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2-pipe steam, big old house--questions

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  • 2-pipe steam, big old house--questions

    Hi there,

    I'm trying to optimize the heating system in the 120-year old, 8400 square foot home that my business partner and I--and our families--have just purchased and moved into this year.

    The system runs off an oil-fired boiler--a Carlin 102 CRD installed in 1978 and recently tested at 74%--and includes a heat exchanger that pushes forced hot air to much of the first floor and 23 radiators that heat the remainder of the first floor and both the second and third floors. (The house was built by the owners of a clock-making factory in 1890 and was originally heated via an underground pipe that fed steam to the house from the factory boiler-room.)

    When we first began heating in October, the house was broken down into 3 zones, each controlled by a valve coming off the near-boiler piping. Zone 1 was T-stat'd on the first floor, not 20 feet from an air grate that's probably 18" X 30". Zone 2 was T-stat'd on the second floor landing (just above the large grate just mentioned) and 10 feet from an enormous radiator (probably 2' X 2 1/2' and 3' tall). Zone 3 was T-stat'd in a narrow hallway in an addition above a two-car garage. (The 3 bedrooms and the bathroom in this addition always feel chilly.)

    There are almost 500 feet of steam and return pipes in the basement, and when we moved in not a one was insulated. The heat ran 5-10 times during the fall while we researched insulation, and everything went well except for a few traps that needed replacing. (We ended up replacing 15 traps altogether.)

    Then we got our insulation shipment and began insulating the mains with 2" fiberglass and the returns with 1" fiberglass. There was a warm spell that allowed us to get most of the pipes insulated without the boiler kicking on.

    The first cold night after that, one of the zone valves (addition above garage) stopped functioning and the system ran all night, until it woke us up sweating. We removed the valve from the system (leaving it open) and tried running the system with two zones. We had a little trouble tweaking the remaining T-stats to ensure that the debilitated zone's area stayed warm (but not too warm), but otherwise it worked OK.

    Two weeks later, another one of the zone valves stopped functioning (2nd floor landing), so we went through the same process, and tried to run off the remaining T-stat (1st floor, grand foyer). That didn't work really well, so we hooked the 2nd floor landing T-stat to the remaining operational zone valve and dialed the monster radiator back to zero, in the hopes that the T-stat would reach temp. more slowly and allow the rest of the house to get warm. (The 3rd floor bedrooms were hardly receiving heat at all.) That didn't work well either, so we hooked the garage addition's T-stat up to the working zone valve and we're trying to make that work.

    That's where we're at. We've read that zoning steam isn't necessarily a good idea, so we're not sure we want to repair the two broken zone valves, but we're also having a hard time regulating the whole house temp. with just one T-stat. It's a big enough house that different areas have different heating "profiles" or "habits".

    We keep the T-stat at 60 and I'm estimating that we're burning almost 100 gallons of oil per week.

    After spending $2000 on insulation and traps and another $2200 (so far) on heating oil, we're really trying to make this work with as little expense as possible, but if we're fools for not replacing the two zone-valve control modules, please let me know.

    Any and all advice is greatly appreciated.



  • #2
    Re: 2-pipe steam, big old house--questions

    So have you determined what was it that killed the zone valves?
    "It's a table saw, do you know where your fingers are?" Bob D. 2006


    1/20/2017 - The Beginning of a new Error


    • #3
      Re: 2-pipe steam, big old house--questions


      That's a big variable, I know.

      The wiring between the valves, the transformers, and the boiler is a mess.

      When the first one went, we called a father-in-law who's an electrical engineer (and used to run a boiler-room years ago). He's the one who identified the problem for us--i.e. that our valve was stuck open and prolonging the heat call to the whole house.

      I don't know enough about the valves to know why they went. The timing suggests that the insulating may have been a factor, but I don't understand how that could have caused the problem.

      On the other hand, the house has been vacant for most of the last decade and maintained "just enough" to prevent catastrophe.

      We bought it from the bank, which was burning 200+ gallons of oil per week!


      • #4
        Re: 2-pipe steam, big old house--questions

        A big house like that with an old steam system is going to very hard to balance, with or without zone valves. Without seeing the system layout, my advice would be to do away with the zone valves. As you now know they are nothing but trouble. I've never been a fan of zoning steam systems. The original design didn't have them and was likely done as a retrofit.

        This is what I would do:
        Disable and/or remove zone valves.
        Skim the boiler and flush it good. This is important and often overlooked when diagnosing steam systems.
        Make sure all the radiators have operating valves and new steam vents.

        If you still have overheating issues have a professional install a outdoor reset control. Here's a link to the one I use. It's not cheap but will provide you with the best comfort out of that old clunker in the basement.


        • #5
          Re: 2-pipe steam, big old house--questions

          Thanks for the advice!

          To be sure I understand:

          You'd disable the remaining zone valve and wire the T-stat directly to the boiler control? Is that better simply because it simplifies the system and eliminates the possibility of further zone valve malfunction or does that direct connection offer other advantages as well?

          Looking at the boiler, I don't believe there's a skim tap. Pressure relief valve is on top. Best bet using something like Squick?

          We've got a couple of low water shutoff valves to blow weekly--one was gummed up when we first moved in and we cleaned it out thoroughly. It functioned well for a few weeks but has now become clogged again. We'll clean it out again, but what does that suggest? Is this the kind of sediment accumulation that skimming and flushing should address, or should we take further action? I've read suggestions to drain and fill the boiler a few times to reduce or eliminate excessive sedimentation...

          The link you provided to the unit that controls the boiler with both interior and exterior temperatures was helpful. Is there a simpler way to achieve the same result? Any way I can program a thermostat to cycle in the same way that unit does, minus the outdoor temp. measurement? Sometimes I feel like the whole system would make more sense if it wasn't temp. controlled. Seems like it runs for an hour, hits temp, turns off, drops temp, kicks on again for 15 minutes, etc. If I could get it running 30 minutes every 2 hours...

          Thanks again,



          • #6
            Re: 2-pipe steam, big old house--questions

            Jeese, by default, a luthier is my pal, especially if you craft something even close to a Taylor Koa.

            Anyway, for the amount of money you're spending in short time, you might give serious adage to a hydronic conversion.

            I'll guess you have no insulation in the exterior walls with the age of the house and the boiler is very old, two very costly things when it gets cold.

            IF you have gas on your street.

            The stimulus offers a 33% tax credit (not a write-off) on the cost of a new high efficiency boiler, plus, if you have gas available on your street, you can get some pretty good rebates for installing a boiler that's better than 85% efficient.

            The cost for running a gas service can be surprisingly low priced as well, depending on how far a service line is located from your home.

            You can look here for more info

            For now, I might suggest you have a heating guy look at6 the problem, though I understand your father in law is an engineer, you might not have as much sticker chock as you're afraid of just to have someone evaluate the problem and maybe offer you an idea for the cost to replace.


            • #7
              Re: 2-pipe steam, big old house--questions


              Squick is good. I use Boiler Colloid. It's a liquid not powed form and easier to use. Pressure relief valve tap is ok but there's probably some others on there that should be easier to use. If the system was neglected for any length of time you'll need several cleanings. One just won't do it. Time the cleanings several weeks apart during cold months when the boiler is pretty active. Cleaning will loosen all the scale and rust and bring it all back to the boiler to be 'skimmed' off. Steam boilers need LOTS of babysitting.

              The Heat-Timer control is probably what you need for that big system. Maybe try one centrally located thermostat on a timer and see how well that does with the zone valves locked open. The timer control will do what you're asking but it won't take into account what the outdoor temps are so you'll still be over/under heating when they fluxuate. The outdoor reset control will pay for itself in one season on that system with fuel savings.

              Other members more familiar with steam systems should chime in soon



              • #8
                Re: 2-pipe steam, big old house--questions

                go to heating and get dans books best $ spent


                • #9
                  Re: 2-pipe steam, big old house--questions

                  Thanks again to everyone for all the advice!

                  Spent today flushing the boiler and cleaning the gunked-up low-water shutoff valve.

                  Started off by draining the boiler (30 min. or so after we turned it off). We have concrete channels in our basement floor that carry water from the boiler to the sump pump, so we connected a garden hose and dumped it directly into the channel. Hoping the water temp. didn't harm the sump pump, which is new, but what's done is done...I'd do it again, too, to make sure I got as much sediment out as possible.

                  Did we ever! The water ran red with rust and debris and the bucketfuls we collected to examine were roiling with an oil slick on the surface.

                  The shutoff valve was muddy and goopy, as opposed to the harder, chunkier sediment we cleaned out of it the first time. It still won't driain water, so our next move is to replace the piping that takes it down to floor-level and 10 feet to the channel.

                  After the initial draining, we let the boiler cool down for a couple of hours. When it was appropriately cool, we filled it through the safety valve tapping (with a garden hose) and drained it again. The water was still nasty, so we repeated the procedure one more time.

                  Finally, we filled the boiler again, added the Squick, re-installed the safety valve and piping, turned on the automatic water feed and fired the boiler up.

                  It's been running for almost an hour now (we cranked the heat a little to be sure we boil out the corrosive gases in the fresh water) and everything seems to be working fine. The water in the glass isn't entirely clear yet, but we'll be draining the boiler again tomorrow or Sunday and then repeating the whole process again next month--and probably every heating month thereafter, or until we get clean water!

                  Thanks again,



                  • #10
                    Re: 2-pipe steam, big old house--questions

                    Originally posted by jeff View Post
                    go to heating and get dans books best $ spent
                    Yes. First thing we did, before we tackled anything.

                    We bought "The Lost Art of Steam Heating" and "Greening Steam."