HHHHHHHHHHHHHHVAC

This post contains large amounts of angry hissing and swearing. You’ve been warned.

hhhhhhhhhhhhhhhhhhhhhhhhhhhhh

I was doing the weekly inspection checklist at the transmitter site when this….. Space Station Toilet….??? went thunk, plunk, and cycled out of Beam On. The display forlornly moaned of a low anode coolant flow alarm. I know the issue is with the flow sensor.

It’s in the middle of all this so I did not try to undertake the replacement single handedly. Look at this glorious mess!!!

But then my attention was drawn to the fact that it started getting warmer in the room… and it just kept getting warmer. Luckily, it was about 68 outside with a strong Delta Breeze, so I just opened all the doors and started to investigate the attempted thermal runway. On the roof I peeked into one of the large RTU (Roof Top Unit) air conditioners and saw a winter wonderland of ice. Hmm.

Hurrrfdongs

Not good. So why’s this thing icing up? It’s practically brand new! I called the HVAC company we have a service contract with and their dispatcher literally told me she was going to see if anyone felt like helping us out today. (No.)

Time to gather tools and investigate.

Ahhh! Copeland Popsicles!

Definitely a low head pressure situation… but why? Remember, PV=nRT even for insufficient levels of T[emperature], so maybe it’s just running too cold due to low heat input into the system. Let’s open up the other side…

Oh. You know, I don’t think that belt is supposed to be flopping around like a rubbery hula hoop.

Note three things in this photo: 1) motor sheave spinning. 2) fan sheave barely spinning. 3) harder to see but— water flying everywhere including spraying on that poor little ABB drive!

Click, power down, go gather more tools, climb up and down the ladder about a zillion times…

I set the thermostat below to system off / constant fan and properly tensioned the belt, which DerpCo HVAC’s techs do not know how to do… At all… then restore power.

No windy whirly. Just freezy fuckery.

The fan didn’t start. The little ABB drive’s cooling fan wailed, but it just wasn’t coming on. Why? Finally on a whim I twisted the red and green thermostat wires together and it ramped politely up to full blast with no slippage. Guess the thermostat just isn’t letting constant fan be a thing. That’s fine…

This economizer reminds me of that enormous gear Charlie Chaplin gets rolled across.

Slowly but surely, the room temperature started creeping down.

I always wonder if I’d get in trouble for naming and shaming DerpCo HVAC. They’re a large, probably national company, and are far more interested with their prime directives of union busting and bumping out any employees with seniority than they are with providing proper service to their customers. I hate dealing with DerpCo mostly, though they have *one* tech locally who actually knows what they’re doing.

Yeah sure you’re keeping up with maintenance

good jorb sweaty, totally glad we’ve been paying for a maintenance contract on this thing all this time

Upon having the staff working below complain they were pretty much freezing down there and looking in this confusing mess and seeing a suspiciously weak output air temperature… it was time to go investigate so I can tell the HVAC company how to fix it.

They do not successfully ever do diagnostics. I basically have to tell them what’s wrong and have them fix it.

Sometimes I wind up fixing it anyway because they have absolutely no clue how.

This is hopefully not entirely one of those.


entirely.

wishful thinking.

but at least there’s no variable frequency drive involved. just a toasted drive belt that’s about two days from snapping off like an over-fried onion ring and leaving us shivering.

i don’t know i’m six days into what should have been a four day work week and my brain is just a bunch of aktivschaum.

anyway I found the thing having trouble lighting, short cycling, and periodically letting out gas farts because the “intermittent pilot” (a high voltage spark ignitor) was all fouled with crap… along with the venturis to the burners…. and pretty much….. everything

glorious!

can i go home already?? youtube is recommending a video to me called “calm your anxiety”.

Apparently that heat exchanger isn’t original. We had another one of these units on which the heat exchanger cracked and Modine has entirely washed their hands of this series – no parts available anymore. The new one that was installed in its place is twice the physical size, makes huge banging and whistling noises, took ONE YEAR from order to delivery, and required a weird custom roof curb to sit in. Charming.


oh and the video is actually a pretty awesome lo-fi compliation

this is our solution

This got pretty badly stuck in my head yesterday for…. reasons

I figured out the root cause of the issue I posted about earlier on with the crazy fan circuit…. waaaait for it:

The pin was never securely inserted and latched into the housing of the fan connector! Welp. Lacking the correct tooling for this connector series (I have yet to be able to identify it!) I broke the rounded end off one of those plastic stirrer sticks from Starbucks and used it to prod the thing into place. It snapped in and I plugged the fan in and it’s happy again. Speaking of fans and drama, this greeted me with a rhythmic pounding noise from the office roof yesterday morning. I sent the HVAC contractor a photo of it and he arrived at the door at 9 AM laughing with a replacement propeller in hand. The cause of this one appeared to be that the “belly band” mounting Trane uses for the fan allowed it to slip down.

By design, these Trane units have a behavior that I consider to be just this side of “broken by design”. When the thermostat calls for cooling, the compressor starts and pumps gas (R-410A in this case) into the condenser, where it gives up heat into the metal finned tubes, condenses into liquid, and is sent to the output lines and into the building to boil inside the evaporator coil, cool the air down there, and come back to the outdoor unit as gas… the usual vapor compression refrigeration cycle. As the condenser heats up, the gas head pressure leaving the condenser starts to rise due to thermal expansion. You can hear the sound the compressor makes change as the head pressure rises, and I’m guessing the motor current starts climbing too. Once it rises to a certain point, a pressure switch trips and starts the fan, which cycles on and off based on the head pressure.

This causes it, in practice, to cycle in about 5-10 second intervals, repeatedly flexing and stressing every part of the nasty stamped sheet metal assembly up there.

The first time I encountered a unit like this in the wild, I thought I was hearing it repeatedly overheating and tripping a safety cutout. I had to ask an HVAC contractor if that’s normal. They said that (sadly) it is. Why?! I guess it might save a LITTLE power, but I don’t think it’s worth the reliability problems.

On a side note, my parents’ house had some ancient Sears “Good Neighbor” condensing unit that was made by Whirlpool, part of a retrofit from the 1970s or so (best I can find from trying to Google the thing). It claimed to be a two-speed condenser, but in reality, was a single speed compressor paired to a two speed fan that’d switch between high and low as needed based on the compressor discharge line temperature/pressure. It never outright STOPPED if the compressor was on. Yes, this was done… better… over four decades ago. Sigh.

It may be worth noting this was a pretty small R-12 system, couldn’t really fight the Florida heat well, but lasted a LOOOONG time. The condensing coil was much smaller than it is on modern high efficiency systems and I remember the temperature of the air coming out of that condenser being fearsome. You couldn’t comfortably touch the top of the unit after it’d been running.

 

Just cool it, FUCKWEASEL.

I should not have to be repeatedly giving attention to the innards of HVAC chillers, but here I am because everything fucking sucks significant amounts of elephant pisstube.

It’s hot and the air is barbecued toxic shit outside so I’m not going to bother taking exterior pictures of the chiller in question, but here’s its story.

It started out life as a perfectly fine York unit with four Copeland Scroll compressors, four inverted A-frame coils, and six axial fans on top to suck the hot air out after it’s moved across them.

Then someone decided, hey, Turbocor compressors are pretty boss, let’s swap it over to one of those. Okay.

Hey, let’s also try to give it variable speed fans, based on…. uhhhhhhh…

Whatever This Shit Is. Uhhhhhhhhhhhhhh—-

Now let’s put a water misted cooling pad system on the air inlets and make it look like something that was field expediently whacked together in the back of a barn OH FUCK GO BACK NO

Here’s the end result. At some point someone cleared out the electrical cabinet of everything but the main disconnect and rebuilt it with……a mountain of weird shit. This is the left side where the contactors for the compressors and fans would have normally been. I don’t know what the deal is with that thing that looks like a transformer, it’s just an 3 phase “reactor” – an inductor.


Not particularly visible at the bottom: a set of current transformers on the Turbocor’s power wires that set off the water misters when it begins to spool up, and a pair of fans rigged in the bottom to keep the VFDs cool…ish. They’re powered through the barrier strip on the far right.


In the compartment which would have formerly held the logic board that controlled the old setup, the two relays to the left of the Turbocor interface board turn on the cooling fans at the bottom, and…. well, I have no idea what the second one does. I couldn’t trace this out and there’s no documentation left with it. In short, I have already run out of fucks to give.


Um, what the fuck happened to R12? Again, lack of fucks to give, the thing still runs ok. Not sure what the LEDs are indicating but when D5 through D8 flicker periodically.

I’m fairly sure the Turbocor must actually be capable of commanding variable frequency fan drives to cool the condenser, but oops, someone put that weirdass blue pressurestat in place instead. That thing is fucking weird. It sits there and does nothing until the pressure is like 4 PSI below setpoint, then the command voltage it sends just abruptly leaps up from 0 to 10v, making the variable frequency drives… not so variable…


Anyway the reason I had to mess with this thing is one of the drives lost a 24VDC cooling fan. Our HVAC contractor looked into ordering a new fan and found out that a replacement would be at least SIX MONTHS OUT. The original, an NMB 3110KL-05W-B50 (80mm, ball bearing, 24v, 0.15A) appears to be Fuck You NLA. In fact, almost all 80mm 24VDC fans appear to be unavailable. I begrudgingly, out of desperation, dug into my own supplies and grabbed a little switching buck converter that’d take the 24VDC from the VFD and step it down to 12V to run a fan that actually IS available and extremely common.

Now the dumb thing spits out cold water again and I’m not quite as mad. I’m still going to swear at the fucking bellend thing though.

Steamed.

I’m a little annoyed with having to deal with air conditioning nonsense right before a weekend I don’t get any time off from work because we’re so understaffed. We have an HVAC contractor who is supposed to deal with this but they’re completely clueless when it comes to large systems. They have one guy in the company who understands the Metasys controls and somehow I know more about them than he does.

🎵 Look at this graph 🎵

The last big issue I had was with this one air handler / fan coil unit on the roof that cools both control rooms and our newsroom via a Medusa head of VAV boxes. First it had been shutting down, it turned out the variable frequency drive was on an HVDC overvolt fault and didn’t automatically restart. I programmed it to do so. The service company looked at me like I was speaking Martian COBOL when I explained this to them.

I also asked them if the belts to that blower it runs were too loose. They don’t know. They couldn’t advise me on this and didn’t know how to check. I’m not touching this with a social distancing pole.

Today it was acting up in a different way and I found Metasys reporting the cold duct pressure was 0.1″ water column. When I opened the blower access door on this totally turdly air handler, it jumped up to 0.7″ and the VAV boxes actually started, you know…… working. Opening the door took an unreasonable amount of force and only after I opened the door, the system started calling for less than 100% blower speed. Hmmmm.

Gee I wonder why there’d be that much airflow restriction on the inlet? Let’s see, shall we?

Gaaaaaaaaaahhhhhhh

These coils were supposedly cleaned! Uh…. No.

On a side note, the fact that our chiller’s variable output capability is simply not used and instead it was just saddled with this foam rubber covered Chipotle burrito tank and set to on/off cycle makes me wonder

the spaghettinator

Here’s to hoping this hot weekend goes uneventfully.

Treat the variable frequency drive with kindness

Variable frequency AC drive controllers are all sorts of amazing. They rectify AC power to DC then give you 3 phase AC at the desired frequency to let you run the motor at the desired speed, anywhere from just a few RPM up to full tilt. They can also, if misconfigured, drive you up the wall at 60 cycles per second.

I’ll save you the pain of having to watch me scream about Johnson Controls Metasys, here’s the data showing that this one air handler is not happy. This graph is showing its air output temperature. This morning I came in to find half the facility nearing meltdown and decided to see if I could do anything about it.

There’s the drive for that unit’s blower. I found it shut off on a DC bus overvolt fault. The automatic fault restart was not enabled, so it just sat there.

I restarted it and watched it ramp up to full speed…. fearsomely. After it’d let the place cool down a while I revisited the settings. This Yaskawa controller actually has pretty good documentation and a setup routine designed to aid in quick deployment (I CANNOT say that for all the controllers I’ve come across in the wild). Right away I noticed the amperage and wattage limits set in the controller did not match the motor, which did not appear to be original to the unit.

Yeah uh I’m gonna have to recommend you not do that. I filled out the proper values in there, turned on fault restart, and ran the auto tune, which sounds like angry crickets on this unit.

Aside from the drain pan looking suitably foul, I’d say it’s happy again.

I dunno, I realize that variable frequency drives are probably a bit of crazy black magic to a lot of HVAC people, but pleeeeeeeeeaasseeeee make sure you have the thing configured right for whatever motor you’ve wired to it! It does make a lot of difference!

Oh, and the Johnson Controls corporation is a bellended bagbiting cockwomble. There i said it ok

assfoam

I can’t even. The wall shaker A/C was iced over when I got to the site and a mix of frost and mildew was coating the front grill. I set it to fan only and let it sit there and think about what it had done while I went up to the Ace Hardware and got some coil cleaner. Here it is initially, after most of the ice melted.

slinger ring fan description
that sloshy noise making thing

Then I shut it and the small backup unit above it off, applied the coil cleaner to the evaporators and condensers of both, waited ten minutes, hosed them down thoroughly with my pump sprayer bottle full of water, and turned them back on.

Seems I forgot about four important things:

A) both sets of condenser coils and evaporator coils had a massive amount of oily smoke residue from the wildfires and the transmitter fire on them;
B) when you use this cleaner, it saponifies oily (non polar) residues into a soap that will bind to water molecules for easy removal, using a nice amount of sodium metasilicate as an alkali reagent;
C) the drain pans on most modern wall/window A/C units RETAIN some water and use a slinger ring on the condenser fan to throw it on the coils;
D) this action will cause a lot of air to be entrained in whatever condensate water runs into the pan….

I heard the fan speed slow on both units after they’d been running a while and looked out to find this great outpouring of suds that smelled strongly like ass. Assfoam. ew. ASSFOAM!!! Get it out of here! Ugh.

While this was all happening, one of the neighbors came walking up, noticed my Golden State Pinball Festival shirt, and asked me how a Death Save is supposed to work. I admitted to him that while I know how it works, I’ve never been successful in coming away with anything but a bunch of tilt warnings and sore hands. (It’s banned in tournament play as it can cause player injury and damage to the pinball machine. Don’t do it on someone else’s game, or on yours if you don’t like the idea of damaging the legs and cabinet, mmkay?) Video of a successful Death Save below.


Here’s the Death Save in action. It’s fairly brutal. If the ball right drains on me I just let it go, but I’ll certainly shake the game around a bit to try to bounce the ball out of the outlane area before it decides to sink in there!

Here’s the more dangerous (to the player!) left-handed brother, the Bang Back… it doesn’t appear to be as likely to damage the game, but as they mention in the video, you can break your wrist trying to save the ball!

Of all games they could have chosen to demonstrate this on— they chose the mighty, heavy, widebody Twilight Zone!!! Hardcore.

Here’s another video where several different types of nudges are shown as a game is being played and explained, including forward nudges to bounce the ball off of the rubber parts near the outlane to get it out of harm’s way, and sideways nudges for slap saves of balls headed straight down the middle [SDTM].

 

More old Honeywell thermostat fun

Previously, and thermionic valve based.

One of the sites I work on has two old Honeywell thermostats on the wall that are like nothing I’ve seen elsewhere and it kinda intrigues me. These have a small bellows inside and act upon temperature changing the pressure of gas sealed within it. I wonder if they have to thus be calibrated for altitude?

I’d guess circa 1960s-1970s based on the date of other gear at this site.

First, the cooling thermostat – it’s a pretty straightforward mercury switch two-stage type. BIG mercury switches, though – much bigger than Honeywell would have put in their standard home HVAC controls…

The setpoint is adjusted using the hex screw on the side.

Next, the heating thermostat, which really had me scratching my head:


The contact arrangement is curious. This thermostat does not appear to just switch on and off, rather, its output appears to be a variable wirewound resistor! Said resistor is also mounted far from the bellows, so it’s definitely not just an anticipator resistor. This makes me wonder if it was actually more of a remote sensor to something fancier—? Apparently it’s a “proportional control” and I wonder what the original heating system up there was. The original HVAC system has been mostly removed and replaced with a boringly modern one.

 

Aww shim

So that buzzing sound my 2014 Forester’s a/c compressor made since last year? Yeah it wasn’t supposed to do that.

I checked the clutch gap today after suffering mild heat exhaustion in 102 degree weather with the A/C blowing warm… .82 millimeter… Factory specs say 0.1-0.6mm.

Thus it was time to subtract a shim from the shaft.

And then my workday jumped to like 10 hours and crap so what follows:

There’s actually nothing to stop this from turning so I just grabbed it with my hand and used the wrench on the center bolt because I’m some scary beast

The compressor drive plate before cleaning

Pulley side after removing all three shims and before cleaning

I saw it recommended to torque the center to 10 foot pounds which worked fine with my bare hands, once again….

Now it seems I just have cold air constantly and no buzzing noise (was that it slipping??)

Update and data for the purposes of making this a little more indexing friendly: This compressor is a Valeo DKV-10Z
Subaru TSB number 10-84-16R indicates there’s a known issue with the electromagnet that contributes to this and that the official fix is to replace the compressor. However, the issue is actually entirely confined to the clutch itself and I’ve seen a clutch replacement kit available for about $90. If your vehicle is under warranty, go to the dealer for service. If not, the $90 kit should do, and you don’t have to evac/recharge the system. Looks to me like the only interesting tool you might need would be a snap ring plier and maaaaybe a puller and the spanner wrench for the rotor (since not everyone can just grab the front plate of the clutch like I can!)