How to connect PVC to cast iron

Though not normally used these days, some homes still feature cast iron pipes in the plumb system .
As such, it becomes necessary to devise ways to join PVC pipes to existing cast iron, for exercise, when upgrading drain pipe installations in your house- which is not an slowly undertaking .
Why ?
Unlike the friendly PVC shriek, PVC is madly difficult to cut.

Worse however, a cast-iron pipe is quite heavy and can be a pain to control .
That said, connecting PVC to cast iron is not an impossibility and there are several different ways you can make the connection .
We share some insights on tackling this plumbing problem bit-by-bit below .

How to connect PVC to cast iron

There are a few great PVC-cast iron couplings in the market and these come in very handy .
If you ’ re to go the connection way, we suggest that you use Fernco ’ south popular rubber eraser couplings .
Keep reading to learn how to connect PVC to cast iron with Fernco ’ s particular couplings .

How to use Fernco coupling to connect cast iron to PVC

Fernco makes lots of different-sized pipe couplings for this sort of joining and they fit about all types of situations .
Besides, their dimensional flexibility guarantees leakproof seals on frame iron and virtually any pipe corporeal .
Keep in mind that you must be sure of your pipes ’ thickness – both the PVC and cast cast-iron pipe openings- when shop for a Fernco copulate ( Fernco Donut to some folks ) .
It ’ south besides worth mentioning that alone shieldless Fernco couplings are to be used for below prime connections .


stage 1 : Cutting the cast iron pipe

There are two ways you can cut out a length of the pipe :

  • with a snap cutter
  • Using your reciprocating saw

We shall concentrate on these two but I must say that form iron shriek cutters make quick work of the pipe and could be an choice ( you may rent/borrow ) .

Cutting the shed iron organ pipe with a snap tender

  1. Measure and mark the point you want to cut the pipe using chalk (draw a straight chalk line).
  2. Grab the chain of your snap cutter and wrap it around the pipe. Be sure to have many cutting wheels against the tape when doing this.
  3. You’re now ready to cut- put pressure onto the cutter’s handles such that the wheels begin to cut into the piping. 
  4. Repeat the above steps at every other chalk line as required.

How to use reciprocating saw to cut vomit cast-iron pipes

  1. Mount a metal cutting blade (make sure it’s long enough) onto the saw.
  2. Mark the lines to be cut, still with chalk (keep them straight).
  3. Hold your pipe in place (ensure its firm or have a friend help you hold it).
  4. Set the saw at a reasonably low speed and leave the blade to cut the pipe for you. 

Tip: Do not apply excessive blackmail onto the attend as it may make the blade cinch. besides, oil the blade frequently specially if cutting several pipes .

stage 2 : Making the connection

Having removed a length of the old hurl iron pipe, we can move on to joining the PVC shriek .

  1. Unpack the Fernco and slide it on the PVC.
  2. Get hold of the PVC and insert it into its cast iron pipe counterpart to complete the connection. Be careful here to prevent possible leaks (the PVC should be fastened tight into the cast iron).
  3. You can conduct a pressure test before concealing or backfiling if applicable.

Tip: Rubbing some dish soap on the insides of the Fernco couplings will help make them slide more easily onto the shriek .
PS: You can order an appropriately sized Fernco coupling from Amazon .

How to connect PVC to cast iron hub

If you ’ re looking at connecting PVC to cast iron hub – possibly a section of your cast cast-iron pipe has corroded badly- the ‘ doughnut ’ will still be utilitarian .
Follow these steps :

Step 1: Cutting the existing cast iron pipe
first, cut your existing roll iron pipe about an column inch ( or even two ) above the hub .
An effective tool to use for the job– if you don ’ t want to use the reciprocate saw or the ratcheting photograph cutter- is the angle bomber ( install an harsh cut-off disk for this job ) .
Try hard until the organ pipe breaks from the hub while being lament not to cause damage .
Step 2: Clear the lead and oakum
You immediately need to get all the lead and oakum out of the hub/socket. Just use a screwdriver for this procedure .
After you have removed the go, proceed to clean up the hub .
A wire brush could be hardheaded to use in this case .
Step 3: Mount the Fernco donut and connect the pipe
Fix the Fernco into the hub then fit your new PVC pipe .
As seen earlier, applying a little dishwashing solution on the pipe helps lubricate the part and will make it slide easily .

option method acting : Make the connection with star

Though not adenine easy as using Fernco particular rubberize doughnut, you can use lead to connect PVC into a cast iron hub besides .
If done well, the run works merely finely – plainly make the properly alignment and pour the mellow lead in the joint and you ’ ra crispen .
We however powerfully discourage this not only because it ’ south more ferment but besides some PVC manufacturers will never approve of lead connections .
Plus, there is a risk of the hot lead could melt your PVC .
last, some build codes only allow the use of arctic accessories to connect PVC pipes to cast iron and you will be courting worry with this approach .


This article has taught you how to connect PVC to cast cast-iron .
Of run, there could be early DIY methods out there with varying levels of trouble and it ’ second upon you to choose the proficiency that you feel works estimable for you.

ultimately, the method with the widest acceptance even among professionals is the use of a Fernco Donut .
We encourage you to prioritize it .
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source :
Category : Tech

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