Looking for some help!

jonadams

Hello all excited to be here and ready to listen!  I have a 2 pipe direct return setup to a natural gas Williamson boiler in my home. I have what I believe to be 3” supply cast iron piping and 2” return piping. I will be doing the work myself. I have a couple of questions. 

1st- I’d like to remove the cast iron piping in my basement and replace with copper piping or pex to allow for headroom. Is this feasible and if so what size piping do I need?  2nd- I’d like to create 2 zones for upstairs and downstairs. I’m an HVAC mechanic so I’m not afraid of wiring and installing pumps and zone valves. Again is this feasible?  

Sorry for the long post but I’m ready to listen to the pros here and am excited to get started. Let me know what other details I need to provide!!!

Jamie Hall

That sounds as though once upon a time it was a gravity circulation system. They're wonderful... it certainly is feasible to convert that to a forced circulation system with smaller pipes. The pipe size would depend on the BTUh load which the pipe is service.

You will certainly need some sort of manifold, though, and balancing valves, or the balance between various radiators and upstairs and downstairs etc. will be way off.

Ironman

In this scenario, you're gonna have to look at removing all of the old mains in the basement or else you'll have a balancing problem as Jamie mentioned.

The be best approach may be to connect properly sized pex-al-pex to each individual riser and connect them to a good manifold like a Caleffi, Rehau, Viega.

You can install actuators on the manifold for each rad that could be controlled by different thermostats. However, a better approach would be to put TRVs on each rad and run the system on constant circulation with a delta P circulator.