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Author Topic: P traps with a sensor inside it?  (Read 398 times)

Offline Sergroum

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P traps with a sensor inside it?
« on: September 09, 2016, 06:08:23 PM »
Good Day.

So I've got an interesting call. Or at the very least an issue that's new to me. I'm yet to actually see the job, but I figured I'd ask. Forewarned is forearmed.

So a commercial place has an air handler installed in the ceiling of their offices. I'm assuming the condenser itself is on the rooftop. They AC would work for a short while and then stop completely. This issue has been going on for a month and the landlord have sent their techs to fix the issue over 10+ times, as per the word of the customer to me. What the techs told the customer is that the problem is with a P trap and a sensor inside it. They say it's not installed correclty. 4 times they claimed they figured out a way to solve the problem, but failed. So far the standing matter is that they cannot fix this issue. So now, I'm supposed to go there on monday with the client and the land lord watching and figure out who's right, who's wrong. What's correct, what's not.

Great. I've never encountered a p trap with a sensor before.

From context I can surmise that it's some kind of a trap coming out of the tray with a pre-installed flow switch, or float switch that cuts out AC, or 24 volt entirely.   But I've never encountered traps with a sensor already pre-installed? And if so. What is the issue? Why cant they fix it? If it's a plugged drain, or a faulty sensor, or a faulty board, I doubt it would take them a month and 10+ visits to fix this.

Does anyone have any experience with these things? Any common/uncommon problems? How do you even install a P trap incorrectly in a way that makes it impossible to fix.

Offline Admin

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Re: P traps with a sensor inside it?
« Reply #1 on: September 09, 2016, 09:32:06 PM »
I would need the model number of the air handler and know how it's installed.  (Horizontal or downflow).  Is the coil installed on the return or supply side?

After 2 vistis I would be reading the installation manual and calling tech support.  It could be the fan and airflow are causing an issue with the drainage.  Sometimes adding an air vent into the drain line can solve these issues.

Has the condensate sensor been replaced?  Where exactly is it located?  Has there actually ever been any signs of a water leak?  Those condensate sensors can be problematic and I would not worry if I bypassed one.  Most coils have a secondary drain port.  I would add a secondary drain line in case the primary drain line ever became blocked.

Offline Sergroum

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Re: P traps with a sensor inside it?
« Reply #2 on: September 13, 2016, 08:19:25 PM »
Heh. So they installed a water cooled heat pump up in the ceiling and the drain pipe for it was a 3/4 copper line that was either absolutely level, or sloping the wrong way. That line runs for 60 feet, through the wall into a different office, then beyond that office into another office, and then finally into a stack. Evidently it did manage to drain for the first few months of operation, but I guess it got clogged somewhere. Purging it with nitrogen helps somewhat, but in the end I only have access to that pipe in the beginning of the run, I just cant create enough nitrogen pressure to reliably punch the clog. It's also a pretty temporary solution.

I ended up removing 26 feet of that drain pipe and then soldering a connection for a condensate pump. If the pump is able to push the water further down that drain line through all the clogs and bad slope, then I guess it'll work out. Otherwise, I'll have to think of ways to repipe this monstrosity.  The unit is pretty much pressed hard against the ceiling and the drain connection begins 20 inches below that ceiling, the atmospheric pressure is not really enough.

There is a rigid pipe going through the office that I believe is drainage. I might have to just condensate pump into it and ignore the whole copper line. There are some considerations with the landlord about that though, I imagine.

As I was nosing around the other two offices, tracking that pipe and adoring it's slope, I found out 'they' have the same issues with their own units.