Type 1 make up air grille - closable allowed?

[Darren Emery]

I don't have a copy of UL 710 - I'm guessing it addresses this issue. On a compensating hood, can the make up air grille be equiped with a volume control/closing damper? Seems counterintuitive to me - the make up air needs to be finely calibrated to avoid negatively effecting the capture, especially in a short-circuit design. Why allow the option to adjust or close the make up air, thus negating the balance test?

Thoughts?

 

[cda]

Are you looking at a listed hood???

 

[Darren Emery]

Are you looking at a listed hood???

Debatable. But for sake of arguement, let's say yes, it bares the UL label. The MUA grill appears aftermarket field installed to me. Thus the concern. The supplied documentation does not completely match, and has been altered.

Lots of ??? on this one.

 

[cda]

Have to look at the books on Monday

If any kind of listing call the manufacture with the question

Do not think that ul 710 will help you

Check imc and nfpa

 

[TJacobs]

From the sound of it I would not accept it. If they altered the hood they would need a new listing, probably a field listing. Call the hood manufacturer...good luck.

 

[fireguy]

I don't have a copy of UL 710 - I'm guessing it addresses this issue. On a compensating hood, can the make up air grille be equiped with a volume control/closing damper? Seems counterintuitive to me - the make up air needs to be finely calibrated to avoid negatively effecting the capture, especially in a short-circuit design. Why allow the option to adjust or close the make up air, thus negating the balance test?Thoughts?

I tihnk you answered your own question with your last question. You recognize that changing the dampers, changed the ability to meet the air flow requirements. At the last class I attended, we were told the makeup air needed to be 90 % of the exhausted air. Closing the intake air registers will reduce the amount of make-up air. There are anometers available so the air movement can be measured.

Is this a listed hood? If so, the listing has been changed and is now void. As a non-listed hood, you now need to use the chart in 507.13 to figure exhaust flow. Now, you need to know the air moved by the exhaust fan and the intake fan. There may or may not information on the fans that will help. Of course, the fans are listed, right? Because we are moving more air, is the duct the right size? I am leaving now, to write an explanation as to why we cannot put a fryer under an existing type II hood.

 

[Builder Bob]

Perhaps the answer may be in the international energy conservation code.......

 

[cda]

if you have a commentary the 03 talks about motorized dampers and being interlocked with the operation of the cooking applaince in section 508

the other thing is have them show you a test they are geting enough air

did you read also 5082. 03 edition compensating hoods, talks about it is required to have min and max flow rate marked on hood

and also testing per 507.16.1

 

[BSSTG]

Greetings,

If the hood is a listed piece of equipment then I would have an issue with it being altered. If it is an unlisted hood as I see frequently then I may an engineers stamp on the design. In any case I would require a thorough acceptance test per 507.16 IMC.

Byron

 

[fireguy]

if you have a commentary the 03 talks about motorized dampers and being interlocked with the operation of the cooking applaince in section 508the other thing is have them show you a test they are geting enough air

did you read also 5082. 03 edition compensating hoods, talks about it is required to have min and max flow rate marked on hood

and also testing per 507.16.1

Then the exhaust system cleaner comes in and sprays Sodium Hydroxide inside the hood. The SH takes off the ink and disolves the glue that holds on the label.