Help in determining what Radiant System to use

[conceptmachine]

Hello fellas, thanks for help in advance.
Within a 40x60 building I have in floor pex ran, 16" on center, with some zones ran. I need to get a system for it. Was wondering if I should do a hot water heater or a on demand type system? I have 3 phase power ran, and the builder that took off with my money mentioned a 3 phase on demand glycol system.
Was wondering what would be most effective and give the least amount of issues. I don't care about spending a few hundred more a year in electricty.
I believe it has 6 lines ran...possibly 8. Got a pic of it, so I'll try and dig it up.
Thank you for any input.
Jimmy

 

[Highbeam]

All of the systems you mention are electric resistance water heaters and that is fine. The tank of a tank heater is of no value but the size of the elements determines the output. Wall hung boilers save floor space and are built for this application vs. a domestic water heater that is meant to heat small amounts of cold water to 120.

How many btu of energy do you need? That will determine your options.

If heating with electric you really only have the wall hung boilers as an option. Several brands are available and some with very high output.

 

[conceptmachine]

HighBeam, thank you. Yes, I only have electric power.
I did a BTU calculator and I came up with: 92,160 BTU/hour or 27,009 watt. It didn't really give specifics, but I'm doing 2" closed cell in walls that are 12' and 40x60 and R40 on ceiling.
I have a 16'x10 Over head door which may proved to be a bear to seal up good, so I'll just assume 110 or so BTU's/hr.

 

[anthony666]

that's 30kw's on 16" centers .. that is a ton of dedicated amperage and poor tube coverage .. that looks to me like massive operating costs

you might wanna invest very heavily in insulation .. and skip over electric boilers and check out a geothermal heat pump

rule of thumb for hvac i tell my radiant customers; the lower the buy in, the higher the operating costs .. conversely the higher the buy, the lower the operating costs

big buy in costs are very often supplemented by govn't grants, rebates, tax incentives and subsidies .. big operating costs NEVER are

fyi, your contractor should have put in two runs spaced at 6" around the perimeter and then filled the rest in on 12" centers

 

[anthony666]

also count the the tubes where they come out of the floor .. if there are 13, that's 6 runs and a slab sensor chase

 

[conceptmachine]

Anthony,
The guy was a walking liar and swindler so who knows what I have going on. My fault totally, as I told him I wanted 12" on center tubing. He claims his havac guy was telling him 16. I knew it wasn't right i was just too sick at the time to want to do the research.
Anyway, from the pic it looks like I have 19 lines.?

 

[anthony666]

first thing you wanna do concept, go out there and blow throw each line, find it's twin, make sure they're all clear .. there will be one that doesn't blow through, that's the chase to slide a slab sensor in

19 tubes .. minus the slab sensor chase = 18 .. 18 divided by two, because one tube is a feed and its twin the return, equals 9 runs

ideally the runs are 300 feet long +/- 10% .. 9 x 300 = 2700, plus 30% because they're on 16"s = 3600 sq feet .. 40 x 60 = 2400 sq feet .. so if the runs are really on 16" centers, the tube length is short, or more likely, they are on 12 inch centers and you remembered wrong .. thats a good thing

why are you wedded to electric heat anyway ??

 

[conceptmachine]

I made sure he did foam the hell out of the slab. Inside 2 " all around 8" slab. 2" under slab entirely. Pex is 4" up off ground. If it were only 6 runs I'd think about scrapping everything, but since it's probably 9 runs and all that insulation under the floor, I'll try to use this for a few years and see how it works. I don't need to be toasty in there. Anything is better than the 45 degree temps I'm at in winter now and 300/month electric bill running baseboard heaters.

 

[conceptmachine]

I'm married right now because money is thin. He ran off with 30k of my money I'll never get back.
Otherwise in 5 years I'll get geothermal. Have it for my house and it's great. 160/ month max.
what sold me on the infloor is that it would be warm on my feet which is nice.
And said that a 3 phase system would be more effecient.
I see one line that is shorter with a plug in it.
Thanks for your help.
What are we talking for electric with this system ...maybe 300/month?
I'm not worried in the least about that, as long as it works and doesn't cause me headaches, I'm fine with it.

 

[anthony666]

spend some money putting insulation on the walls and ceiling sir

 

[conceptmachine]

Anthony, I planned on 2" closed cell on walls and r 40 on ceiling. Only so much can be stuffed in there. Anymore i can do on the walls like the closed cell and then maybe stuff 4 " of fg? Would that help?
Thank you for your input on this.

 

[anthony666]

definitely .. run the btu calc with and without insulation .. see what you get for results

 

[conceptmachine]

Took a look and there are 20 lines total, so he must not have ran a sensor tube? Ugh!!
Also when I was reading the tube ends most of them had 250f at the end, but it varied.
I'm sure he mentioned 16 oc, because he was in an uproar over me wanting to use the rebar to hold up the pex.

 

[sickjuice]

And said that a 3 phase system would be more effecient.

No it won't be. watts are watts

In the larger sizes a 3ph boiler might be cheaper to purchase that's about it

 

[anthony666]

no sensor chase isn't a deal breaker

your shop is 40 x 60 .. 2400 square feet .. 10 runs of 250 x 12" fits mathematically

i'm also from the school of thought where the pex goes at the bottom of the slab .. but i wouldnt have a coronary if the HO/contractor made me lift it up as long as he's paying

 

[conceptmachine]

Thank you, for the input. I'll get down there and blow some air down the tubes. and figure out whats what for sure. He's got them marked...I'll try to read his writing. I know he had a zone for the office/bathroom, so if he did that, I bet he put two sensors chases in. One for that area and one for the shop area. I believe he has 9 runs of 250 feet...but will find out when I get to testing. Being 150 feet shy, would that put a big burden on the system?
I just want them to run all the same. 50-55 degrees constant. My machines warm it up 5 or 10 degrees when they are working for a couple hours. I'll probably have a quarts unit just in case I open the garage door and want it to warm up quicker in there. I read somewhere that the pex should be 1/2 distance of the concrete anything after 4" thick. So if the concrete is not any thicker than 4", staple it to the foam. Mine was 8" thick so I raised it. Rightfully so, because I had it ziptied to the rebar and don't want rebar sitting on the foam. I'm not sure why, but should be some reasoning behind raising the pex.

 

[rburke65]

Anthony666.... When running the wire for the floor sensor....what size wire? Are the sensors 12 volt, ...24 volt..... 120 volt? Thanks....again. Sorry.... Didn't mean to hi-jack the thread.

 

[anthony666]

Anthony666.... When running the wire for the floor sensor....what size wire? Are the sensors 12 volt, ...24 volt..... 120 volt? Thanks....again. Sorry.... Didn't mean to hi-jack the thread.

if i have to extend the wire i just use 2 wire tstat wire .. cut the wire off close to the sensor, solder and tape it .. it's easier to push tstat wire through a chase than the limp noodle wire that comes on them

the way they work is the thermostat sends a known voltage (5v) through the sensor, which is actually a thermistor, which is a resistor that changes it's resistance as it's temperature changes .. the return voltage is measured, compared to a chart and bob's your uncle

 

[anthony666]

I'm not sure why, but should be some reasoning behind raising the pex.

i guess that if the pex was in the middle of the cross section of the slab the heat would soak through the slab faster .. but after the system has been on for a while you're really in a maintain mode and the slab is pretty evenly warmed up, all you're doing is inputting heat to match heat loss from the building

the big reason i want it low in the slab is for protection .. i never ever want to have to go rip up concrete under an interior wall because a framer shot a nail into the pex and a year later it rotted enough to finally leak

 

[conceptmachine]

the big reason i want it low in the slab is for protection .. i never ever want to have to go rip up concrete under an interior wall because a framer shot a nail into the pex and a year later it rotted enough to finally leak

I hear ya...
the same guy that poured my slab was actually going to put a walk up to the front door. It suddenly got freezing so i told him to stop all cement work. Showed up a couple days later and noticed the tie in and hoping he didn't hit any of my lines. That would be a PITA.

 

[rburke65]

Thanks Anthony . "and Bob's your uncle"???

 

[anthony666]

"and Bob's your uncle"???

hahaha .. my grandfather's favorite thing to say

 

[Highbeam]

They make boilers that big. In my location, electric heat is cheaper than propane both operating and installation. Don't be quick to shoot down a cheap reconfiguring cheap watts. It scales too. Cheaper for a small area means big savings for a large shop.

Sure ng or geo are cheaper to run but buy in is high or impossible.

 

[anthony666]

i'm not buying it

 

[conceptmachine]

Around here mid american energy is so invested with wind turbines it doesn't make sense to use anything other than electricty. Its unreal how many of those things are up. of course they are a monopoly and your gonna pay their price, but it seems the future here is EP. Fields and Fields of them things. On another note, I'm not going to use the Infloor heat, so I'm scrapping that idea. I'll just leave it for the next guy if ever I sell the place. I'm just gonna do closed cell and insulate the hell out of it and then use radiant tube heaters. I'll have them on timers. Keep it 45 degrees and crank it up an hour before I get there each day. I may even get them linked up to my smart phone so I can adjust on the fly if I wanna.
Thanks for all your help on this topic.

 

[anthony666]

you're welcome

you should check out a guy on here, i think his name is walrus .. he hooked his floor up to a diy solar water heater .. i doubt it heats the place entirely, but it would take the chill off the floor and it will eat some of the load off the radiant tubes