Can You Spot the Pipe flow design flaw involving the 3-way valve??

elfie

here was a challenge relating to a bldg that had longstanding heating control issues (ie. closing the valve does not stop flow of water to rooms)



the picture shows two 3-way valves (one for upper floor and one for lower floor) - each has the same problem



hint: relates to backflow



the design flaw was resolved very simply



interested to know if anybody has design familiarity involving 3-way valves

furnacefigher15

Bypass line

The biggest problem I see is those bypass lines. Most people have a tendency to open valves, or leave them open when installed.



If the bypass valves were open, the 3 ways would be unable to direct flow. That and it looks like the supply and return are tied to the same point.



It would be nice to know what the three way feeds, and what BFICS stands for.

Tim P._3

From what I can see...

I don't see any way to balance the returns entering the 3-way.



Without any checks installed I believe  there's more than one way for water to flow through the 3-way.

Alan (California Radiant) Forbes

Pump

Isn't there usually a pump on the mixed line after the 3-way?

elfie

bypass pipe is a non-issue

bypass pipe valve is a non issue as it is closed and valve works



the problem area relates to the incoming return lines and the way they come together before flowing into the 3 way



does this area look like its an issue? are there water pressure issues that need to be considered? how would you propose to resolve



the drawings were created in the 60's and relates to an ongoing system that has not been modified since being constructed



thanks

MikeyB

Valves

Were these  valves intended to be 3-Way Mixing Valves, or 3-Way Dirverting Valves? on the drawing these valves appear to have 2-inlets and 1 outlet in which they would be 3-Way mixing valves,

Mark Eatherton

There's an app for that....

The BFICS almost indicates to me that this could be a COOLing SYSTEM.



And those 3 ways may be (more than likely ARE) diverting valves as opposed to mixing valves...



What's the application?



Is it a district heating system, or a local system?



Heating only, or heating and cooling, or cooling only?



Are the 3 ways mixers or diverters?



Is there a loop reset controller?



It appears that these valves are pneumatic. Is there a newer DDC control system on line?



What is the major complaint?



Times, they are a changing, and so are the means of accomplishing mixing. Diverting is still one or the other, but mixing has changed.



Got answers?



ME

furnacefigher15

It looks

Like the 3 ways were installed in a way to maintain 100% flow through the BFICS main loop.



As far as the tee's go, you could have the returns tie in on the run, and the valve connect on the bull, but that's about it.



But, then again there's nothing to show me what is going on on the supply side of the loops. (there could be more restriction on the supply side of the run connected line.)



Okay, I'm ready for a brilliant synopsis.

furnacefigher15

Oh

Did they orient the valve wrong?

bob_46

BFICS?

You are not showing near enough information to pipe these valves.

Three way valves are seldom piped the way they are drawn on the print.

The engineer/draftsman usually draws the valve in the orientation that makes the drawing easy. In his defense he probably doesn't know exactly what valve will be installed.

Without the valve or a cut sheet in hand you don't even know which ports are which they

very from one mfg. to another. I can't remember how many I've repiped because the fitter piped it the way it is shown on the print. What is a BFICS?

elfie

solution !

hi, thanks for all the responses



the 3-ways relate to a hot water heating system



if you notice just above each of the 3-ways (about where the red arrows are pointing) there are two 1 1/4 inch flows coming from the left and right that combine before flowing to the 3-way.   the left side is supplied by a 3 inch supply main and the other is supplied by a 2 1/2 inch main which is further away from the hot water pump.  this is an opening in the water flow loop that is not controlled.



we found that when the 3 way was closed (ie. not allowing flow into the 3 way from above per drawing), the water was creating a backflow probably toward the 2 1/2 inch main.



to correct the problem a simple check valve was installed on the weaker 'right' side (side supplied by the 2 1/2 inch main) to insure water only flowed in one direction towards the 3-way.   troubleshooting by closing valves and feeling pipes allowed this issue to be discovered and lead to resolution of a major problem.



BFICS - I would love to know what this means.  and would love to know why the problem has not been corrected for nearly 50 yrs.  about 10 yrs ago a new higher HP pump motor was installed and maybe this impacted the water flow balance in system, which further limited the 3 way from controlling water flow and chronic over heating.