Wye Filters and Turbulence

ced48

In general terms, do wye filters in a return line create very much turbulence?

Jamie Hall

Eh? Of course they do, just as any fitting involving a change in direction would. How much turbulence is related to the flow rate.

Why do you ask?

ced48

I have one about 15" from the heat exchanger return entry on a small Lochinvar boiler. I have had an on going problem with noise in th heat exchanger as soon as I increase pump speeds. Thinking this could be the cause.

JUGHNE

Could you temporally remove the screen and see if that changes the noise. The Wye configuration is still in the system but if the absence of the screen changes the sound you could be on the right track. Can you move the strainer further away?

ced48

Yes, I was thinking that way. I could move it, but I was thinking of just removing it. I will try without screen tomorrow.

hot_rod

A wye strainer? Not much pressure drop, depending on the mesh size and if it's clean. If you have a clean system really no need for a strainer other than start up.

if it is old iron pipe and radiators it is good to keep them in service and clean.

I've noticed on two fire tube boiler installations that they tend to trap air up high and cause gurgling when the run. Opening the relief valve for a few seconds removes that trapped air. really any of the new small HX boilers need to be purged well.

ced48

Given that, seems like I should get rid of it, rather than fooling with it. Piping system is maybe 30 years old, copper, so I think I will just cut it out-Thanks for everyone's imput.

EBEBRATT-Ed

Cut it out neatly and check the screen. If it's dirty you can sweat it back in with two couplings after you clean it.

ced48

I will check the screen first, before deciding on what to do.

I was just curious as to how much disturbance the wye causes as water passes thru. The stainless steel heat exchangers seem to easily transmit, if not amplify noise. I know there is very little pressure drop, but turbulence may still be a factor, maybe? My thoughts are that a wye would cause much more disturbance than say a 90-I do have a vent next to the prv at the high point of the system, but I think the problem occurs as the return water enters the bottom of the heat exchanger, as rough water, not air, per say.

hot_rod

Really if you are flowing in the 2-4 fps ride none of the fittings of valves in the system should cause turbulence, even a short turn ell. Three way mixing valves have small tight up and down passages and they don't cause turbulence at typical flow rates.

Plate heat exchangers do leverage turbulent flow conditions by design, that is how they get so much transfer in a small "brick". But not to the point of causing noise.

Small chocked down ball valves, plugged devices, even a balance valve that has been closed way down can create cavitation. Small vapor pockets are created and when they collapse, the sound you hear is often confused with air problems.

Fouled boiler heat exchangers also can cause micro bubbles. Scaled copper tube type boilers are known to "percolate" when lime scale coats the tubes, same with most cons, intense heat at the wall surface.

ced48

So, maybe the filter screen in the wye is blocked enough to be causing cavitation, without restricting flow to a noticeable level? After a month or so of operation, the screen was full of debris from the install, tape and dope, etc. I checked it maybe a year later and it was clean. So if clean, Bob, most likely not the wye?

hot_rod

If the strainer is clean, doubtful that it could be causing a problem. Remove the mesh and try it without.

Henry

Do not remove the Y strainer. The little turbulence it cause, will precipitate solids in the water over time. That is why we install ball valves and not plugs. During the yearly maintenance, the plumber must blowdown the strainer. They always find sludge. I would look at an improperly installed pump that would cavitate. One needs 5 dimensions of straight before and 3 after. Also, too much pump can create problems.