If I understand this correctly, there are a few things that must/should be followed when installing a dishwasher.
Now consider this. What happens when the dishwasher isn't going to be connected to the sink or isn't anywhere near the sink that is possible to connect it to the disposal? Perhaps give it a name of a remote dishwasher, dishwasher far away from the sink or satellite dishwasher.
The solution for this seems to be one of two options:
With vent stacks for sinks the vent must extend above the sink 6 or more inches 2015 IPC905.5. As I understand it if the vent is a branch, as such in the case of a separate sink and dishwasher, the highest point is only for fixtures served by that branch (not the entire floor.)
Back to the problem. There is a sink of which is vented to the roof on one side of the room. On an adjacent wall the dishwasher is served on a separate vent joined to the sink branch in the ceiling. Both the sink and dishwasher connect to the main stack in the basement.
So what to do with the air gap requirement? Here is a possible solution I came up with (or at least haven't seen this suggested before)
In theory it solves the ugly air gap on the counter and doesn't have an unnecessary AAV that could fail over time or hole through the exterior wall. The dishwasher still has a high loop in the cabinet but directly connects to the wye through a barbed fitting and flows through the p-trap. The wye connected to the vent would prevent siphoning from the drain back into the dishwasher.
From what I have found most dishwashers have a small bit of water left in the sump. I believe, but haven't determined, that this acts as an air trap. The water from the high loop on the dishwasher side would fall back down the tube towards the dishwasher when the dishwasher drain pump stops. This would then serve the purpose of the sewer gases from the vent not entering the house through the dishwasher hose. If that is true then the p-trap isn't necessary nor is this entire setup.
The use of an air-gap on the sink only solves the problem if the drain is clogged. If the hose is clogged then the water still will not eject from the dishwasher. It would be pretty obvious that there is standing water in the dishwasher that didn't get ejected when the dishwasher is opened.
A Johnson tee would be simpler but if there is already a stack there why not use it? Plus there is no hole through the exterior wall nor waste water spewing out the side of the building in the event of an issue.
What are your thoughts? Is this overthinking/over-engineering it?
1) A high loop (attached as high as possible in the cabinet)
and
2) Some jurisdictions may require an air gap.
b) Connection to a disposal connection in the sink.
and
2) Some jurisdictions may require an air gap.
a) The air gap can be on the counter pointing to the sink
orb) Connection to a disposal connection in the sink.
Now consider this. What happens when the dishwasher isn't going to be connected to the sink or isn't anywhere near the sink that is possible to connect it to the disposal? Perhaps give it a name of a remote dishwasher, dishwasher far away from the sink or satellite dishwasher.
The solution for this seems to be one of two options:
1) An aproved Air gap on the counter (which would just pour water all over the floor if it overflowed as its not anywhere near a sink.)
or
2) Stand pipe (similar situation if the stand pipe overflowed)
or
3) Johnson Tee (apparently used in the upper west coast) Wouldn't water flow out of the house outside or is this just an AAV?
or
2) Stand pipe (similar situation if the stand pipe overflowed)
or
3) Johnson Tee (apparently used in the upper west coast) Wouldn't water flow out of the house outside or is this just an AAV?
With vent stacks for sinks the vent must extend above the sink 6 or more inches 2015 IPC905.5. As I understand it if the vent is a branch, as such in the case of a separate sink and dishwasher, the highest point is only for fixtures served by that branch (not the entire floor.)
Back to the problem. There is a sink of which is vented to the roof on one side of the room. On an adjacent wall the dishwasher is served on a separate vent joined to the sink branch in the ceiling. Both the sink and dishwasher connect to the main stack in the basement.
So what to do with the air gap requirement? Here is a possible solution I came up with (or at least haven't seen this suggested before)
In theory it solves the ugly air gap on the counter and doesn't have an unnecessary AAV that could fail over time or hole through the exterior wall. The dishwasher still has a high loop in the cabinet but directly connects to the wye through a barbed fitting and flows through the p-trap. The wye connected to the vent would prevent siphoning from the drain back into the dishwasher.
From what I have found most dishwashers have a small bit of water left in the sump. I believe, but haven't determined, that this acts as an air trap. The water from the high loop on the dishwasher side would fall back down the tube towards the dishwasher when the dishwasher drain pump stops. This would then serve the purpose of the sewer gases from the vent not entering the house through the dishwasher hose. If that is true then the p-trap isn't necessary nor is this entire setup.
The use of an air-gap on the sink only solves the problem if the drain is clogged. If the hose is clogged then the water still will not eject from the dishwasher. It would be pretty obvious that there is standing water in the dishwasher that didn't get ejected when the dishwasher is opened.
A Johnson tee would be simpler but if there is already a stack there why not use it? Plus there is no hole through the exterior wall nor waste water spewing out the side of the building in the event of an issue.
What are your thoughts? Is this overthinking/over-engineering it?