Plumbing heat exchangers

[lmholmes11]

When plumbing heat exchangers for both the hot water heater and furnace plenum, is there such thing as too many 90 and 45 degree angles with the pex?

 

[Bad LP]

It is always smart to use as few 90's as possible and 45's when you can. Nice thing about Pex is that you can make sweeps with it avoiding almost all restriction.

 

[lmholmes11]

Ok good to know. Thanks!

 

[OH_Varmntr]

Edited to add: Each fitting you use adds more resistance to the circuit. This equates into head losses added to the circuit that the circulator must overcome.

Another thing to consider when needing to sweep PEX around a 90 corner is to use 90 degree PVC conduit elbows readily available from your local home improvement store. Most hard 90 PEX elbows will add more head loss to the circuit than what is added by sweeping the PEX around, if space allows. Size the PVC conduit elbows accordingly so you can easily slip your PEX into them and secure them using conduit hangers. Just take a short chunk of your PEX with you when you go.

There are minimum radius bends that PEX must adhere to, so make sure you find yours and abide by it. You can find the radius of the PVC conduit elbows online.

 

[Bob Rohr]

Ok good to know. Thanks!

Every fitting, valve or device in a piping circuit adds flow resistance. Usually you convert the fitting into feet of pipe to make the math simpler.

This table is for copper, the pex manufacturer would have a table for their fittings. usually pex insert or short turn fittings are more restrictive.

Look for long sweep copper pex ells from Sioux Chief and others, they flow much better that the tight, right angle drilled type ells.

A handful of ells will not add all that much. a couple dozen and you need to re-think