Mixer tap cartridge replacement.

[ProDave]

(almost building related)

 

Just back from the first trip away in out new (to us) caravan.  and come back with a list of faults to fix, the most pressing being all the mixer taps leak.

 

I have dismantled the worst one, the basin tap.  It appears to be based on standard cheap domestic plumbing and appears to use a non thermostatic, i.e. manual 25mm mixer cartridge.  The original cartridge is made my "Mixar" but putting "mixar" into an ebay search gixes 0 results, so looks like I am not going to get an exact one.

 

So I then start searching for generic 25mm mixer cartridges and find they are not all the same with some important but subtle differences.

 

This one is the closest I have found https://www.ebay.co.uk/itm/273823021306?epid=1358563534&hash=item3fc11fb8fa:g:gVUAAOSwEDBdbp9B

 

That's a very useful listing with a lot of dimensions and mine matches those pretty well. The issue appears to be how the cartridge locates into the tap body.  This image shows it well

 

It seems the standard 25mm mixer cartridges locate into the tap body by having two outward "pips" on the bottom that presumably locate into two holes in the tap body.  Mine does not have those.  Instead mine locates to the tap body by two notches on the outer edge of the body.  That picture has 2 notches also but top and bottom, the notches on mine are 90 degrees to that.  So that one is not going to work.

 

I have found one that is close, this one. https://www.ebay.co.uk/itm/265077498057?hash=item3db7d9a0c9:g:vUcAAOSw4tNgQhu1

 

That still has the two locating "pips" but also has the notches on the outer edge in the place I need them. 

 

 

I guess I could carefully cut off the unwanted pips and let it locate into the tap body with the two notches.  The "problem" with this one is the main body of the valve is about 2mm shorter than mine.  I guess I can insert some form of spacer if that proves to be an issue.

 

But part of me is saying i should not have to be doing all this bodgery, I should be able to just buy the cartridge I want.  So I invite the forum to help me find the right one.

 

 

[ProDave]

Well the job is done.  What a morning of bodgery / adaptation.

 

I bought the second one in my first post.  As expected, I had to cut off the two "pips" on the bottom and it located using the two side notches for location.  (bodge #1)

 

As expected the body of this one is 2mm shorter than my original, and the locating ring would not clamp it down.  I had to make a spacer washer. I found a large 2mm thick rubber washer and cut my spacer from that.  (bodge #2)

 

Next issue was completely unexpected and not mentioned as a "selection parameter" anywhere that I saw.  In these, the shaft rotates (to select hot or cold) and tilts (to select flow rate)  My original, the shaft tilts from lets say 10 degrees one side of vertical to 10 degrees the other side of vertical.  The new one tilts from vertical to say 20 degrees off vertical.  So clearly the tap handle mechanism is now offset and does not fit on.

 

That one was a real challenge. I ended up filing 2 sides of the shaft to give it the angle I needed, which of course meant the shaft was now too thin across one dimension so I had to make a flat spacer to pack out the now correct angled shaft, to make it square again.  (bodge #3)

 

Then, due to a slight change in geometry, the microswitch in the tap handle mechanism did not work, I had to reposition the microswitch slightly, which involved a sharp knife and araldite.  (bodge #4)

 

Having re fitted it, the original leak has gone (gross leak from tap body) but only to reveal a slower leak from where the hoses join on at the bottom.  That one I doubt I can fix so it will be a new tap eventually, but for now a cup can collect the drips.