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.

How's This for an Efficient Shell?

All on interior walls, recessed as shown. The mere 2" depth and rads < 12" wide allow simple placement in standard 2 x 4 partitions.

Homeowner expressed a desire for a home that could be "heated by a candle".

I suggested that these rads be decorated as such for the holidays...


  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    825 sq.ft. @ -20F design temp heated using three rads nearly* identical to those used in the photo to heat a BATH! 9,000 mbh output @ 170F average temperature.

    19 mbh system heat loss for 2,400 sq.ft. = < 8 btu/hr/sq.ft loss @ -20F.

    *6' high instead of approx 5' as shown.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    Heat Source for this Efficient Shell

    I suggest a Bradford-White 55 mbh input "water heater" with built-in space heating coil. By my calculations only unusual demand would produce a duty-cycle > 1 CPH @ 80% efficient.

  • Weezbo
    Weezbo Member Posts: 6,232
    Mike, on a mercy mission today....

    i found myself in a driveway near where i was going ,because the home under construction Looked unique , i got out and talked to the builder/homeowner... this man, pretty much all by his lonesome constructed about 6200 sq ft home. this is mostly CIF except for the basement, which is 4 pannels Thick ..each panel being an R- 40 +/- . under slab is 4" foam board.... outside the garage is a simple slab snow melt run off a single ball valve type control *~/:) he designed it and engineered everything to the last. including his heating system , which i felt he did not want to elaborate upon in finer detail..however it went pretty much like this, the fuel oil is stored in huge tanks, the burner fires.. the oil moves, the delta T of the moving oil is used to heat the radiant,.... For the potable water, he is using on demand Propane heating system ..like the Rennai...

    things like this are interesting to me*~/:) thought i would share, as i know you like energy conscious construction. cool rads by the way. seems like something that i have seen in aeroports...

  • do you take a hit recessing the panels? I would think that would inhibt the convection component a bit, plus you have less opportunity for the radiator to "see" the room.

  • what water temp are you designing for? not the 170 obviously...
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    No "hit" for recessing when the both the physical design of the emitters and the orientation of such in the space is perfectly suited to maximize radiation.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    170F is the design AWT based on Manual-J @ 20F delta-t.

    MY design is based on bare adequacy of 140F supply year-round. Regardless of supply temp setting, one cycle per hour unless DHW demand is unusual.

  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928


    Not > 1 CPH

    < 1 CPH without unusual DHW demand

  • But part of the room has to be blocked if the unit is fully recessed.. even completely flush, you can't see the wall the radiator is mounted on, like you can when it is surface mounted. The back side radiates too..
  • bigwilly104
    bigwilly104 Member Posts: 50

    I have used the bradford white combi coils twice. then I talked to the local hydronic rep about them. He told me that the heat exchangers failed all the time and thats why they stopped selling them. I could still get them brought in and I liked the two I installed but noone around here uses them and it honestly scared me. Do you use them much?
This discussion has been closed.