Need some suggestions please. I have been asked for a trusted opinion on a particular scenario. It is a very busy single story restuarant with a lot of in and out traffic with a very common 50+ people occupancy durring lunch and dinner. This is in the south near the coast, which means hot and humid. There is an aproximate 30 to 40 tons of equipment on a flat roof. Inside is a drop ceiling with some insulation, with approximatly 3.5 feet of attic space with no ventilation. The ductwork is sweating as well as the drop ceiling grid and flourescent lighting fixtures and lenses. This problem has been going on for some time. It is not getting better with all of heat and humidity as of late. I understand most of the factors involved in regards to making sure all of the equipment and drains are working properly. Whether the building has fresh air and a positive pressure on the building. My question is, will adding attic ventilation help or hurt the equation? The next step would almost certianly be dehumidification. Any thoughts?
Sweating, Sweating, Sweating
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trashman
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Need some suggestions please. I have been asked for a trusted opinion on a particular scenario. It is a very busy single story restuarant with a lot of in and out traffic with a very common 50+ people occupancy durring lunch and dinner. This is in the south near the coast, which means hot and humid. There is an aproximate 30 to 40 tons of equipment on a flat roof. Inside is a drop ceiling with some insulation, with approximatly 3.5 feet of attic space with no ventilation. The ductwork is sweating as well as the drop ceiling grid and flourescent lighting fixtures and lenses. This problem has been going on for some time. It is not getting better with all of heat and humidity as of late. I understand most of the factors involved in regards to making sure all of the equipment and drains are working properly. Whether the building has fresh air and a positive pressure on the building. My question is, will adding attic ventilation help or hurt the equation? The next step would almost certianly be dehumidification. Any thoughts?
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Many thoughts! Most spaces above false ceilings leak excess outside air into the space because of the exhaust in the kitchen makes the entire building negative. During 3 seasons of the year, the outside air dew point is +70^F, causing condensation on any surface cool surface. Adding more outside high dew point air will aggrivate the problem.
Stop the air leakage from outside into the space by sealing the leakage above the ceiling and providing make-up air in the kitchen for the exhaust hoods.
Install a couple Ultra-Aire XT150H horizontal dehumidifier in the space above the ceiling tile. This will help the a/c remove water during humid time of the year. Also set-up the a/c with a +20^F split to max the amount of dehumidification while cooling. If the space above the ceiling low dew point, sweating will not be a problem.
Regards TB
Stop the air leakage from outside into the space by sealing the leakage above the ceiling and providing make-up air in the kitchen for the exhaust hoods.
Install a couple Ultra-Aire XT150H horizontal dehumidifier in the space above the ceiling tile. This will help the a/c remove water during humid time of the year. Also set-up the a/c with a +20^F split to max the amount of dehumidification while cooling. If the space above the ceiling low dew point, sweating will not be a problem.
Regards TB
I agree with Teddy about bring in more OSA will just make it worse and sealing up all the air leaks in the duct work, but I see you say "Inside is a drop ceiling with some insulation" you don't say anything about if the duct work is insulated. If any of your duct is not insulated including the drops, there is a huge problem. Also you say "The ductwork is sweating as well as the drop ceiling grid and flourescent lighting fixtures and lenses" As far as the drop ceiling you need to insulate the T-bar because they will cause condensation because they are on both sides of the conditioned occupied space and the unconditioned ceiling space. (usually they use pink fiberglass bats) the same goes for the lights, they have air holes in them to help cool them and that will do the same so insulate them too, but some lights have a minimum clearance so you may have to build a box around them.
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Here are the golden rules for restaurant:
1) Hard to keep kitchen area cool unless you way over size it.
2) Exhaust fans and make-up fans MUST work together. I.e if you exhaust 1000 CFM, you must bring in at least 95-98% of fresh air in RIGHT ABOVE THE HOOD ALONG THE EDGE
3) The other 6-3% of fresh air will need to be introduced into the unit in the dinning area (NOT THE KITCHEN UNIT). This will make the dinning area positive and the kitchen area negative. Thus the cooking smoke will not attack customers' clothes.
4) NEVER EVER adjust belts tension. Have spare belts at all time and change them regularly. Both exhaust and make-up at the same time.
5) Steam clean the exhaust. Clean/replace the make-up fan filters regularly. Trust me, the cost of cleaning is cheaper than replacing duct, A/c unit, angry customers, and blow-joe who knows nothing about a/c working on your BUILDING' COMFORT
If you follow these golden rules, you will most likely have to turn the A/C unit UP because customer will complain the place is TOO cold.
P.S. I hate to go into the restaurant thats keep their temperature at 68 degrees. The place is freezing cold because the supplying grills are everywhere and blowing on top of you. My hot T-bone steak comes out hot. But after 3 bites, the doggone thing is cold because the cold air is blowing on it.
1) Hard to keep kitchen area cool unless you way over size it.
2) Exhaust fans and make-up fans MUST work together. I.e if you exhaust 1000 CFM, you must bring in at least 95-98% of fresh air in RIGHT ABOVE THE HOOD ALONG THE EDGE
3) The other 6-3% of fresh air will need to be introduced into the unit in the dinning area (NOT THE KITCHEN UNIT). This will make the dinning area positive and the kitchen area negative. Thus the cooking smoke will not attack customers' clothes.
4) NEVER EVER adjust belts tension. Have spare belts at all time and change them regularly. Both exhaust and make-up at the same time.
5) Steam clean the exhaust. Clean/replace the make-up fan filters regularly. Trust me, the cost of cleaning is cheaper than replacing duct, A/c unit, angry customers, and blow-joe who knows nothing about a/c working on your BUILDING' COMFORT
If you follow these golden rules, you will most likely have to turn the A/C unit UP because customer will complain the place is TOO cold.
P.S. I hate to go into the restaurant thats keep their temperature at 68 degrees. The place is freezing cold because the supplying grills are everywhere and blowing on top of you. My hot T-bone steak comes out hot. But after 3 bites, the doggone thing is cold because the cold air is blowing on it.
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636 Posts
One of the ducts is leaking somewhere, find that leak.
Had this at several location were the flex duct was not attached even though it looked like it was.
Jim
Had this at several location were the flex duct was not attached even though it looked like it was.
Jim
Thanks to all for the advice. Everything suggested makes perfect sence. It appears as if I need to do a little more research. However I am still wondering what adding attic ventilation would do to the equation. I know this would lower the TD between the two spaces, and would also prevent the kitchen exhaust from pulling unconditioned air in from the attic space. Any thoughts on this?
You said: with approximatly 3.5 feet of attic space with no ventilation[/COLOR].
If your code allows and you don't see an immediate fix, I think you should consider using the ceiling plenum as the return and perhaps eliminate the cold grid, and fixtures etc. The fact that it isn't working (did it ever work?) doesn't leave you with many options. The ceiling plenum is kinda part of your cooling load anyway so disconnect the return and put in some eggcrate returns give it a try and use my profile email I would like to know if it did the trick
If your code allows and you don't see an immediate fix, I think you should consider using the ceiling plenum as the return and perhaps eliminate the cold grid, and fixtures etc. The fact that it isn't working (did it ever work?) doesn't leave you with many options. The ceiling plenum is kinda part of your cooling load anyway so disconnect the return and put in some eggcrate returns give it a try and use my profile email I would like to know if it did the trick
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2,032 Posts
Trashman,
If you don't balance your make-up fans and exhaust fans, you accomplish nothing. Whatever you do will not PROPERLY help you.
Go to your front door when the kitchen is fully running CLOSE all doors for 15 minutes and then open the front door. If the wind draft slap you in the face and knock you backward. You got problem.
You can put all bandages on the gun wound all you want. But unless you remove the bullet, it ain't gonna heal PROPERLY.
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