We are installing grease traps in a school system, 90% of them have caused major odor problems in the buildings within a few days. These are older exsisting plumbing systems,that we are adding the traps to. We have tried everything we can think of any suggestions

Are theses actual greasetraps in the kitchen area or are they sink P traps? A properly functioning trap will not have an odor.

It is grease traps for the kitchens,we are not gettig the tank odor. We some how seem to be breaking the vent system of the building. We just haven't figured out how
Or why

it is grease traps for the kitchens,we are not gettig the tank odor. We some how seem to be breaking the vent system of the building. We just haven't figured out how
Or why
Are these manufactured or home built grease traps? If these are manufactured can you give us more details
90% of them have caused major odor problems in the buildings within a few days. Most grease traps are installed out of the building. What am I missing here?
Your complaint's confusing to me. In your first post you complain about the smell and in your last you tell us;"
we are not gettig the tank odor.. Where's the smell coming from?

we some how seem to be breaking the vent system of the building. Please explain what you mean. Have you blocked the vents somehow? Bypassed them? What do the vents have to do nwith a grease trap? Is the grease trap vented? In short we need a clearer question and more details. Regards, Tom

The grease traps are being installed outside. What we are doing is,separating the kitchen drains from the rest of the building and sending them to the trap then tying the trap back to the main. On the average within a couple of days we are having odor problems in the building not the kitchens the rest of the building,where we have never had problems.
What we can't figure out is why,we have vented the traps,pulled and reset fixtures,still have problems,its like we have messed the vents up in the building but can't explain why.

Did you vent the traps into the fresh air intake of the building accidentally?

what we are doing is,separating the kitchen drains from the rest of the building and sending them to the trap then tying the trap back to the main.
Ahhh! But have you capped off the old connection before you rerouted the kitchen drain to the grease trap? The kitchen drain and vent should now be a closed system to the grease trap. What else is tied in with those kitchens that you may have overlooked? It sure sounds like you're still connected to the house system before it reaches the grease trap. What are we missing here? Regards, Tom