Thermostatic shower valve grease.

[Andrew Sinclair]

OK then experts, we've got a Grohe thermostatic shower that has decided to supply cold water only with hot coming after much swearing and provocation (by which time Mrs has given up and run a bath). Main culprit has to be the cartridge but reading the installation book left by the previous owners of the house it talks about using 'special valve grease' (see here

when maintaining the thing.

Before I bite the bullet and replace either the cartridge ($%^£$ expensive), the shower (slightly less expensive but loads more work) I'd like to try greasing the cartridge just in case it is sticking.

Can anyone suggest;

a) Apart from the Grohe grease which is likely to be expensive, what grease could I use? Would silicone grease such as sold by Maplins be acceptable?

b) What bits of the cartridge do I grease, do I just give the thing a good coating on the outside or are there bits inside that need grease?

Help! I need a shower, I hate baths...

Thanks for any tips,

Andy

[Russ]

Hi

Our thermostatic mixer valve on the shower started playing up too.

Get yourself to your nearest City Plumbing shop, as they sell silicon grease in small tubs (for pipe fitting, etc) for about =A34.

I dismantled ours and regreased it and it's been much better since.

You'll probably be able to see which bits rub against what when you take it apart.

Think you tend to have problems with sticking mixer valves in the winter, when the cold water is bloody cold and the hot water is being heated more.

[Ed Sirett]

Agreed. It may well be that the OP is in a hard water area and scale has had an effect also.

It is a very good idea to operate the temperature lever/knob through its entire range of travel at least once a week.

[Andrew Sinclair]

In message , Ed Sirett writes

Hard? I'd say it is. The water comes out of the taps with flick knives!

I've tried descaling the cartridge to no avail so I'll invest in a tub of silicone grease as a final trick.

Thanks for the tips,

Andy

[Pete C]

Hi,

Formic acid based kettle descaler (eg 'Descalite') should sort it out, the milder citric based powder/liquid ones might need a lot of time and some warmth to speed up the descaling.

I'd also try sealing it in polythene with the descaler then dunking it alternately into pans of hot and cold water to get the thermostat moving.

cheers, Pete.

[Dave]

It looks like a high temp lythium grease, so I would replace like for like.

Dave

[Adam]

replying to Russ, Adam wrote: Just fixed mine. Take out the cartridge, clean it. Put the adjusting knob on it and crank it so you get just enough spring pressure to lift the valve and open up a small slot between the two pistons. Run the tip under hot water. The valve should "grow" and the small slot should increase in size - to about 1/8", maybe a little less. Switch to cold, the slot should return to where it started. Do this a few times until you're convinced that the change is made repeatably and smoothly.

Grease the cartridge seal, the tip and the o-ring. A little grease on the threads doesn't hurt either. Re-install.

Important! Make sure you remove the check valves and clean the screens. A partial blockage will make the valve inoperative.

[tabbypurr]

That would have been handy advice for him 10 years ago.

NT