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fozzy12
10-31-2008, 09:22 AM
I am building a 30 x 36 garage. It's 2 x 6 construction with attic trusses. I end up with an 18 x 30 room upstairs. I am putting radiant tubing in the slab and also under the second floor sheeting. I bought the system from a supplier in VT. They are well known. I need a hot water heater that has an output BTU rating of 40K. That is figured by input BTU times efficiency. When I looked around the big box stores, they don't have anything. I checked Rheem and Ruud and they have one although it's a 75 gallon unit. When I called my local plumbing supply, they told me what I was doing wasn't legal. Said in Michigan you aren't allowed to do that with a water heater. This is a closed system, there is no water in the garage. It is not going to be used for anything else. They tell me I need a real boiler to do this. The company disagrees. I have a phone call into the inspector now to figure out what to do. Any thoughts out there?

Thanks
Eric

jadnashua
10-31-2008, 09:39 AM
Using the proper backflow preventers and safety features, it would probably work. Personal opinion, a WH is not designed for continuous use like what would happen during a heating season and you'll probably wear the thing out. A commercial unit might be rated for a higher duty cycle, but again, a boiler is designed to run continuously, a WH is not, so your life expectancy may be low.

nhmaster
10-31-2008, 11:33 AM
Why would you want to go to all the expense and effort of installing radiant heat just to use an inefficient tank heater to drive it? Heating 40 gallons of water or more makes no sense from an efficiency standpoint at all. Do yourself a favor and find a high efficiency Mod Con boiler.

Paso One
11-12-2008, 06:45 AM
I did exactly what you are proposing.

I had a 18 x 30 building attached to my 30 x 30 gas heated shop.

In the 18 x 30 building I have 2 zones with approx 200 ft per zone.

It is heated with 2 40 gallon electric water heaters.

The first year I used only one water heater but I found when the tempetures got to -40 for a week at a time the one 40 gallon was working all the time.

Now with the second unit dumping into the first they are off most of the time.

Shop is warm all the time.

It is illegel around here I believe as well but it has been working flawless.

I went this way only because I wanted a "ignition free " area to paint in.

Don't be turned off your idea it does work. ( 5 yrs now )

comp1911
11-12-2008, 08:10 AM
I was told by my electrical inspector that the equipment needs to be UL listed for heating service. This was in MN.

enosez
11-16-2008, 04:31 AM
[QUOTE=Paso One;166293]I did exactly what you are proposing.

What water temp are you running through your zones?
And are you using a manifold?

Here in NY it would cost a fortune to running anything electric let alone during a cold spell.

I considered it also for a 900 square foot garage but in the end operating costs made it cheaper to go with a boiler.

nhmaster
11-16-2008, 11:04 AM
Here's a pile of other issues also. The slab will want water temps around 85 degrees, the staple up around 160 or perhaps more depending on the substrate and floor coverings. Running an electric water heater at those temperatures will cost a fortune and require a mixing valve for the slab heat. I've seen this done several times before and it has never worked out. The water tank is usually swapped for a boiler of some sort within two years.

Paso One
11-19-2008, 06:12 PM
[QUOTE=Paso One;166293]I did exactly what you are proposing.

What water temp are you running through your zones?
And are you using a manifold?

Here in NY it would cost a fortune to running anything electric let alone during a cold spell.

I considered it also for a 900 square foot garage but in the end operating costs made it cheaper to go with a boiler.

I have 2 zones (see pic) temp tonight is about 130 degrees outside tempature is 20 degree f

nhmaster
11-20-2008, 03:16 AM
If you are running 130 through the slab your cement will crack, powder and fail within a couple of years. Never more than 95 degrees maximum.

enosez
11-22-2008, 05:03 AM
If thats daylight coming through the outside perimeter wall , I'd think about putting insulation there. (Heat loss to outside)
Also all of your loops are uniform, without an exterior zone loop which is usually closer together since more heat loss is at exterior walls.

Paso One
11-24-2008, 06:30 AM
The outside "daylite" you see is actually the aluminum air foil going up the wall.

The concrete hasn't cracked yet But concrete in this area always cracks so It is going to happen anyway. No sign of powerdering at all. ( 5th winter )

My water tank is set at 130 degrees but I'm sure it is less going thru the slab.

I'll try it set lower. I park a bobcat in the area so it heats the steel and is nice and toasty when needed.

This is the first I heard of the max 95 in concrete.

Around here people heat the driveway to melt the snow so perimeter heating is a moot point. ( my loop melts outside threshold )

Bill Arden
11-26-2008, 01:56 PM
Why would you want to go to all the expense and effort of installing radiant heat just to use an inefficient tank heater to drive it? Heating 40 gallons of water or more makes no sense from an efficiency standpoint at all. Do yourself a favor and find a high efficiency Mod Con boiler.

Because it's cheep and a lot easier to upgrade in the future.

Electric boilers have gotten cheaper so using a hot water heater is not saving very much.

frenchie
11-26-2008, 02:03 PM
If the "well-kinown supplier in vermont" is who I think it is, you need to STOP what you're doing. Those guys are notorious for half-assed advice, badly designed systems, they're just very good at "image control" on the internet.

Go to the forums at heatinghelp.com, do a search on that forum for the supplier's name. Stick around for a bit, over there, lotsa good info on designing a proper radiant system. Other good sources: radiant panel association, radnet, warmly yours.

nhmaster
11-26-2008, 02:31 PM
Having designed and installed more radiant systems than I can even begin to recall in the past 25 years or so, it makes me scratch my head when I read threads like this. There is always someone that can and will justify almost any half assed combination for either price or expediancy reasons. Just because you have been running 130 degrees for 5 years now without a catastrophic failure you think that it must be ok and those of us that design and install for a living (and back it up) must be wrong and or overly cautious. So keep on keeping on, and when the you know what hits the fan be sure and not bother to tell those of us who will say " I told you so"

smokinjoe
11-28-2008, 01:05 AM
Having designed and installed more radiant systems than I can even begin to recall in the past 25 years or so, it makes me scratch my head when I read threads like this. There is always someone that can and will justify almost any half assed combination for either price or expediancy reasons. Just because you have been running 130 degrees for 5 years now without a catastrophic failure you think that it must be ok and those of us that design and install for a living (and back it up) must be wrong and or overly cautious. So keep on keeping on, and when the you know what hits the fan be sure and not bother to tell those of us who will say " I told you so"

You are always to the point..I for one appreciate your inpu on here...Thank u..:)

nhmaster
12-02-2008, 11:15 AM
Well I guess that makes you the current expert on the matter. So if you don't mind dancing around on a 150 degree floor then by all means go for it. The rest of us however will be content to design radiant systems that use water temperatures that are comfortable for human occupation.

nhmaster
12-02-2008, 02:51 PM
So is the floor temperature 95 or 150 degrees?

kingsotall
12-02-2008, 05:02 PM
"How's the floors┐"

"Great, no, just great! Really!!"

http://www.firewalkingamerica.com/_borders/firewalking5.jpg

Bill Arden
12-03-2008, 03:44 PM
Well the way my solar hydronic systems works, the floor warms up, the heat transfers to the air space and the thermostat reaches it's set temp, and turns that zone off. The floor in my bathrooms (tile) may reach 90-95 degrees before the thermostat, set at 75, turns off that zone. Floor Temp needs to be higher than about 90 degrees before it feels warm to the touch, so no problem with 150 degree floors in my house.
Witch

I am going to translate that as saying "I don't have a problem with hot floors since the floor itself does not get that hot"

-
I'm playing around with a non UL approved "research" set up as well.

Here's what I've got so far
1. A bronze recirculation pump
2. In floor PEX
3. A plastic non-pressurized tank. (open air system)
4. Plans for a solar trough that will still work at -40F.
5. Two 50 gallon hot water heaters with internal 30sq heat exchangers.

I have to use copper, PEX, or brass for corrosion reasons. (open air)

It is legal to use a hot water heater to heat potable water and then use that to heat the floor via a heat exchanger.

It is also legal to use the hot water to directly heat the floor, but that means there is no way to use antifreeze.

Note: to stay legal, you would have to have some sort of sink to justify having the hot water heater there and to use some water. I would also recommend adding a check valve before such a long and possibly "stale" section of water pipes.

To stay safe you have to have a "safety" expansion tank on the potable water side AND use non-toxic antifreeze on the heat side.

One reason they don't like hot water heaters being used for in floor heating is that you can not use antifreeze with a hot water heater since even the fold back elements tend to scorch and burn the antifreeze.

Electric boilers designed for heating are carefully designed to maintain fast water flow past the elements and this keeps the element surface temp below the point where the antifreeze starts to degrade.

I could build my own boiler that would be safe, but is it really worth my time.

nhmaster
12-03-2008, 07:35 PM
What?

Are the damned floors 150 degrees or not? Not a complicated question I think.

If you want to use an electric water heater than by all means go right ahead. You are the one paying the bill. However all you cowboys need to understand that there are mechanical codes that regulate the installation of all heating systems and to insure that your insurance will pay off when the house floods or burns down, you need to get the system inspected and signed off.

jadnashua
12-04-2008, 08:14 AM
Depends on how close the tubing is to the surface...the probe you have is probably located between the runs, or on the wall. Peak temperatures right over the tubing could be considerably higher than that midpoint between two runs. You're measuring average, not peak temperatures. It could become especially problematic if heating a cold slab verses one that has stabilized at the desired temperature...the difference between peak and average temperatures would be much greater...you have to account for these boundary conditions if you want a safe system, thus the lower input temperatures. You have to realize it will take awhile to bring a large mass up to temp.

fozzy12
12-04-2008, 12:00 PM
I see this original thread generated a lot of posts about radiant heating methods. My system is up and running here in Michigan where the weather is getting pretty cold. So far my building is uninsulated and the second floor staple up piping is getting finished. This is a garage and the inspector has already been in to look at the slab piping prior to the pour. Hot water heaters are allowed in my situation because this is not a single family residence. My choice was a Brad White 75 gallon heater. It has input capacity of 75K BTU's which is enough after efficiency to provide enough heat for what I need to do. So far the system has run three days and the slab is 75 degrees with an outsided temp of 25 degrees. I have to finish and have an inspection both electrical and mechanical before I can insulate. So far I'm pretty impressed wth the system. It uses Grundfos pumps, I have 2 zones. It's running about 23 pounds of pressure and I can monitor input and output temps. I have only one circuit running right now, hope to have the second one up soon.

The piping is 5/8" pex. All of the fittings that came with the system appear to be very high quality. The pex fittings are the ferrule type with large nuts to secure them. Everything was air checked prior to putting water in the system and it was all tight. So far I'm very impressed with the equipment that I purchased from the supplier in Vermont. I did check the website that was recommended by someone and read the comments about the company there. The posts were over a year old. Not sure what to say about them short of mine is a closed system, not an open one, so some of the observations made about open systems would not apply to me. They have always gotten back to me with answers to my questions and to their credit and heat calcs, the system appears to be working fine.

Eric

nhmaster
12-04-2008, 02:37 PM
I did read your posts and they make no sense at all. If your floor temps are running 90 - 95 (which is normal) they why run 150 degree water through them? Lower the temperature to 95 and let the circulator run longer. You will pick up a signifigant amount of efficiency, boiler wise and longer cycle times on the circulator save money also. Also you shouldn't bu running a wall thermostat on a radiant slab system. It should have floor sensors.

nhmaster
12-04-2008, 02:39 PM
I see this original thread generated a lot of posts about radiant heating methods. My system is up and running here in Michigan where the weather is getting pretty cold. So far my building is uninsulated and the second floor staple up piping is getting finished. This is a garage and the inspector has already been in to look at the slab piping prior to the pour. Hot water heaters are allowed in my situation because this is not a single family residence. My choice was a Brad White 75 gallon heater. It has input capacity of 75K BTU's which is enough after efficiency to provide enough heat for what I need to do. So far the system has run three days and the slab is 75 degrees with an outsided temp of 25 degrees. I have to finish and have an inspection both electrical and mechanical before I can insulate. So far I'm pretty impressed wth the system. It uses Grundfos pumps, I have 2 zones. It's running about 23 pounds of pressure and I can monitor input and output temps. I have only one circuit running right now, hope to have the second one up soon.

The piping is 5/8" pex. All of the fittings that came with the system appear to be very high quality. The pex fittings are the ferrule type with large nuts to secure them. Everything was air checked prior to putting water in the system and it was all tight. So far I'm very impressed with the equipment that I purchased from the supplier in Vermont. I did check the website that was recommended by someone and read the comments about the company there. The posts were over a year old. Not sure what to say about them short of mine is a closed system, not an open one, so some of the observations made about open systems would not apply to me. They have always gotten back to me with answers to my questions and to their credit and heat calcs, the system appears to be working fine.

Eric


Give us a ring a couple months form now and let us know what the electric bill looked like.

Redwood
12-04-2008, 07:48 PM
May I suggest reading my latest book...
It covers everything you could ever want to know about radiant heating.

http://i44.photobucket.com/albums/f2/Redwood39/radiantheatingguide.jpg

fozzy12
12-05-2008, 08:36 AM
To NH master,
Mine is a gas fired system, it's not electric. I'm not sure where that thought came from. Electric powered hot water radiant heat makes no fiscal sense at all.

Eric

nhmaster
12-05-2008, 09:20 AM
Might be my own confusion. I have been involved with at least 3 threads on other sites, discussing the same issue and I guess I thought we were tak=lking about using an electric water heater. Gas water heater is slightly better, but not much and if it's propane fired, mighe even be worse. Problem with tank type heaters is the exchange ratio from the heat source to the water is signifigantly less than a boiler that uses multiple and narrow passages to scrub as much heat from the fire as possible.

Bill Arden
12-06-2008, 05:23 PM
To NH master,
Mine is a gas fired system, it's not electric. I'm not sure where that thought came from. Electric powered hot water radiant heat makes no fiscal sense at all.
Eric

I think it's my fault. I was saying that I was planing on using a hot water heater with an internal heat exchanger. but I am also planing other heat sources and the electric element will mainly be used as a backup.

Edit:
I also would rather see someone install PEX in the floor and use an electric boiler than install electric wires in the floor.

The PEX system can be upgraded in the future, while the wires will fail.

CHRISUPNORTH
12-06-2008, 05:59 PM
Edit:
I also would rather see someone install PEX in the floor and use an electric boiler than install electric wires in the floor.

The PEX system can be upgraded in the future, while the wires will fail.


I considered electric wires for my 250 sq' addition but I am putting pex in the floor and heating with an electric water heater (marathon).
My reasons are simple. This will be for floor warming only to supplment existing FAG furnace. I did a heat loss calc on the addition and I only need about 10k btu's (without considering heat from the FAG furnace). A boiler, even a small one would have a initial install cost 15-20 times that of my electrical requirements per year.
Makes no sense to me not to use electric.
I didnt go electric wire floor because if it fails, I am screwed.

C

smokinjoe
12-07-2008, 02:12 AM
I considered electric wires for my 250 sq' addition but I am putting pex in the floor and heating with an electric water heater (marathon).
My reasons are simple. This will be for floor warming only to supplment existing FAG furnace. I did a heat loss calc on the addition and I only need about 10k btu's (without considering heat from the FAG furnace). A boiler, even a small one would have a initial install cost 15-20 times that of my electrical requirements per year.
Makes no sense to me not to use electric.
I didnt go electric wire floor because if it fails, I am screwed.

C

Electric wires are only good to warm the floor..Not much good to heat the room in cold areas..........

nhmaster
12-08-2008, 11:52 AM
Look you arrogent Prick. I already said that I mis-read the post. You however, are free to do any damned thing you want with your solar heat. There's absolutly no point in arguing with you because, even though 99% of us that design and install radiant systems would never run 150 degree water through the floor, explaining it to you is a total waste of time. Go crawl back under the rock you came out of. Be sure to tell all your idiot friends how you one upped an expert. Should make for a good drinking story.

CHRISUPNORTH
12-08-2008, 06:29 PM
Look you arrogent Prick. I already said that I mis-read the post. You however, are free to do any damned thing you want with your solar heat. There's absolutly no point in arguing with you because, even though 99% of us that design and install radiant systems would never run 150 degree water through the floor, explaining it to you is a total waste of time. Go crawl back under the rock you came out of. Be sure to tell all your idiot friends how you one upped an expert. Should make for a good drinking story.


I dont know either of you guys so I am not taking sides but Id like to make an observation.....

I have been reading this forum for a month now. People like me come to sites like this to learn from more experience and knowledgable people. I believe that nhmaster is likely a wealth of knowledge and everything he claims to be. I have also read many of his posts and he for some reason prefers not to share what he knows. Many of your posts (nhmaster) are one line, or even one word responses. If a guy asks if he should use a monoflow system (whatever the hell that is) You should say no and then explain why. Then the guy asks you what you recommend and you reply "LOOP". The way you are answering peoples questions are in my opinion a big waste of time and useless. I get the impression that you are more concerned about making everyone think you are the "Master" rather than helping people with their problems.

It can be very frustrating when people reply with non-answers. Personally I believe that if you want to help others you should put every effort into it or just dont bother.

nhmaster
12-08-2008, 07:04 PM
Well, you may have a point but experiance tell me that a long, convoluted answer is usually followed by other endless questions leading to the land of no where. Unfortunatly, without actualy being there, giving a detailed answer is often a waste of time. I do however answer an awfull lot of PM's, one on one. Let's take the guy with the mono-flow. If I spend a paragraph or two explaining restriction and flow curves, the very next post will be someone that has done it and it works fine. I post accepted engineering and installation practices. That there are bazillions of home designed, hair brained set up's that work is another matter altogether.

I will however post here the most usefull solar link that I know of. www.caleffi.com Then download pdf file Idronics
3

Bill Arden
12-11-2008, 11:42 AM
---- I am putting pex in the floor

Just remember to add foam insulation under the slab.

With under-slab insulation it could be used to heat the room even in cold areas.

Hillbilly Man
12-11-2008, 06:12 PM
This thread gives me an interestin idea...
Whachawl think about a solar heated still for making up my moonshine...
Thats funny right there ya awl I don't care where yur from...
Solar powered, Moonshine!

Maybe NH Master needs a sip o my shine...
Prolly keep his head from explodin.

nhmaster
12-16-2008, 04:07 AM
Though possible, solar power would limit shin'in to sunny days which might be a problem, then again, maybe not. Anyhoooooooo. Will need to see the performance curves and gpm flow rates for the evaporator as well as a sample ( a gallon should do ) of the finished product for evaluation. In the meantime a good old wood fire should keep her up and running.

If you am too durned drunk to notice over the next day or so Merry Freekin Christmas and to all a good night. :)

Hillbilly Man
12-16-2008, 08:22 PM
Merry Freaking Christmas to you too NH Master!
I'll be sending a special jug your way. It wrung out at 150 Proof and we're going to call it Northern Comfort in your honor.
The extra zing should do well to keep you warm this winter.

I jes wanted ta let yawl know that Southern Man is doing okay now.
He kinda wen offfa the deep end when yawl started pickin on im.
He stayed down by my still fer quite a few weeks jes sippin on the hose whenever he woke up then passin out again.

Anywho he finally stopped drinkin and sobered up... took a few days but I got him helpin me on converting the Whirlpoof gas water heater to a still down in my basement. He's been puttin all sorts of fancy temperature controls together and he says this is gonna be is finest work ever. He says that this thing is gonna be completely automatic... Some sort fo fancy computer thing called a PLC is gonna control the whole process.

I tell ya wen he ain't drinkin he's a genius!:D

After we git r runnin on gas we'll be workin on the solar portion of the project!