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?air space between staple up with plates and insulation
radiant_4
Member Posts: 30
Had our staple up radiant replaced with staple up with plates at contractors suggestions since it was not heating efficiently. Should foil faced fiberglass insulation still have 2 inch air gap for best results?
0
Comments
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If you have a gap, the heat will be more even.
Ron0 -
why did you replace your staple up?0 -
Original design was not suited for our situation, unfortunately we found out after the fact. Geothermal hydronic radiant and designer said rubber staple up without plates would suffice. Wrong.0 -
Just seemed odd that removing staple up to install pex with plates, would help.If transfer is a problem with the poor design, why not a new design with the same staple up materal?0 -
If the tubing is installed at 8" o.c. and has plates, that is not a concern. The airspace will also lower output.
Having insulation right up to the bottom of the plates is best practice for plate applications. The 2" airspace for stapleup/suspended tube is to create convective loops which are not needed or desirable in a plate application.
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I'm not following. You mean just putting plates on existing (edit: tubing), I assume?
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I'd skip
the foil faced insulation with a plate install. If that foil touches the aluminum transfer plates it will conduct a small amount of heat away from the goal, I suppose. Foil faced is not really needed with conduction transfer.
I suspect you already have the foil faced from the staple up install??
Actually if you are above unconditioned space the foil should really be on the down side for a vapor barrier in most cases. This was the original intent of foil faced insulation, not really a radiant heat reflector. Dust and printing on the foil pretty much puts the breaks on the reflectivity. In my opinion and experience
With aluminum transfer plates 8" on center you should get a stronger transfer than just bare tube stapled against the subfloor, and even more if the tube was just suspended below the floor. Especially with the low, below 120°, temperature common with geo heat pump systems.
Still the original heat loss and design should spell out the supply temperatures needed to meet the heating load regardless of the method. Maybe run a new calc with as built conditions and floor coverings to double check this important number. Pretty low output, according to the experts, from staple up with 120 or less supply.
Now if the old tube was rubber, by chance, you will have about a 7° delta t between the actual fluid temperature and the outer wall temperature. This too may work against you at low supply temperatures.
The key lies in the actual load (BTU/ sq. ft./ hr.) you need to meet to heat (the space) The heat load may still be beyond the reach of a transfer plate install, with just geo temperatures. Most manufactures have output charts available to help you determine output at various suply temperatures. Try www.radiantenginnering.com for the best transfer plate data and experience.
hot rod
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Thanks for the input. Now if we can only get the contractor to return our call.0 -
> Had our staple up radiant replaced with staple up
> with plates at contractors suggestions since it
> was not heating efficiently. Should foil faced
> fiberglass insulation still have 2 inch air gap
> for best results?
Ron0 -
Hi radiant,
Since even most insulation contractors don't fully understand air barriers, vapor barriers and radiant barriers, it's not surprising that there is some miss-information about them in this thread.
The foil should face up and have a space whether it is a staple up or a plate installation. With staple up and even more so with suspended tubing installations, the gap should be at least 2" since they rely on both radiant and convective heat transfer. With plates or tracks, the size of the gap is not as important but it should at least be enough to not touch the tubing. Having an air space will slightly raise the output not lower it. If the insulation does touch, there will be a slight reduction in output since a little more of the energy will be conducted downward. The gap will also reduce heat striping with all kinds of under floor tubing installations.
Since the foil will also act like a vapor barrier, it should face up to keep moisture from the house from migrating down into the cooler parts of the insulation and condensing there. The moisture from the soil will not condense in the insulation since the insulation will be warmer than the air in the unconditioned space. Don't forget to insulate the ends of the joist bays.
An air barrier (not a vapor barrier) would be benificial below the below insulation to keep the air in the insulation stagnent which gives a higher R value and also reduces infiltration of warm moist air into the conditioned space in the cooling season. If you put a vapor barrier below the insulation in an unconditioned space, it should be just on top of the soil not just below the insulation so it can reduce the moisture in the basement or crawl space.
The foil's radiation barrier capabilities will degrade somewhat with dust and printing but it will still be better than no radiant barrier at all.
Ron Schroeder
WD8CDH
Brookhaven National Lab
NABCEP Certified Solar Installer0 -
I beg to differ. Output has been studied for insulation gaps below plate systems, and you lose output with a 2" air gap if you are using plates. Not a lot, something like 10-15% if memory serves, but for a minor installation detail and no difference in cost why not go for the best? If you use insulation up near the bottom of the plates... that is, furthest point from the subfloor... you get about a 5/8" airspace which is ideal for plate systems, at least according to the research I've read. Perhaps back off a fraction of an inch from the tubing if the conductive loss is troubling.
"Better than no radiant barrier at all" may be true, but any radiant barrier in the joist application is not worth the money to get it in there, unless you are going for the vapor barrier and it's not much more money to make it a radiant barrier as well for some small amount of benefit. From the heating system and envelope standpoint the money wasted on a radiant barrier there could go to something else. Better (or any, if you're comparing to a suspended tube) plates or more real insulation for example would both have far greater and far more reliable long term benefit, IMHO.
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> I beg to differ. Output has been studied for
> insulation gaps below plate systems, and you lose
> output with a 2" air gap if you are using plates.
> Not a lot, something like 10-15% if memory
> serves, but for a minor installation detail and
> no difference in cost why not go for the best?
> If you use insulation up near the bottom of the
> plates... that is, furthest point from the
> subfloor... you get about a 5/8" airspace which
> is ideal for plate systems, at least according to
> the research I've read. Perhaps back off a
> fraction of an inch from the tubing if the
> conductive loss is troubling.
>
My studies were done by putting different insulations in different bays on the same floor and viewing the floor with a FLIR thermal imaging camera. With the plates, a gap of 1 to 2 inches showed a higher floor surface temperature than with the insulation touching. There was very little differance between a 1" and a 2" gap, in fact a 4" gap was about the same too. The tests were with R-11 foil faced fiberglass batts. Foil down was also always slightly worse than foil up.
> "Better than no
> radiant barrier at all" may be true, but any
> radiant barrier in the joist application is not
> worth the money to get it in there, unless you
> are going for the vapor barrier and it's not much
> more money to make it a radiant barrier as well
> for some small amount of benefit. From the
> heating system and envelope standpoint the money
> wasted on a radiant barrier there could go to
> something else. Better (or any, if you're
> comparing to a suspended tube) plates or more
> real insulation for example would both have far
> greater and far more reliable long term benefit,
> IMHO.
>
If the Radiant barrier had to be added, I wouldn't do it either but if you have a choice of foil faced batts or kraft faced batts or unfaced batts for about the same price for under a radiant floor, go with the foil faced ones.
For a sidewall or some other application with no air space, then unfaced is the best choice since you can usually get a better fit with no gaps against the studs. (don't forget a poly vapor retarder on the inside with unfaced batts.
Ron0 -
not trying to be difficult, but you are contradicting the study I saw sometime last year on this, slightly, so please understand why I'm not just taking what you say at face value without questioning; absolutely nothing personal!
Can you describe the test setup in more detail? You sound like you know your stuff, but a 10% drop in output would be a small variation in surface temperature and many things could contribute like proximity to outside wall and joist position on the loop. Did each joist bay get its own dedicated loop, for example? How precise is the thermal imager you used?
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> not trying to be difficult, but you are
> contradicting the study I saw sometime last year
> on this, slightly, so please understand why I'm
> not just taking what you say at face value
> without questioning; absolutely nothing
> personal!
>
> Can you describe the test setup in
> more detail? You sound like you know your stuff,
> but a 10% drop in output would be a small
> variation in surface temperature and many things
> could contribute like proximity to outside wall
> and joist position on the loop. Did each joist
> bay get its own dedicated loop, for example? How
> precise is the thermal imager you used?
>
> _A
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> 340&Step=30"_To Learn More About This
> Professional, Click Here to Visit Their Ad in
> "Find A Professional"_/A_
Ron0 -
Hi Rob,
I am sure that the differances were way less than 10% output because the surface temperatures differances were less than 1 degree. Each bay had it's own loop and the loops were within 1" of the same length. They were plumbed reverse return to further help the flow balance. I only changed a couple of bays near the middle of the room to eliminate the near wall effect. Also as a control, I looked at the evenness of temperature with the bays all insulated the same. The thermal imager would show temperature variations of less than 1/10 degree F and had a "false color" display. I could place my hand on the floor for one second and the imager would show the residual heat like it was a wet paint palm print.
Although the differances in surface temperature were so small that they would not make any measurable fuel usage differances in the real world, the imager showed the bays that were insulated differently almost like they were spray painted with a different colour.
Ron0 -
wow that sounds like fun
I'm gonna have to get one of those toys!!!! Thanks for the detail.
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I'm with Ron on this one. Would like to add that the space allows the angle of reflection to spread the reflected heat a little wider making it more even. Never did buy into the dust thing much either - Physics teaches us that energy is never wasted - even if the dust absorbs the heat it has to get reflected back up at some point - More than anything... A vapor barrier ALWAYS goes toward the heated space... I've seen more mold, rot, and termite damage from condensation due to improper installation than I can count. Ron definetly knows his stuff...
Kyle Kubs
Benchmark Home Inspections/NJ0 -
just because energy isn't wasted doesn't mean that it's going to go where you want it nor will it necessarily remain in the same form. If it isn't reflected as radiation hitting the aluminum, why would it reflect from heated dust in contact with the reflective surface? Then you simply have a warmer layer that can heat the foil through conduction which it isn't good at stopping.
It seems even Ron agrees that the reflectivity benefit is minimal, that simply having an airspace of a small amount is the benefit he was promoting, primarily, for even heating and reduction direct downward conduction into the insulation... real insulation... that you have installed below the plates.
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slightly different tack
I've been following this thread with much interest as I am pondering the next step in my sandwich system, where the PEX/plates are on TOP of the 3/4" Advantech sub-floor.
The space beneath has 2X10 joists over a crawl space that has overlapped and taped poly on the dirt, and FG filled and poly faced wood foundation side walls. Joist cavity also FG'sd and poly'd.
What insulation/barrier combo would you recommend in the joist bays?
I'm thinking the Advantech subfloor serves as an adequete vapor barrier on the heated side, and I've been assuming that I would get good performance out of R11 or R19 kraft faced with the kraft paper on the BOTTOM, stapled to the 2X10 joist edges. That would be easy to install but WOULD leave an airspace between the bottom of the subfloor and the top face of the FG...also isolate the FG itself from being able to rid itself of any moisture build up. But then where would the moisture come from? The crawl space itelf is entirely sealed, and unless there was a plumbing leak or something, how could moisture migrate down through the advantech?
My wife and I are going around and around on this and we will be the installers...she did most of the foundation wall FG and poly single handed so has strong opinions on this.0 -
I too am at the stage of insulating my floors with a staple-up plate installation and have been following this thread closely as well as previous discussions on this topic. I have 12 inch TJI's on 16 inch centers and my 1/2 inch Wirsbo is on 8 inch centers (we had to have the plates made with the omega grooves offset to get the 8 inch tube spacing). Would I be better off installing R-38 insulation with no air gap or R-30 which would provide a 2-3 inch gap below the plates? I only plan to do this once and would like to get it right the first time. By the way, this is a great site.0 -
Hey Dave; hope the rest of your install went well. Drop us a line sometime to let us know how it's running.
So the question is, does breaking downward conductivity to the insulation provide more or less value than the extra R8 over unheated space.
Well, your heat loads were figured at an R30 floor, first of all, so you are definitely ok there. Shifting that up to an R38 has a very small effect on your heat load. You're getting into the point where there is a diminishing return from additional insulation.
With Ron's thermal info and your heat load data, I would say go ahead and do the R30. Make sure those rim joists are insulated and sealed well though.
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This is
without a doubt, one of the best threads I have seen this year!!!!!! Excellent exchange and very important info!!!
Dan, I think that we should have an award ceremony once a year at the last wetstock of that year to give out the "Wetties" or some such, for things like, best thread, or prettiest picture, or most beer drank in one sitting......~
Funny how things are, in the last couple of weeks, I have been pricing a few staple up projects, which has been very rare. But it just seems that a lot of people are finding out about this radiant thing, and as they reno their homes, they want to be comfortable too! So this topic is like butter on toast for me.
Thanx to all of you who so freely share your knowledge! As I have said before, if the install is done right, no matter who does it, we all benefit!!!
Leo G0 -
Staple Up
Great thread. Radiant heat is by far the most comfortable system I have ever installed. I have been putting Watts radiant onyx in all my radiant remodels and use it for most of my baseboard( high temp) feeds.It doesn't matter what type of tubing you want to use, if you have a lousy design and a poor insulation installation you'll have nothing but problems.0 -
So glad you are enjoying all the discussion and information that our question has provided. For part two of the question: the original fiberglass foil faced insulation was put back up under the thermofin plates and tubing; problem is the basement is over heating. It is a concrete slab with pex and we have turned the thermostat down to 50 yet the temp is around 67 degrees. Obviously coming down through the insulation from the plates and tubes in the basement ceiling? Would more fiberglass insulation help? Thoughts on this one.
0 -
was anything else done to the system? any work on the plumbing or electrical?
adding plates should not increase downward heatloss, if this is a new problem and you're using the same amount of insulation, and it was reinstalled the same way it was put in originally, I would look elsewhere first for a solution. Not say that more insulation wouldn't help, but it wouldn't be the first thing I looked at. Maybe a miswired thermostat or something?
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bump
> I've been following this thread with much
> interest as I am pondering the next step in my
> sandwich system, where the PEX/plates are on TOP
> of the 3/4" Advantech sub-floor.
>
> The space
> beneath has 2X10 joists over a crawl space that
> has overlapped and taped poly on the dirt, and FG
> filled and poly faced wood foundation side walls.
> Joist cavity also FG'sd and poly'd.
>
> What
> insulation/barrier combo would you recommend in
> the joist bays?
>
> I'm thinking the Advantech
> subfloor serves as an adequete vapor barrier on
> the heated side, and I've been assuming that I
> would get good performance out of R11 or R19
> kraft faced with the kraft paper on the BOTTOM,
> stapled to the 2X10 joist edges. That would be
> easy to install but WOULD leave an airspace
> between the bottom of the subfloor and the top
> face of the FG...also isolate the FG itself from
> being able to rid itself of any moisture build
> up. But then where would the moisture come from?
> The crawl space itelf is entirely sealed, and
> unless there was a plumbing leak or something,
> how could moisture migrate down through the
> advantech?
>
> My wife and I are going around and
> around on this and we will be the
> installers...she did most of the foundation wall
> FG and poly single handed so has strong opinions
> on this.
0 -
Some more questions, Ron
good work on those studies. I too have played around with a Flir on some panel testing. I must say you have a steady hand if you are measuring 1/10 degree. I felt good with a one degree temperature spread!
I wonder how you keep you supply temperatures that tight, less than 1°, to know you outputs at the floor (cameras eye) are not being effected by supply temperatures, as opposed to insulation installation tolerances? I've used VS mixing and thermostatic to supply the temperature but 1° delta t is pretty tight to maintain. I also used flowsetters to assure each test loop got the same flow, as that too will tweak the output.
As for actual in the field insulation installation. Takes an extremely willing insulator to keep exactly a 1- 2" air space! I suspect more often than not the insulation is touching the plates. Generally insulators use those wires to keep the batt suspended in the bay when the barrier is facing up as you indicate. Depending on joist depth, keeping the air gap is a challange. Much easier to do in a lab
Should you have a 6 or 8" joist to install a R-19 it is real tough to maintain any air gap without a spacing mechanism top side.
Like to get together to compare Flir data sometime. I had a fairly new version of their camera with a skilled operator. It was fun, we did both still and video of 4 panel configurations.
Thanks for you input. I'd still like to talk insulation. Both FHB and JLC have had some interesting articles on proper installation. Location and climate seems to matter as to how the batts and barriers are installed, so the pros indicate. Also foil faced is real hard to find anymore. All special order in my area.
hot rod
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We have had many problems with our system. Original installer claimed system didn't "work" because of flooring we used and has signed off. Second contractor replaced compressor and capacitor in the 5 ton heat pump and added more tank storage. Third contractor (unable to get second contractor back on the phone) replaced entire 5 ton unit (locked out and desuperheater melted insulation off pipe to hot water tank) and replaced 1" supply and return tubing to 1 1/4" and repiped field leaders. They tore out all the under floor rubber tubing and foil faced insulation; but kept the insulation to be replaced at end of installation of new pex and thermofin plates. And repiped the hydronic system with 1 1/4" supply and return headers feeding the zone pumps (there are 8 zones). The 5 ton heat pump ran well during the summer as the source for AC for Unico system; but when turned over to heating for the fall, the 5 ton failed again - locking out and melting the insulation again off the pipes to the hot water tank. We are heating now with the back up 4 ton heat pump.
To answer your question, yes, a lot has been done to "tweak" this system. The basement zone is not calling for heat - there is a panel box that has lights for each zone and it is not lighting so the thermostat is not over-reacting. The foil faced insulation was not replaced obviously as it had been originally - it sat in a pile in pieces as the renovation was being completed - and piecing it back exactly as it was wasn't possible. A reason for heat to not go up? That is why I asked about more insulation since the original had been "smushed" (technical term). Or the flooring, as original installer claimed, is not transferring heat to the first floor?
I really appreciate everyone's interest and suggestions.
0 -
From my personal experience
when you use a transfer plate the added cost of the aluminum foil insulation does not pencil out. Sounds like we all pretty much agree an unfaced batt of at least R-19 should be good for your application. If a 1-2" air gap can be maintained, all the better.
STILL you want to know that all these redos will solve your original problems. I'm not clear if the major problem was the inability of the heat pump to supply uninterrupted hot water, or that the HP could not provide hot enough temperatures to meet the load with the rubber staple up. Or both
The contractor that did the redo should be able to run a calc and assure the plate system will meet the design load with the temperatures your HP will provide.
My experience shows there are times when the HP temperatures may fall short of the target for radiant at design days. This too, is easily fixed with a backup element in your buffer or storage tank. Very easily done if you use an electric water heater as your buffer tank.
Sounds like you are in the home stretch The emitters (plates) have been upgraded, the HP issues addressed, and winter knocking at your door.
hot rod
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Thanks hotrod for the encouragement. Except for the fact that the 5 ton heat pump is NOT working. Locked out. And melted the insulation off the supply lines to the domestic hot water tank again. First time the 5 ton locked out this fall, contractor recharged the refrigerant. Ran for one day and has been locked out since. Contractor is buffaloed, so to speak. By the way, he is someone you recommended; and a very busy guy.0 -
heatpumps
are a different animal. Need to find a factory trained HP guy for your brand, in my opinion. Not many guys, usually HVAC shops, work on them around here. A lot going on, or not, inside those sheetmetal boxes
Keep trying, someone knows how to babysit and repair that HP. Hydronically you should be up to speed. Sounds like the heat source continues to plague you.
hot rod
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Hi Johnnyd,
You definatly did the right thing by putting ythe poly on th floor of the crawl space. That will keep the relative humidity down in the crawl space. Due to the stack effect, very little moisture will have the chance to move down from the conditioned space thru the insulation.
Since the kraft facing is such a poor vapor barrier unless you caulk the flanges to each other, you might as well install it between the joists in the easiest way leaving some space between the insulation and the bottom of the flooring. Even if it touches, it would make very little differance. With the tubing in the floor instead of below the floor, as long as you have R25 or more and no gaps between the insulation and the sides of the joists, your only real worry is keeping critters from making a nest in it.
Ron0 -
NRT bob,
It's only a $30,000 toy.
> good work on those studies. I too have played
> around with a Flir on some panel testing. I must
> say you have a steady hand if you are measuring
> 1/10 degree. I felt good with a one degree
> temperature spread!
Hi hot rod,
I used a tripod.
>
> I wonder how you keep you
> supply temperatures that tight, less than 1°, to
> know you outputs at the floor (cameras eye) are
> not being effected by supply temperatures, as
> opposed to insulation installation tolerances?
Remember, I was only looking for differances of temperature not absolutes. All of the pipes were the same length in each bay and they were run reverse return so they were very well ballanced. I could easily see the similarities between equally insulated bays and the differances to the bays that were insulated differently. I could even see the spots where the insulation touched where it wasn't supposed to.
> I've used VS mixing and thermostatic to supply
> the temperature but 1° delta t is pretty tight to
> maintain. I also used flowsetters to assure each
> test loop got the same flow, as that too will
> tweak the output.
>
For relative measurements done simultaniously, absolute temperature is unimportant. I could even see a wave of heat moving across the floor (and back) when I bumped the supply temperature.
> As for actual in the field
> insulation installation. Takes an extremely
> willing insulator to keep exactly a 1- 2" air
> space! I suspect more often than not the
> insulation is touching the plates. Generally
> insulators use those wires to keep the batt
> suspended in the bay when the barrier is facing
> up as you indicate. Depending on joist depth,
> keeping the air gap is a challange. Much easier
> to do in a lab
1" to 4" gap, not very noticable. .5" to touching could be seen easily
>
> Should you have a 6 or 8"
> joist to install a R-19 it is real tough to
> maintain any air gap without a spacing mechanism
> top side.
The key is to try to keep "some" gap.
>
> Like to get together to compare Flir
> data sometime. I had a fairly new version of
> their camera with a skilled operator. It was
> fun, we did both still and video of 4 panel
> configurations.
Try to do the tests simultaniously not one after the other.
>
> Thanks for you input. I'd
> still like to talk insulation. Both FHB and JLC
> have had some interesting articles on proper
> installation. Location and climate seems to
> matter as to how the batts and barriers are
> installed, so the pros indicate. Also foil faced
> is real hard to find anymore. All special order
> in my area.
>
> hot rod
Some times you can "get by" with things in one are but not in others but certain methods seem to always work well.
Ron0 -
Hi Dave,
> I too am at the stage of insulating my floors
> with a staple-up plate installation and have been
> following this thread closely as well as previous
> discussions on this topic. I have 12 inch TJI's
> on 16 inch centers and my 1/2 inch Wirsbo is on 8
> inch centers (we had to have the plates made with
> the omega grooves offset to get the 8 inch tube
> spacing). Would I be better off installing R-38
> insulation with no air gap or R-30 which would
> provide a 2-3 inch gap below the plates? I only
> plan to do this once and would like to get it
> right the first time. By the way, this is a great
> site.
Hi Dave,
R30 should be just fine but more important would be to get 16" wide batts not 14.5" wide batts so there is no void between the side of the batts and the web of the TJI's.
Ron0 -
Hi radiant,
Your heat source in the basement might just be all of the plumbing for the whole system that is in the basement. Is it insulated?
Have you measured the water temperature going to the slab or have you valved it off compleatly to make sure it is not still heating the basement floor? Lights and other devices could also be adding to the basement temperature. If your basement is well insulated, it would take very very little heat to keep it at 67 degrees.
Do you have a non-contact IR thermometer? If you do, you might want to aim it around at things in the basement.
Do you have a heatpump AND a boiler or a heatpump only? Is the heatpump ground sourced? Do you have any gauges on it?
Something melting on a heatpump sounds like a serious flow problem.
Ron0 -
The house is new construction 2001 and is well insulated. All the pipes in the basement are insulated. Just seems strange that both 5 ton heat pumps (original and new one) melted the insulation to the hot water tank and locked out.0 -
Hi radiant,
Was that the insulation on the pipes between the de-super heater and the DHW tank? How much flow is in that loop?
You may also not have enough flow in the radiant loop to extract 5 tons of heat from the heat pump.
Water to water heatpumps can be very efficient but only if you have enough load on the heating side to keep the temperature down.
This sounds like an oversized heatpump with an undersized radiant loop. You may have to add a buffer tank.
What is the desigh heat loss of the house?
Do you have thermometers on the supply and return of the heatpump?
Ron0 -
The house is approximately 3100 square feet with heated garage too. Two heat pumps, 4 and 5 ton, for closed ground loop geothermal system. The 4 ton is backup for 5 when it is very cold. 5 also does AC. Yes, it is the insulation between the desuperheater and DHW heater that melts off. Sorry, don't know flow. We already have three buffer/holding tanks and plenty of gauges everywhere. The heat pump is set at 115 degrees and the gauge out of the 4 ton now (don't know 5; not working) is 120 when running. Each zone has a gauge for return temp. We had a heat loss done by contractor #2; total heat loss 79,360 Btu/hr with design temp of 0 and 115 degree water supply temp. His conclusion was that the radiant system was 27 % undersized to meet total heating requirements with a maximum source temperature of 115 degrees from geothermal system. Since then we have had contractor #3 make changes to the system - plates and ipex, larger piping, more buffer tank capacity. So far this fall, the 4 ton is working well to heat entire house; but we'd like to get the 5 ton with the desuperheater back into service.0 -
OK, It does look like a flow problem. It could be airbound in the desuperheater or some restriction or even a controls problem.
Usually a lockout is sensed by over preassure not over temperature but over temperature of the freom causes the overpressure. The main hot water output should have enough capacity to extract all of the heat from the freon if it has enough water flow even if nothing is coming out of the desuperheater.
Low flow in the ground loop can also cause the problem but it is less likely. If you have low flow in the ground loop, you probably would have had problems in the A/C season.
What kind of pump do you have for the radiant loop?
Are the buffer tanks plumbed so the water goes from the heatpump to the tanks and then back to the heat pump? And is the radiant loop from the tank to the floor and then back to the tank (primary/secondary loops)?
What pump goes in the loop from the heatpump to the buffer tanks?
The flow from the heatpump to the tanks is more likely the cause than the flow from the tanks to the radiant if it is plumbed like I think it is.
Do you know how hot the buffer tanks got when the 5 ton heat pump locked out?
Not directly related, but is the A/C using cold water from the heat pump thru a water coil in an air handler or is it cold freon to an evaporator in the air handler?
Ron0 -
Look outside the box...
Wow, whatamess! Sounds like you've been through geohydronic HELL. Did you use an IGSHPA certified loop designer/installer?
The fact that the insulation is burning off the desuper heater may indicate loop field problems. Someone needs to get in there and diagnose the WHOLE system, not just the load side of the system. There are ciritcal flows (high flow rates, low delta T's) that must be maintained on the source side in order to avoid problems. I also wouldn't be suprised to find that the load side pump is grossly oversized, thereby causing zone valve bypass, which would be the reason the basment "appears" to be overheating, if in fact it is. The fact that the basement won't go below 67 degrees F doesn't necessesairily indicate a problem. Could just be the basements point of equalibrium.
Mr Schroeder, got any pictures you could share with us on your experiementations? I know of at least one non profit organization that would LOVE to get their hands on your study (www.radiantpanelassociation.org)
Interesting thread. Hope we find a solution for this poor guy. If nothing else, we're all learning a great deal from it.
I'm of the camp that trying to get anyone to maintain ANY kind of uniformity in air gaps on below floor insulation is a pipe dream, and that no gap would be better than inconsistent gaps on a conductive system, but then again, I live in the real world...and what do I know, I'm just a stinkin' hot water plumber:-)
Radiant, let me see if I can get someone with some super GSHP knowledge to drop by this site and make comment.
ME
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