Hood Exhaust 24/7

[Joewf]

I have a hood exhaust over a commercial dishwasher at the facility I maintain that runs 24/7 is this normal? Shouldn't it be mechanically linked to the dishwasher control?

Old Maintenance Man

[yellowirenut]

depends..sometimes the control for dish washing hood is tied into cooking hood also..all fans on including the makeup air that may need to be tempered by heat. If just the dishwasher fan is on or off u may have an air balance issues with make up air and a cooking hood

[ray mcbriarty]

you wouid thing so. but they went the cheaper route.

[madhat]

Look at the dish machine wiring diagram, should have a relay and a run on Time delay after the cycle is complete. The Hobart dish machine at work, with conveyer, has this feature. Hooked it up last year. BTW the Dish machine exhaust fan is in a different area than cooking hood exhaust fans. Dish machine exhaust make-up air is drawn from the dining room. CFM is small compared to cooking hood fans.

[iron]

I have seen dishwasher hoods controlled 3 ways
1) interlocked with the dishwasher cycle
2) interlocked with the hood fans
3) on an independent switch
never seen one that was supposed to run 24/7
perhaps the starter coil is jumped or welded shut
or maybe bypassed all together
starters are usually in the main hood panel or above the ceiling
thats where I would start.