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Sharkbites in an old cast iron radiator system

jopinoff Member Posts: 2
I have a gravity feed, single zone, hot water system with large cast iron radiators in a century old Victorian style house. The heat does a fine job of keeping the majority of the house warm (the house is quite leaky though). It does accumulate some air in the highest radiator, I usually have to bleed it about once a month when it's operational.

My unfinished field stone basement has a single radiator right in the middle of the room, it's about 10 feet from the boiler and it appears to have just been tapped off the main input and output lines which are running across the ceiling. There is a T-fitting on the large (~2") iron pipes which then go into half inch copper that comes down to the floor for the radiator itself. A current project requires that I move the radiator about 2 feet, it should be a relatively simple cut and rejoin job on the copper pipe but I would have to drain the entire system and then try to find a way to drain the radiator since it won't drain through the boiler (since the inlet and outlet pipes are both above it). This would also mean adding fresh water to the entire system which to my understanding is not desired if at all avoidable.

My current idea is to shut off the freshwater feed and release the pressure from the system, then cut the copper pipe and push on a sharkbite ball valve ( I would do this on both the input and output copper pipes to that radiator and deal with whatever water I get while I'm doing that). Once the radiator is isolated I can drain what I need and shorten the pipe I need to, connect it back into the other side of the ball valve and open the valve.

The current copper system is all soldered joints, I obviously can't do that with any water spilling out of the system, I can use either a sharkbite or a compression ring fitting. Is there any issue with using either of these fittings in this system? Is there any issue with using a valve in this location if it's going to be almost always opened?


  • Zman
    Zman Member Posts: 7,446
    Shark Bites are kid of the "Band aid" of the industry. I would not recommend them for your application.
    You don't want to constantly add fresh water to a closed system. An occasional drain and fill for service work is no big deal.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • duffy_4
    duffy_4 Member Posts: 79
    You could freeze the 1/2” copper lines and propress on two valves then repipe after relocating radiator
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,127
    I'd use a Jet Swet to block the pipes. Then you could either solder or pro press.
    If you're bleeding monthly, you're already adding too much fresh water to the system.
    Best to go on a leak hunt.
  • Ironman
    Ironman Member Posts: 7,119
    If you drain the system, there won't be that much water in the rad. Put a large trash can underneath where you wanna cut the pipes and let it drain into that.

    As others have mentioned, don't use Sharkbite fittings and find out where you have leaks that are requiring that fresh water be added.

    Is the system still gravity or is it now pumped? If pumped, where is the circulator located and what is the cold static pressure on the system?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • jopinoff
    jopinoff Member Posts: 2
    Thanks for the advice all, any specific reason not to use the Sharkbites? The alternative at this point might be to just not do the job at all.

    There are 5 radiators on the second floor and 5 on the first floor, at least half of them are very large, I'm not sure how many columns but I suspect they are at least 10ft long. It's going to be a bear to drain and I'm wary of uncovering issues that I'd rather not know about!

    As for the air in the system I've only actually had to add fresh water to the system once in 3 years so either the air pockets are very small and are not impacting the pressure or it's a build up of gas from corrosion in the system. It is still a gravity fed system.
  • Ironman
    Ironman Member Posts: 7,119
    “Any reason not to use Sharkbites?” Yes! They will eventually likely leak.

    Find a Supply house that sells ProPress fittings. They will usually rent the tool also.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    JUGHNE Member Posts: 10,561
    Compression fittings with the ferrule rings have been quite reliable......all the supply stops under sinks & WC's I use are compression fittings on copper pipe....seldom have a problem in 40 years of installs. Also they are subject to full house pressure of 40-60 PSI.....you system would not see over 20 PSI.