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Why doesn’t Mr Unit Heater work?

Chuck_17Chuck_17 Posts: 114Member


And why does he make noise?

This unit heater was installed in a room in a building which has convectors in most rooms. (It was a convent and most of the rooms are small bedrooms). It is Is in a corner sun room that is currently used as an office. The person working there says when it goes on it is hot then cold. And it bangs a bit.

The steam system is controlled by a tekmar 279 with a few space sensors. I assume the unit heater is blowing cold waiting for the boiler to start up it’s cycle.

Water hammer – There is no drip on the steam. And not much of a leg on the condensate. I’m don’t know about putting a thermostatic trap on a unit heater either.

Comments

  • EBEBRATT-EdEBEBRATT-Ed Posts: 6,047Member
    would need to see how the piping and boiler and unit heater are connected. you may or may not need a trap
  • HVACNUTHVACNUT Posts: 2,549Member
    A pic of the back side too.
    And the wiring diagram if its there.
    If there are sensors, what does the thermostat control? Just the fan? Is there a temp sensor on the piping or coil?
    How far away from the heater is the desk? It probably looks like that old Maxell Hi-Fidelity, guy in the chair commercial.
  • DanHolohanDanHolohan Posts: 14,782Member, Moderator, Administrator
    Does the discharge pipe from the heater go to a wet return or to a dry return? How does the air get out of the unit? Is there a boiler-feed pump? Condensate pump? Is there a control valve on the heater?
    Retired and loving it.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 6,047Member
    @DanHolohan

    Thought you were "retired and loving it" Up early posting I see.

    LOL

    Glad your still involved!!
  • Chuck_17Chuck_17 Posts: 114Member
    I'm in the building for different reasons (so I didn't look at it in detail) but the unit heater caught my interest .

    No control valve.
    Line voltage thermostat.
    Dry return.
    Boiler feed pump.
    Nothing behind the UH (pipe just goes up top the top).

    Air? Good question. Steam pushes it out the trap?
  • Chuck_17Chuck_17 Posts: 114Member
    HVACNUT said:

    A pic of the back side too.

    And the wiring diagram if its there.

    If there are sensors, what does the thermostat control? Just the fan? Is there a temp sensor on the piping or coil?

    How far away from the heater is the desk? It probably looks like that old Maxell Hi-Fidelity, guy in the chair commercial.

    I didn't know the reference until I googled it. (I knew as soon as I saw it)
    I don't think it would be too bad. The UH is in the corner and the desk is maybe 10 or 15 feet.

    The room really does need separate control. It is a corner sun room so I am sure it is hot when the sun is out and cold otherwise. I don't think there was any heat there originally.
    They just put in new windows which the women in the room says helps a lot. Se was using an electric heater.
    New windows may be to only update to this building - ever.
  • DanHolohanDanHolohan Posts: 14,782Member, Moderator, Administrator
    @EBEBRATT-Ed part of being retired is waking up before dawn. So much to do! ;)
    Retired and loving it.
  • Jamie HallJamie Hall Posts: 11,171Member
    A few thoughts here... first, I can't see anything amiss with putting a thermostatic trap on the return, except you may need to do some fiddling to get gravity flow. If the dry return it feeds to is vented, that will still allow air to get out, but not allow steam to get into the return -- which can mess things up elsewhere.

    There should be a thermostat on the supply, though, to prevent the unit from blowing when there is no steam. A strap-on aquastat could be used.

    I'm not a bit surprised it bangs a bit. Check the pitch on the steam inlet line -- from the picture it looks pretty darn flat. Also the return line. They don't usually bang, but they can.
    Jamie

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Chuck_17Chuck_17 Posts: 114Member
    Note that the steam is going up to the top connection. So any condensate in the (uninsulated) steam line is running back against the steam.
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