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Replacing Baseboard with Radiators

dtotzzdtotzz Member Posts: 4
I found this website from

I'm a first-time homeowner and bought a circa 1900 home last fall in new england. It is heated with an oil boiler and has ugly baseboard heat throughout. I'd like to eventually put radiators in to restore some of its historic charm.

I'm curious if anyone can recommend a good book from Dan Holohan that could help educate me on this subject. I don't have natural gas available where I live and that seems to be a common fuel for steam systems. I'd like to figure out what was originally in the home to heat it and try to recreate it as much as is practical/possible.

Anyone who has done a similar conversion I'd love to hear your stories too. Or if you can point me to some relevant threads in this forum that would also be a huge help.



  • mattmia2mattmia2 Member Posts: 1,738
    I would just get cast iron radiators and set them up as hot water from the existing system. If you mix fin tube and cast iron you have to be careful because the cast iron will heat slowly and continue to heat a long time after the boiler/zone shuts off but fin tube will heat and stop quickly.
  • Jamie HallJamie Hall Member Posts: 13,209
    You mention steam, but is the existing baseboard steam? That's uncommon. You also mention gas not being available -- that's quite common, and not a problem. Oil heats water just as well as gas! There are lots and lots of oil fired steam and hot water boilers out there -- it's mostly a matter of what's available where you are, and at what price.

    @mattmia2 is right on. Go for it.
    Br. Jamie, osb

    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
  • STEVEusaPASTEVEusaPA Member Posts: 4,365
    Take some pictures of the boiler and the piping. Could've been originally coal, so how far back to you want to go :) ?
    Could have also been originally a coal gravity furnace, and was changed to a water system years later.
    @Jamie Hall where does he mention steam?
  • dtotzzdtotzz Member Posts: 4
    Thanks for the replies!

    @mattmia2 that's the most likely approach for me, and figuring out how to balance baseboard and radiator heating will be tricky, or possibly I might just need to convert one zone completely to radiators.

    @Jamie Hall the current system is forced hot water. I've heard of gas being the most common way to fire steam boilers where I am in new england, but would be open to an oil-fired steam boiler too. Trying to learn the pros and cons of oil vs gas, and steam vs hydronics when it comes to heating with old radiators.

    @STEVEusaPA My cast iron boiler cracked this winter and when I discovered it this spring I had a Pensotti boiler with Rielo burner put in. I would love to have an octopus, but I like the look and sounds of steam radiators. Unclear what the home originally had since it was remodeled down to the studs in the 1990s and most of the flooring replaced. The boiler feeds a DHW and my first and second floor. There's a circulator and everything for the "3rd floor" finished attic space, but that was disconnected. The attic was finished but the seller put in a garbage electric baseboard. Everything is controlled with a Taco 504, and circulator pumps.

    Not looking to do anything soon, just looking to learn and plan for the future so I keep things historically accurate.

    Also, FWIW, the home has a double flue chimney that was rebuilt in the 1990s. One flue is used for the boiler and I had the other capped off this spring since it's unused and I wanted to preserve it. No evidence of a fireplace in the home and I spoke with owners who lived there in the 1950s and they didn't remember any fireplace/woodstoves either.
  • mattmia2mattmia2 Member Posts: 1,738
    edited August 27
    This book is good for learning about hydronic systems:

    This series of articles covers probably most if not all of what is in that book and more:

    I would not put CI and fin tube on the same zone, I would either replace the whole zone or split it. You need to understand about the different system layouts and how those affect the sizing of the emitters.
  • EdTheHeaterManEdTheHeaterMan Member Posts: 724
    edited August 27
    You will want a master plan. What it will look like in 5 or 10 years. once you have that, you can start to purchase cast iron radiators from the internet, local supply house or from scrap yards. The scrap yards will usually let you return them if they leak, so make sure you ask upfront what the policy is about returns on used radiators. Gently used radiators are commonly repurposed in projects like yours.

    Once you have a game plan, you can size the main piping from the boiler room to the radiator location. Allowing for future radiators will sometimes mean that the piping from the boiler room to the radiator location is oversized for now, allowing for additional radiators in the future. I would recommend a parallel reverse return design, but a standard parallel design may also work with proper pipe sizing and EDR sizing.

    You already have a nice oil fired boiler, so now you make a new zone with the Cast Iron piping design to handle a different water temperature by use of a bypass on that zone.

    this illustration is from a book written by @DanHolohan for the B&G circulator company. They no longer print this version. the newer version is missing some important stuff.
    The bypass is on Zone 2 and will have a lower operating temperature than the baseboard zone(s) that do not have a bypass.

    As each room is renovated with the new (or old cast iron) radiator you remove the copper baseboard from that room and just connect the copper pipes together in some fashion (below the floor if possible) to keep the copper/aluminum fin baseboard loop in service. The thermostat locations will be critical, so keep in mind that you may need to change the thermostat locations as the project moves on. ( you will need 2 thermostats: one for the Baseboard, one for the Cast Iron).

  • vtfarmervtfarmer Member Posts: 18
    For what it's worth, and there's a thread about this on here somewhere, I did the same thing and i did it all at once (rip off that band aid!). I did a BTU calc for each room in my house then I spent several months watching craigslist and collecting cast iron radiators which matched roughly how many BTUs I needed in a given room. One big room needed two. Then once I had bought all of the radiators I would need I paid a guy who does dustless sandblasting (basically high pressure media+water slurry) to strip the rads to bare iron. This was the largest cost.

    Once I had the rads back I primed and painted them and began the plumbing project. I planned the whole system out (pipe runs, circulators, valves, control wiring, etc) and drained the system. I sawzalled the system apart and took it down to the boiler to start over. It took me months to get it all done but I did one zone at a time and we were still doing other work on the house so it worked out to not have heat in areas we were still doing other work on as summer became fall and fall became winter.

    If I had to do it again I would probably pay someone to do some of the plumbing as that was time consuming and didn't come out quite as nicely as I wanted. I will say it was super satisfying to cut and rip those awful baseboard convectors off the walls, bend them into pretzels, and cart them off to the scrap yard.

    Good luck with your project! Radiator heat (steam or water) is AWESOME. Each room feels like it has a wood stove in it when the rads are really cranking and that feels quite nice.
  • gfrbrooklinegfrbrookline Member Posts: 620
    I have two homes, one with steam one with CI hot water. I don't see a huge difference in comfort. I will say the steam is a great deal harder to balance but once you get that right you are done. There is also the weakly blow down with steam so it is a little more work.

    That being said, I prefer steam. I think the fact that you have to be more involved with it makes it like an old friend. It's like having a classic car vs a modern car. The classic car might be more work and harder to drive but it is much more rewarding to drive then a new car the you turn the key and drive away connection to the road.
  • dtotzzdtotzz Member Posts: 4
    @vtfarmer thanks for sharing! I think that's the route I'd like to go.

    @gfrbrookline that's why both of the cars I drive are stick shifts! Maybe I can switch from baseboard to radiators, and then from FHW to steam at a later date, since some radiators can do both. I just hate the thought of getting rid of a perfectly functional boiler.
  • mattmia2mattmia2 Member Posts: 1,738
    Most conventional boilers can be set up as hot water or steam.

    Steam is very difficult to zone. it is fairly easy to put thermostatic valves on radiators that will keep them from heating at the start of a cycle, but hot water is much more controllable in a small system. Hot water is very easy to separate in to multiple zones.
  • newagedawnnewagedawn Member Posts: 566
    hello, i am doing that very thing now, you will need to find out if you have a monoflo heatloop this is the best way to heat radiators, as a series loop will not get the job done!!!
    doing a whole house btu calc is a good way to start for sizing your boiler, then your room to room for sizing your rads, its alot of work to convert but the end result is a way better heat in my opinion!!! good luck!!!
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"
  • luketheplumberluketheplumber Member Posts: 76
    I have always loved Old House Guy's blog. his website taught me a lot about old houses that I didn't know about. I also partially found this site from Old House Guy. He taught me how to glaze and paint old windows, He also why I hate replacement windows!
    17 years old and wants to learn about steam and hot water heating
  • EdTheHeaterManEdTheHeaterMan Member Posts: 724
    edited September 1
    @newagedawn ... I must disagree, "Monoflo T system is not the best for radiators" in this case. When properly designed the Diverter Tee is a good design. When redesigning, the diverter T can be a nightmare.

    If you don't get the pressure drops across each branch just right, the system may never operate properly.

    My advice is: "Reverse Return"

    Direct parallel return is second best
  • hot_rodhot_rod Member Posts: 13,738
    With diverter tees you still need to account for the temperature drop around the loop as it is a series.
    Also consider homerun. Each rad sees the same SWT, easily zoned, purged, and serviced. Least amount of pumping power with short parallel runs.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • dtotzzdtotzz Member Posts: 4
    I appreciate all of the input - any recommendations on where to start with all of this? There are just so many books by Dan Holohan that I don't quite know where to begin.

    As far as I know, when the house was remodeled in the 90s they gutted everything and put in a modern hydronic system. The seller more recently did some other runs of baseboard where he ran the baseboard the length of the room which is mostly just covering up some pex tubing with a small section of actual baseboard heat in between. I'm not super eager to start unwinding that rats nest of likely issues.

    What I would like to do is find some appropriately sized radiators for my first floor since those could be more easily worked on from the basement.

    @luketheplumber yes! death to replacement windows!! John Leeke's books are another great resource, especially in regards to windows.
  • mattmia2mattmia2 Member Posts: 1,738
    Replacement windows come in many varieties. You can buy good wood or clad wood sash, or you can buy poor quality plastic or aluminum contraptions.

    Modern hydronic heating or the Idronics articles are a good place to start. You need the background in how water carries heat and then move on to the types of piping schemes and need some knowledge of the characteristics of different boiler types and the near boiler piping as well. The baseboard trim with pex with a short section of element sounds like someone did it properly, calculated how much heat the room needed and put a section of element in there with that output. Any of piping schemes will work, you need to start with a heat loss and calculate output of the emitters with the piping scheme you use. With series schemes the water temp will drop as it progresses through the loop so you need to increase the size of the radiator to get the same output. Home run or direct or reverse return systems are more forgiving of some miscalculation.
  • luketheplumberluketheplumber Member Posts: 76
    mattmia2 said:

    Replacement windows come in many varieties. You can buy good wood or clad wood sash, or you can buy poor quality plastic or aluminum contraptions.

    I have grown up with 1935 window with crappy storms and no weather stripping. Its pretty easy to take one apart and re-glaze the sashes and add spring bronze weather stripping to the tracks and meeting rails after you paint them. You also should buy only high quality storm windows.
    When done correctly with the right quality materials, old wood windows can last for hundreds of years with minimal maintenance. I am surprised with how many steam gurus on this site talk about replacement windows being an "upgrade". Properly maintained old windows can be just as efficient as replacement windows and last as long as steam systems.
    If I was building a house for myself, I would consider modern windows if I was convinced that they could last 100 years. Unfortunately as with most other parts in a modern building, I just don't see it happening. Modern windows are just another product from our throw away society.
    17 years old and wants to learn about steam and hot water heating
  • hot_rodhot_rod Member Posts: 13,738
    A good analysis of the entire system, first the load calc, then determine emitters and how trey match the loads and at what SWT.

    Why the added fin tube baseboard? were some areas under-heated?
    Hard to know what the previous owners were up to. assuming you have adequate boiler, I'd start a plan with the type of emitters you want and work the numbers.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Joe_DunhamJoe_Dunham Member Posts: 46
    check out for refurbished cast iron rads
  • EdTheHeaterManEdTheHeaterMan Member Posts: 724
    I find this book an easy read and helps you understand the basics of what you are doing
    This addition is no longer available from B&G the new version has some sections missing.
  • newagedawnnewagedawn Member Posts: 566
    to all, as long as you dont overload a monoflo system with more than 60% on one side you will never have a problem with flo to rads. EVER!!!.
    "The bitter taste of a poor install lasts far longer than the JOY of the lowest price"
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