Uneven loops

SteamtoHotWater

So how bad is it to have uneven PEX loop runs to aluminum plates?
I've got four rooms on the second floor - large, medium, small and smallest (the bathroom). It only makes sense to have one loop per room. And, there are physical barriers that would be difficult to get around to combine or average them in some other way.

So that means my loop runs are going to be like 200 ft, 200 ft, 120 ft and 100 ft. Aren't they supposed to be within 10% of each other? What bad thing is going to happen if I ignore that guidance?

Jamie Hall

Not much -- if you have things arranged so that you can balance the flow in them. You'll want to be able to reduce the flow in the smaller loops.

hot_rod

Are the loops going to a manifold? That is the best place to balance those small flow rates.
Those manifold flow setters typically go down to .25 gpm

SteamtoHotWater

The loops are going to a manifold with flow control on each loop - so that's good. But I need to read up on the appropriate way to balance things, no idea on what I'm doing. Currently have the system running on for the first floor with whatever defaults the manifold came with. Seems to be working well enough. Once I have the second floor hooked up and running I'll revisit - priorities.
Thanks for the answers.

hot_rod

A few choices, if you have a heat load and design sheet, it will indicate the required temperature and flow for each loop. Without that information it will be mostly trial and error. Most balancing will need to be done when you are at or near a design condition.
The system needs to perform and provide even heat under the coldest conditions.