forced air and slab heat I would not hesitate to spend the money on slab heat not to mention things like resale value. As well I imagine that slab heat is much more common where Adam and I are versus you.

[KS Toy]

I don't know if it will answer all of your questions or not but here is a link with tons of info.

http://www.pirate4x4.com/forum/showthread.php?s=&threadid=131906

[The Adam Blaster]

To tell you the truth, i never went and calculated how long this system would pay for itself vs. a standard forced air unit.

Specically for me, it has a lot of benefits that i am willing to pay for up front, and then not have to worry about a $200+ gas bill in January.

I like the idea that the slab retains the heat longer than just the air in the shop. When you open that big door (mine is 9x16) all that hot air just gets sucked out, and you'll have to wait a little while to get that air heated again.
With the infloor, you just close the door, and your cement is still nice and warm. ;)

With only a 20'x24' shop, my space is kind of limited as is, and i have a stairwell going upstairs, so i lose even more floor space. AND i wanted a small washroom IN the shop so i wouldn't have to trek grease and crud through the nicer upstairs. So, even less space.

Now, with the infloor system, all i need for my entire heating of both floors, and all the hot water i could ever use, is a small boiler that is like 18"x24"x6" that will hang on the wall in the bathroom downstairs.
Now, if i used a standard furnace, i would also have to use a hot water tank, and both would take up valuable space. As well, that combination isn't nearly as effiecient as the one i will have.

The other option that you can try with infloor heating is to use a standard hot water tank. Problem is that the water that flows through the pipes is no longer safe to drink due to the chemicals that are added to prevent freezing. So, in my case, i'd have to get a 2nd water tank for all my potable water.
Again, i run into the space issue.
And the water tanks that are available today are like 80% efficient, so i'd be spending more month to month in gas bills.

I think i mentioned this earlier, my lines in the cement as well as the boiler have a 25 year guarantee. So, if i get a line failure, the manufacturer has to come and replace the lines as well as the repairs to the slab.
And you guys probably know/agree that when a company puts a guarantee on a product, it should last quite a bit longer than that guarantee, like a built in safety margin for the company.

As well, in the thread that KS_Toy linked, the guys are talking about puncturing the lines within the slab...
For me, i doubt this will ever be a problem because my lines sit at the base of the slab, and it is anywhere between 6" and 7" thick depending on what area of the shop you are standing in. (Slopes a little towards the big door)
So, you'd basically have to drill down 6" before hitting one of the lines.

I don't plan on drilling down and using those cement bolts to secure anything to my floor. You can use Tapcons for the same purpose, and not have to go more than 3" into the floor, leaving me quite safe from puncturing my lines.

Ok, now let's talk up front costs...

The lines themselves are priced decently, i think it was less than $900 for me (both floors), and we have high taxes in Ontario unlike those Alberta bastards!! :flipoff2:
The lines are spaced either 8 or 16 inches apart, i can't remember now...

Anyway, so, it was $600 for the insultarp underneath, then another $900 for the lines, and the manifolds and all that is an unknown cost to me, but i'd say around $200 for those incidentals.
Big cost for my ultra-powerful-efficient-king-of-the-world boiler:
$2500

So, i'll be around $4200 in supplies.
I'm not really including the cost of the gas or water lines coming into the garage, because they are required no matter what type of heating i would have installed.

Now, installation would have been done by myself and a buddy that is in heating and cooling, and i'd throw him a couple hundred bucks plus some beers.
However, when i first started looking into this in the late winter this year, i found out that all the suppliers here in town will not sell "just anyone" the lines and stuff for the heating system.
You have to take some course and get certified and blah-blah-blah...

So, i got stuck having to go through a professional, and of course paying for his time. And if i remember correctly, his total bid for the job was just under $7000.00.
Now, of course, i've tried to cut back on those costs by just having him buy the supplies and tell me what to do, but that of course only goes so far.

Ok, that's all i feel like typing about that right now....

[86turbodsl]

I have a heated slab in my shop, and let me say a few things.

If you live in Arizona year round, and haven't spent significant time in the north where it gets truly ass-numbing cold 6 months out of the year, you should not be dissing slab heat. Because you have no concept.

My dad ran an old 100K BTU air scorcher furnace in his shop for years
and it didn't matter how long he ran it, it didn't heat up the concrete. And cold concrete sucks the life right out of you and your feet. It severely fatigues you and makes you want to quit wrenching and go sit on the couch.

Any HVAC engineer can tell you that warm feet, and cool head will make you the most comfortable you can be. When you heat air, it rises and you end up with cold feet and warm head. Then you lay on the cold concrete and wrench and your back aches and you get sick.

A nice warm concrete floor makes all the difference between a painful annoying time on your saturday afternoon and a pleasant productive afternoon.

Yes, it costs a lot more, but the payoff can be quicker than you think. In floor radiant heating is the MOST efficient type of heat available. And contrary to what some people here think, boilers are very efficient. Oil boilers like the Weil-McLain Gold series have had 86% efficiency without condensing flue gases for years. The gas boilers from folks like Vitodens are even higher. Recent gas boilers are condensing and quiet.

Slab heat has a lot of advantages, such as immediate heat once you close overhead doors, comfort, long cool down time, and effiicency. You can turn off the heat burner and paint in there, and not get cold. The slab holds the heat. System is very quiet. There's no blower and cold breezes.

Some disadvantages are: Long heat up time, and cost.

This means that if you spend a LOT of time in the shop, like every night and weekends, it's worth it. If you only occasionally work in the shop, consider overhead radiant tubes.

Feel free to check out my radiant heat install:
86turbodsl.homelinux.net/shop.html

Just look at Europe, which has some of the highest heating fuel prices in the world, and they use a LOT of inslab radiant heat over there. Because it's cheapest in the long run.

If you sell your house within 15 years, it's a selling point. I'd pay a premium on a house with a slab heated shop if I was looking.

So GO AHEAD! You won't regret it, I promise.

[The Adam Blaster]

Just got off the phone with the guy that will be installing the boiler for my system, and he said that the slab should take between 4 and 6 hours to heat up in the shop. Again, 6-7 inches thick.
And the upstairs, i am going to run the piping on the sub-floor, then pour a small layer of cement on top of that (1.5" thick) and this will aid in the efficiency of the boiler, and that slab will take considerably less time to heat up since it is so thin.

[jasonmt]

The lines themselves are priced decently, i think it was less than $900 for me (both floors), and we have high taxes in Ontario unlike those Alberta bastards!! :flipoff2:


While we have 300 Billion barrels of oil I have no intnetion of paying a sales tax. :flipoff2:

Don't be so upset, I guessed at $300 US for only one floor :p . So I am guessing that you got 1000' of 1/2" Wirsbo MultiCor? If you bought from your installer the price isn't bad, locally from a wholesaler ~$700 + Tax would be a decent price. I would guess from your price that you are getting something like a Baxi Luna boiler? They are nice all in one units with the circ pump, expansion tank, air vent and relief valve built in.

[The Adam Blaster]

I'll have to wait until he installs it to give you the name of the boiler. ;)

I think that there is a name stamp on the lines though, and i should be able to check that out next time i get over to the garage...

[XtremeJ]

I have a heated slab in my shop, and let me say a few things.

If you live in Arizona year round, and haven't spent significant time in the north where it gets truly ass-numbing cold 6 months out of the year, you should not be dissing slab heat. Because you have no concept.

My dad ran an old 100K BTU air scorcher furnace in his shop for years
and it didn't matter how long he ran it, it didn't heat up the concrete. And cold concrete sucks the life right out of you and your feet. It severely fatigues you and makes you want to quit wrenching and go sit on the couch.

Any HVAC engineer can tell you that warm feet, and cool head will make you the most comfortable you can be. When you heat air, it rises and you end up with cold feet and warm head. Then you lay on the cold concrete and wrench and your back aches and you get sick.

A nice warm concrete floor makes all the difference between a painful annoying time on your saturday afternoon and a pleasant productive afternoon.



Couldn't have said it better myself.

Don't expect the slab to heat up in a matter of hours, it's more like days. From a cold start it will take a long time to get the slab warm, then minor adjustments take a few hours.

Colorado isn't exactly the cold north but it does get below freezing for extended periods. The radiant floor heating in the shop is the best system for a shop by far. forced air sucks big time.

Beware the costs though, like most systems it is much cheaper set at 68* or below, but gets $$$ the hotter you set it.

If your area gets decent sun in the winter, I'd seriously consider attempting to get as much day time solar gain into the slab as well. south facing windows would work well, use darker stained concrete etc.

[PAToyota]

I managed to pick up the tubing and fittings from a job I was working on. Getting the materials was legit -- rush job so they could not wait for custom lengths and bought 1000' rolls and had a lot left over. So putting the tubing in was a no-brainer. Still have not gotten around to hooking up a boiler to it yet.

For the insulation, you want to use an extruded foam insulation -- not an expanded. The extruded (such as DOW Styrofoam SM -- blue board) is impervious to moisture. Definitely something that you want when in ground contact. Expanded will deteriorate and then you'll have the slab settling and cracking.

I did what you are suggesting -- 2" DOW SM with a 4" concrete slab. Have to get around to hooking up a boiler before I could tell you how it works!

[TLCObsession]

I would guess from your price that you are getting something like a Baxi Luna boiler? They are nice all in one units with the circ pump, expansion tank, air vent and relief valve built in.

I am looking at putting the Luna into my house when I remodel next year -

It will allow me to add radiant in the new garage (not my shop), feed the exisitng baseboard (unless I pour 1.5" lightweigh concrete in the xisitng house) and get rid of my 220V HW heater... Would love some feedback on the boiler.

Jim

[pmurf1]

The quicker return of heat when the door is opened and the painting without fear are good points. I used to live in Illinois, so I've experienced cold. Maybe not Canada or UP north for more than a week, but for what we needed, the cheapo used furnace worked great. It would heat up my buddies 20x30 shop to t-shirt weather in less than a hour from 50 degrees. If I remember it right, he figured it cost him about $30-50 a month to run it after work most nights. We painted cars in there, so you did have to shut it off while spraying until the fog lifted. Not dissing slab heat at all, and if anything I'm more familiar with the radiant heat given off by objects than most. Nothing like Phoenix asphalt and concrete to keep it nice and warm here when it's butt ass cold in the desert. It's just that initial cost, my butt hurts from even thinking about it. At least you guys are pouring new slabs not retrofitting.