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Discussion Starter · #1 ·
I would like to replace a washing machine drain pipe which is 1.5" wide to a 2" wide pipe... hopefully to prevent back washing from the drain pipe.
Should I replace all the metal pipes shown in the pictures, which are in the crawl space immediately below the wash room, or is it best to just replace the final 1.5" pipe (seems to be about 4' long) which extends into the washroom as shown in the pic? The metal pipes are from the 60's, the PVC below the metal pipes is all new. I got one bid from a plumber but it wasn't specified which pipes, if any, beyond the final 1.5" pipe, would be replaced.












 

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Imo, now would be the time to upgrade to 2 inch pvc. pvc is cheap, you can replace that small section of cast iron and tie into the other pvc. But that's me.


Easiest thing to do is, as you mentioned, is replace the 4 foot piece of pvc drain pipe. Just remember, the new washers today pump out much faster than the old washers of yesterday. I would upgrade to 2 inch if you can.
 

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just another suggestion, while you are upgrading the plumbing, now would be the time to replace those old 60's gate valve shut offs with the newer quarter turn ball valves. You will be good to go for another 60 years. Good luck with your project tone. hope you get everything working the way you want.
 

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First I am not a plumber but I am old. Second I am looking at photos.

Your washer drain is not cast iron it is galvanized steel pipe. Looking at the photo of it looks like I see threads on its end. You don't thread cast iron. The galvanized pipe goes down to approximately floor level where there will be a galvanized steel trap. The trap will be connected to the cast iron with a lead and oakum joint. Unless you know something about lead and oakum joints and have the proper tools, you don't want to mess with it. You may be able to replace the galvanize trap with a PVC trap and a rubber bushing but good luck finding the bushing. And actually doing that won't be the easiest thing you have ever done.


That cast iron pipe is a wet vent. It is a drain for the washer and also a vent pipe for other plumbing. It goes up thru your roof. Look up at your roof in this area to confirm this fact.


Cast iron is heavy, you can't just cut out a section and replace it with PVC. You have to support the cast iron above somehow or you have to replace every thing above.


If you have a restriction in the washer stand pipe, it is probably in the trap. Before doing anything else I suggest you run a small drain snake down the washer stand pipe and hope to get through the trap. Run lots of water while snaking.


Because of its flexibility a toilet auger would make your best snake. A regular toilet auger probably won't be long enough. Get a long one or cut away about half of the plastic sheathing (up toward the handle) to make the effective working length of the auger longer.

If you can reach the trap but can't get through it, cut off its end so it will go through the trap.
 

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Discussion Starter · #5 ·
hkstroud,



Thanks for the detailed reply. I don't plan to do the work myself, just want to know as much as possible before I hire a plumber. If I understand, there is a vent tied into the pictured cast iron pipes, and you can't just replace the cast iron pipes with pvc as the vent leading to the roof needs more support than pvc can provide, so both the vent and the pipes would have to be replaced with pvc. Based on what you said, the easier option would be to replace the trap and top threaded galvanized pipe with pvc....but it wouldn't be an easy job, at least not for a diy'er........I'm wondering what kind of shape the cast iron pipe is in......I use the drain there for a water filter system, and at least a water hose at full pressure drains fine, but when we installed a modern washer, the water back washed into the wash room.....
 

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hkstroud,



Thanks for the detailed reply. I don't plan to do the work myself, just want to know as much as possible before I hire a plumber. If I understand, there is a vent tied into the pictured cast iron pipes, and you can't just replace the cast iron pipes with pvc as the vent leading to the roof needs more support than pvc can provide, so both the vent and the pipes would have to be replaced with pvc. Based on what you said, the easier option would be to replace the trap and top threaded galvanized pipe with pvc....but it wouldn't be an easy job, at least not for a diy'er........I'm wondering what kind of shape the cast iron pipe is in......I use the drain there for a water filter system, and at least a water hose at full pressure drains fine, but when we installed a modern washer, the water back washed into the wash room.....
There is a simple solution for your dilemma and a thread here on the forum about how to accomplish that for a couple of bucks, and your drain system can remain as is, but I don't have the NH to research it.
 

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Discussion Starter · #7 ·




Here are some more pictures of the situation. I'm now thinking, if possible, of leaving the cast iron pipe that goes into the crawl space in place, and just replacing the pipes above the crawl space.
 

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I agree with Jmon now is the time to upgrade to pvc. I just did a property not to long ago, and I replaced small sections to get it operational and the drain was still just slow moving tried snaking it and eventually I decided to replace it all together.

This is what I found once I got all the pipes cut out.
 

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