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European style panel radiators and cast iron on same zone?

Can Runtal baseboard or panel radiators be installed on the same zone as cast iron radiators? My contractor's plumber says no; manufacturer says yes.

We are renovating and the structural changes have resulted in a need for new radiators in 2 upstairs bathrooms, the 1st floor lav, and the kitchen (which will be heated by toekick fan convectors). My contractor's plumber plans on putting the kitchen fan convectors and 1st floor lav (i.e. Runtal baseboard) on a new zone. However, he doesn't think it's a good idea to put Runtal in the upstairs bathrooms on the same zone as the remainder of the house (cast iron) and doesn't think it's worth the cost/effort to separately zone the upstairs baths.

The structural changes don't allow the old cast iron radiators to fit anymore (large header now in wall).

I have a 1930's home with a hydronic system. The system seems to have been originally gravity hot water, but converted to a single circulator in the 50's (probably when they added a small addition heated with cast iron baseboards. Most of the other radiators in the house are Arco convectors.

Can the Runtal baseboards or panel radiators be combined on the same circulated zone as the old cast iron radiators and if so what 'fudge' factors should we consider in calculating sizing? (water temp currently set at 190 at the Peerless 175k boiler)



  • CoanyCoany Member Posts: 90
    I have seen it done with good results

     usually in a bathroom where space is tight.

     I think the hydronic towel warmers are really slick.

     I can't guess why they would not be compatible.
    " Do what you can, with what you have, where you are" Teddy Roosevelt
  • dondon Member Posts: 395
    two different emitter

    i'm sure the reason he does not want to do because ont emitter (cast iron rad)

    Has more mass which means...slower to heat up as well to cool down.The euro rad not alot of mass, so its quicker to heatup and quicker to cool off.

    Now when you think of a bathroom some people like it hot.So knowing you may be one that likes it hot then the euro rad may be a perfect fit your bathroom.Now if you are one who like it cold then..maybe the panel rad on the same zone may not be right for you.

    You could however tweak the panel rad if the one you choose has the option for a diverter valve and flow setter.Keeping in mind piping limitation and space.
  • ChrisChris Member Posts: 3,056
    Yes and Yes

    You can combine them. As the othe poster suggested towel wamers give  a bathroom a nice look at can heat the space provided they are properly sized. Whomeves panel rads you are looking at have correction factor charts to size the rads accoording to the heat loss and water temps you are trying to run.

    You state that the manufacture says it can be done. Did you ask them for a contractor or wholesaler in your area that installs/sells their products? I would and get a second opinion. Ultimatly you live in the house and it's your comfort and decision on what you want installed not the contractors. If he can't do it find a qualified contractor that can.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • differing emitters on same zone

    Thanks for the tips. We do like it 'hot'. I'll ask to tweak the BTU/ft3 up and install a diverter valve and flow setter. If doing that, does it make sense to use a TRV or is that just overkill for a bathroom?
  • It's the contractor's plumber so...

    Thanks for the post. We don't have room for the towel warmers (no real wall space, ankled wall/dormer over windows), but we plan on mounting a panel or baseboards under the windows.

    This is part of a larger job where the contractor is using his own folk. The contractor is great, and I'm sure the plumber is good at what he does, but just may not have used a lot of European style radiators (seems to be more familiar with SlantFin and cast iron). They seem amenable to my requests (with some prompting from me). It doesn't seem that complicated, I imagine he can do it, but it's outside his routine.

    Thanks again
  • David107David107 Member Posts: 1,189
    Pressure Drop Issues

    HO here who was advised that certain kinds of panel rads have higher

    pressure drops than the cast iron rads. So that IF the rads are piped

    in series and if the panel rad was near first in the run it might need to be on its own sub-loop, diverter tee or however it was described to me.
  • sub loop

    Thanks for that tip. The old system involved the 2 upstairs bathroom radiators being on a single sub-loop. So, it makes sense to recreate that with the new panel rad's in those 2 bathrooms being on a sub-loop as well. I don't know what the pressure drops will be in the Runtal panel rads compared to the remainder (old) system. However, the old system was originally designed as a gravity system, so resistance should be low.
  • Paul PolletsPaul Pollets Member Posts: 3,017
    Combining Rads

    wall panels and CI rads are compatible on the same zone. make sure they are piped in parrallel, reverse return works best. we always make sure all rads have a TRV when re-pipng, so balance can be achieved. series piping is NOT recommended.
  • TRV or manual diverter valve

    Thanks for the tips.

    All the old radiators have manual diverter valves. What's the advantages/disadvantages of installing TRV's vs manual diverter valves on the new panel rads? Is it just a cost issue or is there a pressure drop advantage/disadvantage?
  • Paul PolletsPaul Pollets Member Posts: 3,017
    edited December 2009
    diverter valves

    diverter valves are fine, the allow direct shutoff to the wall panel radiator. The wprads should be installed with a TRV, which attaches to the circuit setter. The existing cast iron rads should be retrofitted with TRV's on the supply inlet. I size the radiators for a 140 degree design temp, rather than 180. the rads are larger, but they heat with a lower water temp. the correction factors come with the manufacturer's technical guides.
  • TRV's it is

  • And then there's the kitchen

    Have you ever had a kickspace heater?  Yes, sometimes it's the only option and then you've got to live with the noise and lack of (in my experience) adequate heat.  If you have any wall space available or even the bare end of a cabinet, install a radiator or better yet, a towel warmer.
    Often wrong, never in doubt.
  • scott marklescott markle Member Posts: 611
    panel or Runtle

    I'm not sure I understood what was planed, is it a Runtle or a panel rad? Most panel rads integrate a valve so all you have to buy is the operator.

    Runtles are a bit more high design and aren't generally installed with exposed TRVs.

    Keep in mind that panel rads don't want to be over pumped, the maximum flow rates are low, erosion corrosion issues I think. Check with the manufacture before you pump a lot more water through a radiator than it needs for it's specific heating requirement. In other words it's not suitable to be directly in series with significant additional radiation

    Runtle rads on the other hand have wider passageways and thicker steel and can accept higher flow rates.

    You can put panel rads and iron on the same zone but avoid piping them in series. As far as the diverting valves are concerned they provide a nice shutoff and union, but I would be careful designing a system that depends on their carful calibration. I like to to plumb panel rads with 3/8' home runs.
  • Runtal panels or baseboards and the kitchen fan convectors

    The bathrooms have little wall space under the windows. I'd like to put Runtal panel rads under these windows. The 14.4" would fit

    The Runtal baseboards could also work in the bath with a longer run under the window.

    The 2nd floor 2 bathrooms won't be in series with the iron, but on a sub-loop off the old (originally gravity) larger diameter supply and return pipes from the basement. I'm not sure how I'll figure out how much flow is actually going to get to these radiators as I guess that depends on the differential of the resistance of that subloop, that of the reminder of the system, and the circulator of course.

    and the kitchen... I haven't had fan convectors before. We don't have any wall space. There is space under the counter of the island where people will sit. Runtal has a photo of a panel in such a location in their residential catalog, but I'm not so sure that's a good idea for us. I'm not entirely keen on the look and I'm concerned it's just too close to folks feet, esp the kids.

    Thanks again
  • I see your reasoning,

    but you should cast around for other options.  Sorry, I just don't like fan convectors, mostly because none of my customers who have them like them.  I'd even consider installing a panel radiator on the ceiling; call it an art object.
    Often wrong, never in doubt.
  • The final plan

    Thanks everyone for your help. I very much appreciate it. This site is spectacular.

    No fan convectors, will do radiant in the kitchen, mudroom and 1st floor 1/2 bath. Our GC will have to sub this to a different (dedicated) heating contractor than the original plumber/heating guy (who doesn't do radiant). Original guy still the plumbing guy on the job and will install Runtal panels in the upstairs 2 bathrooms, but is still reluctant to do the TRV's, trying to convince me the look is not good and I can just control these subloops from valve in basement.

    I'm still working on this and will ask him to look into a 'nicer' TRV like the ones Runtal has on there site and it seems Danfoss makes chrome and white sensors for valves as well.

    The radiant guy hasn't landed on the job yet (insulation just done and inspection nxt wk), but I wonder if he'd have some additional insight into how to supply the Runtal panels in context of the existing system and now a radiant system. Perhaps such a guy would just run the Runtal's off a manifold shunt or install a mini shunt? I don't know.

    Thanks again.

  • MikeT_Swampeast_MOMikeT_Swampeast_MO Member Posts: 14
    System Temps

    You say your boiler is set to 190F and it would seem that you still have your gravity-sized piping.

    On a nice cold morning when you have not used nighttime setback, I'd suggest measuring the temperature on the suppy pipe of one of your iron radiators.  You may be very surprised...

    Converted gravity systems are amazingly forgiving as long as you stay with the same form of heat emitter but start mixing emitters (iron, floors, panels) and you're begging for control, comfort and efficiency problems.  You should never, ever assume that the original supplies to rads have anywhere near the temperature setting of the boiler itself regardless of how the near boiler piping has been changed (or unchanged...).
  • temp reduced to 170


    Boiler temp backed down to 170
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