John Fritz
New Member
I am installing a new shower and was going to adjust the location of the drain and convert it to an ABS shower drain using a horizontal fernco. This seemed like a simple plan at first. However, on closer look at the existing copper shower drain configuration, I am unsure about that plan.
The existing shower drain arm is a copper 2" which is roughly 5 +ft from the stack. The slope on the drain is only a few millimeters on the first 5 ft and the suddenly drops down 3.5" through two elbows into a wye which connects to a T at the stack (see closeup photo attached). The Wye goes off to a toilet bend which also needs a fernco as it's a lead bend (part of original plan).
From online research it appears that a 3.5" drop would put the trap weir too high and it might be siphoned. There should be a max of 2" drop as far as I can tell for a 2" pipe. Also there is a very very shallow slope on the first 5 ft and it is unclear how that would drain. I could theoretically run water through the drain to test it.
So I am hoping someone can suggest if this drain needs some modification.
One idea I had was to desolder the 3" pipe at the T and redo the toilet and shower drain in ABS. However, desoldering a 3" copper pipe might be virtually impossible. Also, there is a vent for the sink which might be of use to tap into.
The existing shower drain arm is a copper 2" which is roughly 5 +ft from the stack. The slope on the drain is only a few millimeters on the first 5 ft and the suddenly drops down 3.5" through two elbows into a wye which connects to a T at the stack (see closeup photo attached). The Wye goes off to a toilet bend which also needs a fernco as it's a lead bend (part of original plan).
From online research it appears that a 3.5" drop would put the trap weir too high and it might be siphoned. There should be a max of 2" drop as far as I can tell for a 2" pipe. Also there is a very very shallow slope on the first 5 ft and it is unclear how that would drain. I could theoretically run water through the drain to test it.
So I am hoping someone can suggest if this drain needs some modification.
One idea I had was to desolder the 3" pipe at the T and redo the toilet and shower drain in ABS. However, desoldering a 3" copper pipe might be virtually impossible. Also, there is a vent for the sink which might be of use to tap into.
