Replacing low-hanging, large diameter gravity hot water heat pipes
My wife wants to get rid of the low-hanging supply and return lines running across the most useable space in the basement. which we want to finish for living space. The ceiling height will only be 6'4", and the pipes cut into that. However, we are all short enough to walk under them without hitting our heads.
I want to leave it alone. The system works fine. I don't know enough about the potential impacts of changing the pipe diameter (short cycling, air pockets, etc.) and don't trust the contractors who say it would be no problem (both because they won't be around to solve the many small or not-so-small problems that arise, and because the contractors I've spoken with and DO trust suggest leaving it as-is).
Here are the broad strokes:
- Boiler: oil-fired 1996 Thermodynamics VTF Series with 220-gallon steel tank. It has a circulator pump and an expansion tank near the boiler. It's regularly maintained, has a new burner nozzle, and works great.
- Piping: original 2-inch ID steel supply and return lines (2 branches; one on either side of the basement, which have the radiators connected in parallel via 1-inch ID steel pipe. It was a gravity system with a small coal boiler. The attic tank is long gone. The pipes have some light surface rust from summertime condensation (the basement is pretty dry, and I run a dehumidifier in the summer).
- House: 1,600sf (it's a Craftsman Vallonia built in 1928), plus 800sf of basement
- Radiators: cast iron; eight on the first floor, three upstairs.
- Consumption: We're on Long Island, and we use 400-500 gallons of oil per year. (I insulated the attic and it's definitely not like Florida in here in the winter… put on a sweater!).
- Piping Runs: There are two branches; one on either side of the basement. The radiators at the end of each run were both relocated 15-20 years ago, and re-plumbed with copper. (That said, they were at the easy-to-disconnect, smaller-diameter ends.)
As I mentioned, I've gotten a range of opinions on this, from "Just re-plumb it all in 1-inch copper" to "I wouldn't mess with that if I were you." My wife seems only to care for aesthetic reasons. I'm thinking more about how difficult it will be to separate 100yo steel pipes from one another, and the possibility of every joint being its own miserable odyssey, along with the potential of damaging the in-wall piping leading to the second floor in three places. I figure it would be fine to paint the pipes silver where they run through the living space, leaving an open, airy look that won't block light from the windows. Beadboard plywood ceiling above, in white. Lots of natural light from bigger windows.
Thoughts? Recommendations? Should I bite the bullet, drain the system, and try cracking some of the smaller pipes free? Can I put smaller diameter pipe at the end of a 20-foot run of 2-inch pipe to avoid having to disconnect numerous ancient fittings? Or does the whole system have to be replaced if at all?
Or should I pay attention to the little man in my gut, leave it the heck alone, and just be careful to warn people not to hit their heads on low-hanging pipes? (Digging out the basement is not an option here.)
Comments
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If it was me I would leave it alone if it aint broke don't fix it.
But you got to keep the wife happy or you will never here the end of it.
You can recipe it with pex or copper and change it to a manifold system at least for the first floor.
As far as working with the old pipe this is not an issue with Someone That Knows What They Are Doing
Hot water heat is all about having the correct flow to each radiator. This involves correct sizing of pipe and circulators. A lot of contractors WING IT because they won't take the time to do the math.
With a good contractor you will be fine
Post your location and check "find a contractor " on this site. make sure to allow for combustion air for the boiler if you finish the basement.
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I did this recently and my only regret is not doing it earlier.
In my case, I got rid of the big runs across the basement and left all the black pipe at the ends which connect to the rads. This meant I didn't have to deal with any piping inside the house plus most of the existing rads continued to be supported by the piping (when you go full home run with PEX, you need to support your rads to the walls to avoid tipping over).
It felt wrong to connect 5/8 pex to a 1.5" black pipe riser but works. It not only works, but works better than the previous setup ever did. One of my rads never got enough heat before, now I can dial in exactly how much flow that gets.
There is some design that needs to go into it but not too hard. In my case, all the new pipe is run through the floor joists so a ceiling install would be very simple down the road.
One thing to watch, I've seen plumbers mangle joists by drilling too close the bottom (ie 2.5" hole about 3/4" away from the edge). Fix for that was very expensive and there really was no need for it.
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Good tip. Question: Who vets the contractors listed on this site? Contractors on Long Island aren't particularly hungry, so it can be tough to find a good one who's willing to do something other than a complete remodel. And finding someone who knows what they're doing can be difficult because when I start asking technical questions, they ghost me. Easier customers abound!
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this is a common question on HH. And yes it can be done.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Because this is no longer a gravity flow system the world is your oyster. Like @Kaos you can now repipe it with either Pex or copper and either zone each radiator or balance the system at a manifold located in the cellar. Make the pex to the existing black pipe radiator supplies (as long as the valves and fittings are sound) to keep the look of the old system in the living spaces. This will lend itself beautifully to any future boiler upgrades.
Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker0 -
I don't think you'll gain much height and pex supplies will need support.
But it can be done, probably copper is better in this application.
Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.0 -
I have 6 feet, 4 inches total height. Every quarter inch matters here.
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Ok, copper along the joists will be it then. You'll also have to shorten the risers.
Not an insignificant task.
Your contractor will also have to refigure head loss and flow for the new arrangement.
Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.1 -
If your contractor runs the numbers, you will probably find that 3/8 inch copper tubing will be enough for most rooms. 3/8 branches can feed about 6,000 btu/hr…and that's using the high flow rates for traditional American designs ( 20F drop between supply and return when at peak load). Using more modern flow rates that provide 30F drop, you can deliver even more heat. Since most old radiators are greatly oversized, using low flow rates can work very well, if you can balance the supply to each radiator. 3/8 soft copper tubing is very nice to work with in retrofits like this.
To learn more about this professional, click here to visit their ad in Find A Contractor.
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I just want to point out that at 6' 4" you cant finish the basement per code. Minimum is 7' if I'm not mistaken. You two maybe good at 6' 4", so would I, but many wouldn't be. I have family members who would knock themselves out on those ceilings.
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This is another option called a home run method.
Each radiator gets it's own supply and return, 1/2" tube, sometimes 3/8 as Whisper mentioned.
You can add thermostatic valves so each radiator in the home could have temperature adjustment.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Ben...There ARE competent & Hungry contractors out there. What town are you in? Mad Dog
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Babylon.
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We're not too worried about that. No permits will be applied for, and if we ever sell the house (was planning on staying here for the duration), it'll be "finished storage" or whatever. In the intervening years, finishing this space will provide an unquantifiable improvement in our standard of living for relatively little money. Also, finished basements (we're talking paneling and some floor paint) with low ceilings are a hallmark of Long Island homes. In other words, I may not need a permit, but a tiki bar may be required! :-D
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Well whatever you do, do yourself a favor and insulate those walls before you frame. 2" polyiso with the joints between the panels taped or sealed with expanding foam. Spray foam the rim joists from the subfloor to the polyiso with an overlap to seal that. Then frame out with furring strips, 2x2's or 2x4's and your choice of wall covering. If you have the space use 2x4's. Makes running electrical much easier and you can pack in rockwool insulation @ ~r15. Your basement will stay warmer and dryer than the rest of your house.
Do not worry about your foundation having to "breath" or dry to the inside. That is a BS myth. The foundation is in direct contact with mud and clay with a near unlimited source of moisture. It will NEVER dry. It will only leach out minerals as the moisture moves to the inside, weakening the foundation in the process. The polyiso moves the edge of the thermal envelope to the outside edge of the polyiso. The foundation is than considered outside of the envelope. The largest risk factor with this approach is that the possibility of enough moisture wicking up into the sill plate, which is old growth wood in your case, is increased. This can be mitigated by making sure there is enough space between the outside grade and top of the foundation and keeping vegetation far enough away. And of course proper slope and drainage. If the house has been waterproofed from the outside this is not a concern.
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Xps works. I prefer polyiso simply because you can get a higher r/inch. Where I have framed walls in my basement they're approaching r28 with the r13 polyiso and r15 rockwool. The unfinished areas(storage room/old coal bin, boiler room, and laundry) its just exposed rated polyiso at r13.
My computer room where the server, fish tank, and pc are at is actually overheating. i've been contemplating opening one of the windows. The heater in my aquarium hasn't had to run once since I moved it down there and I keep it set at 77. Thats a 65 gallon reef ready with a 20 gallon sump worth of water holding steady at 77f. Had to shut off one of the light fixtures to keep it from over heating... In a northern ohio basement in november.
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I had thought of this. The problem is that we won't be finishing the entire basement, only the center section that runs across the middle of the house's footprint (east to west). That'll leave most of the concrete walls exposed in the two utility areas along the south side of the house, and in the northeast corner. The northwest corner (laundry room) was already framed and drywalled when we bought the place, so I'm not going to mess with it. It's freezing in there in the winter, but probably because a) the original wooden window lets in a lot of air, as does the "rim joist" (which, on the north and south sides of the house consists only of wall studs nailed to the sole plate, with no blocking, and only exterior tongue-and-groove sheathing/tarpaper/cedar shingles nailed to the outside), and b) because there's only a few feet of heating pipe in there, next to the air-leaky window.
Most of the basement stays fairly warm during the winter. What I really like about the space is how cool it is during summer. I don't want to lose that. It's the best place in the house from June until October. I don't even need air conditioning. I figure spray-foaming the rim joist, and putting board foam on the top half of the concrete wall will insulate the part that actually gets cold in the winter, and hot in the summer. (I can install a vent in the boiler room for outside air.)
My only other concern is fire safety. Board foam insulation, when it finally burns, releases heavy toxic smoke—not a great thing in a basement fire. I suppose I could mitigate that by installing a sprinkler system down there. I need to reconfigure the plumbing system anyway.
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Absolutely your call however DOW Corning brand XPS "Scoreboard" has been certified to meet ASTM C578 Type IV and can be installed without a Prescriptive Thermal Barrier. See excerpt from ICC-ES Evaluation Report ESR-2142 (October 2022, 2023).
"4.2.2 Application without a Prescriptive Thermal Barrier: ASTM 0578 Type X and Type IV Styrofoam”
Brand insulation boards may be installed without a prescriptive 15-minute thermal barrier required by applicable code when the maximum thickness does not exceed 2 inches (51 mm)."1 -
The moisture control is low key the biggest advantage. Prior to finishing my basement I ran a dehumidifier 8-9 months a year nonstop. And would empty it 2 times a day. Now i can go a week between emptying. And that is with two aquariums(there is also a 29 gallon in my kids playroom). That helps keep it cooler in the summer. The bathroom, and kids playroom basically stay right around 70 year round' now.
But like PC7060 said, your call.
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You asked a question up there somewhere as to who vets. the contractors who advertise or post on The Wall. The answer is — no one. The contractors who are listed voluntarily provide the money which goes to operate this site (which is non-profit). Now that said, in fact most of the "old timers" on The Wall know each other personally or by interacting for years here, and have a pretty fair idea as to who can do what, and how well.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
I suppose the floor would still keep it cool in summer. It'll just be vinyl on top of concrete.
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