How to Make a Connection to a Pre-Existing Loop Vent How to Make a Connection to a Pre-Existing Loop Vent

What You'll Need
Flexible Pipe
PVC connectors

If you want to add more ventilation to your bathroom, then you might consider adding a secondary vent to your loop vent. This type of ventilation plumbing is common in kitchens and bathrooms, and when you look at the loop, you should be able to see it arching high against the sink or appliance. Adding a connection to this vent is not going to be easy, and you need to be aware that building regulations are quite tight about this type of loop. Once you have permission to add more ventilation to the loop vent, you can start re-plumbing the loop.

Step 1 - Preparing

Before you can proceed with this connection, you will need to make sure that you have the permission of the building's inspectors. If they don't give you prior permission, they can order any connection be removed, and the item which needs to be vented could also be removed. It is therefore much better to get permission to alter the loop vent before doing any work. You may also find that they will offer you advice and hints on what to do if you are not sure about proceeding.

Step 2 - Building the Pipework

Turn off the water supply. Before you complete the connection, you should add as much pipework as possible between the loop vent and the item which needs to be vented. Lay the pipe as usual until you are within a few inches of the vent pipe. You should then add a connection, and install a flexible pipe.

Step 3 - Open the Loop Vent

You will now need to open up the loop vent. Choose the straightest part of the vent, and remove the top connection. You may need to slightly reduce the pipe at this point. Place a Y connection onto the pipe so that the two branches of the pipe point downwards. Add a layer of caulk around the connection, and then tape it over with a little piece of pipe tape. You can then add the flexible pipe to the other part of the branch. You may need a screwdriver to open up the clamp on the end, and then tighten it around the Y connection.

Step 4 - Close the Loop Vent

You can now add the other end of the loop vent to the straight part of the Y pipe. You should fit the pipe in as tightly as possible, and then use the wrench to seal the end. Add caulking around the seal, and then add some pipe tape over the top. This should allow you to complete the connection. You should then turn on the water supply, and check that the venting system is working correctly. You should make sure that none of the connections you have just made are leaking, and also that the ventilation is going in the right direction.

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