Make up air

[mcclary's electrical]

Is it illegal, or a liability to run a restaraunt without the make up air fan running? I went to a service call that ended up being a bad fan motor. The head chef didn't want to run the kitchen without it. Is there any liability on me for telling the owners that they can run? They still had and exhaust fan. The fire marshall visits this district quite often. Is there a chance of anything happening like a fine?

 

[iwire]

In a restaurant my wife worked the lack of running the make up air was dragging the flue gasses from the boiler down the chimney and into the restaurant. Someone dropped a dime to the local fire chief, the FD showed up with a CO meter and ended up closing the place down. This got the building dept involved and they bagged a plumber for an un-inspected additional boiler installation while they where checking out the CO problems.

 

[mcclary's electrical]

In a restaurant my wife worked the lack of running the make up air was dragging the flue gasses from the boiler down the chimney and into the restaurant. Someone dropped a dime to the local fire chief, the FD showed up with a CO meter and ended up closing the place down. This got the building dept involved and they bagged a plumber for an un-inspected additional boiler installation while they where checking out the CO problems.

sssshhhhheeewwww!!!,,,,,,that's all I have to worry about :grin:

 

[ESC2008]

NFPA 96 8.3.1 requires replacement air so you don't create a negative pressure in the space. It is also a building and mechanical code violation to have a negative pressure.

Also, in order to exhaust at the designed CFM you must use the designed MUA. Some systems are designed to use the fresh air from HVAC around the building but most hoods are designed with integral MUA fans.

There are case studies that show true electrical savings when they keep their MUA running properly. If you don't not only do you dramatically reduce the exhaust hoods ability to remove the heat, smoke and fumes but you also starve your HVAC systems substantually reducing their efficiency. In fact we've been able to show a customer over time that replacing his non-heated MUA with a heated MUA had such a quick ROI that it essentially paid for itself.

So in short, it is code, NFPA, BOCA as well as other codes, and it is common sense.

 

[One-eyed Jack]

In a restaurant my wife worked the lack of running the make up air was dragging the flue gasses from the boiler down the chimney and into the restaurant. Someone dropped a dime to the local fire chief, the FD showed up with a CO meter and ended up closing the place down. This got the building dept involved and they bagged a plumber for an un-inspected additional boiler installation while they where checking out the CO problems.

If the boiler had been installed to code with proper ventilation and combustion air this would have been less likely. Possible but less likely. Benefits of permit and inspection????

 

[muckusmc]

Is it illegal, or a liability to run a restaraunt without the make up air fan running? I went to a service call that ended up being a bad fan motor. The head chef didn't want to run the kitchen without it. Is there any liability on me for telling the owners that they can run? They still had and exhaust fan. The fire marshall visits this district quite often. Is there a chance of anything happening like a fine?

Must have the MUA, but until the fan can be repaired and for airflow - open all doors and windows in the kitchen area.
There are still some old hood systems out there that don't even have a MUA installed.

 

[gadfly56]

If the boiler had been installed to code with proper ventilation and combustion air this would have been less likely. Possible but less likely. Benefits of permit and inspection????

When you're pushing 5,000 CFM out the building without make up air it won't matter that your HVAC was designed to code. I've seen kitchen doors slam shut when the MUA went off with the exhaust still on. Pull a quarter inch over the surface of the door and you'd be surprised what a struggle it can be to open! Not to mention what it can do to a chimney.

 

[iwire]

If the boiler had been installed to code with proper ventilation and combustion air this would have been less likely. Possible but less likely. Benefits of permit and inspection????

It was a fairly small restaurant with only a front and back door to bring air in with the make up air inlet sealed off. With the exhaust fans for the DW room and the grills on there was a great breeze coming down the chimney.

There had been an electric water heater, that gave out and a plumber installed a gas fired unit venting it to an existing but unused chimney. That is when the employee headaches started, their break room was in the basement near the unit.

 

[kwired]

If the boiler had been installed to code with proper ventilation and combustion air this would have been less likely. Possible but less likely. Benefits of permit and inspection????

I have run into this also. Older gas appliances with natural draft ventilation will not care if proper ventilation and combustion are provided. If you have an exhaust fan taking air out of a building and there is no make up air it will pull air from wherever the air is easiest to pull from. If it happens to be a gas appliance vent that is where it will be.

Now if the boiler is located in newer construction it may have been required to be located in a room that is better sealed from the rest of the building and the exhaust fan will have a harder time pulling a back draft through it.

If the building has negative air pressure because of lack of make up air you will also find in many cases it is hard to open the doors.

 

[One-eyed Jack]

It was a fairly small restaurant with only a front and back door to bring air in with the make up air inlet sealed off. With the exhaust fans for the DW room and the grills on there was a great breeze coming down the chimney.

There had been an electric water heater, that gave out and a plumber installed a gas fired unit venting it to an existing but unused chimney. That is when the employee headaches started, their break room was in the basement near the unit.

That was a problem all by itself.

 

[mcclary's electrical]

That was a problem all by itself.

Good point, I left all vents open

 

[LarryFine]

From what I've been told, most of the year, the cook is happy to have outside air blowing around him. It gets hot in there in many kitchens. I've worked in some that have AC on in the kitchen when the heat is on in the dining room.

Make-up air isn't always mandantory. Many smaller hoods have no make-up. It depends on the hood area and the appliance heat load (in BTU's, I guess). I've never heard that make-up couldn't be separately switched; its use is optional.

 

[One-eyed Jack]

From what I've been told, most of the year, the cook is happy to have outside air blowing around him. It gets hot in there in many kitchens. I've worked in some that have AC on in the kitchen when the heat is on in the dining room.

Make-up air isn't always mandantory. Many smaller hoods have no make-up. It depends on the hood area and the appliance heat load (in BTU's, I guess). I've never heard that make-up couldn't be separately switched; its use is optional.

508.1 of the 2006 IMC requires makeup air for all commercial kitchen exhaust systems that exhaust commercial cooking equip. They are required to be interlocked electrically when it is mechanical vs gravity.

 

[ESC2008]

Must have the MUA, but until the fan can be repaired and for airflow - open all doors and windows in the kitchen area.
There are still some old hood systems out there that don't even have a MUA installed.

I think his question revolves around a system that does have a MUA and the code is clear that it must be working. Again, opening doors and windows almost triples the electric operating costs for the restaurant due to it's affect on the building envelope and HVAC systems. It is a temporary solution but depending on where in the country you are it's really not feasible most of the year. I believe the biggest selling points in this case are:

1. The NFPA 96 requires it.
2. Your operating costs will far outweigh the repair costs if this is not repaired.

 

[mbeatty]

Positive and negative pressure (and doors)

Positive and negative pressure (and doors)

This is an interesting topic. During my Navy shipboard duty, I experienced numerous occasions of positive and negative pressure in different spaces. We always set positive pressure to keep smoke, etc. out of unaffected spaces during a fire. The space with the fire was put under negative pressure to starve it of air. You can sure feel both on your ears!

 

[mbeatty]

Positive and negative pressure (and doors)

Positive and negative pressure (and doors)

This is an interesting topic. During my Navy shipboard duty, I experienced numerous occasions of positive and negative pressure in different spaces. We always set positive pressure to keep smoke, etc. out of unaffected spaces during a fire. The space with the fire was put under negative pressure to starve it of air. You can sure feel both on your ears!

Almost forgot the doors. They can be very difficult to open under negative pressure, but watch out when they open under positive!