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Radiant + radiator heating plans -- could use some validation, critiques

joekannooks Member Posts: 3
edited June 2019 in Radiant Heating
HI, new here... we're renovating a ~4500 sqft. house, going with:

- Radiant floor heat (Eco Warm panels under hardwood) on floors 1 and 2
- Keeping the the radiators on floor 3
- Secondary radiators for the two sun/sitting rooms
- Adding two radiators in the basement in lieu of the old oversized iron, to be removed.

Existing boiler: Viessmann Vitogas 100 GS10-72
Circulating pump: Astro 230
Secondary pumps: Grundfos Alpha2 15-55F
Controls: Tekmar thermostats for each zone w/ 315s and 402s to make it work

I had an engineer put together plans and a design for everything. According to them, the design is relying on injection mixing... but I've got a few concerns (maybe it's just that I know enough to be dangerous):

- It doesn't seem to be consistent with injection mixing designs I've seen (no primary/secondary loop, parallel or otherwise).
- The radiators and floor heat can't run on separate temps.
- The secondary loops will not be able to manage delta T (flow) separately from the actual Tsupply.
- The radiators in the sun/sitting rooms can't necessarily be run independently of the other radiators when they're supposed to be second stage heat for their respective rooms.

So, please let me know what you think, or if you have any questions.

Appreciate the input!

(the removed zone (manifold 3) will be combined with manifold 1)


  • Jamie Hall
    Jamie Hall Member Posts: 23,322
    Hot water heat and radiant aren't my special thing. That said... I'm not quite sure just where to start on listing the problems I can see with that design … in addition to the ones you have listed, which all appear to be valid concerns.

    Where are you located? We may know someone in the heating field in your area who could come up with a much better design. Much as I hate to say it, engineers don't always know what they are doing... (I am one, by the way!).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Zman
    Zman Member Posts: 7,569
    Maybe they gave it to the FNG and didn't keep an eye on him. :)
    There is absolutely nothing correct about the drawings. I just don't know where to begin...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • joekannooks
    joekannooks Member Posts: 3
    edited June 2019
    Ha! Feel free to begin somewhere :). Work is starting but there's an opportunity to correct issues before things are put together.

    First thing, thinking we move toward something like this: https://www.hpacmag.com/features/siegenthaler-hydronic-piping-layout/#attachment_1004104433. One pump for radiators; the other pump(s) for the radiant behind a mixing valve? Thoughts?

  • hot_rod
    hot_rod Member Posts: 22,157
    Here is some additional reading. Find a whole selection of these Idronics at Caleffi websites, as downloadable pdfs.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    The Vitodens 200 is designed to do 2 separate heating temps plus DHW. All that is needed is the mixing valve and motor actuator for the low temps. The 100 is designed really for a single temp.
  • Zman
    Zman Member Posts: 7,569
    edited June 2019
    Incorrect expansion tank location
    No primary/secondary
    Pumps in series
    No check valves on zones
    Even with checks, main pump will ghost all zones all the time.
    There is no injection mixing. If you vary the speed of zone pumps, it will just make the zone heat unevenly.
    Some zones are calced at 46btu/ft, even if panels will produce that much, it will be uncomfortable.

    There is seriously nothing that looks correct. You could give a kindergartner crayons and they would do better, completely by accident.

    There are lot's of ways to do this correctly, this is absolutely not one of them. I would recommend stopping all boiler and distribution piping until you sort this out.

    Here is one way that works very well. This is from a ridiculous "mountain cabin" 17,000 square feet with tons of snow melt.
    The 31 zone valves were all existing remote valves located all over
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    joekannooksPaul PolletsIronman
  • joekannooks
    joekannooks Member Posts: 3
    Thanks, all. Zman (thanks for posting that plan), the two zones I believe you're referring to (1 and 4) have CI radiators to help them. They're supposed to work as second stage heating for those areas specifically, but I don't think the plumbing completely supports that.

    To be fair, here is the breakout for each pump. And the Vitogas manual does indicate the expansion tank off the back of the unit.

    This is all supposed to be controlled by a combo of Tekmar 402s and 315s btw.

    Will be connecting with engineer and contractor later...
  • ScottSecor
    ScottSecor Member Posts: 856
    I gather the engineer/draftsman did the old cut and paste with regard to the pump details. The pump depicted appears to be a commercial vertical shaft model, not your typical wet rotor "canned" type circulator. For example we have worked in homes as small as 700 square feet and as large as over 10,000 square feet, maybe ten of them had gauges on the inlet and outlet of the pumps. However, on about one third of the commercial jobs there are pressure gauges on the inlet and the outlet of pumps, especially base mounted and the vertical inline that your drawing shows. In addition, the lubricated plug valve serves almost no purpose in your system, especially if the circulators are variable speed ECM type.

    While your engineer may be excellent at what he does, I urge you to have a hydronic specialist at least consult before you move forward. We do not discuss price here, but I can tell you that if the pump details were followed exactly as drawn you would likely spend 1.5 to 2 times more than you should. In other words there are much better and simpler ways to install residential pumps (and heating systems for that matter).