Replace iron heat pipe? PEX??


  #1  
Old 05-15-09, 05:26 PM
J
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Replace iron heat pipe? PEX??

This is probably an question that has been answered many times but I can't find a good answer to convince me in my situation.
Background: My current system consists of a Lochinvar minifin with what I suspect is mostly original iron piping and radiators in my 1920 home. The piping starts at about 2" dia stepping down to 3/4" running from the basement to the radiators. I suspect the system originally used natural circulation and steam. I now have a pump.
The main problems I have are headroom and valves. I could gain near a foot of headroom in some valuable areas in my somewhat short basement. Being over six and a half feet tall this would be extremely nice. Also there are virtually no valves in the system making maintenance in one area a real problem.
My question is: what are my possibilities for replacing this piping in the basement? Can I use PEX? If that is an option can it be nearly entirely 3/4" or maybe 1"? 3/4" would be great as I would not have to buy a tool. I would like to leave the piping going up to the main floor and 2nd level, but could replace it if needed.
Any insight is appreciated. I will try to provide any more information that may be needed.
Thanks in advance
JNZ
 
  #2  
Old 05-30-09, 07:59 AM
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This may be the wrong question. A better question might be how to correctly size the loop piping. The piping at the boiler is new-ish copper, the rest is old iron. I have a two pipe direct return setup with iron radiators. Any advise on calculating sizing requirements would be appreciated.
 
  #3  
Old 10-24-09, 02:30 PM
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Any solution?

Hi jnzaharia, all,

Did you ever resolve this issue?

I am in a very similar situation in my 1920s home in Pittsburgh... tall homeowner, low-hanging hot water heating pipes (man those old brackets are pointy too!). If I could raise the hot water heating pipes in my basement, it will be a much safer place for me.

I'm trying to determine whether it's even reasonable to consider keeping the existing pipe and trying to raise it. I could also try to replace with copper but there would be a lot of dielectric unions... probably around 16. Is this asking for long-term maintenance trouble? And copper pipe is expensive.

I guess my real question is... if this pipe has been in place for 80-something years, do I have a prayer of unscrewing the existing fittings and then reattaching new ones?

Are there any regulations regarding clearance between the pipe and joists that I need to be aware of?

Thanks for any and all feedback!

-Jon
 
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Old 10-24-09, 05:31 PM
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I haven't quite figured out why dielectric unions are required in a hydronic system. It is a sealed system. The one here doesn't have any (from what I've seen, and I've looked at quite a few areas of the system). And there is a lot of cast iron, iron pipe, copper pipe, iron baseboards, and so on.

As for un-threading the iron pipe, again, it is a sealed system and the odds are slim that the joints have corroded. I recently did some work on a 50 year old system and didn't have any issues un-threading the old pipes.

Just get some 3' pipe wrenches (aluminum is recommended) and have at it. Some cheater bars may also come in handy for any stubborn joints. A SawZall takes care of any that just won't cooperate.

The original poster asked about PEX. Me, I'm the type that likes to see something work for 50 years before going with it. So I avoid it.

For the required pipe size there is info on many hydronic sites that have charts of what size pipe is required to carry X amount of BTU's. The first place to start is to map out the current system. How many feet of radiation along with the type is on each feeder. And so on.

From that you can calculate the required pipe sizes to carry that load. One good thing is that it won't be as large a pipe as the original gravity feed set up.

Al.
 
  #5  
Old 10-24-09, 07:25 PM
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Thumbs down Black Pipe

Hi.
I have to tell you that PEX is the way to go. All you need to do is have the crimping tool for the size you need, in this case you need 3/4 or 1". I have been using PEX for nearly ten years and NEVER had any problems with it. Now you can even get red and blue pipe for convenience. If you can, try to replace all that old crap with PEX. The nice thing about it is that you can run it through walls and up and down and around corners without fittings. You can lose a lot of flow when you have to stack on all those 90's. the fewer fittings the fewer potential problems. Have fun!
 
 

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