Diameter diff between flow pipe and component connector

[TSN79]

So many places I've seen components (fancoils and such) with inlets that are let's say 1", but where the pipe leading up it is maybe 1 1/2". Does that make any sense at all? Can pressure drop have something to do with it?

 

[FredGarvin]

I know this was probably just an example, but please, don't fall into the trap that MANY people do which is to base your piping size on the inlet size of a component like a pump. There is indeed a lot of examples out there where people were over generous in their sizing "just to make sure" there won't be a problem.

That being said, every installation is different and may have its reasons for doing so. It may very well be pressure drop. If cost per foot of pipe is not of real concern, then increasing the pipe size to the component is the easiest thing to do.

 

[TSN79]

Thx for the quick response :)
With pumps I believe it's a bit different, since they actually increase the flow. But with components where the water just flows through isn't the most logical thing just to just to base the pipe size on the inlet? The only reason I can see not to is if the manufacturer of the component based its pipe size on a much higher pressure drop than what the pipe leading up to it will have.

 

[gmax137]

"But with components where the water just flows through isn't the most logical thing just to just to base the pipe size on the inlet?"

No, sizing your pipe to match the component inlet is a lazy, ignorant thing to do, and doing so defies logic. The "most logical thing" is to get the fluid to the inlet at the proper conditions. The component vendor has no idea whatsoever what your system looks like, or what you have to do to meet his assumed inlet conditions.