Staple-up radiant without heat emmision plates

heatboy · February 2003

Justification?

I don't know what you mean by the phrase "The heat loss wasn't there to justify spending the extra $3000 on plates." Who couldn't justify it? You or your client? If the load is that small and the "budget" is tight, maybe the best option would be to use the plates then use a water heater , such as a Bradford White TTW2, with a heat exchanger to take care of heat and domestic hot water. That way, the client still gets the ultimate in joist bay heating while keeping budget costs lower with the water heater, which can be easily upgraded to a quality boiler when the budget allows. That certainly doesn't sound like a Cadillac system, does it? But it is a way to get much more efficient heat transfer to the actual structure.

At 15 btu/sq ft/hr water temps are going to be in the 150° range. That's if it is a hard surface like tile or wood. While that is already unacceptable to me, it will work. With extruded plates, your water temp drops to less than 125° making your heat plant all that more efficient with the lower water temps the radiant requires. That starts to cut into the extra money plates require in upfront money. Win-Win. It is my job as their resource to show them all of the benefits of plates.

heatboy

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Boilerpro_2 · February 2003

Just did that too....

Makes alot of sense, put the heat where you need it the most and supply floor warming for the rest. The house I have set up this way does not have the insulation behind the tubing in yet and it is staying comfy in our sub zeror weather

Boilerpro_2 · February 2003

Just did that too....

Makes alot of sense, put the heat where you need it the most and supply floor warming for the rest. The house I have set up this way does not have the insulation behind the tubing in yet and it is staying comfy in our sub zeror weather

Boilerpro_2 · February 2003

Dave, somthing looks fishy about those numbers

How are you getting the same amount of heat output from a floor with a surface temp of 104.7F, one at 81.4 and 80.6?

Boilerpro

Boilerpro_2 · February 2003

hb, only at 150 few hours a year

Not going to see much efficiency gain in the boiler if its not a condensor at 125 vs 150 design temp. Also that 150-F system is only operating at that temp a couple days a winter with reset controls. In my 6000 DD climate 90% of the season its running about 120F.

Boilerpro

Unknown · February 2003

You can get 150 degree water out of several water heater units, so where is the need for plates to bring that down to 125 (if indeed that is the outside limit of your heating needs)? You're still dumping $3k or more into plates that may not even have a payback period!

POINT IS... there *are* jobs that do not need plates. As I have pointed out, I am not a proponent of plateless jobs, but to refuse to acknowledge this one simple statement... that the situations exist... dont' know what to say. You're wrong. Sorry.

Hell the guy I was originally responding to would rather put in a forced hot air system, or BASEBOARD running 180 degree water temperatures, rather than cave in and allow his customers to have radiant comfort if it doesn't live up to his standards of what radiant "should" be... even if it delivers on the comfort for a price in efficiency, it's still more efficient than forced air and probably more efficient than baseboard. Now is that wise? Still failing to see how it's better to go baseboard or Forced hot dust if push comes to shove and plateless is adequate to meet the heating needs.

BUT WAIT maybe we should make all baseboard systems that don't use the proven efficiency-improving reset controls non code too!!!!!! They aren't what baseboard "should be"!!!!

If you want to talk *energy* code... and require reset controls on baseboard... I'm fine with that. Big, Big fan of energy efficiency and I push it as hard as I can. But unless you want to do that, I'm tired of seeing people trash methods of installation that work even if it is dead last on my list of preferred methods. And this call to make it non-code is completely ridiculous. Non-code applications should be applications that are dangerous or DO NOT WORK. Plateless CAN WORK. If some guy undersizes a baseboard unit in a cold room do you blame the baseboard itself?

Hit the designers/installers when things go wrong. It's not the installation's fault it was put in where it shouldn't have been.

hot_rod · February 2003

excellent

question. Look at the thermal image located (somewhere) above. The tube only application shows a fairly narrow band of high energy while the plated version shows wide disbersement of thermal energy. I have to believe the Wirsbo program designers took that into account & that that is represented in those numbers. Striping of high temps vs more even wide spread comfort.

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Unknown · February 2003

actually the "staple directly against the subfloor" method is no longer recommended by wirsbo and hasn't been for a few years. They now recommend a 2" airspace from bottom of subfloor to top of insulation with the tubing hanging in clics or long leg staples so that heat striping does not occur. The staple up method they recommend instead relies heavily on convective heat transfer to the floor via the airspace rather than trying to get direct conduction out of a fraction of an inch of physical contact between the tube and subfloor, which was a joke anyway and result in.. heat striping.

That kind of temperature variance, especially at the water temperatures you're dealing with in plateless applications, isn't good for floors or comfort.

hot_rod · February 2003

HB is wrong?!?

If that's the case, I'm going back to scorched air & heat pumps(G).

Tell you what, I'll confess. I thought that way too & did my house without plates (forgive me father, for I have sinned). Partially based on price, but mostly based on piss poor advice from a salesman who - to this day - continues to mislead, beguile and otherwise convince unsuspecting mechanical contractors that he's got the answers.

Over the lifetime of my home and my existance within its four walls, I will one day rip up and tear down what I have done and if I still have a staple-up system there will be plates. In my mind it has no connection to payback and I never promote radiant work using payback. For me it is the comfort and ongoing economy realized from top notch well designed systems. Are there applications where no plate strategies weigh in as being better than utilizing extruded plates? Maybe. I haven't found one yet, but I have installed a few - reluctantly. But only after I've presented the options available.

Two other suspended applications I've had the pleasure of rescuing this past week. One where the pumping strategy and tightly packed-to-the-floor-deck insulation combined to choke off output and the second being run off of an electric water heater. At least they used a FPHX. Problem was just like you indicated - lower water temps from the water heater than they could have obtained from a boiler. Oops - not enough output. So, they raised the thermostats to within upper limits, created scalding potential (their complaint - not mine) and still can't meet the heat loss. Plates will ratchat up the overall performance, deliver what's needed and - perhaps more importantly - lower the outlet temps for safer bather contact.

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hot_rod · February 2003

suspended, not staple up

that's what they've based those numbers upon according to their latest 5.0 program version.

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Unknown · February 2003

well you're absolutely right... as i noted several times, I too only reluctantly go along with plateless installs (as I noted my ratio was rather low, less than 1%

). yes there aren't many times which plates won't be a major advantage, but those times *do exist* is all I am saying.

and the water heater units I prefer to deal with.. Polarises.. run best above 140, we use tempering valves to prevent scalding on the DHW end if it's doing double duty, whether we need it or not (never know if some defect can cause superheated water, right?). *Always* better safe than sorry there. Course in that case (double duty water heater) you have temp drop across the heat exchanger as well, further reducing your output and requiring you to be sure of what you are doing.

I've also seen my share of jobs improperly installed.. it's always bad. And misinstalled (installed badly or in a place it should never have been used) staple up is indeed a relatively common problem.

It sounds like we get the same charge out of truly great, elegant systems though

.

Unknown · February 2003

whups... thought the picture was showing tubing stapled direct to the subfloor *ulp*...

Boilerpro_2 · February 2003

Twas thinking that

Those temp numbers must only be the peak temp at the hot strips, not average flor temp. Only thing is, I thought that one of the things that is promoted about suspended tube (by Wirsbo,I believe) is that it doesn't strip because of the indirect heat transfer, which does make sense. I guess I am going to go back to the suspended tube job (with plates under the windows) I just did and take some floor temps. BTW, This job is heating just fine at near design temps despite large glass areas, high ceilings and they haven't installed the insulation behind the floors yet. Surprised me, but much of the large glass areas face south.

Boilerpro

Boilerpro_2 · February 2003

Design changes

I'd also check and see if the house was actually built as was communicted to the system designer. My first rad floor job wa for an old home being renovated. After the system was designed and in, the homeowners decided to tear off the old wood siding down to the T an G sheathing and wrap it with one of those cheap perforated house wraps, as recommended by the siding contractor. Now, the system couldn't keep up, so therfore it has to be a system problem. I could walk around the home with insulated walls and they were ice cold for about 2 feet around every window on the first floor. My belief is that perforated house wrap was allowing tons of air into the walls as it passed through wide gaps in the T & G siding, washing through the insulation. It was more prevalent on the first floor because the cold air would enter the bottom of the wall and warm up and the walls were then warmer upstairs. Despite the fact that the owner had a friend run a heat load calc... not radiant though... and the system was putting out that much heat and couldn't keep up, it still was considered my fault. I coughed up the time and materials to add additional capacity, instead of the siding contrator. Sorry for venting, this still gets my goat.

Boilerpro

[Deleted User] · February 2003

What happens

when the new homeowner moves in and drops a wool Indian rug on top of the hardwood floor? Can you turn it up and compensate? Or do we become interior decorating cops and tell them they can't have their heirloom rug?

I can tell you what I can do with plates in place...

I do agree, there is a place and time for everything. As Dirty Harry once said, "Sometimes ya just gotta know your limits.."

Suspended tube does not work everywhere contrary to popular opinion. It also cost more to operate, for which I feel a definate responsibility to my customers.

When the environment revolts, and we're REQUIRED to use solar as our heat source, suspended and stapleup WILL be outlawed. It may not happen within my life time, but mark my words, it will happen.

As for the theoretical limit of 80 degrees F for hardwood floors, if this is true, why do they allow it to be installed in rooms with south facing windows where it will typicall be seen at temps around 120 degrees F?

Makes ya wonder, huh,,,

JM$0.02W

ME

Boilerpro_2 · February 2003

Yup,

I always tell potential radiant clients the same thing when they ask about potential damage to hardwood floors.

Boilerpro

Unknown · February 2003

well when that happens you can use solar electric to run a geothermal heat pump to get high water temps if necessary

If you're using solar hot water collection, at least up here in new england, plates are not going to help. You need high mass for that or a severely large array of panels. You can't reliably provide even 120 degree water up here in the winter at least.

And for radiant you are a bit of an interior decorator cop. I've seen more than one plate job underperform because new owners came in and put down big thick area rugs without thinking. You're still limited by the amount of output you can get from the uncovered floor; that's a little higher with plates, but still limited.

Now the floor temp requirement you mention.. THAT is something I'd be willing to see in a code!!!

Steve_11 · February 2003

Staple-up radiant without heat emmision plates

opps, see next post, sorry for the double post

Steve_11 · February 2003

Staple-up radiant without heat emmision plates

Since we have all the knowledgeable fellows following this thread let me ask if heat plates are necessary in my application?

I am contemplating a staple up in my 800 square foot floor plan. This system will be secondary to the natural gas forced air that is in use now. 1 5/8" subfloor and hardwood throughout. Bathroom tile. Joists 16" on centers. The insulation is as follows. R40 in the 9ft ceilings and old R12 in the 2x4 walls ( thats optimistic!)Aluminum clad slider windows ensure plenty chill to the existing situation! R12 in the basement walls too.
The radiant floor will supplied by a Rheem 60US Gallon 50 000 btu input that will do double duty providing domestic hot water. I am hoping to run 1 zone and two circuits with either 1/2 or 7/8" pex. I am leaning towards the7/8" pex as I'd like to run cold water through the system in the summer for outdoor watering. Might as well use it to do the reverse in the summer, and 7/8" will allow for this option.

So the question is, knowing that this system is secondary to the forced air already in place, Do I concern myself with adding plates? The basement is heated by the way.I am looking to make my home feel warm in the cold Canadian winters(-30 degrees possible) I am going to finish the basement after this is installed so a little heat in the basement will be a good thing! A foiled fibreglass batting Or perhaps if I add plates then the radiant will become the primary and the forced air secondary?
Let the plate debate rage on! Your inputs greatly appreciated,
Steve
Calgary AB

ps
remove the _butspammenot from email address to reply direct

Staple-up radiant without heat emmision plates

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