Mira Excel thermostatic cartridge assembly (903.33) | Mira 903.33 | Mira Shower Cartridges | National Shower Spares
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Mira Excel thermostatic cartridge assembly (903.33)

Manufacturer: Mira

Product Code: Mira 903.33

Product Type: Shower Cartridges

Categories: Mira shower cartridges, shower cartridges

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Manufacturer: Mira

Product Name: Mira Excel thermostatic cartridge assembly (903.33)

Product Code: Mira 903.33

GTIN / EAN Code: 5013181903331

Product Type: Shower Cartridges

Colour: Black

Fitment: Push In

Type: Temperature

Condition: Brand New

Returns Policy: 30 day money-back guarantee


Mira 903.33 Excel thermostatic cartridge assembly.

Also known as a Mira Select MK1 thermostatic cartridge assembly.

Suitable for high and low pressure installations. Adjustment key included.

This 903.33 model replaces the earlier versions of 903.27 (low pressure, yellow hub) and 903.28 (high pressure, green hub), which are both now discontinued.

This product is for shower models made prior to 2003. For Mira Excel models after 2003, please see the Mira 451.71 thermostatic cartridge assembly instead.

Product code also known as Mira 1.903.33.6.0.

The Mira Excel thermostatic cartridge assembly (903.33) is a genuine Mira product, covered by a minimum 1 year Mira manufacturer's guarantee.

Available for same day despatch if ordered before 3:30pm Monday-Friday (otherwise despatching will be on the next working day). For the delivery options available for this product, please add it to your Basket or see our delivery options page.

For advice on this or any product, please call 01452 619836, e-mail us at support@showerspares.com, or see our contact page.

The Mira Excel thermostatic cartridge assembly (903.33) will fit the following 8 showers/units... (lists sorted vertically)

May fit other showers/units. If you are unsure or would like more information, please contact us.

For advice on this or any product, please call 01452 619836, e-mail us at support@showerspares.com, or see our contact page.

Do you have a question about the "Mira Excel thermostatic cartridge assembly (903.33)"?

Click the button below to write and send a question to one of our expert members of staff and we will e-mail you back a direct response. If we feel the information might be useful to other customers, we will add your question below for others to see.

Ask a Question

i am going to replace my old low pressure Mira cartridge after boiler upgrade does the Mira Excel/Select Thermostatic Cartridge Assembly 903.33 have Non-return valves integral to cartridge or will i have to fit check valves externally.
thank you in advance if you can help
best regards John

Hello, the Excel does not have non return valves or need them, as the flow control is on the inlet side, therefore crossflow is not possible.

We have a Mira excel mixer shower probably 20 plus years old. Over the last few years the shower pressure seems to have diminished slightly, have fitted new head and hose recently with no improvement to pressure. The hot and cold control is fine, would just like to improve the pressure slightly any suggestions ?
Still gives a decent shower but we do not think it is as good as it used to be when first fitted, water supply and pressure is fine just wondered if it was due to age of the unit.

Hello, it sounds like the inlet filters on the side of the 903.33 cartridge are getting a bit blocked up, remove the cartridge and flush the filters out.

Hello. My Mira Excell approx 2005 is "screaming". Do I need a new cartridge and is this the correct one?

Hello, it will be worth checking the inlet filters first, as screaming is usually a sign of an imbalance between the hot and cold flow into the shower.

I cannot move the control from low to high pressure, the plate appears to be locked in position.

Hello, the base plate can be VERY stiff, but brute force usually works, if you really can not move it, please return it and we will do it for you.

I have a mira exel shower but am unsure of the age and type- it has 410.0c3 43/99 and Excel BIV written on a sticker - what type of cartridge would I replace the old one with ?

Hello, an Excel of this age would need the 903.33 cartridge

Our Mira excel shower continually drips hot water. Do we need to replace the complete thermostatic cartridge?

Hello, yes if the shower drips, it will require a new cartridge.

I have a Mira shower that was installed in 1999 and I am looking to get a new cartridge for it, the original cartridge has the legend:
410.01 25/99

Yes, the 903.33 is the correct cartridge for your shower.

I have an old Mira excel Thermostatic Control shower unit. Recently I noticed the water is cold and I cannot seem to up the temperature. Can you pls advise. If I were to buy the replacement parts can I change it myself.
Thank you.

Yes, it sounds like the thermostatic cartridge needs replacing. This is quite easily done. There are two types of cartridges so if you have the older type this one 903.33 should be suitable.

I managed to lose one of the screws while changing the Mira Excel cartridge (I forgot to put the plug in the plughole!). Is it possible to get a spare screws?
Thank you.

Hello, they are part of part number 937.14

Does the Mira Excel thermostatic cartridge assembly (903.33) come will all the seals needed or do these have to be purchased separately?

Hello, it comes with all the necessary seals

The cartridge on my shower has died (stiff & clicks & no water). Is the kit complete or do I also need to get seals, etc? Does it contain all the control knobs? The pic only shows the temperature limit ring. If not can I get them? Can I also get replacement chrome bezel and the plastic base it clips on to? If I have to replace the expensive bit I might as well freshen up the whole thing! Thanks.

the part 903.33 is the internal cartridge for the shower and there are various different styles of control knobs/plates available. If you could forward a picture of your shower to support@showerspares.com they will be able to identify the one you have and send a link to the relevant site

Hi. There is no cold water going into the shower. Took cartridge out and filters ok, put back in and all ok. Few hours later same problem, took out again put back in working then not working later, weird. Do I need a new cartridge, don't understand the intermittent working and not working.

Hello, this sounds like you may have a partial air lock in the supply, ea time you remove the cartridge you are clearing it, but then it returns, you need to get a plumber in to fully flush the supply.

My Mira excel shower was fitted around 16 years ago. The knob has been stiff to turn for a while and yesterday it clicked loudly and spence then no cold water has come out at all. Is this the cartridge? Don't want to spend all this kiney if not! Many thanks

Hello, yes the stat has gone, it will need a new cartridge

Are the two seals for the back face of the Mira Excell 903.33 cartridge available separately?

Hello, they are in the seal pack, part number 935.12 (the oval ones)

The outer ring turns and clicks when I turn on the shower. Some times it works and others it doesn't.
I've taken the white plastic covers off and tried to turn the black gear ring manually but again this is intermittent.
Is the cartridge unit on its way out?
Also, do you have to isolate the hot/cold water supply on the shower before replacing the cartridge?

Hello, yes you do have to isolate the water, it does sound like the cartridge if faulty.

Hi I have a Mira Excel shower installed in approx. 2000
The temperature and flow rate have become a bit variable so I am guessing that a new cartridge is what is required.
Can this be replaced from the front of the unit, ie the shower side or do I need to gain access to the back (which is currently sealed in!!)
Thanks Steve

Hello, everything is accessed from the front, you need to check the filters, first, if they are o.k, you will need a new cartridge.

Hi Ive got a MIRA shower and before I buy a new catridge I wonder if you can help me understand if I really need one? The shower gets to the right temperature only if I have the outside slider all the way to the left in the red. Can I adjust this internally to make it more balanced or not??

Hi your shower is set up in a normal way, you can however reset the point at which you get the hottest water, but this could allow other users to select a temp that would be too hot for them, but it is up to you how you set the maximum temperature

My Mira Excel won't stop running!

Hello, you will need to replace the Excel thermostatic cartridge, Mira part number 903.33, a seal kit alone will not cure this fault, the shut off seals are internal to the cartridge and not serviceable.

My Mira Excel won't get hot. I've tested both hot and cold water pressure.

Hello, Please check the inlet filters on the 903.33 cartridge, if they are clear then you will need to replace the cartridge 903.33.

How do I stop my old Excel from dripping from the shower head?

Hello, you will need to replace the Mira 903.33 cartridge to fix a dripping excel

Will this fit my old excel that has a Green hub on the front?

Hello, yes this cartridge is adjustable and will suit both the Green hub version High pressure 903.28 and the Yellow hub version Low pressure 903.27.

(5 of 5 stars)

This is the second replacement cartridge that I have purchased from National Shower Spares, and as before, I was very impressed with the efficient service and fast delivery.

Written by Roy Haley on 19 April 2017

(5 of 5 stars)

Very speedy delivery

Written by Vicki Middleton on 19 April 2017

(5 of 5 stars)

Fantastic service, part dispatched as promised and arrived the next day. Will definitely be using the service again, great prices and easy to navigate website.

Written by Neil Holmes on 12 April 2017

(5 of 5 stars)

Easy to fit. All necessary parts included with very comprehensive instructions and a help line number (not used) if one were to encounter any problems.

Written by Chris Orme on 10 April 2017

(5 of 5 stars)

Great service

Written by James Mussenden on 5 April 2017

(5 of 5 stars)

fitted easily. works as expected.

Written by Stephen Evitts on 23 March 2017

(5 of 5 stars)

Excellent service, speedy delivery, no fuss.

Written by Miss Smith on 9 June 2014

(4 of 5 stars)

Easy to fit and to adjust if needed. There is even a video on YouTube to help. It's very expensive so check that cleaning out the old cartridge and the filters along with a little silicone grease won't improve things first. Otherwise it's a good investment and has certainly transformed our shower which is over 15 years old but now works like new.

Written by Mr Lees on 30 May 2014

(5 of 5 stars)

quick and prompt delivery

Written by Mr Robinson on 29 May 2014

(5 of 5 stars)

Good price and very quick delivery. Simple to fit, only took five minutes. Now I have a fully working shower and works like new. Would definite buy from here again.

Written by Mr Adam on 28 May 2014

(5 of 5 stars)

Fast efficient service, thanks.

Written by Mr George on 27 May 2014

(5 of 5 stars)

The part was quickly despatched to me and is working perfectly.

Written by Mr Gratwohl on 22 May 2014

(5 of 5 stars)

Genuine replacement Mira part for excel shower about 12 years old. Husband fitted cartridge and major improvement in the shower flow and it's behaviour. Would use National Shower Spares again.

Written by Otter on 12 May 2014

(5 of 5 stars)

Easy to install basic DIY job, arrived day after ordering and good price. What more can you ask for?

Written by Mr Davies on 2 May 2014

(5 of 5 stars)

Very good value and amazingly fast delivery - great service.
Product was a genuine Mira cartridge and easy to replace the old one.
Thank you.

Written by Dr Lindsay on 4 April 2014

(5 of 5 stars)

Arrived in good time and as described.

Written by Mr Black on 26 March 2014

(5 of 5 stars)

Product very satisfactory. Very easy to fit. Replaced in half an hour!

Written by Mr Hill on 25 February 2014

(5 of 5 stars)

Following the guidance on the National Shower Spares website this was a very easy project to change over from the old (12 years old) to the new cartridge. Commissioning was also very easy with the guide on the Mira website. Excellent delivery service as well.

Written by Mr Webb on 23 February 2014

(5 of 5 stars)

Great service and great product.

Written by Mr Magee on 20 February 2014

(5 of 5 stars)

Purchased two of these, delighted with the product and the service I received.

Written by Mrs Campbell on 10 February 2014

(5 of 5 stars)

I am pleased with your product. Bit of trouble with the delivery company temporarily "losing" the parcel, but this wasn't your fault.

Written by Miss Kelly on 27 January 2014

(5 of 5 stars)

Excellent item. Fitted within ten minutes and the shower is now as good as new.

Written by Mr Marriott on 23 December 2013

(5 of 5 stars)

Replacement cartridge fitted easily and has worked from day one without any problems.

Written by Mr Gawthorn on 23 December 2013

(5 of 5 stars)

This is a great product but before installing read the instruction manual, unless you have done one before as this can help with the installation which takes about five minutes.

Written by Mr Curle on 20 December 2013

(5 of 5 stars)

Excellent way to make a worn out shower "new" again. Easy to fit without having to be an engineering mastermind!

Written by Mr Martin on 20 December 2013

(4 of 5 stars)

It was a good product,the product was easy to fit in the customisation was good.

Written by Mr Singh on 20 November 2013

(5 of 5 stars)

Good price and quick delivery!

Written by Mr Trinder on 15 October 2013

(5 of 5 stars)

Excellent service.

Written by Mr Ruffles on 29 July 2013

(5 of 5 stars)

Exactly the part requested and supplied. The order was filled very quickly and I received it only two days from the order (which was a Sunday)

Written by Mr Mowbray on 10 May 2013

(5 of 5 stars)

Excellent bit of kit and the service from National Shower Spares was first class.

Written by Mr Hammond on 9 May 2013

(5 of 5 stars)

Very easy to fit the unit. Once the water is drained it was just 4 screws to remove and set the flow rate at the back, then replace the screws.
Note there was a bit of an airlock that took a while to sort out. It has been working well ever since.
Would reccomend this unit.

Written by Mr Mckillen on 29 April 2013

(5 of 5 stars)

Very speedy delivery. Product provided at a good price. Very happy with the transaction

Written by Mrs Lovell on 19 April 2013

(5 of 5 stars)

Thank You all at National Shower Spares
Part fitted and shower fully operational without hitch

Written by Mr Burton on 15 April 2013

(5 of 5 stars)

Received cart Assy in less than 24hrs.
Then received excellant product support when I rang with a technical query.
Very good service.

Written by Mr Nobbs on 8 April 2013

(5 of 5 stars)

Cheapest on the net by a long way. Very quick delivery. AND, no more dripping showerhead.

Written by Mr Odlin on 8 April 2013

(5 of 5 stars)

Fast and accurate spares delivery

Written by Mr Thomson on 4 April 2013

(5 of 5 stars)

Easy to fit and complete with all seals needed

Written by Mr Cahill on 3 April 2013

(5 of 5 stars)

Superb service. I didn't know know which part to order but on providing a photo of my shower I was advised on the part. Really fast delivery as well.

Written by Mrs Everett on 29 March 2013

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