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Originally Posted by ballane89

haha I like that......
When we think its the diaphragm well pull the diaphragm and check flow without it, if its stuck then you'll have full flow without it.

That was my second move after blowing it down. Normally it is one or the other. The rubber was in decent shape save a small tear so I replaced it anyway. It wasn't till I alternated closing valves and blowing down that I saw the ghost. Pulled the strainer and cautiously looked through at the ball to see it moving. So glad it didn't magically clear at that moment!

Originally Posted by abcreech

What kind of plug? Where did it come from? something in piping or part of system component failure? Would be curious to know what it is and where it came from ! VFD really glad you found problem! Sometimes you have to think like a Ghost to find what's haunting your system!!

The plug was mostly flaking and fine sediment. I think the water quality wasn't great here until about 5 years ago and we have recently changed the psi and dp of our loop. This isn't the first plugged line but it is the first with a gap between plug and strainer. The last few have been from stuck open valves that maintain constant flow so the crap backs up from the strainer. No extra large chunk so I'm not sure why it happened this way but I have a suspicion I may be back in the near future.

Yes, on call for heat, the piping that supplies the coil does get hot from the valve to the coil.

Originally Posted by abcreech

What kind of plug? Where did it come from? something in piping or part of system component failure? Would be curious to know what it is and where it came from ! VFD really glad you found problem! Sometimes you have to think like a Ghost to find what's haunting your system!!

haha I like that......
When we think its the diaphragm well pull the diaphragm and check flow without it, if its stuck then you'll have full flow without it.

You said you blew air through coil, did you do this where it is located or did you take out? If you took out did you cut piping or undo unions? Is there a maida-mist on the outlet/return piping? If there is you can unscrew mist, put a pipe nipple there with some clearing tubing attached ran to bucket, close balance valve on return piping if it’s after maida-mist. Turn supply back on water flow through coil and out tubing, see if you got great flow through tubing if so coil is fine, then you know problem is after maida-mist in return piping. Also make sure that balance valve is really open, sometimes those red handles crack and you think you are turning it but it’s not, I usually take it off and make sure it open with crescent wrench, sometimes the plastic handle is stripped. I don’t know if you have restriction being you said that it never had a problem before, but one important question would be do you keep up on your water treatment chemicals? If you have not since installed then I could believe blockage due too poor water quality treatment.

What kind of plug? Where did it come from? something in piping or part of system component failure? Would be curious to know what it is and where it came from ! VFD really glad you found problem! Sometimes you have to think like a Ghost to find what's haunting your system!!

Exactly why Thermometers and pressure gauges are needed!

I just cleared a line that was plugged +/- 12" before the isolator valve/strainer. It was trickling through some water but not nearly enough to warm the coil. I found it because I got very little water out of the strainer with the coil drained and the outbound control valve closed. Had to remove the plug with poking through the strainer and banging with a rubber mallet. Took a little while but it cleared. In this case, the trickle was big enough to warm the pipe heading into the coil so I had one hot and one cold valve. The plug is probably upstream if your coil is clear, the strainer clean and the control valve is functional. Find your shut-offs and get after it!

On call for heat, does piping supplying coil get hot from valve to coil ?

My money is on strainer or control valve. If you have a control valve that keeps constant pressure across the coil, there is a regulator of some sort that is probably stuck shut. My campus has griswolds that have rubber diaphragms that get stuck closed.

Originally Posted by Joe Howell

No thermometers or pressure gauges on this coil. We have 54 of these fan/coil units throughout the church where this system is installed. This fan/coil unit seems to be to only one with flow problems through the coil. The bypass pipe gets plenty hot when the thermostat is not calling for heat leading me to believe that the three-way valve is working OK. System has been running since 2004.

So how can you trouble shoot the issue!

if you have the installation manual, it tells you how to check flow through the unit.

No thermometers or pressure gauges on this coil. We have 54 of these fan/coil units throughout the church where this system is installed. This fan/coil unit seems to be to only one with flow problems through the coil. The bypass pipe gets plenty hot when the thermostat is not calling for heat leading me to believe that the three-way valve is working OK. System has been running since 2004.

Do you have Thermometers and pressure gauges on this coil?

The balancing valve on the hot water outlet pipe is fully open (as is the shut-off valve on the hot water inlet pipe). I am not familiar with balancing. How can I determine if a balancing issue may be the cause of the low water flow through the coil?
Thanks.

If the 3 way valve is installed and operating properly and the coil isn't plugged or restricted then it sounds like a balancing issue to me

Kind of sounds like a balancing issue to me

You can use Compressed Air, I just didn't carry a Compressor on my truck. Just Nitrogen and CO2. Just don't blow it through an empty coil. Think Scrubbing Bubbles.

Whats the system pressure, and how high up is the coil?


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Is there a balancing valve?


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