Pipe Slope or Pitch in a homerun/manifolded rad system - Important or Not so much?

HydronicRookie

I'm running my pex-al-pex rad lines down to the manifolds in the basement and my Godfather, who's helping me do the job, keeps on harping on me to always have them slope downwards. He's concerned about air getting trapped of course, but in a properly purged system, where each rad is purged of air on an individual basis, are my pipes not allowed to have a few subtle ups and downs ?

Having the lines always sloping downwards is tedious business and in some cases impossible. Am I allowed to not worry about it?

Thanks for your feedback.

icesailor

Listen to your elders, sonny boy.

HDE_2

Forced circulation system it doesn't matter. They can go up and down, the air if not purged or eliminated will settle in rads or highest point in some cases.
If a micro air seperater is installed, often the air will be extracted from the rad over time.

HydronicRookie

Haha, thanks @icesailor‌ ! I definitely should listen more, and he means well, its just I needed to settle the matter for my sanity's sake with experts having the final say.

@HDE, thanks as well. That's what I thought. I'll do my best at purging the air out of each line individually while keeping the rad air bleeder open until just water comes out. THere's an air vent at the LLH that will hopefully scavenge the remaining air bubbles.

icesailor

"" thanks as well. That's what I thought. I'll do my best at purging the air out of each line individually while keeping the rad air bleeder open until just water comes out. THere's an air vent at the LLH that will hopefully scavenge the remaining air bubbles. ""

Don't do it like that. First, vent the radiators, starting at the highest or top floors and work down. Then, fire up the zones. If you didn't Series Loop the radiators (I sure hope that GF didn't let you do that) all the radiators should get hot. If some don't. let the system get hot and raise the system pressure to 25# and wait a while. If you get any flow at all through a non working radiator, it will sooner or later, start working completely. You can't purge individual radiators and the added expense is ridiculous. You can purge series loops, you can purge mains (but you won't need to). You can't purge individual radiators that are connected to other radiators. The purging will stay in the mains and go right by the other radiators. That's why it is a REALLY good idea to remember that "Pitch" isn't a musical term and "Low Points" aren't just a sad or bad time in your life.

Ironman

As long as a system velocity of 2 fps or more is maintained, sloping is not necessary. If you're using a manifold with purge valves and flow setters, it would be hard to imagine the velocity dropping below 2 fps for very long, if at all.
Like Ice said, be respectful to us old men.

HDE_2

Just to remind others that may have missed the OP's description.
He said it's a home run system to the rads.
Since you have a home run system (individual runs to each radiator) use it to your advantage isolating radiators one or two at a time. The velocity will be higher and move air to the purge and air elimination point. As mentioned an elevated system pressure will assist you.

icesailor

"" Like Ice said, be respectful to us old men. ""

Being one of those old men, I've found that you really have to work hard to screw up a hydronic system. That doesn't include Steam.