[AutoPilot]

I've been in the controls business for over 35 years. More than half my life. Lately I'm seeing things that are now scaring the $hit out of me.

Lets start the list with Heat pipes that have 24 VAC solenoid Valves wired in parallel which draw an inrush current of 3.4 amps each with a holding current of 1.2 amps. No problem until you have about 30 or so of these valves setup for three stage control. The installing electrician spent a few days trying figure out why the circuit breaker on his 75va transformer was tripping. Ended up installing a 2 kVa 24VAC transformer, conduit for the increased wire size. Of-course the control guys get stuck with supplying 30 amp contactors.

How about the Daikin BACnet interface with 100 or so FCU's connected. 2900 points don't mean a thing when the Daikin start-up guy didn't bother to keep track of which address he assigned to a room FCU.

A primary variable speed pumping system with bypass valve that's supposed to maintains minimum flow through a Chiller piped from the pump discharge pipe to the chiller discharge pipe. Engineer was worried the return water would get to cold comming back. Solution close and disconnet bypass valve, Install 3-way valve at largest AHUs.

Don't even get me started on Multi-Compressor Colmac heatpumps with Carel controllers.

Please feel free to add to list. I cannot believe I'm the only one suffering in PC crap world.

 

[smsmechanical]

Although I am not a control tech my award goes to maintenance staff changing a ton of setpoints right after an air balanced and myself have set everything. Talking about minimum flows, K factors, diff setpoints, and other things. I've even seen static set to 21,000. Also setting the schedule to turn on chillers just 30 minutes before the building opens and expect it to be cool.

 

[smsmechanical]

Air balancer

 

[tjrobb]

Dunno if I'm allowed to post here, but a contrary to SMS' post is our building being balanced before the air units were running.
We also have several thermostats 12 inches from a south window, above the fintube, below the air vents.
There's more, but they're not controls.

 

[Control Man]

Air compressor for PNEUMATIC CONTROL SYSTEM removed ( relocated to maint mgrs. side business work shop ) then the pneumatics tyed into air supply for the air tools in the plant , bypassed the dryer and filters. Control system turned into a HYDRAULIC system rather than a PNEUMATIC system as the plant air supply had an oil injector to lube the tools.

 

[control$]

The dumbest thing I've ever run into? Top ten from memory.

#1 I saw a whole floor of unit vents with the 277/24 wired backwards. And the electrician turned it on!!
#2 Supply fan and return pointing at each other.
#3 Canned manufacture program that turned on the fan, opened the oa damper and closed the hw valve when the freezestat tripped.
#4 Janitor didn't like the cold air so he decided to unlink the combustion air damper in a school. And bypass the safety.
#5 Looking for gas leaks with a torch.
#6 A flat elementary school roof with all the roof drains plugged. Had to clear the drains before walking to the ahu's. The roof was so rotted my fat 170 pounds was enough to cause some of it to cave in at the office.
#7 Broken sump pump at school. Janitor was using pallets to keep his feet dry to reset the tripping MCC.
#8 Was sent on a service call to a very expensive private school in NYC. After a few hours I found every single control was in place and but nothing was wired. The install was "completed" years ago and the owners insisted that it mostly worked fine. Getting flustered I ran into an old Polish maintenance man and asked how he controlled this building (8 floors). He brought me down to the basement and walked passed the BMS system to buildings main steam valve. "When building get cold I open, when building get warm I close." With that I said please sign my ticket.

 

[bigguy158]

Air compressor for PNEUMATIC CONTROL SYSTEM removed ( relocated to maint mgrs. side business work shop ) then the pneumatics tyed into air supply for the air tools in the plant , bypassed the dryer and filters. Control system turned into a HYDRAULIC system rather than a PNEUMATIC system as the plant air supply had an oil injector to lube the tools.

Been there on a DDC retro job. First time I had been on site. Cut the first supply tube and got sprayed in the face with oil. Asked my coworker why there was oil all over the VAV cabinet and he started laughing at me.

 

[JSLLC4Life]

Support staff in an egg processing facility unplugging the JACE multiple times to charge their phones.

 

[Control Man]

I could not access a DDC job remotely , customer ( nursing home ) had changed the phone # on the line provided but never told us , some poor little old lady kept getting weird beeping phone calls all hours of the day / night as we tried to access the nursing homes MODEM as they had switched her over to the # we had used for years

 

[clogic]

1.) A piece of copper tubing cut to fit in fuse holder in a MCC Bucket.

2.) Wire nut between the cover and the heater overload reset, held down by the screwed on cover.

 

[bacnet>CCN]

Might have figured out why the communication on the MS/TP bus wasn't working.
The way the wire was laying, the shield was laying across both + and -.
About 20 of the 24 modules looked this way.

 

[MatrixTransform]

commissioning 2 new chillers for a big data centre.
everytime a chiller started and its associated cwp started there was a horrible surging noise.
The mechanical commisioning guy freaked out at me...he doesnt care why I screwed it up..."just effing fix it", he squealed

Next morning at 6 am in a little bit of quiet time and under no real cooling load I decided I had better get fixing my er...screw-up.
about 5 minutes ... after following the common cw pipework I discovered that where the plumbers had cut in the new cw pipwork to the existing cw pipework they had swapped flow and return.

every thing was fine when no chillers ran...the secondary cwp would circulate water just fine.
everytime a chiller started... the local cwp was pushing water the wrong direction.
only 450mm pipes...no big deal

anyway, since the mechanical commissioning was already finished ( ?? :eek2: ) and apparently all fine, I had to call in the mech project manager and quietly show him the piping problem. Didnt need to embarrass or make a big deal about it.

I swear it took me about 1 hr to convince him that it was wrong.

and this is why everything is a controls problem I suppose ... it does seem that every time the controls people get called in the issues seem to just disappear.

...didnt even get a thank you.

 

[hvac69]

Had a job with a severe communication issue suddenly. Found this done in multiple areas with the slack com wire.

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[deadheaddave]

A hospital kept complaining about the chiller not keeping up. We finally noticed it only happened when the sprinklers were on. That's right, they were watering the lawn with chilled water

 

[control$]

A hospital kept complaining about the chiller not keeping up. We finally noticed it only happened when the sprinklers were on. That's right, they were watering the lawn with chilled water

Reminds me of another one, a pneumatic vav system. Time after time, tech after tech was sent to the Airport. The problem was the ticket area overheating. So after hours we went box by box, stat by stat. Again and again no problems found.
Then we got a early start, and found the problem. The pneumatic for the vav's were tied into the pneumatic automatic doors (or the other way around). Everytime the the doors opened the vav's lost pressure and went to full heat!

 

[MatrixTransform]

A hospital kept complaining about the chiller not keeping up. We finally noticed it only happened when the sprinklers were on. That's right, they were watering the lawn with chilled water

*chuckled out loud

 

[tridiumtech]

Got a service ticket call from a site that hired an electrician to replace the RTU evap. fan blades
with efficient ones. The site later complained of poor RTU performance and bldg. pressure issue.
After spending the better part of an hour shoveling snow to get to the RTU (Rocky Mtn. territory),
got a look a the running fans. Kind of deceiving at first - you think air is being pushed out when
you put your hand around the grill. Took my snow shovel a placed it on the fan grill - it quickly
got suck down! The electricians got the fan direction backwards and they said 'everything's ok'.

To prove it to my mtg. (lots of politics going on and you're the 'messenger') I taped some paper
streamers on to the fan grill - with the fan running you would expect the streamers to fly out - the
photo show them suck'd in.

 

[tridiumtech]

oops - condenser fan blades. Ok - shoot the messenger ;-)

 

[scc]

Recently had a chiller startup issue where the Smardt chillers were indeed smart - telling us there was no water flow. Of course the problem was my 4" isolation valve was not opening causing the flow problem. No one would believe the valve was open even though it was plain as day. It wound up being be me and a mechanical tech running a fishtape through the piping all the way to the chiller to prove it was open. Even though the plumbers supplied and installed the chiller they just washed their hands of it. After some serious head scratching we took the end bell off the chiller.

Turns out the factory had installed the wrong end bell blocking the tubes internally.

Like you said, call the control guy and the problem disappears.

 

[Austins]

Controls setup to allow the maintenance office personnel to override the supply fan off and the dx cooling on on RTU.