Efficiency of boiler pipes in hot water system

[Easy Livin’ 3000]

Many years ago, a previous owner converted from a steam boiler to hot water. They kept and used the existing iron pipe and radiators, much of it 2" and 1 1/2".

Now, in the age of PEX, I'm considering replacing the old iron pipe with PEX, all appropriately sized, I'm guessing 1" and 3/4".

None of the iron pipe is insulated, and mostly runs in an unconditioned cellar and crawlspace.

How much efficiency might I gain by replacing the steam pipe with insulated PEX?

 

[WiscWoody]

Many years ago, a previous owner converted from a steam boiler to hot water. They kept and used the existing iron pipe and radiators, much of it 2" and 1 1/2".

Now, in the age of PEX, I'm considering replacing the old iron pipe with PEX, all appropriately sized, I'm guessing 1" and 3/4".

None of the iron pipe is insulated, and mostly runs in an unconditioned cellar and crawlspace.

How much efficiency might I gain by replacing the steam pipe with insulated PEX?

I’m not a expert by any means on heat transfer rates in pipes but I worked on large boilers and the pipes, pumps, steam traps etc in large schools all my life. I don’t think iron or black pipe as they call it transfers heat as readily as copper does but any insulated pipes are going to keep the heat where you want it better than uninsulated pipes. If it were me and the pipes are in good shape which they most likely are I’d buy some of the foam pipe insulation sold at home center stores and insulate your iron pipes. How long of a pipe run do you have? And for getting pipe insulation in for larger pipes you might have get it at a HVAC wholesaler. You can call some places like Goodin Companies, Ferguson, etc. or call a plumber and ask if they have some to sell....or... look online and have it shipped to you. Hope this helps...

 

[Easy Livin’ 3000]

I’m not a expert by any means on heat transfer rates in pipes but I worked on large boilers and the pipes, pumps, steam traps etc in large schools all my life. I don’t think iron or black pipe as they call it transfers heat as readily as copper does but any insulated pipes are going to keep the heat where you want it better than uninsulated pipes. If it were me and the pipes are in good shape which they most likely are I’d buy some of the foam pipe insulation sold at home center stores and insulate your iron pipes. How long of a pipe run do you have? And for getting pipe insulation in for larger pipes you might have get it at a HVAC wholesaler. You can call some places like Goodin Companies, Ferguson, etc. or call a plumber and ask if they have some to sell....or... look online and have it shipped to you. Hope this helps...

Thanks WW!

The pipes are too big (around) for the foam insulation at the home centers. The HVAC stuff, I've found, is very pricey, like $9 per 3' for the big stuff. And, despite it's small size, this house has many feet of pipe in the cellar and crawl space, making the insulation job payback, like, never (in my lifetime).

So, this is why I was thinking about the PEX, probably would cost less, with the smaller insulation included, than insulation of that big iron pipe. Plus, then we'd be ready for the day we upgrade from the old inefficient furnace.