Mira 723 mixer

Is it exposed or built in?

Mike

 

The reason why this problem arises is because people force the unit when turning off the shower. I have this unit fitted and when I stripped it to sort out a leak I discovered that the H & C flow is opened and closed by a hexagonal brass piston inside a hexagonal cylinder. Forcing the on/off knob causes the shoulders on the piston to round over thereby affecting the closing of the H & C flow allowing the unit to leak. Replacement of these parts, plus a service kit cost a total of around £50.00 from a local plumbers merchant. It has worked perfectly ever since. The flow should be opened and closed using fingertip pressure only.

 

try http://www.showerdoc.co.uk/spares/mira/ quick next day service and give good advice over the phone.

 

That was an excellent link, Chalky. There is an exploded drawing with all the items numbered. The part I was trying to describe is the cartridge assembly, item number 902.65. These shower units do need occasional servicing, and service pack B has all the washers and O rings needed along with a sachet of grease

 

HELP I bought the service pack managed to get everything out, but could not work out how to take apart the cartridge assembly to replace the o rings etc... Is there a knack or what, i'm going mad here !

matt

 

Hello, new here(!) had the same problem, that having isolated shower and started stripping it down, and got to the bit where you 'pull' the assembly from the body - yeah right! its been in there for 20 years or so.
Ended up replacing just the giant 'o' ring and reassembling it, mind you just doing this cured the drip-drip, but still no thermostatic control over the temperature.

Have now posted a pdf file at my homepage for maintenance of Mira 723, its a big file at 5MB, so will take a while to download, but you can print it off if you like. (hope Caradon MIRA don't mind!!)

its here:- http://homepage.ntlworld.com/patrick.beane/mira723maintenance.pdf

 

I had the same problem, stripped it down and cleaned it up.

Its a complicated set up. The piston turns the water on and off. The coil spring damps down the movement of the temperature lever to move the spindle sleeve over the hot and cold water chamber and allows for mixing.

This chamber was difficult to prize apart. The Spindle sleeve has holes drilled in it which divert hot and cold water. This sleeve rotates only a small movement over internal chamber which mixes hot and cold water. This sleeve needs to be loose for the spring to be able to work against it and control the temperature. Over the years this seizes up and locks the two sleeves together making the water to either very hot or cold.

The answer is to strip it down and brush it down with a toothbrush and kettle descaler the manual from the previous post explains how to strip it down. I used the service pack a packet of rubber orings, but probably did n't need them.

Make sure you don't miss an oring or thrust washer or you will get a leak. Also make sure you line the housing up correctly with the locating pin at the bottom, and that the coil spring is correctly aligned.

Hope somebody finds this helpful, took me 5 attempts to get it right, I put the temperature setting in the middle when I put it back together and adjusted it a one notch left or right to get the right temperature.

Anthony

 

What a great thread.This is the stuff that this forum should be about and not the drivel that has been posted lately. Well done.

 

Mind you no-one said that even the newest MIRA 723 valve will be 19 years old! They were discontinued in 1990. Get rid of them and put a decent new valve in!

 

Well said that man! These valves are all ancient now and should be replaced!

 

Many thanks to you all!!!

We have just moved into an place with a v.old Mira 723 which dripped and was stuck on a constant temperature. We are renovating and installing a new bathroom but the only working bathroom was this one so I decided to have a go with the service pack.

4 hours and 4 attempts later (the last attempt was only because we put it all back together and then "found" a washer!!) it seems to be working.
NO MORE DRIP DRIP DRIP DRIP

I printed off the instructions from the earlier post and then when the water was scolding hot, managed to move the sleeve a little more central - everything was clogged up with scale! - and now my husband has had the best shower since we moved. Which was in November!

Anyway, thanks to you all, I did most of this on my own.

Happy plumbing!

 

If the old b*er has gone 3 months without a shower no wonder you're so pleased. I'd have had the hosepipe on him by now.

 

Thanks for your information, folks. I wish I'd found this thread sooner.

My GF has a Mira 723 - the majority of it mounted inside a wall panel - which had developed a drip that could empty a reservoir. I ordered the service pack, dismantled the Mira 723, replaced the components and re-assembled the unit.

At the first attempt of putting water through, the temperature was far too hot, so I needed to break the shower back down to adjust the flow of water in to the mixer. But I noticed, before I went any further, that there was no drip!

Yay!

I adjusted the flow, re-assembled the unit and the water temperature was perfect. However, the drip was back. Grrr!

So maybe I need a new piston, if the shoulders have been rounded over the years, as you describe above?

I'd appreciate any thoughts, before I go out and get a spare part.

 

Mira 723 showers need to be serviced every 12 to 24 months depending on the water hardness and quality. They should last a lifetime as long as there are service parts available and looked after.
They contain moving parts and 0 rings, some that slide back and forth to control the water flow and others that simply fit in grooves to seal spindles etc. and one that is used as a body gasket.
The spring that people are mentioning is a thermostat coil, and fits onto the port pillar and sleeve, its detachable. The port pillar and sleeve can seize up if not taken apart and lubricated, regularly if the water quality is hard or the shower is not used for a time. There is a service pack available with all the O rings needed, I don't use the black grease supplied as it only lasts a few months in hot water and doesn't do much in the way of protection. I use a heavier silicone grease that can be bought from plumb/drain centre (meant for joining push fit waste pipes and fittings but has many other uses in plumbing) and used very sparingly on moving parts especially between the port pillar and sleeve so as not to restrict movement. To gain access to the valve spindle and flow control O rings the bell housing must be removed, the thermostat pulled away with the sleeve by pushing the spindle through, this will expose the hexagonal flat on the spindle valve it can be unscrewed which will expose the O rings, the cartridge is repositioned in the key in the main body to do this as there is no other way of holding against whilst unscrewing.
I have had my 723 valve since 1989 bought from Sharp and Fisher (now Travis Perkins). for £50 + vat. price reduced as it was a discontinued line. The insides are still in great condition and haven't really changed since the first years service. I find I rarely need to renew the O rings every one or two years as the silicone grease I coat everything with (even the thermostat to stop it rusting) does a fantastic job of lubricating them and keeps the water away from the brass body and valve cartridge etc. year after year, although living in Wales a softer water area helps
The only body part I have replaced is the main white plastic flow control knob as it had started to crack.
Being a plumber by trade I have serviced and repaired all the old Mira valves since around 1984 and many others such as Rada, Meynell, Gummers, Barking Grohe, and Grohe as well as all the cheaper valves found in B & Q, Aqualisa and Triton etc. All these in houses, schools, hospitals and retail outlets.

 

New member
Have just moved into a house and getting a combo boiler fitted , at present have a Mira 723 shower that is fed by water cylinder ! Water pressure is really poor at moment . My question is if I replace cartridge for a high pressure one will I also need a service kit ???