This was a service call on a negative air pressure problem, I found that the building needed more makeup air supplied to it to balance out the building. I made some temporary adjustments and have submitted a repair quote to the customer.
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All right, so the complaint is, is that they've got a sewage smell throughout the building. The customer is called the plumber. The plumbers done all kinds of work to try to solve the problem. Everything's shorter, replacing all the plumbing going from the building to the street, so they called me after they did all this work because their facilities director came out here and said: wait a minute, something's, not right with the building balance so sure enough.
I come out and right when I come to the doors I could already tell they have a mass of negative air pressure problem so currently, right now, I have all the air conditioning units running. I have all the exhaust fans running and we are in a negative air pressure situation. That's negative, 0.2. 7 inches of water column is the building pressure.
This particular restaurant has three air conditioning units that are acting as their make up: air, okay, so they're bringing fresh air in they have no dedicated make upper unit. We have a restroom exhaust and a dishwasher exhaust right there. The restroom exhaust actually isn't working. So that's going to create an even worse problem once I fix the restroom exhaust, but we're gon na keep on checking the rest of the building.
What we're gon na do right here is come up to the r2 units. The air-conditioning units make sure that we've got a call for occupied and a call for tea, so these Lennox units you have to have that call for occupied for the outside air dampers to open up the occupied signal is basically telling the unit that someone is in The building, okay, so the occupied in the G call, is good. I have that same call on every r2: u or AC unit. I also verified that all of these exhaust fans are working okay.
So what I want to show you guys is how much of a difference it's going to make we open up these outside air dampers, so this one right here is actually partially open we're pulling outside air. This is the only unit that has a full economize, er notice, that it has dampers down here and dampers up here. These other units only have minimum outside air damper, so it still hasn't actuator but notice. There's no dampers down below it's just right here to pull fresh air, so this units the same.
This is the third unit. The outside air damper is closed and there's no dampers down below I'm gon na show you guys an example here so notice that I opened up the filter door for every AC to three. Now, let's walk over to our manometer and see what our building pressure is. Let's come on over here and check this out.
We're reading point zero, two of positive pressure now, okay, so this is essentially what we're gon na do. We're gon na get these outside air dampers opened up, so we can bring this building into a slightly positive pressure. I don't know if we're gon na be running point zero, two, but we're gon na get it just ever so slightly positive, okay, because they're not running full economizers. We need to run these mode, these units in a minimum outside air position setting okay. So we flip our dip switches on our economizer logic board. That's that board right there. Okay, that is the 856 board. We need to flip our two switches to D set D.
Se T that's going to allow us to set a minimum outside air position and the dampers not going to fluctuate so for now, what we're gon na do is we're going to start by setting that out a hundred percent. It was completely closed at this moment. We're gon na let that guy modulate and we'll do the other acs too. Adjusting those guys is opening these outdated outdoor air, dampers or minimum outside air.
They call Michael and fresh air dampers, so we're just waiting for them all to modulate, open and then we're gon na close, all the filter, access doors and we're gon na test the building pressure again, all right with all the outside air dampers, a hundred percent open. We are still running slightly in the negative air pressure and that's still with an exhaust fan that is not working, so the negative air pressure is going to get worse. What we need to do is verify that all the AC blower belts are running and tight and all the minimum outside air filters or fresh air filters are cleaned because those are all going to affect our balance also, so these filters are actually pretty dirty and then We're gon na go check the belts on all the units too, but the filters are kind of dirty on every AC, so turned off the unit, just checking the belt tension. It's actually pretty good.
So far on two of the ACS, I'm gon na check the third, but the blower wheels are something to be said for this one's, not horrible, but every little bit makes a difference. The kitchen AC is pretty dirty, so we'll definitely recommend a blower wheel. Cleaning on these things, too, okay, this is the last a seat belts, pretty tight, blower wheels kind of dirty too. We need to get that cleaned up if you guys can see that, but the AC drains full of water hard to see but yeah the drains plugged up we'll get that blown out okay.
So this building has a smart hood system or it's a hood system made by a company called Mae link and it's called the intelligent system. This particular restaurant is no longer using the intelligent system to its capabilities, because the cost to repair the intelligent system to them far exceeds the savings costs, so they've been bypassing them. Now I haven't done a full hood bypass on this system, but temporarily what happened was as the motor starters failed or their variable frequency drive. Motor starters they've had me just bypass them, so the exhaust fans are running a hundred percent and what has happened is the exhaust fans are now running out a hundred percent and we had to open up the outside air dampers to compensate for the makeup error.
So this system is not balanced at full speed when its operating properly the system is air balanced at medium speed, so they don't need as much outside air when the exhaust fans are not running 24. You know full blast, but because all the VFDs are bypassed now, as they have failed, the exhaust fans are running essentially at 60 Hertz full speed and the building balance has suffered because of it. That's why this call came out now. They didn't tell me that they had this problem, the air balance problem, but you know whatever, interestingly enough, once I opened up the outside air dampers on the ACS, the vent pipe right, there has sewage smell coming out of it. Now, when I walked up here, I had no sewage smell, so that just shows you how the negative air pressure was pulling in the sewage smell into the building. Now another thing the customer has to think about that vent. Pipe sticking out of the ground right there when I walk over to my tool bag, I can smell sewage, now look at this minimum outside air damper on this AC. Potentially they could pull that smell in through that outside air dam for now, so they may have to do something to get that to get that then pipe.
You know vented over somewhere else, so they don't get the sewage smell inside. They may have to extend that over and you know go to the other side of the building or something like that, but they'll have to figure that out. Okay, so I thought this was a good example to talk about air Balance. You guys see how important it is in these restaurants, and especially in this particular setup, where they don't have a dedicated, make up air unit and they're using the minimum outside air dampers on every AC.
So we definitely have some work to do here. My recommendations to the customer is gon na, be that we're gon na do a full bypass properly on the hoods put in traditional motor starters, because they don't want to fix it. Okay, I would rather put in the factory components and get the system operating the way that it came from the factory, but the customer doesn't want that. So I'm gon na do what they want and we're gon na recommend they go ahead and do what they call a mailing hood bypass.
I've done it out a few of them and then we're going to come through and go through the ACS blow out the drains clean. The blower wheels they're gon na have to get this other exhaust fan over here. This restroom exhaust running because the restroom needs to be running properly, but again, that's gon na make the negative air pressure even worse, so cleaning those blower wheels and cleaning those minimum outside air filters or outside fresh air filters, I should say, is - is crucial to this Building also going to be a slight recommendation that they let me go ahead and put full economizers on each AC, so that way we can essentially the way that it works. Right now is.
Is I have to open up the kitchen AC, a hundred percent, so they're not pulling any building air into the kitchen AC right now, they're only pulling outside air into the kitchen, and I would like to get and that takes away from the efficiency of the unit. So in the summertime they're going to struggle in the kitchen, so what I would like to do is put full economizer with the full dampers bottom and top on each one of these other two ACS. Because if I do that, then I can close down the kitchen. A little bit and open up these ones a little bit and get a little more air, because right now, all that these are doing is is just pulling outside air and it's not being forced. So we need to get these economizers. You know installed on these other two ACS and then we can. We can balance this building. So when this hood system is operating properly, there's a laser beam, that's shot out of that it shoots over to this side, and when that laser beam gets interrupted with smoke, it speeds up these exhaust fans, 100 %, but normally they just run in like a medium Speed mode now, their friar section over here doesn't have the laser beam.
It just works on the temperature. So when the temperature in the friar section gets to a certain temperature, it speeds up the exhaust vents to a hundred percent. The system should be controlled from this keypad, which has broken buttons and it's not operating. You see all the error messages.
That's because we have the system white house right now. This is our control section and you can see it and none of the VFD drives how the display - and we just have a bypass. You see the wire nuts just tie in line one and load one together, all the way there and find you mine, 3. All that so, but normally it would be operated by the brain inside that baling control panel that listens and sees everything and then determines whether or not to speed up the exhaust vents and slow them down.
The cool thing is: is that they're variable for a saucepan? So if only one hood has smoke in it, it's only going to speed up one, but it not all of them, but unfortunately the customer just doesn't feel the need to repair these anymore because of the cost.
Are those real green trees in the background? Are you sure you haven't moved to Tennessee?
When I was working in the hotel as a maintenance supervisor, there were some guest rooms which had negative pressure problem. The Rooms were smelling sewage. The Chief engineer told to the mechanical supervisor to fill gaps with foam between the guest rooms and shaft where sewage pipes were passing. But still no effect. I entered the rooms and figured out fresh air dampers were closed or someone put towels in order to prevent slight blowing air sound. I explained to the chief engineer that what are negative and positive pressure. It took several years to get him to understand.
If you have sewage smells (methane or H2S)due to negative pressure inside building that could mean one or more waste pipe P traps or gas traps in the waste lines are not fitted on all waste pipes or some have no water in them.
Should never happen that sewage smells come back from waste pipes except for above mentioned issues.
Hygiene hazard in an eating establishment.
Oh wow no make up air. How is that possible. Those 4 exhaust fan may pulling out so many thousand cfm. They gonna have cooling or heating problem while using economizer sucking those outside air in.
Excellent diagnosis! Methodical, as always.
Good video! When you had the manometer tube going through the roof hatch did you just have the magnetic metal probe that comes with the meter dangling taking pressure that way or did you have something else on the end of it and how far down did you dangle it? Are you in Ottawa ?
Couldn't toilet smell be coming from bathrooms where exhaust fan isn't working? Service area Orleans??
Hi, what is the acceptable pressure difference?
Raise the sewer vent pipe high up. Sewer gas is heavy and tracks to stuff below the parapet wall. Give the gas a chance to get blown away.
Ha, hate this problem. One of the Perkos I used to service always had this problem. Same deal.
Dang, could not kill one of the exhaust fans? Are you in Kanata ?
Altering factory installations voids all ul ratings and leaves your company suseptable to a huge lawsuit. Believe me, telling the judge the client didn't want to won't get you off the hook. In the trades we have to do what's right regardless of what client wants
It's amazing how many Tech's and Companies don't understand building balance. I have gone on some call's where it is hard to get the front door open…………………..dah? A dedicated MUA is the correct way but no one ever want's to foot the bill or "maintain" the ones they have. Achieving a happy point with what is installed is what we are dealt in the field. Good vid!
This video is so informative. How in the heck could I've ever known that sewage ventilation is related to the building pressure. Like the bypassed VFDs in the video, I bypassed few years of experience and a giant pain in the neck with this video! XD
They’re not gonna pay for economizers if they won’t pay to fix the exhaust system lol. Fixing the exhaust is the only solution and the money they’d save with the vfd’s in play
I learn more on an 11 minute video than in a year of doing routine field work.
This video got me thinking. We've had some intermittent problems with sewer gas coming in our house for a while, mainly during the warmer season. The biggest cause was that someone had put a cap on the vent pipe that runs to the kitchen drains. But I'm also starting to wonder if the basement radon fan is causing some negative pressure as well. The house is over 100 years old and is pretty drafty, but maybe it's still not enough to self-balance? Service area Kanata??
Captiveaire hoods. Uses 80% of it own make-up air and only 20% of HVAC . Thank you for the video. It will held in the future. Only issue I have is humidity. Last guys turned the humid sensors off on 10ton unit because Delta-T was off. Units use heat in summer to help dry air. It just created a worse situation. Either customer thinks things are to expensive to fix or you get a screwball tech. Which is worse.
Isn't vent pipe supposed to be 3ft above everything else?
Multi speed motors are not available at Are you in Orleans ?
I swear I wonder my brother if you should go commercial but that is my uninformed opinion. Reach-ins and Mom's and Pop's are the trenches but you are definitely Graduate level. Love your videos.
What about opening the sheaves on the exhausts (while measuring amp draws on the motor) then close sheaves a bit on rtu's while testing static pressure.
I clean kitchen exhaust hood systems for a living. That place looks like Chili’s. Cleaned dozens of those in NJ and PA area. Everyone of them had Melink bypassed. That system works well only on paper. Beam Sensors aren’t water tight. They get ruined all the time. No one opens them to wipe the lens. Small fans above the hood blow air through the sensor box – those die and no one notices. Vfd burn out often.
Awesome videos. I subscribed.
Looking forward to more exhaust fan and make up air vids.
Whats with the high temp silico e at the bottom of exhaust .. interior?
Sewage smell? P trap? Restaurant applications definitely require slightly pos. Press. In dining area vs. Kitchen.
Where do you go to learn more about this kind of problem calls. My boss asked me the other day if I knew how to work on them. I thought about you when he asked.
Hey man cool videos im a tinknocker i work for a commercial hvac company its cool to watch how you go about your work
Great video and information, does the dishwasher hood get tapped into that system?
I've had to do this same thing with these Vfd"s . Ended up wiring in contactors with toggle switches mounted on face of hoods so they could shut them off vs throwing breaker. They don't like power surges at all ! Good job as always!
Do you have minimum outside air requirements? We have a % per m2 or per person whichever is greater.
Also if there is no make up air for your exhaust system you are exhausting all your conditioned air out, it’s a wonder they haven’t had temperature issues during the weather extremes. Unless your power is very cheap the power cost should have a short pay back period on repairs or installation of a make up air system.
Can be frustrating/difficult trying to explain things like this to customers.
Good vid 👍👍
So this might explain why a supermarket in my area winds up with a seriously bad odour on occasion especially after rain Are you in Barrhaven ?
times like this its best to just think positive
I have a customer with that exact layout, equipment, and problems ! It used to be an Italian restaurant but it will now be reopened as a sports bar. I am very worried that with the big crowds and of people they will have a lot of problems keeping up with coolings needs. Keep me posted on your results please . Awesome video !
By the way thanks for the suggestion of the broken drain line there was one thing that was suggested by someone else on the internet when I mentioned running things things moved are they said have you tried just running the heating system turns out it's an HVAC issue when the unit is running that's when we smell it when heating system is running first of all old system do furnace disconnect switch is like a Cutler-Hammer or something like that still in use and the thing is not 220 original 30 amp cartridge fuses probably like either oil-fired or possibly a coal furnace very big return air ducts more likely originally gravity feed may have been boosted with a blower at one point his to get disconnect switch or power burner or navy coal Stoker or all the above at one point or another as I said 30 amp disconnect switch 30 amp cartridge fuses about what you find for the window unit connected to arrange disconnect pull the house is wired originally of black pipe like what's looks similar to gas pipe except this is the rigid conduit the size boxes that do not fit modern covers I think this should help update you on the date of building and one thing of note that disconnect switch for the furnace in the Asian wiring more about that disconnected moment I do believe that possibly the original service funeral who would very well have been wait for it fused neutral panel it don't worry it's every 110-volt circuit and that's why I'm may have had to fuse one in line what Dallas black heart the AR is what now will be white neutral very very very dangerous I've run across to the few tulips usually podcast or I was able to bring some sort of bypass temporarily or swap out the neutral fuses for 30s SM plug fuses usually although I have seen we're not this is not your afraid thing but here Fairwater fuse links one of these was installed in Joyce hey hey hey an attic full of insulation just we start a fire and above that the old first entry systems had to say systems as in fire grenades that most themselves or potion themselves and I think it generates maybe wrong I think it was carbon tet carbon tetrachloride he knows things we want to come across a used it's ever went off the occupants could be dead I'm not talkin smoke inhalation or fire I'm talking about the products of the earth system trying to put out said fire poisoning them if you're interested Google Fire Grenade or Wikipedia or even here on YouTube where fact there's a few of these or somewhere search where talks about these things around the Border a few good examples here on YouTube they were disinterested on Fire Equipment source of book I have one that's not hermit at but it's an earlier one than that it's a little salt water and it's confirmed that salt water because that the markings it's a bracket that's their brass in my parents I'm sure the bedroom where I stay when I'm with them same one that has the odor not sewer they said that it's very possible the gurgling toilet maybe due to a septic that needs to be pumped because I remember it happened to my grandmother sometimes when I was younger that's the first thing she am I then living grandfather would notice it later it back up into the bathtub was it worse yuck but then you'd have to dig up the lid now they have a pump out connection that they just hook up a hose quick coupler for pump out.
Oh by the way how often should a septic tank be checked roughly on average for two people living at the house and go dishwasher and Wanda washing machine one shower 1 sink double occupancy roughly and as I said before it's datrek issues so looks I will look to the right channel to the first place go figure thanks peace out and keep up the by the way the one about the one that starts with the propane I was in that same restaurant as working on this computer system ones and this is just helping someone and weather Refrigeration use fire like I don't think that was strictly logical I said to them I think there's a flammable gas fire refrigerator and gas heating unit know it's Refrigeration what was that would had to be one that runs on propane right and he says yes it's charged for propane or was he said not anymore I looked at it I said yep there's a nice big hole with that compressor where that compressor Terminal ship and that was no more and I speak skidmark in the paint on the unit actually that was some sort of tag or schematic the blower that was clearly chard good proper looking forward to new videos also could you please talk about some of the old I'd say almost antique units that use refrigerants now that can never legally be recharged because the dangers involved mainly because of Hazards of the refrigerants you don't like ones that would gas you if you ever broke it and also I have witnessed an old refrigerator be move with the coils on top I think it was at a campus at when we were cleaning out the old junk yard for scrap impossible resale of anything that could be a value mainly as a antiques such as the old sharpening stone with a treadle that was a museum-quality piece.
back to that refrigerator I think it may have been ammonia based on what has happened and how they react to the as it was like when it went you could see a cloud of white not like your refrigerant spray from the damaged line like at seeing some videos Note. that refrigerator did have a compressor this is not one that used ammonia absorption hydrogen water in the boiler and gas flame or electric heater or a caarosenelamp with a mettle chimney instead of glass.
Sort of like a modifide magic lantern chimney for erley projection.
of course we called the EMTs and they said is a possibility but they could not rule out out or deny or confirm does ammonia because there's no documentation on the unit we searched everywhere on it oh by the way to compressor the connections should have compressor from valves lines or flanges with a fairly decent size screw on your side look more like a hydraulic flange then a refrigeration or are coupler almost like what you might find on some small engine Muffler connections and gaskets in cylinder heads
by the way it look more like an icebox Style or made from parts for an ice box is then converted to refrigerate box for one thing the car scheme was off for the coils or of a different type of paint although almost insane car but not quite but slightly different finish like the refrigeration was an afterthought
the only other place I've seen where these is a museum
One more clue SCH I just remembered actually to the cord was not well you might think 2 wire cloth covered or possibly silk although it was white if I can remember well maybe another color and the plug end of it not what you think. Pins or prongs but medium Edison screw shell AKA Vue or standard size 40 or so watt 200 some-odd watt light bulb base AKA
Well. before we would normally use the two prong socket most places where you would use a convenient light socket to plug in an electrical Appliance more corectley scrue in it
oh by the way in that place also someone else to date probably a lot of stuff was there probably before even that time possibly
What was then the Art Shop
is what used to be a laundry facility which was interesting for thing 30s that log sink is trough sink there's also similar one on the bathhouse where I used to go to camp
As well as in that laundry for soy has now the orange shop there was what store made of an old line shaft system and the boiler was still in the O building one time I ask for permission to pull some boards out and check it out I did get photos and also I salvageable gauges in your gauge siphons Since I'm interested in steam power and boilers and such
They may change their minds after they start getting the A/C bills to cool 100 % outside air
I have absolutely no idea what you and everyone else in the comments is talking about, but it makes me feel smart watching these videos
I had a customer that for years refused to install new make up air units so that his kitchen would feel comfortable for his employees and so that his restaurant would feel comfortable.. Few years ago he decided to get another company to install a 10t AC just for his kitchen.. I told I wouldn't do that , that it wouldn't solve anything. So anyways he got it done and $10k later still had same issues. I ended up disconnecting that ac the following summer, some people just don't get it
I ran into a similar negative air pressure problem where I work only ours was with the updraft spray paint booth exhaust fan. They're so cheap where I work, a door has to be open every time the spray booth is used.
So glad I found this video. We have a sewer smell and an air balance issue at out restaurant. We called a company out and they sped up out MUA units which helped a little but they also told us thats the best they could do because the units are old, not sure what they means because they are in proper working condition. When the back kitchen door or roof hatch is opened, the air balance gets much better. I will look into the AC dampers also.
Do you have any videos that how how to clean the MUA blower fans?
How do those Allen-Bradly VFD's break? What were the error codes? They are serious industrial equipment, it doesn't just break in a kitchen. Don't you think it might be the control box? Service area Nepean??
Wow. Kitchen grease hoods need dedicated makeup air provided around the perimeter of the hood to make them draw and operate properly. How is this place getting by with using the comfort heating and cooling units for make up air?? Huge draft will be set up that drags air across the food the cooks set up on the counter, which cools off the food. Sounds like a design nightmare. The dedicated makeup air units are usually tied into the exhaust fans to run any time the hood is on. The good ones provide heat and cooling as makeup air is supposed to be conditioned. Kitchen makeup air should not be provided by the comfort cooling system.
also, forgot to mention blocked or improper sewer vent sizing and "bad" neighbors causing large positive sewer line pressures!
and partial clogged/restricted lines can cause enough positive when draining to push through traps, "plumbers" could easily miss things like that, without many years of experience 😉
could also be wind direction change/lack of it from the exhausts being pulled back in via the "makeup" air, it really needs bright fella to figure it out, I'm betting you can 🙂
restroom exhaust not working, probably 1/2+ the sewer smell, followed by other comments on dry traps/bad primers or lack of traps, plumbing issue causing trap siphon.
I forget at what negative pressure the traps will end up letting gasses in, but sees to me it's pretty high (many inches of water column)