Re-Piping Multi-Zone Boiler Room

OldHouseRenovator

My current 20+ zone heating system does a terrible job of distributing heat (perverse hydro-static pressures, too complex, poor heat transfer between sub-loops, constantly failing zone valves, etc.). Just badly done by original contractor and then patched-up to fix deficiencies, making things worse. It is so bad, new HVAC contractors run the other way when they see it!

I want to replace it all with our two boilers feeding a hydraulic separator to a single high temperature loop, off of which I can feed the 20+ zones each with their own pump and, where needed, mixing valve.

Lots of hardware because of zone count, but otherwise simple, one-dimensional design -- it can't help but deliver BTUs.

1. Does this make sense?
2. I will be building out the zone trees (pump, mixing valve, bleeders) myself. Anything that will save effort is good. Can anyone suggest where to get suitable pre-built manifolds? Any other pre-fab items to consider?
3. Given the large additional cost of assembling this with press fittings, should I consider sweating all this together?
4. Favorite hardware recommendations (pumps, etc.)?
5. Any other helpful ideas before I leap?

Thanks!

EBEBRATT-Ed

I would sweat it all but I am old and don't like the cost of Propress although it is a is time saver. Depends on how you want to spend your money. More material cost and less labor or more labor and less material.

Sounds like you have a pretty high dollar amount of equipment.

I would put a shopping list together and get 3 quotes, Taco, Armstrong and B & G

What I would pick may be determined by the zone flow rates and pipe sizes.

If you use wet rotor pumps be sure to include a magnetic separator and don't forget air removal

OldHouseRenovator

Thanks for the input. I appreciate your encouragement to sweat it all together, and I'm already covered on the last point.

Your comment on flow rates and pipe sizes touches on existing conditions. All I can see are the copper pipe sizes entering the boiler room, not the number of elbows or the lengths of the pex loops at their destinations. Some of the loops have known issues (original installation kinks/obstructions). All currently deliver insufficient BTUs. Sounds like its time to do some heatflow math to inform the plan.