Replacing shower mixer

moneysaver1978

We are going to replace an exposed valve mixer shower and we picked up a Triton Muse along with a PTFE tape.

Other than the obvious like shutting the water supply with a stopcock (if we can find it!), are there any gotchas we need to be aware of? Should we turn off the combi boiler first before turning the water off?

Is a PTFE tape worth doing even though the instructions didn't mention this?

FreeBear

moneysaver1978 said: Is a PTFE tape worth doing even though the instructions didn't mention this?

PTFE tape should only ever be used on taper threads like you find on radiators. For compression fittings, ideally one should use new olives. And if a sealant is needed, just a thin smear of something like Plumbers Mait or Fernox jointing Compound.

rob7475

PTFE shouldn't be needed. There's usually washers in the shower bar connectors. If you have "easy fit" threaded backing plates, you should be able to just unscrew the old bar and attach the new one. Water shouldn't make it past the sealing washers so no PTFE required.

Isolate the supply before starting and open all taps in the house to release any water in the pipes. Remember to close the taps before turning the water back on.

moneysaver1978

Thanks both! The PTFE tape was only 39 pence so will keep it for future if we ever need them for the radiators!

Should I power down the combi boiler before turning the water supply off (and then open all the taps)?

FreeBear

moneysaver1978 said: Should I power down the combi boiler before turning the water supply off (and then open all the taps)?

To be sure the boiler doesn't inadvertently fire up, switching the power off is prudent. turning on taps downstairs and up will get some of the water out of the pipes - You may also find a draincock or two close to the boiler too (I have one on the cold feed, but not on the hot).

moneysaver1978

Brilliant thank you!

ThisIsWeird

Examine your new mixer - chances are it'll have simple rubber washers in the connections. In which case, add no sealant, although a smear of silicone grease is always a good thing to do - it'll help prevent them perishing and sticking, and make them seal better too. 
A wee tub or tube of SG is always a good thing to have anyway - kitchen tap spout getting sticky to rotate? Bicycle pump getting squeaky? 
No need to drain your system - simply turn off the incoming mains stopcock, and turn on the shower until water stops coming out. Cover the waste in case any bits fall into the tray or bath.
Use cloth or card to protect chrome finishes when undoing the large nuts. Do not overtighten when doing them up. 

moneysaver1978

ThisIsWeird said:

Examine your new mixer - chances are it'll have simple rubber washers in the connections. In which case, add no sealant, although a smear of silicone grease is always a good thing to do - it'll help prevent them perishing and sticking, and make them seal better too. 
A wee tub or tube of SG is always a good thing to have anyway - kitchen tap spout getting sticky to rotate? Bicycle pump getting squeaky? 
No need to drain your system - simply turn off the incoming mains stopcock, and turn on the shower until water stops coming out. Cover the waste in case any bits fall into the tray or bath.
Use cloth or card to protect chrome finishes when undoing the large nuts. Do not overtighten when doing them up. 

Thank you - this is golden! When you say silicone grease, do you mean something like https://www.toolstation.com/plumbers-grease/p34053?

ThisIsWeird

moneysaver1978 said:

ThisIsWeird said:

Examine your new mixer - chances are it'll have simple rubber washers in the connections. In which case, add no sealant, although a smear of silicone grease is always a good thing to do - it'll help prevent them perishing and sticking, and make them seal better too. 
A wee tub or tube of SG is always a good thing to have anyway - kitchen tap spout getting sticky to rotate? Bicycle pump getting squeaky? 
No need to drain your system - simply turn off the incoming mains stopcock, and turn on the shower until water stops coming out. Cover the waste in case any bits fall into the tray or bath.
Use cloth or card to protect chrome finishes when undoing the large nuts. Do not overtighten when doing them up. 

Thank you - this is golden! When you say silicone grease, do you mean something like https://www.toolstation.com/plumbers-grease/p34053?

Interesting stuff. It doesn't say 'silicone', and doesn't mention 'rubber' seals and washers. I suspect it'll be fine, but cannot confirm - very annoying.
Anyone on here know if it's good for rubber and neoprene? 
Until confirmation, this will do: https://www.ebay.co.uk/itm/386912834654? A little goes a long way.

moneysaver1978

ThisIsWeird said:

Interesting stuff. It doesn't say 'silicone', and doesn't mention 'rubber' seals and washers. I suspect it'll be fine, but cannot confirm - very annoying.
Anyone on here know if it's good for rubber and neoprene? 
Until confirmation, this will do: https://www.ebay.co.uk/itm/386912834654? A little goes a long way.

Good shout for ebay! I did see https://www.toolstation.com/arctic-hayes-silicone-grease/p52744 but balked at the cost and wanting to MSE as much as I can.

casper_gutman

The 'plumber's grease' says on the label that it meets 'Mil-G 10924 C' standard. I think it will be lithium grease as it seems to be related to this document: MIL-PRF-10924.pdf (chemsol.com) which mentions that "grease should be made with biodegradable material and a lithium complex thickening system". Lithium grease isn't normally what you want on rubber, so in the absence of a clear statement from the manufacturer as to suitability, I'd personally look for something specifically silicone based.

ETA: something like the tube @ThisIsWeird linked to should be fine.