appliancesdraindrain-waste-ventwashing-machine
I currently have a washing machine and dryer in the basement and wish to move them both upstairs. I can tap into the same drain line, but it will be about 20' from the old p-trap. Should I install a new p-trap upstairs and take the old one out, or can I have 2 in the same line, or is the one in the basement sufficient?
Also there is no vent in the basement for this drain line just a p-trap and about 3' of pipe sticking up; will I need a vent now that I am moving it upstairs?
You can tap in to the existing stack to drain, the only issue (like bcworkz said above) is you need proper venting. If you were to tap in to that stack without a vent, you could potential pull the water out of any traps above (via suction).
No. Well maybe it can, but it shouldn't.
If you check the documentation that came with the washer, it should contain the maximum drain height. Generally, the maximum height is around 39" (99 cm).
Newer washers often have a drain hose permanently attached, which is designed to make drain installation fool proof. The supplied drain hose shows you exactly how high the washer can discharge.
Depending on the machine, and whether or not you're already using a pedestal. You may be able to raise the whole machine up, to accomplish what you want. The maximum height is not height above sea level, it's height above the bottom of the washer. So if it's possible to do so, raising the machine up a few inches (safely) might be the solution.
If it's a front loading washer; and you're not already using a pedestal, you may be able to purchase (or build) a pedestal to raise the machine up. If not, you may want to think about building a raised floor to raise the whole area up.
International Residential Code (IRC) says.
International Residential Code (IRC) 2012
Chapter 27 - Plumbing Fixtures
SECTION P2706 WASTE RECEPTORS
P2706.2 Standpipes. Standpipes shall extend a minimum of 18 inches (457 mm) and a maximum of 42 inches (1067 mm) above the trap weir. Access shall be provided to all standpipe traps and drains for rodding.
Which means if you connect the drain hose to a standpipe, the standpipe has to be at least 18" above the point at which water will begin to flow from the trap. So your 43" height, could quickly become 61".
Best Answer
Ideally, you should move the P-trap upstairs, and vent through the roof. Under no circumstances should you have two p-traps in one line. You get an air-lock between the two, and funny stuff happens.
You want something like this: