Replacing the flush mechanism in a concealed toilet flush

[DIYJunkie]

My house is plagued with low quality dual action flush mechanisms that continually leak water - these are the originals installed by the builder and are manifestly of a very low quality. The water in my area is very hard and the whole cistern is hidden behind a plasterboard wall with no removable access panel. I am planning to do the following

• Cut a largish section of plasterboard around the cistern
• Replace the current, leaky, mechanism with a well reviewed generic replacement from Fluidmaster that I found on Amazon
• Close the hole with a decorative removable panel that screws into two battens held on the inside by the plasterboard wall

My first task here is going to have to be to cut out the plasterboard. I am thinking of using a Jigsaw with the depth of the cut adjusted to be only a few millimeters deeper than the thickness of the plasterboard itself. My concerns here

1. I have never cut plasterboard before - will I be able to do it with a Jigsaw?
2. I do not want to risk cutting into piping or into the cistern itself or the metal frame on which it is installed

A picture of the current cistern assembly once the faceplate has been taken away is attached. The yellow stuff you see all around is plasterboard. My questions

1. How much clearance should I leave around this hole in order to stay well clear of the cistern and its metal installation frame
2. Don't I nevertheless risk cutting into (or atleast touching) the front legs of the frame
3. Any other tips on how I should go about this job

I'd be most grateful for any advice.

 

[He who knows]

I'd advise using a oscillating multitool, (Fein Multimaster, Bosch GOP type of tool) rather than a jigsaw, which is overkill for plasterboard. Or just a hand padsaw.

If you use a multitool, the type of blade you'll use for plasterboard won't do much to the metal frame if you do make contact, as long as you stop as soon as you feel/hear contact.

With the hand saw of course you'll immediately know when the blade has touched the frame, but cutting the hole may become tedious if you have very little depth to play with, i.e. have to make very short strokes. What is the gap between the plasterboard and the frame?

However, and this also addresses the size question, I would have thought that you wouldn't want unsupported edges of plasterboard so you'd be cutting along lines central to each stud and noggin (again something for which an oscillating cutter is ideal).

 

[DIYJunkie]

Thanks. I had in the mean time figured out that it would be best to use an oscillating cutter. I have three cisterns to repair. Believe it or not I cut out the panel for the first cistern with my drill and a 10mm Forstener bit after having first worked out the measurements of the cistern and the location of the metal frame through a combination of measurement, guess work and a powerful magnet. I figured the Forstner bit gave me the the best chance of not cutting into something I should not be touching. It worked but - Never again! I am getting myself a multitool to do the other two cisterns!

 

[He who knows]

Can't go wrong with a Bosch GOP (that's a blue one, not green). Buy a used one on eBay - if it doesn't look as if it's had a hard life it will be fine. You've a choice of corded or battery - for a tool like that I'd prefer the latter.

Avoid the new models with the Starlock Plus or Max system - as a DIYer you don't really need quick tool-less blade changes, and right now Bosch and Fein have, to their shame, decided to go down the Gillette route of corporate enrichment and you can't get 3rd-party blades.

There are, I'm sure, equally good alternatives to blue Bosch tools, and I'm sure that people here can suggest models from Makita/Hitachi/Ryobi et al. Important thing is to avoid the products aimed at the DIY market (like green Bosch), and if you're going cordless to look for something where there's a family of tools which share batteries. Again, you can pick up good bargains on eBay if all the seller is offering is a bare tool with no batteries or charger, so later down the line you'll probably be able to get other tools to exploit your initial investment