Post by: 280plus on January 26, 2007, 06:40:09 AM
Incidentally, I am only running 105*F water in the system.
Post by: Perd Hapley on January 26, 2007, 07:59:44 AM
Post by: 280plus on January 26, 2007, 09:10:59 AM
Post by: K Frame on January 27, 2007, 04:22:54 AM
Wow.
So, basically, it's a constant circulation system?
I was out grabbing a smoke this morning and I noticed that the house down the street has a heat pump problem. I told them about it a year ago, and they didn't do anything. Right now it looks like a big damned ice berg sitting beside their house. It's so totally frozen up that I'd not be surprised if the fan can't turn.
They're going to lose their compressor.
I told them once, but if they're not interested in doing anything about it, fine, let them get into a situation where the compressor fails and they're on toaster heat for the rest of the winter, then on the first REALLY nasty DC heat day they'll be screaming bloody murder for someone to come and fix the system.
Idiots.
Post by: 280plus on January 27, 2007, 04:44:01 AM
The first floor for example will rarely shut off. The pump that does the first floor draws about .5 amp, so that's 50 w/hr x 24 = 1200 watts a day or 1.2 KWH x 30 = 36 KWH per month x $0.185 per KWH = ~ $6.60 per month of continuous operation. Which ain't bad considering. MOST of the pumps will cycle off periodically. I've got them figured for about $100 per month for total electrical usage to heat their 8000 sq ft house. The only figure I can't really determine yet is GAS usage for a cold month. I won't know that until the house is finished, they move in and operate the system under normal conditions.
Chances are your neighbors already ARE on toaster heat if it's that frozen. I can't imagine what their electric bill must be. This is how heatpumps get the bad press. They're pretty darn efficient when they work right but as soon as they malfunction and the electric heat starts to do the work people get big bills and blame the HP, not the fact that it is broken. What? You have to periodically MAINTAIN that complicated piece of machinery? Who woulda thunk?
Post by: Ron on January 27, 2007, 04:44:59 AM
Quote
and they're on toaster heat for the rest of the winter
If it is that frozen over they are probably only getting toaster heat already.
ha ha you're fast 280
Post by: 280plus on January 27, 2007, 05:00:55 AM
Post by: K Frame on January 27, 2007, 05:11:22 AM
With the coils completely blocked no heat exachange can take place. Even though the compressor is, or at least has been, running (by virtue of the fact that the coils are iced, other wise they'd be clear), the system is calling for resistance heat to make up for the shortfall.
There's also likely very little refrigerant phase exchange going on right now, which means that the compressor could be hit with liquid refrigerant. When that happens failure normally occurs within a matter of moments.
It's been darned cold here the last couple of days -- the other night it went down into the low teens.
My system ran almost constantly, but the resistant heat came on only probably 5 to 7 minutes every hour, and the place has been comfortable. At least as comfortable as this crap shack can be.
Post by: Fly320s on January 27, 2007, 05:13:19 AM
Is the entire house heated with the radiant floor heat?
Does it have a thermostat or is it controllable?
If the water in the pipes is at 105*F, what is the highest temperature that can be expected in the house? For instance, can they crank the heat up and get it to 80* inside when the outside temp is 30*?
Just filing info away for a future house build.
Thanks
Post by: Ron on January 27, 2007, 05:17:22 AM
Of course I don't know where you are at so it may not get that cold. The fact that you service heat pumps tells me you aren't up here
Post by: K Frame on January 27, 2007, 05:43:28 AM
He's in New Hampshire, or something like that.
He's never dealt much with heat pumps, for obvious reasons.
"For instance, can they crank the heat up and get it to 80* inside when the outside temp is 30*?"
That, to me, should be more a function of the insulation and sealing in the home. The fact that you can't get rapid changes in temperatures with a radiant floor system means that you have to be a lot more scrupulous about sealing and insulating.
Another advantage of a radiant floor system is that since the heat washs up over you from the whole floor, you're often able to keep the temperature much lower than with other systems.
Post by: 280plus on January 27, 2007, 06:25:59 AM
This new fangled heat pumps are gas fired air source ammonia absorption types and are brand new technology to the US. These are actually the first on the North American Continent I am told. They've been in operation in Europe for ~ 2years. So far I am totally impressed. They chug away drawing only 4 amps and every so often fire up the gas for a few minutes to keep the process going. The colder it gets, the more gas they use though. Still, at ~ 45* outdoor temp they use gas at 157% efficiency and will use it at 100% down at -4* ODT. No other gas fired heating appliance in the world will do that. draw back, below -4 it shuts off. But given the slabs and floors, plus the sprayed in insulation they used and the fact that it rarely goes below -4 here in central CT my little design team thinks this is not a problem and should not require any additional forms of heat. I wouldn't go much farther north with them without adding some form of supplementary heat though.
As far as reset. That is what I had planned BUT because there are 2 HPs I installed a Direct Digital Control to operate them as a plant and the DDC does not offer this reset option, nor does it offer a way to add this option that I can figure, though I have some ideas. Ideally I would have set the water temp for something like 90* at 60* outdoor temp and had it go up as the outdoor temp went down. Hence my quest for the ideal water temp for all conditions.
The fun part is in the summer, I turn off the floors and reverse the heat pumps sending chilled water to the air movers through the same tubing and coils as the hot water and now we have A/C.
Post by: 280plus on January 27, 2007, 06:31:12 AM
Note, we did and do put R-10.5 insulation under the concrete slabs. If you are building a single story dwelling with an insulated basement, heating the slab will handle the whole house down to fairly low temps before you have to start turning on your blower and HW coil to keep up. And that's with 90* water.
Post by: Ron on January 27, 2007, 06:36:07 AM
When i build a house I will definitely do the heated floors system. The comfort level of that type of system is a huge advance over every other type of system out there.
Post by: 280plus on January 27, 2007, 06:41:44 AM
You CAN go conventional boiler on this too. Today they are making boilers that will accept very low return water temps. In the past you were limited to no lower than 135* return water temp due to things like thermal shock and flue gas condensation. Buderus comes to mind for oil and there a boiler out there now known as a "Munchkin" that is gas fired and has a cast aluminum heat exchanger. ~ 93% efficiency IIRC. Hook these up to a rset and your going to save a LOT of energy money.
Post by: K Frame on January 27, 2007, 06:41:50 AM
Many radiant floor heating systems have used not boilers, but water heaters, and VERY successfully. Water heaters are out of the box designed for lower operating temperatures and handle low water return temperatures just dandy.
The original Levittown designs in New York, Pennsylvania, and where ever else they were buit used slab radiant heating systems and were extremely successful. Unfortunately, though, many of these systems have now been abandoned because of leaking copper pipes (and I wonder how much, if any, insulation was used under and around the slabs?). Many Levittown houses have been converted to either forced hot water baseboard (not bad in and of itself), hydronic (water/air exchange) systems, or water has been totally abandoned for forced air.
New systems using PEX as the heating tubes are promising to eliminate slab leaks (unless someone rams a nail through a tube), and the technology has been in use in Europe since just after WW II where many original PEX systems are still in operation.
As for hardwood over in-floor radiant, it can be done successfully. However, I feel it's a much better choice to go with engineered laminates when installing "wood" over radiant.
Post by: 280plus on January 27, 2007, 06:45:10 AM
Incidentally, FYI, the gas fire used in these HPs does not heat the water directly, it heats the ammonia solution. It operates JUST like your old propane fired backwoods camping refrigerator. Very few moving parts, which makes it very reliable.
Post by: Ron on January 27, 2007, 06:48:43 AM
Quote
If you understand how an air conditioner works, then you understand how a heat pump works.
Don't get me wrong, i understand the principle and have even worked on them here in Chicagoland. Often large buildings have heatpumps tied into central plants that provide warm water in the winter and cooling tower water in the summer.
I just haven't been exposed to them to any degree.
Post by: K Frame on January 27, 2007, 06:53:25 AM
Many commercial buildings, especially those with lots of people and lots of computer equipment, don't need much added heat at all. The people and the equipment provide the heat, with any additional necessary heat being added on a zone by zone basis using electric resistance. At least that's how it is in the mid Atlantic and up into Pennsylvania.
Post by: 280plus on January 27, 2007, 06:55:37 AM
Post by: K Frame on January 27, 2007, 06:55:45 AM
Pretty much... A heat pump is just a backwards A/C.
Incidentally, FYI, the gas fire used in these HPs does not heat the water directly, it heats the ammonia solution. It operates JUST like your old propane fired backwoods camping refrigerator. Very few moving parts, which makes it very reliable.
Incidentally, FYI, the gas fire used in these HPs does not heat the water directly, it heats the ammonia solution. It operates JUST like your old propane fired backwoods camping refrigerator. Very few moving parts, which makes it very reliable.
Yep, it creates the "Mr. Coffee" convection effect needed for absorption units to work.
My old hunting camp had a gas fired refrigerator that was older than dirt (1930s) and worked like a frigging champ.
The guy who maintained it was a long-time local gas company employee and he wouldn't even touch an electric refrigerator for his home.
Every see a wood or kerosene fired refrigerator? Pretty bizarre!
Post by: Fly320s on January 27, 2007, 06:56:54 AM
Post by: K Frame on January 27, 2007, 07:03:58 AM
A lot of people in this country, especially in the east, are really leery of PEX because of the horrific problems with Qest (sp?) Qwest (sp?) polybutylene pipe and fittings that Shell Oil's petrochemicals division came out with in the 1970s.
Great stuff, really reduced the amount of time it took to plumb a house, and really looked good as a means of replacing copper, prices of which were spiraling...
Then the systems got some age on them and fittings started to shatter and tubing started to split.
Those class-action lawsuits are probably going to go on for a LONG time.
"How does one insulate under a concrete slab or along basement walls?"
Best way these days is to use polystyrene board or a spray-on closed cell foam system. Impervious to water, rot, and insects, and with no exposure to sunshine and minimal exposure to oxygen, effective lifespan should be measurable in decades.
Post by: 280plus on January 27, 2007, 07:06:07 AM
Under the concrete some guys use the pink styrofoam board but I think it will make the concrete prone to cracking. What I use is a product called "Insultarp" which is basically a few layers of thin sheet styrofoam and bubble wrap sandwiched between an outer covering of rip stop nylon and comes in rolls. When you lay it out you just extend it up the wall enough to clear the expected level of concrete. When it's poured and hardened you go back and trim the excess. It's not necessary to fill the remaing gap but you can. Some people are afraid if there's a flood in the basement thw water will get undernaeth the slab and ruin the system. But, it would just dry out in a few days anyways so it's really not a biggie.
Post by: 280plus on January 27, 2007, 07:11:04 AM
Shell's problem supposedly came from the fact that they were making their tube from the sludge leftover after the emptied oil tankers and the product was inferior. This new PEX is amazing stuff. I tell my potentil customers that if we were to put PEX in their concrete slab and the world were to explode they're concrete slab would be found floating in space still in one piece.
I GTG, lunch then a lecture on the forensic investigation at Little Big Horn by the guy who led it. I'll check back in later today
Take care all!
Post by: K Frame on January 27, 2007, 07:19:20 AM
We expect a FULL report on that in another thread!
As long as your sub base is properly prepared and the correct styrofoam board is used I don't see how the slab would be any more prone to cracking than when using any other type of insulation.
Compaction of the sub base is absolutely crucial to maintaining the integrity of the slab, no matter how it's poured.
My only concern with insultarp is...
Have any independent studies been done on how much effectiveness it loses due to the compressive weight of the slab on it?
Post by: 280plus on January 27, 2007, 07:31:12 AM
I'll check on the R value thing.
Post by: 280plus on January 27, 2007, 07:33:43 AM
http://www.radiantmax.com/insul-tarp.html
Post by: K Frame on January 27, 2007, 08:36:54 AM
Think of it this way...
The slab and the panels are dimensionally very close to the same size -- that means that the entire surface of the styrofoam is bearing the weight of the slab, giving an extremely low pounds per square inch value on the styrofoam.
It's like when you go out on thin ice... if you're standing, all of your weight is concentrated on your feet, and you'll crack the ice surface. If, however, you lay down, the ice can support you because your entire weight is being supported by a much greater area of ice.
Granted, the installation of panels is much fussier than the tarps because the subsurface has to be very flat and very well compacted. With the tarp, you don't have to spend nearly as much time leveling the surface -- it still has to be highly compacted, though. If it moves, the slab is going to crack.
Don't get me wrong, I'm not advocating one against the other. I can certainly see advantages to the tarp, if it works as advertised.
Hum... In reading through the Insultarp information it's being a bit disingenuous... It gives the impression that there's no under-slab foamboard on the market that can mitigate radiant heat loss. That's a lot of "hot air" so to speak. Slab-Shield is but one of the faced under slab products on the market.
Oh SNAP!
Check out the letter from the Federal Trade Commission on this website: http://www.thebarrierinsulation.com/7128.html?*session*id*key*=*session*id*val*
"...it may be misleading for industry members to suggest that such foil products will reflect radiant heat when installed under concrete.
Interesting. And the underlining is in the letter...
Post by: 280plus on January 27, 2007, 11:50:15 AM
Oh, actually not too much exciting stuff at the lecture. The interesting part was the Cavalry only had 2 weapons, the 1873 Springfield trapdoor carbine and some kind of Colt pistol, I can't recall what it was exactly. Turns out the Injuns had no less that 47 different kinds of firearms from all types of cap and ball to the 1876 Winchester repeaters which were the cutting edge of the technology at that time. The Guy (Dr Douglas Scott BTW) says MOST of the weapons used by BOTH sides in the battle came from CT and Springfield Mass. They actually located lots of empty brass and through the magic of ballistics were able to determine which rounds were fired in which gun and how that gun made it's way around the battlefield. Short lecture but informative. The ratio was 210 soldiers to 1500 indians. Not very good odds I'd say.
