Plastic pipe to a cast iron soil stack
Here is some useful information from one of our jobs.
Technically you should use a cast iron boss when connecting to a cast iron soil stack. If you use a plastic one they are more likely to leak due to differences in expansion and contraction between metal and plastic.
We are using a product called Timesaver. They make this cast iron strap on boss. I ordered this from my local plumbers merchant at the time.
The most difficult part is drilling the hole through the cast iron down-pipe.
This required a 64mm hole. We used a starret hole saw with a corded drill. The progress was very slow with this product and i’m guessing there is a better tool for the job.
reasearch suggests that lubrication or cutting oil should not be used since it may slow the cutting process further. You should keep the blade as cool as possible using a water spray or dipping it every so often. It is much quicker and easier if you have an assistant to spray on the water while you drill.
30 minuets later and the hole is still not through but nearly there.
It took around an hour of drilling with with a few breaks in between but it was worth it.
It would have taken more time and money to do it any other way.
Never try to rush the drilling.
If you break the cast then its possible you could have to remove the whole top section and replace with plastic. this would be a costly mistake.
For a better seal, clean off all the paint from the edges with a grinder
Use some quality silicone on both sides of the rubber ring.
Fit the rubber onto metal boss and bolt on to the soil stack ensuring the hole is centered. Do not over tighten as you could break the cast iron strap. You can always tighten a little more later if it leaks when tested.
Fitting is easier with an assistant but not impossible on your own.
Put the rubber’o’ ring around the a pipe reducer.
Then push it in the hole and put the front cover on….this creates a good compression joint
Insert your new pipe into it using solvent cement to stick and seal it.
Tip: use small sections of 15mm copper pipes to make a spacer for the brackets. This will prevent strain on the connector. Use plenty of brackets to ensure proper stability and prevent bowing which could cause a block. In this instance the pipe was connected to a Saniflo macerater to carry raw sewage to the soil stack.
The finished job before adding external pipe insulation, it’s important to add this to avoid frozen blockages in the winter.
All work carried out by BBS building services, Ilford, Essex
See also manhole covers
The boss Timesaver boss strap can be found here