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Cast Iron on upper floors, Slantfin on 1st floor, one zone for entire house and NOT working well

LI_CJ Member Posts: 11
Hello all. I moved into a 1930s house 4 years ago, and it's been a jolly old time plugging air leaks and trying to improve the heat retention of the place. I know you can only do so much to an old house, but the frigid spells we get are really when you can analyze how poorly (or how well) your heating system is working.

I have a brand new Peerless WBV-03 which was converted to gas via a Carlin EZ. There is a back story to this - the short of it was that my old Burnham died in the middle of last winter, and with no gas line in the house (and a tough town for permits) I had no choice but to replace with another oil designed boiler. I got the full gas conversion finished this summer and with the new peerless, decided to give up some efficiency and use with the gas burner for now.

Now that I've been in the house for some years and know how the system performs in the milder weather and then the frigid weather, I am in the thought that the previous owner modified this system incorrectly. The first floor was all converted to base board radiators, presumably for aesthetics and wall space. 2nd and 3rd floors remain the trusty old cast iron radiators.

One zone for whole 2,700 sf house, and MAN is does not warm up. The thermostat is on the first floor in a room warmed by the baseboard. With the temps below 20 degrees, the system can't get much above 65, and that is in the room with the t-stat. My kitchen is on the larger side with an 8 foot base board run, and that room was in the high 50s this past weekend.

In my research, it sounds like my franken-system is just a no-no in the heating world. With radiators retaining their heat and baseboard having much more significant temp swings, is there any way to balance this system based on the details I've provided? Seems like the boiler is working hard and the results are poor.

I know cast iron baseboard is an option, albeit a pricey one. My other thoughts were electric heat as a supplement on the 1st floor. A 3rd option would be a 2nd boiler for the first floor. All pricey ideas.

Please let me know your thoughts on this setup, and any advice would be appreciated.

Thank you.


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
    Water or steam?--NBC
  • Jamie Hall
    Jamie Hall Member Posts: 23,433
    Step One. Do a room by room heat loss calculation -- SlantFin has a good download for that.

    Add that up. Can your boiler handle the load?

    Step Two. Using that room by room, look at what the radiation in each room can provide at various water temperatures. Can the radiation handle the demand? If so, at what temperature? You may find that the baseboard either can't handle the load at any reasonable temperature, or that in order to handle the load it needs to be run at a higher temperature than the big radiators.

    Which leads to Step Three: consider the possibility of dividing the system into two zones, possibly running at separate water temperatures.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Brewbeer
    Brewbeer Member Posts: 616
    Agree with @Jamie Hall heat loss and emitter analysis are required as a first step.

    More and or better baseboard on the first floor may be one of several possible answers for making this better. 8 feet of baseboard in the kitchen sounds low (I have 18 feet in mine with a 5k BTU design heat loss.)
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
  • Gordy
    Gordy Member Posts: 9,546
    edited January 2018
    I'm assuming the second, and third floor heat fine?

    Thermostat location comes to mind also. You state its in the 65 degree room. Maybe itneeds to be moved to a better location more representative of the down stairs.

    Have you tried balancing the upstairs rads if over heating is an issue on the second, and third floor?

    In the end you need to be sure through a heat loss that first floor radiation is sufficient for the AWT you are using.

    Since you have a CI boiler I see no reasons to over size a lot. Make sure they are sized for design day.
    JUGHNE Member Posts: 11,075
    Is it possible to throttle down the upstairs radiators with the hand valves?
    You would want to be sure the pump would not suffer because of less flow.
    It that would work, another option is to place restrictive orifices in the upper floor rad valves.
    EBEBRATT-Ed Member Posts: 15,616
    Check baseboard size versus heat loss as mentioned above. Run some new pipe and zone the first floor so you have two zones. Cast Iron and baseboard do not heat the same.

    If you fiddle with it trying to balance it you can make it work. IMHO it's not worth the struggle
  • neilc
    neilc Member Posts: 2,707
    if you're not making 65,
    what temp is the boiler making for supply water?
    or are we chasing room temp inbalance between floors
    known to beat dead horses
  • LI_CJ
    LI_CJ Member Posts: 11
    The system is hot water. Sounds like I definitely need to begin with a heat loss analysis. Will check out SlantFin's site.

    To answer a few other questions - the thermostat is in my dining room on the first floor. The room it's in is of course base board but it's not as cold as the kitchen. Kitchen is the coldest room by far, and likely parasitic to the other first floor rooms.

    As far as comfort level of the other floors, the third floor, which is seldom used but finished (so I'm not dealing with the biggest heat loss issue of an uninsulated attic) is the most comfortable and this is not a surprise given heat rises.

    The second floor; well, not exactly toasty either. In these nights where the temp is down to the teens or lower, if I have the t-stat set back to 64 downstairs, our master bedroom will drop to 61 or so. I really think one of my massive problems is lack of insulation. My next post will be people's opinions of blow in insulation and it's effectiveness :)

    I think the kitchen is clearly outgunned in terms of the current baseboard run. It's the one room that is 5 degrees colder than the others. Short of the kitchen, the house is surprisingly balanced in temp (no, upper floors are not infernos if trying to get 1st floor to 70...but I imagine for every incremental rise in 1st floor temp, the upper floor heat would accelerate at a greater pace).

    I need to work on air leaks and insulation in addition to improving the balance of heat.
  • Robert_25
    Robert_25 Member Posts: 530
    If your 3rd floor is comfortable and the 1st floor is cold, you need to work on air sealing. The stack effect of the house is drawing cold air in the basement/first floor.

    After you determine if there is enough radiation on the first floor, I would plan on spilling the first floor and second floor into separate zones.