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Secret life of low temp panel radiators ?

ECW
ECW Member Posts: 14
Been searching web for panel radiators. A few distributors sell rads directly -- looks they are all Chinese or  European in origin, but most sell only through HVAC contractor supply houses or through independent HVAC contractors. My HVAC designer/installer has left it in my hands to select the brand of panel rads and he will design to them. There is a wide range in prices but the limited info I can get indicates that most of the low-temp panel rads are virtually the same visually, rad dimensions (LxWxH), structural featuers, material and output ratings/panel size and type.



Problem - its real hard to get detailed info from anyone. Several differently named models/brands and several unnamed models (from independents) look and sound identical in the product info. When I ask for detailed specs (cross sections, mounting system, heating performance and efficiencies, corrosion resistance, life cycle facts, etc), I get little help or avoidance.



I am told be a couple of folks that most of the panel brands come from the same manufacturer; so the differences are largely in the way they are marketed, not in the materials, performance, life cycle characteristics.

How to I make legitimate comparisons between the available option? Is it appropriate to name/discuss Brands on this Wall?

Thanks

TW

Comments

  • kcopp
    kcopp Member Posts: 4,089
    My Panel rad of choice....

    Are the Buderus ones. They have a wide selection of sizes and shapes... I prefer the 22 series. The 33 series are special order. Here is a link w/ the info on sizing.

    http://www.buderus.us/products/radiant-heat-products.html
  • I like Buderus as well,

    but they have limited sizes.  For more of a selection, check out Runtal:



    http://www.runtalnorthamerica.com/commercial_institutional/index.html



    Even though they are called commercial/institutional, we still use them in homes.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Did You Go To

    www.hydronicalternatives.com They won't sell directly too you but every spec you are looking for is there. These panel rads also come from across the pond.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • ECW
    ECW Member Posts: 14
    Radiant panel smoke and mirrors

    Gents

    I was hoping for some solid advice on Panel Rads (not advertising):  comparing BTU/$ of purchase, in field performance evaluations, life cycle, corrosion resistance, vale of package (ie. standard add on components and their quality). So here is what I found out on my own,

    There are 4 or 5 major manufacturers that I have been able to find (in NA and Europe - didn’t look for China: Runtal, Quinn, Buderus, Ritteg, StelRad. There are all, except for Runtal, made in Europe, mostly Germany. Rettig is the biggest.

    Most panel radiators are subsidiaries of Quinn Group of Companies. Myson, VEHA, Dianorm, Pensotti and Radiant and Hydronic Alternatives are either Quinn or Rettig products.  Buderus may be a private label product made by Quinn or Retig; Stelrad seems to have it's own plant in UK but that is the home land for Quinn as well. Rettig and Quinn supply virtually all the European rads recommend to me on this Wall and some others. The independent contractors/suppliers recommend sell these two companies lines.

    Panel Rads are essentially commodity products; largely the same in design, mass produced cold rolled and pressure formed steel, same essential performance features, aesthetics (they call this, the "emotional factor" in the industry) -- but the problem is that the market in NA cannot support commodity marketing (yet).  For most it’s a steel making business, not a heating system business.

    Other than a minor variation in wall thickness of the steel (1.2, 1.25, 1.5 mm), some different tap hole set ups, different wall mounting hardware, and different locating of the T valve, I see no fundamental difference. The supplies do not have great warranties – mostly 5 years – and do not talk about corrosion and life cycle costs or facts in their materials.

    Runtal’s panel rads is a US up market luxury item) -- is the only one that is unique BUT its BTU’s per panel volume, wall area and per temp input and D-T are pitifully bad and totally uncompetitive for serious heating systems (they might dress up a fancy foyer, but they won't heat a living room). Runtal’s panel rads are little more then baseboards set on their sides.

    Runtal is the only company to offer a color selection (its very wide). But color cannot make up for lack of performance.  Everyone else sells “white” panels - except for a few prettied up specialty towel warmers – not serious radiators, though.

    There are some variations in the European products’ BTU outputs for same sized panels but the differences are not dramatic. Most single/sngel, single/double and double/double panels have the same BTU’s for the same panel area, flow rates and D-T.

    There are two issues facing the supplier market right now. (1) Stock availability and stock inventory – the European manufacturers and home companies have a wide range of model sizes; most US distributors are independent, full service hydronic contractors and they don’t have the size options – stocked items are limited and take a few days to a week to get, special order items (the bulk of the options) take months and options fro NA are very limited compared to the same product line in Europe; (2) Price is the primary comparative factor – a couple of brands sell direct from the US importer/distributor and so the independents’ prices do not compete on either a Brand to Brand price or on equivalent price across Brands on a  BTU to BTU comparison.

    Advertising and specs info are not generally well outline. Uneducated buyers will have a hard time comparing the rads’ $/BTU factor because the suppliers/contractors distinguish themselves by BTU/panel area and supply temp/D-T.  How can someone compare two virtually identical products when one’s BTU’sa re listed for 180 F and another is listed for 190 when I want a 140 supply temp.  How can they call the items “radiant”/”hydronic” modern residential heating products and then emphasis high temp supply (180, 190 even 212) numbers in their literature and base the D-T on a 68F room temp when this is not at all suitable for wall panel radiator heating system (that is a warm floor D-T). 

     

    Most obviously missing in the literature and the performance info is (1) the % of heating that is convective and radiation and (2) the direct vs indirect radiation patterns of panel shape and surface design (forming and texture). And comparing this to other heating systems models.

    No offence, and thanks, to you guys who gave me advice, but I remain unrequited.

    TW
  • CMadatMe
    CMadatMe Member Posts: 3,086
    No Smoke

    Hydronic Alternatives does offer panel rads in colors. You must not have gone to the proper section of the web site. They also have the conversion factors for btu ouput at give supply water temps based on your setpoint with the math equations if you want to figure them yourself. They are hiding nothing. The catalog offers dozens of different panel type radiators and towel warmers. Price ranges are all over the place depending on what look you want.



    There are dozens of rads that I could size based on a heat loss and what water temp I want but in the end what look do you want. I don't feel your paying at that point for btu's but for the decor of the room.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • ECW
    ECW Member Posts: 14
    $/BTU - stock vs non-stock

    Thanks, Chris, for pointing out some of what I missed. Hydronic Alternatives has more and better organized product presentation than most. Their Correction Factors explanation is perhaps the clearest; but a different formula than provided by suppliers elsewhere. Which formula is best to use? 

     

    My wife will love you for pointing out the color options although as you see, as my point was made previously, the Stock items are limited, and are NOT available in color.  

     

    Like fridges, stoves and washer/dryers … they need a selection of a few stock colors.  A stock rad that puts out 4000 - 6000 BTU’s, at 140 F supply, 20 degree drop, 72 F room temp, is not cheap. With color and other features, they are in the 1000’s of $’s per unit. That’s just too much money when we consider the piping, fittings, controls, add-ons and boiler room costs.

     

    Not to pick on this company, but that’s what I meant about the industry not being geared to residential, low temp hydronics.

     

    Compare the Hydronics Alternatives (Purmo, Radson – Rettig companies) Stock items to VEHA (Quinn), and Myson (also a Rettig company) stock items. Apples to apples: correction factors based on same temperatures, deltas and similar panel features (price per BTU per same panel type and size). The issue remains price.

     

    Hydronic Alternative is distributing Rettig Group Co's rads (Purmo and Radson) from Germany. Check out the Euro sites.  Looks like the same steel, same design, but better warranty than most (10 vs 5 years).

     

    [u][color=#800080]http://www.purmoradson.com/[/color][/u]

     

    [u][color=#800080]http://www.purmo.com/docs/FINAL_Panel_Rad_Broch_PURMO_UK(1).pdf[/color][/u]
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    you're right

    that the industry does not expect radiators to be designed around low temps here in the US. they are competing with baseboard in most cases.



    your characterization of Runtal is a little off the mark though. They have a ton of options and you can make radiators as thick, tall, long as you like to get more or less output for a given placement area. they are certainly not cheap though and even less so when you get to the real custom stuff.



    Nearly all other panel radiators are identical though or so close to it they might as well be. knowing that your analysis needn't be much more advanced than area of radiator and cost. right? though I'll note the cost differential between them is usually small enough that it's not really worth stressing to any real degree over it.



    I saw some from Jaga a friend turned me on to that look interesting. incorporates low voltage fan control in a radiator... jacks up the output quite a bit. I wonder if anyone will be carrying those over here anytime soon.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    nice

    I shudder to think of pricing ;)



    but they sure do make some cool radiators.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Yup They Do

    If you see something you like let me know. I can get you pricing. They are my rep.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • ECW
    ECW Member Posts: 14
    Beaming vs diffusing the radiation

    I was told by an HVAC contractor yesterday that ...  old style and tubular rad shapes send heat out into a room (radiating solid bodies) more effectively than flat panels, sending heat in many directions. Whereas it was claimed that flat panels direct heat only in the direction perpendicular to the surface and so tends to concentrate or "beam" the radiation. If this is true, is it significant?



    What is the final analysis about how much rads heat by radiation vs convection? 
  • Rich Davis_2
    Rich Davis_2 Member Posts: 102
    Take a Trip

    Last spring I needed a radiator to fit into a very narrow space with a 1500 btu outoput.  I found a place in England that would have one made for me for $85.00.  I had to pick it up at the importer/supply house.  I brought it back as oversize baggage, no problem at either end.  All the radiator co's on the net in the UK seem to all deal with this importer.  Was a great transaction and got to visit and vacation while I was there.  So think about it.

    Rich Davis

      3M's 
  • ECW
    ECW Member Posts: 14
    Getting nervous - 20% difference in CF's

    Don't correction factors (CF) have to take flow into account? I have now compared about 8 suppliers radiators and I get CF ranges from 0.6 to 0.37 per foot for the exact same size (height, and depth) of radiator (same configuration of panels and fins), with the same math on temps (supply, return and room temp) .

    20% can be a sizing  disaster.

    Do I need to ask suppliers what flow rate they basing their CF's, the water volume/rad, and the pressure drop/rad ... so I can make apples to apples comparisons ...?
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    it's not really about flow

    it's about Average temp. they should be quoting average temp, or supply and return temp, or supply and temp drop.



    If one quotes supply temp and another quotes average temp, that could be your difference right there. Many will quote "Dt" or "difference from room temp", and when they do that, they are talking about the radiator average temp and not the supply temp.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • zacmobile
    zacmobile Member Posts: 211
    edited March 2010
    rad sizing

    Yes, average temperature must be taken into account, here is a handy output correction chart from a Biasi I/O manual (they are a typical fluted front pressed steel panel rad)
  • jfig
    jfig Member Posts: 2
    AIM comparison

    Like others, I've been trying to compare different brands of radiators. I just spent weeks emailing a man at aimradiantheating.com (distributor of AIM panel radiators made in England), creating a list of sizes to fit our house. Has anyone looked at this brand?
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    to me

    looks like they are rebranding myson.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Paul Pollets
    Paul Pollets Member Posts: 3,568
    Try DiaNorm

    The DiaNorm wall panel rads are very similar to the Buderus models. Their technical literature has charts for sizing at a condensing load. I typically size for 140 degrees at design temp. 



    www.heatlines.com
  • jfig
    jfig Member Posts: 2
    Regarding AIM panels

    This is what I rec'd when I asked what company makes their panels"



    Panels can be made by any of the manufacturers at any given time as we send out our criteria to all and the ones who can meet the criteria we award our business to. The design temperature is 72º room with a 180 º water temp flowing through them.



    They're 18 ga steel.
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