Pipe Sizing Replacement

Grumpy_Guy

I'm replacing all the old steel (cast) pipe in the basement.Multiple reasons but the most overwhelming one is I will need to move pipes in the wall during renovations this year and there are no individual shut offs to do so.



The pipe starts and ends at the boiler as 2" then it transforms along the route to 4" one way and 1.5" the other way continuing to 3", 2", 1" and some in-between sizes too.  The system is a two pipe system with connections between the supply return at rads only. I have access in basement but can not tell you what happens in the 3 floors above with the pipe.



According to Taco Flow-Pro I should be able to replace the pipes using 2" only as the 2 pipe supply and return, the system seems to need 27gpm at 20ft of head.



Are there any got ya's to watch out for when changing pipe size, I could go to any size?

icesailor

Piping:

Sounds like it was a gravity system and converted to a pumped system.

You need to do a complete heat loss calculation on the building including what is on each riser and where they go.

The pipe isn't "Cast Iron", it's steel. It probably has Cast Iron threaded fittings that the steel pipe screws in to but not cast iron pipe. Cast Iron pipe is never used on heating systems. Only on sewer drainage systems with lead and oakum joints on bell and spigot connection. New ones may have gaskets and new ones may also have clamp connectors.

If you haven't done this before and you are not a professional, you could really get in trouble. I've seen "competent pros" get in trouble.

Grumpy_Guy

Thanks for replying icesailor

I concur on that gravity feed speculation, (coal burner at one time).



I have done a heatloss, it comes in at about 2626000Btu/h using the FLOpro software. (10624 sq ft)



No I do not plan on doing the work myself, I will be using a Pipe Fitter to replace the pipes. Smaller then 2.5" threaded pipe, if 2.5" and greater then he would use Victaulic pipe fittings.



I Have no idea to where I can find that pro everybody suggests, every answer I have gotten so far is "leave it; you do not want to upset the balance or replace the boilers with a larger one to handle DHW". (my current boilers are 900,000 btu/h input)



I come here for education, second opinion boots on the street answers. I guess I will have to call an engineer to design my pipe replacement and boiler replacement/relocate. And we know they always get it right! (ya right)