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  1. #1
    Join Date
    Jan 2010
    Location
    Philadelphia, PA
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    Question Radiator Heat in a Rowhome

    I live in a 2-story rowhome and I am noticing a very counter-intuitive effect of my heat flow; the downstairs stays much warmer than the upstairs. I have radiator heating, and I notice also that the downstairs radiators are always much hotter than the upstairs. The thermostat is located on the first floor, and it reaches the desired temperature rather quickly. As a result, the upstairs radiators aren't getting as hot because the furnace kicks off before they have a chance to get hot enough to heat the rooms. In order to solve this problem, I am considering installing a vent and a small duct in the ceiling above the thermostat in order to transfer the warm air at the thermostat into the room upstairs. I am hoping that this will drop the temp. at the thermostat and cause the furnace to stay on longer to properly heat the upstairs.

    Before I take on this project, I want to ask the question if anyone else has dealt with this sort of issue, and if anyone thinks that this plan will not make a difference. Your responses are greatly appreciated.

    Thank You

  2. #2
    Join Date
    Feb 2008
    Posts
    555

    Default Re: Radiator Heat in a Rowhome

    jb:

    Several things could cause the symptoms you describe---let's try a few things before you make any changes.

    This type of situation could be caused by an easily fixable condition where the WATER PRESSURE at the boiler gauge on the front of the boiler is TOO LOW to push the water up to the 2nd floor, thus, only the 1st floor rads heat up--simply "bleeding air" out of the upper rads is usually all that's needed.

    1) Check the boiler gauge---it should read at least 12 psi to 15 psi (pounds per square inch)---there are usually two needles on the gauge, the RED one records water temperature, and the BLACK one records water pressure.

    When the boiler is cold, the pressure should read approx. 12 psi---it will rise slightly to perhaps 20 psi when the boiler heats up----if the psi reads less than 12 psi--say perhaps 5 psi, there's not enough pressure to get the hot water up to the 2nd floor rads.

    2) Also, take a screwdriver or a small coin & a cup & try to open the BLEED VALVES on the 2nd floor rads---these are small chrome valves usually with a insert on the top side of the rad for a flat-blade screwdriver.

    You should get water escaping; if you hear air escaping, leave it open until you see some water come out, then close---do this for all the 2nd floor rads, then see if there is a difference in how quickly (if at all) the upper rads heat up.

    3) Take a metal rule & measure the approx. vertical distance from the boiler, to the 1st floor & then to the 2nd floor rads (also add the totals between floors/cellar) & add up the totals---the boiler will "push" the water thru the height of the pipes at the rate of 2.31 feet for every pound of pressure as read on the psi gauge.

    Thus, if the boiler psi gauge reads 8 psi X 2.31 = 18.48 ft.---if the measured height from the boiler is greater than 18.48 ft., the water isn't getting up to the 2nd floor rads & the pressure has to be increased---simply "bleeding" the upper rads, as explained above is usually enough to sufficiently raise the psi water pressure.

    Please post back.
    Last edited by NashuaTech; 01-01-2010 at 01:29 PM.

  3. #3
    Join Date
    Jan 2010
    Location
    Philadelphia, PA
    Posts
    3

    Default Re: Radiator Heat in a Rowhome

    Thank you very much for the info. I bled the radiators this morning and they were full of air. I neglected to do so in the fall like I was supposed to and like I have the past 2 years. The calc for the pressure and distance was very helpful. My boiler pressure was at 5! the gauge on my boiler has a meter for Pressure, written in black, and one for altitude, written in red. Then there is an entirely separate gauge for temperature. The altitude has a red arrow that is fixed at 35, which makes sense as the distance in feet to the furthest upstairs radiator (I measured to check, per your advice). Therefore, as you said, I needed to get my black pressure arrow to align with the red altitude arrow...which puts the pressure at a little over 15 psi. This all makes perfect sense with your formula.

    After making these adjustments, I cranked up the heat to 73 degrees. The radiators heated up like a charm both upstairs and downstairs. However, as I walk up my staircase, as soon as my head gets above first floor ceiling level, I notice a big temperature differential. I am surprised my steps don't have condensation on them! The upstairs is much cooler than the downstairs, which to me completely ruins the law of hot air always moving to colder air. The only conclusion for this that I can come to is that the ceiling is holding the warm air down to the first floor and the exterior walls are performing very well thermally. This also makes me think that there isn't adequate roof insulation, maybe warm air is escaping through the roof. Either way, that's why my initial reaction is to install a relief vent in the 1st floor ceiling to balance out the temperature between floors. Or, maybe it's a better idea to install new roof insulation. I believe that my roof is currently insulated with that old blow-in black asbestos. Maybe I need something better.

    I am interested in your advice on this. Your comment to check the pressure and bleed the radiators was spot-on. I'm just at a loss for how to better balance the air. Currently, the downstairs needs to be uncomfortably warm to get the upstairs to an acceptable temp.

    Thanks again.

  4. #4
    Join Date
    Feb 2008
    Posts
    555

    Default Re: Radiator Heat in a Rowhome

    jb:

    Good work jb!

    Glad to see you made some good progress.

    But again, before spending $$$ on insulation, vents or a fan to blow warm air to the 2nd floor, let's try a few other things.

    The WATER TEMP on the boiler gauge should be approx. 180 degrees when the boiler is heating up---this is the temp at which the rads are designed to operate.

    If the downstairs rads have on/off valves at their base, try slightly turning down (clockwise) the rad valve (to prevent a lot of hot water from flowing thru the downstairs rads).

    This should direct more of the hot water (and more of the heat) to the 2nd floor rads (hopefully, anyway).

    Also, go up to the 2nd floor rads & if they have on/off valves at their base, make sure they are all turned all the way on (counter-clockwise).

    Also bleed the 2nd floor rads again---it usually takes additional time to get the air completely out (new water is added to the rads & pipes--this "new water" contains entrained air, that separates from the water & always gravitates to the highest point in the system.

    Also, when the 2nd floor rads are heating up, use your hand to touch them at various points---be careful not to burn yourself----but the "touch test" is the best way to calculate if the rads are operating at the right temperature.

    Thus, lick your finger & quickly touch the rad at the middle & quickly remove your finger----if you can't hold your finger on the rad for more than a second or two, the water temp at that rad is correctly at approx. 180 degrees.

    If you can hold your finger on the rad for several seconds, the 2nd floor rad is for some reason not getting enough 180 degree water.

    The rad should be too hot to touch for more than a second or two on any part of its surface---so try various spots.

    If you can, try to leave as many 1st floor doors and partitions open wide so the heat has a chance to gravitate to the stairway & 2nd floor.

    If these tricks don't work, there are others that can be tried.

    Please post back.
    Last edited by NashuaTech; 01-01-2010 at 11:38 PM.

  5. #5
    Join Date
    Jan 2010
    Location
    Philadelphia, PA
    Posts
    3

    Default Re: Radiator Heat in a Rowhome

    Nashua

    Yesterday, per your suggestion, I turned the 1st floor radiators 3/4 of the way closed. This seems to have helped balance the heat much better than previous..I no longer have a fear of condensation on the steps. The upstairs is still cooler, but in general it is no longer uncomfortable. It was still a little chilly this morning upstairs. I also notice that the radiators on the second floor stay hot for longer...this is a major difference from previous.

    The downstairs has no doors and only one partition that is mostly a doors opening.I have been keeping all of the doors upstairs open in hopes that the warm air from downstairs will migrate better into the rooms.

    In general, it has been a big improvement but it is still not 100% balanced. I wonder if my second floor windows aren't sealed as well as my first floor...I haven't been up there to caulk them. I am definitely interested in any other tips you have.

    Thanks again

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