Plumbing basics toilet
Set up a new toilet

Cistern installation instructions

How to replace a toilet: how to replace a toilet cistern:

How to replace a toilet
Installing a new toilet

Now if you want to change your toilet over to a more modern style or are wanting to move it to another position in the same room or nearby. Can you get under the floor to access the main trunk line serving this existing toilet?  As if you have a concrete floor then look to see if the toilet pan itself is a P-trap going outward’s by flowing through the wall. Or is it an S-trap pan flowing outward’s through the floor? And sometimes you can strike a turn to the left or to the right P-trap pan called a turntrunk pan.

These all go through the wall or may as an afterthought discharge through a bend through the floor also. Either way if you have a concrete floor and you wish to change the position of your toilet by an amount left or right see if you can plan it so your new position is still on the outside wall near the drains, and wall pipe work beyond this wall. If you do wish to relocate this new toilet to a position in towards the middle of the room off the outside wall then know that you will have to cut up the concrete floor and place a new section of 4-inch (100 mm) PVC drain underneath this slab going out and joining into the main sewer drain outside this room under the path or ground thereof with a Y-junction.

New toilet cistern cold feed: toilet water supply line leak after fill valve replacement:

For the wingback for the cold water feed inlet to your new or existing toilet cistern check where the cold inlet feed valve male thread is located. In most modern cisterns if a bottom entry valve you can swop the side the valve comes into the tank by undoing the bottombacking nut repositioning and retightening.

Some toilet cisterns demand entry of the cold water feed into the top just under the lid coming in from the wall cavity behind a cut-out section of the cistern tank and for this type position the pan on a flat floor and place the cistern accordingly. Measure the new wingback center to be placed ½-inch (15 mm) above the cutout in the cistern. Take this measurement off the floor and place your timber noggin in the wall using the measurement you just took to give accurate placement of the ½-inch (15 mm) male wingback.

new toilet cistern installation
Toilet cistern installation

You will also need a small inline ball fix valve to come off the wingback and bridge between the cold-water inlet valve by way of a flexible hose provided. If a bottom entry cistern is to be installed place your noggin (noggin) timber about 4 inches (100 mm) above the finished height of the floor skirting board around the wall. Again using a ½inch (15 mm) female wingback. This bottom entry cistern valve will be reached by way of a straight stainless steel flexi hose longer than the measurement between the cistern wall tap and the bottom of the male thread of the cold valve inlet. Please note: For the bottom entry and side entry cisterns you will need a small compact right angle cistern tap.


Pan Connector installation

Hidden pan connector concrete floor: soil pipe installation diagram

When placing a close-coupled toilet pan and cistern with hidden connections underneath onto an existing concrete floor drain position. If the old collar rising up through the floor is PVC then use a carpenters’ wood saw and cut it off flush with the concrete. And If the collar rising up through the floor is clay place a tight rag down inside the pipe up stand and working with inside to outside tapping with a hammer break this collar off even with the concrete floor. If the collar is cast steel you will have to grind it out of the way.

Then go to your plumbers’ merchant store and buy a rubber ribbed at the bottom plastic pan connector that has a drop over into it rubber seal on the top. Take home any other type of pan connector you can get to also try out (do not try and use a full rubber connector). At the end of the exercise you must clean off the concrete surface and run a masonry grade silicone around the new connection onto the concrete to make sure it is an airtight watertight seal.

Note: There are also offset pan connectors that you may have to use if the new pans centre of its outlet is different to the existing drain collar centre from the wall to the centre.


new toilet installation
Sewage line connection

Best practice is to buy the best fitting pan and cistern you can get that closely matches your existing wall to centre of spigot measurement. Likewise if the existing collar is coming out of the wall.

Your new P-trap pan spigot centre-to centre measurement cannot be lower than the existing pipe centre allowing for the change in slope change in measurement off the floor.

Relocating a through the wall P-trap pan


Stand the new pan on a solid floor and measure from the floor to the centre of the outflow spigot. Write this measurement down and then measure from this spigot to the finished wall. Place your floor to spigot centre measurement onto the wall and drop down about 3/4-inch (20 mm) below this for the true centre of your 4-inch (100 mm) hole in the internal wall.

Use an off cut of 4-inch (100 mm) PVC pipe and mark around it to mark off this hole. Cut out this hole and using either a wood or a masonry drill gain a hole through the outside just big enough to sight on the other side outside. Then measure down from this at centre hole and remark it 1-inch (25 mm) lower to give this outside hole gradient. Note: This outside hole must be made big enough for the size of the collar on the PVC bend.

Next you must work out the gradient slope from the bottom of this hole to the bottom of another 90-degree bend or tee junction if a stack or vent coming down from above. Wherever this slope strikes will decide what you are to do to complete this new pan project sewer wise.

Relocating a through the wall P-trap pan
Water line leakage

If on the ground floor and the size of the existing soil pipe is less than 4-inch (100 mm) follow it into the ground and below until you can reach and join in where the drain is 4-inch (100 mm).

If not 4-inch (100 mm) diameter to begin with, lower the bend or the tee in this 3-inch (80 mm) PVC line and then run this section of piping in 3-inch (80mm) all the way to the pan using an 80 mm pan connector at the end. Note: If possible always go to 4-inch (100 mm) size pipe for this run from the new pan. Note: To either connect into a copper or lead soil pipe or cast as the case may be use rubber couplings.

If having to work in a tee junction you will have to use a rubber coupling for this top most joint anyhow. Simply slide the rubber coupling up over the top most vent or top stack pipe fit the tee and then slide it back down. Sometimes it may be necessary to use a second rubber coupling below the tee to ease the union of these rigid PVC fittings into place.


New Toilet Floor installation


How to install a toilet flange on wood floor: How to install a toilet flange on concrete


If you have a wooden floor underneath your toilet you can either get under the floor directly or cut a hole in the floorboards and gain access that way. Either way you are in a position to easier spigot. If the existing drain is clay grab a felt tip pen and mark a line around the barrel of the pipe below the bottom point of any offset made by bends you may need to use to give yourself the correct center for your new pan. Then take a cold chisel and with a hammer strike the chisel against the clay pipe.

Then simply do so 1/4 of the way around the barrel and then 1/2 way adapt the pipe to bring the new PVC pan connector up through the floor center of the new pan round and 3/4 the way round and then in-between these blows. Going around and around until the pipe cracks completely all the way through. If it breaks unevenly you can tidy it up by nibbling away with a large shifting spanners jaws. A rubber earthenware to PVC couplet will complete this joint being done up with large stainless steel clips with a screwdriver to seal after you have made up your offset of bends as required.

How to install a toilet flange on wood floor
Toilet papers on wooden floor

To finish off the top end through the floor. Just let the new PVC 4-inch (100 mm) pipe rise up past the floor level and cut it off later flush with a carpenters wood saw and glue up the finishing pan connector collar which will fit inside this pipes interior bore. In cases where this riser is fairly short and hunched in concrete below the floor above the dirt of the ground. Snap off the pipe at the point where it touches the concrete and use a PVC fitting designed to fit inside the clay pipes internal diameter. And either use a masonry silicone to make it airtight or use a mix of 6 to 1 sharp sand and cement mortar to create a seal around this slip socket and the existing concrete.


Toilet Position Movement


How to move a toilet over a few inches: moving toilet drain across joists


Do the same as above to gain your bottom most connection then come off this connection with a 90 degree bend and come across using hanger clips off the wooden floor joists. Then turn and go up to the new position with your second 90-degree bend. And rise up through to place your pan connector. The gradient is formed naturally by the over 95-degree angle of the bends you are using.

Temporary toilet installation


Wall hung toilet installation instructions


Wall hung toilet installation instructions
Wall hung toilet design

Be careful to place timber in the wall behind where the screws are to go to hold up the weight of the water cistern of the toilet. And place your female wing-back some 8-inches (200 mm) away from the water entry point on the cistern. Or if an in behind under the lid model cistern place the male wing-back as detailed earlier under New Toilet Cistern Cold Feed.


Temporary toilet flush: how to empty a portable toilet


how to empty a portable toilet
Temporary moving toilet

During a new bathroom build it is always possible to temporally flush the toilet pan so placed by using a full bucket of cold water.

Fitting off a close-coupled toilet: wall hung wc installation manual


Place pan on floor over the top of and inside the pan connector.

Take rubber cistern to pan connector and place silicone on both its top and bottom. Carefully place it. Then carefully lower cistern down onto top of this rubber keeping an eye on the line up of the cistern to pan bolt-holes, as this is paramount. Then resting the cistern place the bolts and do them up keeping an eye on the gap closing down between the cistern bottom front edge and the pan. You may find you will need a screwdriver to tighten these nuts up properly.  Now with the water shut off to the cold wing-back remove the barrel nipple and place the new cistern tap following instructions for the use of nippling brass or brass threaded tubing given under the heading Replacing or placing a tap into a wing-back in the wall:

You will need ½-inch (15 mm) threaded brass nipple tube.

Now that you have your new cistern tap pointing upwards measure the distance between the male connections and add 4-inches (100 mm) and buy a flexi hose that is straight and this rough length and install it by first tightening it onto the bottom of the male thread on the inlet feed valve. And then holding against yourself on the flexi hose tighten the other end onto the cistern tap.

Fill cistern with water through the tap and flush to test for leaks. Once you are happy with this installation take a white adhesive silicone and with a nozzle cut to a 45-degree angle by about ¼-inch (10 mm) gap in the tip. Work from the very back of the pan where it touches the floor and seal it off from any moisture. Also fill the screw holes, as you will not be using them the silicone will do all the work. Using damp wipes clean off the excess silicone around the pan and off the floor finish.

A note on traps and their waste pipes:


A note on traps and their waste pipes:
Waste pipe

The trap always goes as close to the plug as possible as it is the prevention of drain smells rising up through the system. The exception to this is a washing machine outlet trap that is placed just above the floor with a waste pipe rising up to the very top of the machine to take the flexible drain hose off the washing machine.

Sometimes a tee junction may be placed underneath the trap on the laundry tub and run up to the near side of the washing machine to take in the drainage hose.

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