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Should We Use Old Pipes, or New Ducts?

Tremolux Member Posts: 28
We've been getting contradictory feedback for quite a while, and it's time to make a decision. Should we use the old pipes, or install a new set of ducts & returns?

The 2 story brick house was built in 1930 with hot water radiators. ( it was a first-rate job, built by an architect as his personal residence ) The previous owner was a recluse who allowed the gas and water to be disconnected for two years, so most of the radiators froze and cracked.

All the first floor radiators were bunko, but five upstairs remain intact. There were 20 originally, including 2 hanging from joists in the basement. When the broken cast-iron was removed, the pipes sealed, and pressure tested, the pipes held. ( there was one odd, small, in-wall unit with cracked pipe, but it was easily cut off, & isn't needed )

If those pipes are still reliable ( the Big Question ) we can either find wall panels that put out enough BTU's and allow opposite/bottom connection ( not easy ), or spend big. big, bucks for new cast iron.

If those 70 year old iron pipes, and their threaded joints, can't be relied on to hold water for another several decades, we'll have to consider the only other option: ductwork from the attic down and basement up.

Is it worth the risk to use the old pipe system ( with a new mod/com boiler ) or should we err on the side of caution and go with all new equipment?

Thanks for your time and consideration.


  • Gordy
    Gordy Member Posts: 9,514
    edited November 2010
    Lets just say

    You stay with the hot water. The pipes passed the pressure test right. They only have to hold 12 to 15psi.  What will you be doing for AC?

    There is nothing like hot water heat, but if you have plans to duct for AC then maybe you should make the switch. Or you could stay with hot water, and install a high velocity ac like space pak, or unico.

  • TonyS
    TonyS Member Posts: 849
    inverter mini splits

    and hot water heat. You cant go wrong!
  • 3 rd choice

    If you are worried about the pipes, just install new pipe with new radiators. Why would you want to destroy your walls and ceilings trying to put in leaky, drafty hot air heat.  I've done this before, and the homeowner is very pleased, even with using just fintube baseboard and a standard atmospheric vent boiler with outdoor reset.  You could include a alittle radiant floor in the main halls and in kitchens and baths.  Use TRV's on the radiant panels and you have about the most efficient and flexible hot water heat system around.

    Or if you really want to move up, install a new steam heat system.  High efficiency, high comfort, without having to worry about freezing up radiators.
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert

    Noisy Radiators are a Cry for Help
  • Steamhead
    Steamhead Member Posts: 15,257
    You could probably

    use the existing piping for Vapor (ultra-low-pressure two-pipe steam) if you're worried about them holding pressure. A steam system runs at less than a tenth of the pressure a hot-water system needs.

    I've seen several gravity hot-water systems in Baltimore that were converted to Vapor. They work great!
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Jack
    Jack Member Posts: 1,045
    This system has been empty

    and open to atmosphere for two (?) yrs. It is 70 yrs old. If you use the old pipes and they develop a leak, what is your fall back position. I think I'd advise the customer to do it once, do it right and abandon the old pipe all together. Good luck!
  • Tremolux
    Tremolux Member Posts: 28
    How exactly can we do that?

    " just install new pipe with new radiators. Why would you want to destroy your walls and ceilings trying to put in leaky, drafty hot air heat"

    Well, for one thing, we'd have to destroy walls & floors & ceilings to remove the old pipes and install new stuff ... either pex or pipe. It's a brick building with heavy lathe & plaster walls.

    What's the cost of a steam radiator anyway? Less than hot-water?

    Those new Burnham cast-iron radiators will average well over $1K each.

    When we checked the BTU output of Buderus, Myson, Burnham, and Runtal flat panels, none of them put out enough heat. The "Thermo Tech" models might work, but they're made in Turkey, & if not in US stock, it's a long, long, time to get shipment.

    We haven't thought about steam heat ... we'll have to check out that possibility.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,214
    Impossible to guess over the net

    If they will keep holding pressure. If they held for the pressure test being exposed to air for 2 years means nothing they go through worse as a gravity system with an open expansion tank for their first 50 years of life at least. Radiators can be purchased used for less than new. They will feel better in the winter than force air will. If you can as Steamhead said vapour may be the way to go. it has a high temp than hot water so the radiators need not be as large. You may be able to move the larger ones to where they will be most needed and buy smaller ones for the places ones are missing.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Tremolux
    Tremolux Member Posts: 28
    Thanks for the feedback / Changed mind ... etc.

    The biggest factor in our decision turns out to be "fear of the unknown".

    We're aware that used radiators ( tested ) are available, but our spouse doesn't want to take a risk with any major "old" tech components, and cast iron is certainly that.

    There's one way to get a better clue: firing up the old boiler, turning on the pump, and waiting to see what happens. We're just not willing to take that step.

    Two reasons: the numbers are way, way, out of whack, and the pipes above the basement are just not accessible without major tear-outs. Since unpainted woodwork & original floors are a large part of the buildings charm, we just can't put them at further risk.

    To replace all the cast iron, just the radiators, would cost about as much as 2 complete high efficiency furnaces ( basement/attic ) with 2 zones, ducts and returns, installed. Add in the cost of mod-con boiler, pump, new expansion tank, plus installation, and it gets much higher

    Though installing ducts, cutting holes, & all will be a mess, and not as comfortable as hydronic, we won't have to worry about cracked cast iron pipes leaking all over at the worst possible time ... ( that's ever ).

    Now we have questions about furnace features & sizing ... will start another thread.

    Thanks everyone.
  • Steamhead
    Steamhead Member Posts: 15,257
    Looks like

    the scorched-air pushers low-balled themselves into your favor.

    Get ready for all the "change orders" that will boost the price of the finished job.

    And you will never, ever, be comfortable in that house again.

    You get what you pay for.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Tremolux
    Tremolux Member Posts: 28
    We'll Take Our Chances ...

    Figure out the numbers yourself, since the TOS prohibits talking price. There's only one US maker of cast iron radiators. 20 of them, from 2 x 2 to 2 x 7 or so. There are 3500 sq ft, and an adjusted BTU load of 123K. . Have you priced carpenters and floor specialists lately? How are you at re-lathing, plastering, and brick-work? Won the lottery recently?

    We don't think it was a low-ball bid. The furnaces were actually "overqualified" 97%+ direct vent & variable output ... more than we need, want, or will purchase. There's no A/C included ... ( we don't need it ).

    The house was/is built like a tank. Adjustments are hard-won, expensive, and messy.

    A new piping system, even with Pex, would be a nightmare. The second floor is two separate units, and 1/2 of one is cantilevered over a porch. Most of the other 2nd floor radiator pipes, since they're above other windows, aren't a straight drop down. Vertical cuts are bad enough without going sideways through brick & plaster and tearing up floors to boot. Butcher your own house, sir.

    We have a new heating system that works fine for now ... a Vermont Castings "Montpelier" fireplace insert with a thermostat controlled, blower.

    Been burning Oak & Hickory for almost a week, and it's worked quite well.

    It's kept most of the 1st floor at 50 easily ... and it was 15 degrees last night. With a couple strategic electric heaters in the bathrooms, there's no danger of another freeze taking out the Pex. or the small amount of Copper. The foam insulated attic hasn't gone below 40.

    We'll get another few bids on hot air, do some research on furnaces ( and direct vent water heaters ), and consult again with an architect, but it looks like "conventional" is where we need to go with this rehab/restoration project.
  • Jamie Hall
    Jamie Hall Member Posts: 18,679
    I am really sorry

    to see that you have decided to go with forced air in this situation.  Not only did you have a system which would have worked, and worked beautifully, either as vapour as Steamhead suggested (with essentially zero chance of leaking) or as forced hot water or -- even better -- as gravity hot water, but you will, in the process of putting in the ducts, go against every possible tenet of conservation and restoration in older buildings.

    This is really just too too bad; I almost cry.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,214
    I am curious as to where you are located?

    Nothing is guaranteed to be trouble free. forced air does have its issues, dust, allergies, dry air, trouble some humidifiers. We stock used radiators we cherry pick to make sure they are safe for reuse. The combustion efficiency is only one factor. the forced air requires more electricity to move all that air around the house and drafts become a major factor. Air is also a great insulator and with force air you are trying to use it to transfer heat, this in its self is a contradiction. We do have an ac section on the wall where your answers can be found if you chose to go that way. Every home owner has the right to do as they chose, Us steam installers just want you to have the whole story before making your choice. I do install forced air systems but I prefer not to.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • rlaggren
    rlaggren Member Posts: 160
    edited December 2010
    Not sure what your main decision points here are...

    You do have to live with the SO, so deep set opinions there have to be honored. And you do need to work with your local contractors and hopefully find one or more that you feel real comfortable with. That in itself swings a lot of weight.

    But I never heard of anybody who went and bought all new old style cast iron radiators - the darn things only fail when they're dropped or when they freeze and then it's pretty obvious. I have and do live in two 100 yr-old houses since 1950 and the heating systems (water) are at least 70 yrs old. Never a problem (that wasn't self inflicted) to date. And I have really _cranked_ on some of those pipes. Started life as an open gravity system so there's nothing special about them.

    _IF_  your SO hasn't made a moral or stylistic commitment against it _AND_ you come across a steam guy that you get good vibes from you might consider a very simple basic no-frills system which might save you some money initially by using your existing assets with essentially zero risk of damage from leakage.  If the boiler could provide domestic hot water also than if you decided it was a bad idea you could limit it's use to supplying hot water and keep getting some value from it and go with ducting at a later date. The main issue would be any finish work needed then (as opposed to now) to install the ducting.

    Forced air works OK, mostly. It shines in mild climates where heat isn't needed much or very often, just short spurts - and the space heated is relatively small. It brings up the temperature fairly quickly. You get more iffy if you need to run ducts in unconditioned spaces and when your heat load gets higher. My sister has a 2000SF ranch with dbl-glazed windows and doors and insulated walls and attic in McHenry IL (70mi northwest of Chicago); she's got forced air and she's kept the t'stat at 65 the last 20 years because the gas bills offended her so deeply.

    Best luck with your project.

    disclaimer - I'm a plumber, not a heating pro.
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