Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Radiant Heat System - Loop Question

Options
ALH_4
ALH_4 Member Posts: 1,790
Very good catch, Al. Somehow I missed that completely. While those loop lengths would work for 1/2" tube, they are long loops for 5/16" tube. It sounds like your installer could stand to attend some classes on hydronic heating. You might call a different company to evaluate the system. Who knows what might be hooked up incorrectly?

Comments

  • Underfloor Fred
    Underfloor Fred Member Posts: 9
    Options
    Radiant Heat System - Loop Question

    I recently had a radiant underfloor heat system installed. Quick track was used over subfloor with quarter sawn oak above. System was spec'd for 6 loops - Install only used 5 loops each between 225 - 240 feet. Installer said max was 250 per loop. Anyhow, problem now is loops not heating up properly - Have installed high velocity circ pump today but wondered if others have opinion.... Temp at supply manifold is at 90 - Can i go higher w/out damaging floors? Thanks Guys!
  • jp_2
    jp_2 Member Posts: 1,935
    Options
    return temp

    what is your return temp in each loop? change up to 100F see what you get on your returns.

    ps what is the floor temp?
  • Underfloor Fred
    Underfloor Fred Member Posts: 9
    Options
    Radiant Heat System Loop Question

    Return temp is approx 72. Seems to me that the heated water is not flowing through the loops properly - One other thing to add, is that orignial install positioned the 007 circ pump b/w the boiler and mixing valve. I say that is incorrect and circ pump should be between mix valve and supply manifold. Hoping 0012 HV pump will address issue - other thought was to put 2nd circ pump on return to pump in both directions - presuming length of loops is issue.....
  • ALH_4
    ALH_4 Member Posts: 1,790
    Options
    Flow and Heat

    Yes you can go higher than 90°F, but if you have outdoor reset, that may be why you are at a low temperature if it is warm outside. Generally, you do not wan the floor surface temperature over 84°F on the coldest day of the year. 90°F supply temperature will probably get you nowhere near that. The outdoor reset curve may need adjustment. What kind of boiler do you have?

    225-240ft is a nice length for the loops if this is 1/2" inside diameter pex. You should need a pump in the range of a Taco 007 or a Grundfos 15-58 3-speed, probably on speed 1 or 2. Either something is piped incorrectly, or there is some flow restriction in the distribution piping.

    Can you post digital photos of your mechanical room and manifolds?
  • ALH_4
    ALH_4 Member Posts: 1,790
    Options
    Pump location

    You have found the problem. You are absolutely correct about the circulator location. The circ absolutely must pull on the mixing valve. The valve will not function properly if the circ is trying to push fluid through.
  • Underfloor Fred
    Underfloor Fred Member Posts: 9
    Options


    Thanks for the input - Will post some pics later tonight or in the AM.... Might be onto something with the location of the pump as originally installed.... was pushing water into mixing valve instead of pulling...
  • Dave Holdorf_2
    Dave Holdorf_2 Member Posts: 30
    Options
    Circulator placement

    Fred-

    Exactly as Andrew prescribed and your original thought, the circ should be after the mixing and before the main header into the radiant floor.

    I would also consider using the smaller circ originally planned, that large of a circ could create noise issues and you are using alot more electricity. You also do not need the second circ before the mixing valve.

    It does not sound like loop length is an issue, however the only way to know what the proper circ to use is to look at the heat loss and radiant design for the flow rate and developed head for the system.
  • Underfloor Fred
    Underfloor Fred Member Posts: 9
    Options
    Pump Location

    Thanks - That is what I was thinking, based on a few other systems i have seen as well as stuff i have seen on TV.

    You see, i am only a homeowner so did not want to piss off the pros by pointing them in that direction. They told me changing from low volume to high would make a difference - I will suggest pump location to them now... Hopefully without rocking the boat...
  • Underfloor Fred
    Underfloor Fred Member Posts: 9
    Options


    Thanks for your response - Will lobby to have pump location moved to b/w the mixing valve and supply manifold. Do you have any opinion on the 5 loops versus 6?
  • ALH_4
    ALH_4 Member Posts: 1,790
    Options
    Circ

    As Dave said, if the piping and valves are sized correctly, you can very likely go back to the 007 and have more than enough flow.

    As long as everything is zoned correctly, there is nothing bad about having 5 loops verus 6 since your loop lengths are good.
  • Al Corelli_2
    Al Corelli_2 Member Posts: 395
    Options
    Quicktrack?

    I checked the Wirsbo manual. The 250 foot loop length includes the leaders.

    However, the current placement of the circulator is not optimal, by any means. Please move the circ to the mix side of the tempering valve, before the manifold, as previously discussed.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

    There was an error rendering this rich post.

  • Dave Holdorf_2
    Dave Holdorf_2 Member Posts: 30
    Options
    # of loops

    Fred-
    Well that answer can only be fully answered by looking at the design flow rate/head loss.

    When we discuss the overall loop length, these are only rules of thumb and not set in stone. The loops lengths are only a general idea and most often to design around typical small wet rotor circs. With that being said, can you go longer then suggested?; yes....it depends on the size of the circ.

    Are there times when the recommended loop lengths are too long?....yes, heat loss is high or small circ and the loops must be shorter. But to summarize on number of loops....it depends
  • Underfloor Fred
    Underfloor Fred Member Posts: 9
    Options


    The 225 - 240 loop length included the length from the supply to the return manifolds. I believe the pex used was 5/16 ID.... So, is this a huge problem and is there a work around?
  • ALH_4
    ALH_4 Member Posts: 1,790
    Options
    Head loss

    You *should* still be ok with a 007, pure water in the system and a 20°F DT, even with the 5/16" tube assuming a 25btu/sf heat load which is a WAG. It does not allow a lot of room for error, but you dont want to oversize the pump either. If you have glycol in the system, you need to know the concentration. Someone needs to analyze the hydraulics on this system.

    I think you will be fine with a 007 pulling through the mixing valve. I would feel a little better if it was a Grundfos 15-58 3-speed pump.
  • jp_2
    jp_2 Member Posts: 1,935
    Options
    1/4 sawn question

    Is that a floating floor or nailed/glued?
  • Bob Forand
    Bob Forand Member Posts: 305
    Options


    I would go at the mixing valve location before I would worry about the loop lengths. Ask your contractor for a copy of his design. He may have designed at those loop lengths. I would imagine that your system will work fine once you have the location of the pump changed. You should check the surface temperature on the hardwood floor. I believe the magical temperature to be 85 degrees. If you are much above that you take the chance of damaging the floor. Good luck...
  • [Deleted User]
    Options
    Mythical floor bunk...

    Does anyone know where the magical number of 85 degrees F as it pertains to hardoowd floors came from? It came from the RPA. Unfortunately, the hardwood people read it to mean the maximum WATER temperature, and not the maximum FLOOR temperature.

    If, in fact hardwood floors are NOT allowed to operate in excess of 85 degrees F because they might curl up and die, then it should be illegal to put any hardwood in front of a south facing window. I have personally seen the floor surface temperature of NON HEATED hardwood flooring at 140 degrees F just due to the incoming sun shine... and other than typical yellowing, the hardwood floor was fine.

    And, if wood is SO unstable under high heat conditions, then why is it permissible to use it as sheathing underneath roofs? Although I've never tested it, I can almost guarantee that in the middle of the summer, that a dark green standing seam metal rib roof's substrate surface temperatures exceed 200 degrees F on a daily basis, and I don't see anyone making a big deal about that...

    The problems with hardwoods comes from people getting into a hurry and installing the hardwood over the radiant floor heating system before the floor is fully cured (gypcrete or equal) or before the wood is FULLY acclimated to the back ground relative humidity, or the GC pulled the insulation package becasue of the "heat rises" theory leaving no alternative for the HO but to "turn it up" in an effort to find comfort. Then when it does curl up , and try to crawl off the floor, it is blamed on the radiant floor heating contractor...

    Personally, I think it should be illegal to put hydronics under a hardwood floor... But then again, I have ulterior motives :-) and alternative methods for increasing human comfort :-0 And it DOESN'T involve the floor!

    And while we're at it, I think we hydronic floor heating contractors have been doing it all wrong for all these years. Think about it.

    We put high density tube bands (6" OC) near the outside walls, and low density (12 to 16" OC) bands near the interior. We then feed the hottest water to the outside walls first. How many people do you know (other than a few bad students) that stand with their nose to the outside wall? What we SHOULD be doing is putting low density bands (16" OC ) near the outside walls, where the water will be the hottest, and then increase tube density (8" OC) as we move to the interior, and the water tends to be cooler.

    Am I wrong? We all know I'm crazy...

    Just food for thought..

    ME
  • Tim Gardner
    Tim Gardner Member Posts: 183
    Options
    where to put the heat

    Are you suggesting radiant ceilings? Radiant walls?

    And I thought the idea was to put the heat on the outside walls where the dead men put radiators.

    Please explain.
  • Weezbo
    Weezbo Member Posts: 6,232
    Options
    *~/:)

    Mark,

    i for one have definitely been in more than one home with radiant heating in the floor or under the floor, not built in this century ...maybe they made trees different back then :)

    the floors are beautiful, and the heat Barrels off of them...

    i know for a fact that the water temp was well in excess of anywhere near 85 degree F :)

    over the decades ,i think we have dialed the water temps down:) the materials we buy are likely Scientifically engineered to :cup, twist, check , shrink and have a generous PHOTO finish in each and every circumstance..i recall seeing massive amounts of water on those old floors, as the Mop Bucket was bought out to swamp the deck every week end, do That to some of the junk on the market these days and the stuff would act like a circus contortionist:)

    i hope that helps
    *~/:)
  • Gordy
    Gordy Member Posts: 9,546
    Options
    Your not Crazy

    Most of the problems with hardwood in addition to the acclimation to the enviroment effect, are the rings. Growth rings to be specific. The slower a tree grows the tighter the growth rings are in the trunk. This makes for the strongest, and most stable woods. We had alot of that type of wood decades and centuries ago. Now we have genetically engineered faster growing trees to replace deforestization, there is a trade off.

    There is a gent fishing in lake superior for thousands of trees that went down on barges to the bottom of the lake in storms years ago. He is spending millions to bring the wood back up because this wood is the real McCoy.

    Your ulterior motive is an exciting one. One question though, you know the throw rug on radiant floors issue. How are you going to field the window treatments. You know how the Mrs. can be :)).

    Still Lovin my radiant ceilings, kinda throws all the issues of heating floors out the window.


    Gordy
  • [Deleted User]
    Options
    For the modest women in your life.....

    and you are correct, thay can be persnickity...

    I present...

    http://www.pella.com/products/unique/detail.asp?path=/products/unique/blinds

    I actually had a product similar to this one in the mid seventies that had chrome plating on the tops of the blinds, and flat black on the bottoms of the slats.

    You could adjust the slats so you either totally bounced the energy back out the window, or allowed it in in the form of reflected diffused lighting, or bounced the incoming light onto the bottom of the slat, thereby absorbing it and converting it into thermal energy.

    I see no reason why I can't bring that concept back to life. Then, at night, when the windows are really cranking, the reflective surface can be pointed to the interior, thereby enhancing the radiant output while minimizing back losses to the outside from the heated pane.

    If the Mrs HAS to have interior window dressings, she can do so, but the R value of the dressing must be a minimus as possible, like shears...

    ME
  • [Deleted User]
    Options
    How about the WINDOWS!!

    I consider myself a Human Comfort Technologist. I have LOTS of tools to deliver my product, comfort. Radiant floors are just one of them, and in my professional opinion, that partiicular tool should only be used in areas where it really makes sense, like the bathroom.

    For other areas of the dwelling, radiant windows will virtually eliminate the heat loss of the window (typically 50% of the load), thereby reducing the thermal energy load and substantially increasing the human radiant comfort factor. In those areas where the window is not capable of carrying the thermal load by itslef, you augment with either radiant walls, or radiant ceilings, both of which are significantly less expensive to install than radiant floors, and bottom line, we ARE delivering the ultimate in human comfort, that being radiant heat.

    Don't get me wrong, I LOVE hydronics, but in this day and age, we have to be competetive and cost and efficiency aware. I just want to keep people as comfy as I can for the most "cost effective" way. Or at least that's what my customers keep throwing in my face. "Is this "cost effective""? Can somebody please explain cost effective to me as it relates to human comfort?? How do you put a price on comfort? I've worked for attornies who know how to put a price on discomfort, but not comfort.

    For more information on the radiant glass windows, go to http://www.rgiglass.com/

    And think OUTSIDE the box...

    Enjoy

    ME

  • jp_2
    jp_2 Member Posts: 1,935
    Options
    HI glass losses

    but mark,

    aren't your heat losses directly out the window going to be large, big delta T where your insulation factor is the smallest, I know it will work, but see large losses.

    better off with 4 pane windows.

    long time ago I saw a program showing a house with a vacuum systems that filled a void between the windows with styrofoam beads at night and vacuumed them back out in the morning, wonder why that never took off. automatic blinds would also be a good soultion.
  • [Deleted User]
    Options
    Why it never took off...

    was because during the day, when all the beads of insulation were sposed to be asleep, tightly pack in their day time sleeping quarters, some of them were hanging out in the window, obstructing views. Static Guard anyone...

    They had them at the Aspen Colorado Airport. They were a great idea before their time.

    Peak back losses from the i-Glass is less than 15% of its total consumption, AT design condition (115 degree glass temperature, 10 above zero OSA temps). Obviously, not 100 % efficient at THAT condition, but...how often does THAT condition occur AND how long does it last there. In my professional opinion, the windows will save significantly more energy than they "waste", all while maintaining a higher level of human comfort. Did you know that people are willing to pay more for comfort? Especially when backed by reliability. I have NUMEROUS customers that wouldn't mind paying what they're paying for heating IF they were comfortable. When they're not comfy, they turn that source off and go to another source (wood fire places). These situations are typically in a large, high volume rooms with a TON of glass in the room. Cold 70 come to mind? They have to jack the thermostat on their convective system (HWBB) up to 85 degrees F to be comfy. Sound familiar? Well, if you eliminate the energy sucking cold windows, the MRT comes up REAL easy, and that's where the comfort is. And if "neutralizing" the windows loss don't cut it, you can kick the glass into heat production mode, and turn the room into a freaking microwave oven. Beckram Yoga Studio anyone??? ;-)

    One of the guys who invented this told me that they decided to do an acid test, worst case scenaio, and see what coditions caused the glass to fail.He said he got it up to 400 degrees F before the glass failed. He said you could have literally cooked an egg on the surface it was so hot. Glass shattered into a million pieces. Which is what it's meant to do (safety glass).

    We're working on plans for a DC thermal generator using this, and some already known and proven hydronic principles. Off Peak storage any one???

    Let's see, each cubic foot of this glass holds how many btu's per degree F.? Times a differential of 300 degrees (390 minus 90) and the thermal conductivty of glass is,,, Oh, where's J-P when you need him :-)

    My mind is whirling on this stuff... Can you tell???

    ME
  • [Deleted User]
    Options
    SawFish story...

    These guys know how to put a "premium" on wood.

    http://www.ehponline.org/members/2004/112-15/innovations.html

    Saw actual footage of the process. PRetty tough on the water.Turbidity was difinately noticeable...

    ME
  • jp_2
    jp_2 Member Posts: 1,935
    Options
    DC thermal gen??

    I agree this can be a large cold window solution, otherwise its an increased window loss of 15%.

    what do you mean by DC thermal generator?
  • [Deleted User]
    Options
    Google D.C. boiler...

    and see what happens. Nothing. That's because there are none. With the efficiency loss of going through an inverter, you could use a conventional electric water heater if you wish...

    A DC thermal converter could save the electricity generated by your PV system as hot water, which to the best of my limited knowledge can't be easily done at present.

    And you are wrong about the 15 % loss. It is not a constant, as proven out by the Gas Machine Lab's testing. And the bottom line still remains, you will use less enegy staying more comfortable...

    ME
  • jp_2
    jp_2 Member Posts: 1,935
    Options
    PV electric boiler?

    mark,

    i thought it was well understood that trying to heat water via PV system was a poor idea(poor efficiency, high cost), especially when you can heat water directly as in a vacuum tube solar collector. just look at you watts/meter output of a PV panel compared to a solar collector of same size.

    I'll have to read more on heated windows, to tell me you heat a window, drastically increasing the delta T across the window but at the same time reduce the heat loss of the window?

    kind of goes against the equations for determining heat loss of a window to begin with?
  • [Deleted User]
    Options
    Interestingly...

    These guys that invented this thing have a test rig set up in the glass factory where they're made. An old freezer, maintained at 0 degrees F in the freezer, and the door replaced with i-glass. At a room pane surface temperature of 115 degrees F, they were still seeing ice forming on the inside of the outside pane. It goes counter to everything you thought you SHOULD know. Even Kirby from the gas labs couldn't explain it away.

    Something about a lack of convective current space between the panes or something...

    As for using the PV electricity fo making heat, if your batteries ae fully charged, and there are no significant loads, why not convert it to thermal. It's FREE after all...

    ME
  • jp_2
    jp_2 Member Posts: 1,935
    Options
    iglass

    I'd sure like to see that frig.

    as far as heating with PV's:

    I've seen my battery charged mid day and thinking of those un-used photons...

    but when I get a frig that will change.

    also, you should already have a solar water heater, therefore the excess will most like be at the same time you have excess of solar hot water. then what? most of summer I never use lights, by the time its dark its bedtime.

    maybe running extra ventilation during peak times? or sub cooling the frig/freezer so they can coast at night?
  • Underfloor Fred
    Underfloor Fred Member Posts: 9
    Options
    Radiant Loop Update - Grundfos Added

    In theory the problem should be solved tonight when i get home. My GC brough in heating contractor #2 - As we all suspected, contractor #2 immediately agreed that circ pump was in wrong spot - pushing to valve instead of pulling. Contractor #2 was going to eliminate original TACO 007 at heat source and replace with Grundfos 15-58 3 speed in between mix valve and supply manifold. Hopefully will have toasty floors tonight!
This discussion has been closed.