Things I like to hear from my customers...

[280plus]

In regards to that huge house where I have been installing the fancy newfangled heat pumps and all that floor warming. It's all up and running and and complete with minor exceptions. Today I talked to Mrs owner and she says, "No matter where we go in the house there isn't a cold spot anywhere. The whole place is nice and toasty warm." Now there's words that'll warm the heart of pretty near any heating contractor. 

Incidentally, I am only running 105*F water in the system.

[Perd Hapley]

Good job.

[280plus]

Thanks man, could I interest you in an $18,000 heat pump? Actually, I'm jealous now cause the heat here in my house SUCKS!! But ain't that the way it usually goes? 

[K Frame]

105?

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.

[280plus]

Yea, 105* Aint it cool? uh,warm? 

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? 

[Ron]

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

[280plus]

Just call me "Zippy", no wait, Zippy is a horse! 

[K Frame]

Oh, no doubt that they're on toaster heat.

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.

[Fly320s]

280,

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

[Ron]

Another question, do you have the boiler temp controlled by some type of outdoor reset that will raise the boiler temp as the outdoor temp drops?

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

[K Frame]

Uhm...

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.

[280plus]

The house is what I call a hybrid. What I have done is heated the slabs in the basement and garage as well as warming what were SUPPOSED to be all tiled areas in the house: kitchen, bathrooms, foyers etc. I don't normally warm under tile or wood. Mr homeowner put down wood instead of ceramic tile in certain areas against all strongly worded advice. Now he's whining because the wood (mahogany of all things) is shrinking and the seams are separating. But that's another story. Anyhoo. The concrete slabs are designed to heat the spaces and are controlled by air sensing programmable T'stat's that I actually set back 1*F during the day, so they are storing heat overnight during off peak electrical times. The upper floors are designed only to warm, not heat, and are controlled by floor temp sensing t'stats that limit the floor temp so it doesn't get too hot in the space. Right now they are set for 77*. This makes up the bulk of the heating to the house and will satisfy it to at least down to 20* outdoor temp. The rest of the heat consists of 6 small air movers with hot water coils and set to run on the lowest speed (for now) They are all controlled by programable air sensing T'stats which I set back 3* at night. What I am doing now is "testing" for the minimum temp that will heat the floors to 77* at low outdoor temps. So far 105* with continuous flow seems to be doing the trick, though I haven't been there to see what it's doing now that we have some true winterlike temps going on, but the homeowner is happy so I'm happy too. I may still have some tweaking to do. If I wanted to crank it up and get it to 80* all I have to do is call in the air handlers and that will take the temp up, though it would take a while becasue of the low water temp and the low air velocity. The object with the air is to have no register noise and so far so good. The guy wants absolute silence.

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. 

[280plus]

One thing I have found with heating the concrete. If I set the water temp at 90* and let it run continously, the affected space will become unbearably hot in about a day. 
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. 

[Ron]

My understanding of heatpumps is pretty limited. I didn't even realize you were heating the water in the system with them until your last post.

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. 

[280plus]

Yea it is, just beware of the hardwood. If you don't keep your humidity up to ~50% the floors will shrink.

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.

[K Frame]

If you understand how an air conditioner works, then you understand how a heat pump works.

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.

[280plus]

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.

[Ron]

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.

[K Frame]

Most of the industrial-style heat pump systems used in commercial buildings aren't used to heat at all -- they're water chilling units only.

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.

[280plus]

Righto on Levittown. What was being said was the lime in the concrete was eating away the copper. I Used PEX or actually HePEX which has an oxygen barrier to prevent oxygen infiltration and subsequent rotting away of ferrous components. Almost ALL the tubing I used was HePEX, I used very little copper. Something on the order of 8400 ft of tube went into this house. I did it this way because its way easier to pull a flexible tube 150 ft to a spot than it would have been to run and solder copper pipe everywhere.  I chose chilled water as a cooling medium becasue I could use the same coil and tubes to feed the air handlers as opposed to having to pipe heat and A/C seperately. It cut a LOT of labor and materials out of the picture doing it this way. Not to mention 6 condensers around the perimeter of the house and 6 high amperage electrical feeds to power them.

[K Frame]

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.

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!

[Fly320s]

How does one insulate under a concrete slab or along basement walls?

[K Frame]

HePEX, is that the stuff with the aluminum shield? Or is it the reformulated PEX from Wirsbo?

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.

[280plus]

Wood fired gas absorption HP. I think we're on tho something!  

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.

[280plus]

I'm not sure exactly what the barrier is. I know they use aluminum but not in this case. I AM using Wirsbo and supposedly all the kinks have been worked out.

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!