radiant floor heating prob

Dave_4

So with that said, should i just go to pex and plates? I am installing it all myself...I don't know what way to go now...

phil_23

poor heating transfer

I have a 2500 sq. ft house in which i installed a staple up radiant system I used the entran onix tubing as sold by the local supply house. They sized the job and said i needed 4000 ' of tubing in 200' lengths There are 3 zones. the floor consist of 3/4' subfloor with 3/4 t&g heart pine flooring. I am sending out 140 degree water, heated by propane furnace, and have a return temp of 133-135 degrees. My floor temp never gets over 70 degrees and when its cold out in the teens and twenties for a week or so the house temp falls I cant get any rise in temp in the house.I have r-13 insulation wiyh a foil face between the joist below the tubing to create a heated air space, but it to never gets over 80 degrees. I am using a lot of gas and still have a cold house, what is wrong. i have bled this system several times for air blocks, butit doesnt help .I am open to suggestions.cold in md.

kevin coppinger_4

a couple of ...

things...What is the heatloss? Lot of windows? How is the temp in the basement? Toasty? What in the circulator size? are ther zone valves? or is it one zone? You may need to increase the water temp...add supplimental heat...add insulationor shorten your loops. Are you getting

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Alan(OnVacationInOregon)Forbes

Entran

Onix is a good product. We used it twice on jobs in San Francisco in the 90's and it seems to be performing well, but that's on the West Coast where we have a Mediterannean climate.

Without the Entran snapped into aluminum heat accelerator plates, your output is limited. I'd check with Watts to see what the maximum temperature water Entran will take and raise the supply water temperature.

Your system is obviously not providing the ouptut necessary to overcome the heatloss of the house.

Mike.C

my guess'

What pump are you running. if your return temp is that high you are either pumping it too fast or the floor just can't absorb the btu. Did you use any heat transfer plates on the tubing? If you don't have plates I would seriously reccomend them!! Barnett sells them that just cover over the tubing and you staple them to the floor with a hammer tacker or pneumatic stapler. They are aluminum and work really well.I believe there was an article not too long ago in P&M by John S (can't remember how to spell his name)
about if you don't use plates don't even bother trying to heat the house.Hope this helps.


Mike.C

hot_rod

is it over un-heated space?

If so that is not enough R-value. At least R-19 in my opinion.

Was it staples AT LEAST every 6"? Also be sure the foil faced insulation was not pushed against the tube. It needs the air space.

Like the others suggested, check the heatloss for those zones. If it is over 20- 22btu/ft. I doubt that temperature will get you there.

Remember a 8.5 to 10 degree loss through the tube wall itself. Depending on who's numbers you use.

hot rod

Glenn Sossin_2

Seems Like you need the plates

Your Delta T (difference between supply & return) is very low, which indicates that either you have a very high flow rate, and/or, little transfer of heat energy. I would opt for the latter, and agree with the prior comments fully.

Pumping the heat energy around in the tubes is one thing, getting it out of them and to your floor is another. Foil, is certainly a plus - properly installed, but air has virtually no mass, it can't carry/conduct heat energy very well. This is why the HVAC guys push around hundreds of cubic feet per minute to heat a typical room.

Somebody screwed up here. It sounds like you need transfer plates around the tubing to draw the heat out of the tube, and conduct it to the underside of the sub floor. You will see a tremendous difference in the ability of your system to heat your home.

A properly calculated heat loss is necessary to design your system properly. Assuming the heatloss is correct, the delivery system doesn't appear to be. Pine has a higher R value than typical 3/4 oak - approximately 33% higher. Did your supply person know this ?

I agree with the other comments- the plates are a missing component.

Glenn Sossin_2

IR Pics

HR post those pics again of the tube with and without plates. That really tells the story better than words.

hot_rod

FEA models

show the difference between plates or direct tube staple up.

What I believe happens with tube stapled up is you get the 82F right above the tube, but not much beyond that. So how do you calculate that 2btu/ sq. ft./ degree difference. You would need to do a heat flux model to determine the % that's at the various temperatures.

The FEAs match my infrared experiment very closely.

Carpet does spread that pattern fairly well, but the R-value works against you also.

Direct staple up as well as dangaled tube can work, but the output numbers we frequently see published are a tad on the high side, from my experience.

It's the design days, and below that customers notice the shortfall

hot rod

Unknown

I'm finding this interesting as I have a house right now where I ran 300' x 1/2" lengths of HePex suspended 1 loop per bay and insulated in the same manner with about an 1 1/2" air space. I have no problem heating the floors to 77* with 120* water. I'm running it at 110* right now and find my first floor wants to settle out at 73* with constant circulation but the rest all satisfy 77*. The basement is heated by the slab to 67* so none of the floors are over unconditioned space. What is the temp in the space under these floors you are heating? or, might more R value under them help? BTW my floors were designed for warming not heating and the house is not yet occupied so I'm still experimenting with water temp etc. I'm finding a 77* main floor tends to overheat the space on milder days.

additional FYI My floor sensors are centered between the tubes and are insulated so they are sensing floor temp not airspace temp. and at what should be the coolest spot in the floor.

hot_rod

A floor temperature of 77F ?

in a room with air temperature of let's say 68F that is @ 18 btu/ square foot output. Fine for warming, although 77 will not feel warm when skin temperature is 82F -ish.

hot rod

Unknown

Yea, it was sold as warming not heating. I only did what were supposed to be tiled areas. Some tile turned into hardwood but that's another story. All the house is heated hydro air, the way it is the floors and the slab in the basement do a pretty good job down to ~25* ODT before any air handlers kick in I'll guess. Of course, I'm only heating it to 65* right now. It's still under construction. Almost done though!

I think I'm glad I didn't try to do heating without plates however!

Tim Doran_4

Insulation & Infiltration

I would suggest that you get more insulation under the tube and that you chech the insulation at the rim joist. Any un-insulated area at the rim joist can have huge losses and any air blowing into the joist bay can be a big problem.

Tim D.

jp_2

77F is a warm floor

maybe its age but I think 77F is warm, at least a tile floor.

think of putting on fuzzy socks in the winter, they are at room temp, but soon after you put them on, boy your feet feel warm and toasty, but the sock contain no BTU's to heat your feet.

joel_19

HR

> maybe its age but I think 77F is warm, at least a

> tile floor.

>

> think of putting on fuzzy socks in

> the winter, they are at room temp, but soon after

> you put them on, boy your feet feel warm and

> toasty, but the sock contain no BTU's to heat

> your feet.



Where can i download those FEA models???

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Unknown

I sell it as "just taking the chill off the floor" and explain that the floor won't feel warm, it just won't feel cold. I've noticed that if the floor DOES feel warm it gets too hot in the space above.

jp_2

heating vs floor warming??

i don;t really get that, seems to me if the whole floors 'seem' warm, its going to heat the room, standard house I'm talking here, not a warehouse.

how can the floors be warm and the room not? unless theres no insulation, but then it seems the floor will not get warm then either??

I've yet to hear a compliant that the floors were 80F but the room only 62F?

john_83

Onyx

Phil i install miles of this stuff and i never really have any problems i know alot of guys feel you need higher temps but if properly installed and designed this product works well. I've been installing this onyx for quitesome time and have never used plates and i use 3/8 onyx so your already ahead with 1/2. First as far as i know heatway reccomends R-19 foil with a two inch air gap not R-13. Also any unheated area above the area your having the problem Ex. lofts or open rooms to below create a waterfall effect of cold air downward. Also make sure your entire box band or rim joist is insulated so the heat cant escape outward. In my expierance 140 is high for your smaller zones, Zones with a lot of heat loss Ex. Glass high ceilings etc require greater temps. Also Check piping to manifolds and pump Sizing thse all contribute to system performance. Besides if your house is finished you cant think about plates at this time anyway. I have never used them pex installers use them .

Unknown

oops...

Unknown

It will heat the room down to a certain ODT but once the real cold hits they can't keep up, then the hydro air kicks in to make up the difference. The idea is I already have to have air handlers for A/C why not use them to heat as well and save $ by only warming key floors (kitchen, baths and foyers) instead of the whole house? FYI I used gas fired chiller/heaters and I get chilled water and hot water through the same tubes so on this job I only had to run 2 tubes to each A/H to feed both heat AND cool, saved a few dollars there too.

hot_rod

J-P, the socks

are adding r-value to your feet. If the floor surface is cooler than your skin temperature ... heat flows to cold, always.

The socks slow the transfer from the warmer surface (your feet) to the cooler surface of the floor.

The colder the floor surface, the thicker the socks you would need


Have you ever heard Holohan explain his trip to the supermarket?

He takes a thermometer down the dry foods row and records an air temperature of 72F.

Next he moves over a row to the frozen food aisle with rows of glass freezers. What is the air temperature in that row?

hot rod

Dave_4

Onix

I second John. I'm a home owner with Onix for radiant under oak floors which works fine. The floor surface temp is 80* with a water temp of 140*. When the outdoor temp dips below 10*F, the water temp goes up to 150*. Check the band joist insulation, which you may be able to do with thermography if the underside is covered with a ceiling. Also verify your heat loss accounts for the pine floor and any carpeting. You may need a supplemental baseboard for the really cold days.

Weezbo

Cold enough to bring the heat out of my bodyand...

produce Frostbite on my hands....

[Deleted User]

onix

To John and Roger, Do you think that adding plates to Onix 3/8 tubing would help? I had a design done that calls out for onix 3/8 tubing, 140 degree temp, one zone, approx 1,200 sq ft, very open great room with loft, 2 sky lights and lots of windows, and now after reading this, i am concerned about running into the same problem? BTW, this is over a 3 car garage, TGI -joists, and I am currently in the building stages. I have a hot dawg heater in the garage. I wouldn't mind spending the extra money now if it would definitely help putting plates on...I'm new to this and doing it myself, so i am getting concerned!

Thanks for any suggestions
Mike

[Deleted User]

forgot some more info

I currently have a 2,400 Sq Ft rated gas fireplace installed in the great room, and a small bed and breakfast gas fireplace in the master bedroom next to the great room. All gas is propane....

Thanks Mike

ALH_4

Onix

This is the problem with bare staple-up tube, particularly Onix. The thick wall of the EPDM tube works against you, and the price is higher than pex. Once you pay for labor to install sheet metal plates and Onix, it is no longer economically competitive with pex and extruded plates, and it will never perform as well as pex and extruded plates. Additionally, I question the Onix oxygen barrier, which appears to be foil faced mylar.

As Hot Rod mentioned, I also find the published output numbers of many well known RFH products very suspect. Unfortunately, when published output numbers are not achieved, the blame falls on the structure.

Onix staple-up is much easier to install than pex and plates. You can kink it and it springs back. This is the primary selling point in my opinion. Onix works fine if you have a relatively low heat load, but even then you are using a higher fluid temperature than you would with pex and plates.

ALH_4

vag1fr45,vag1fr45,125vd4sghg

I think pex and extruded plates is the way to go, but there are a lot of installation methods that work well.