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How to Clean the Filter in a Mira Pumped Electric Shower

Eugene is a qualified control/instrumentation engineer Bsc (Eng) and has worked as a developer of electronics & software for SCADA systems.

Mira Vigour pumped electric shower.

Mira Vigour pumped electric shower.

This guide describes how to clean the filter in an electric pumped shower. This particular model is a Mira Vigour, but a similar process can be used for cleaning filters in other brands of shower.

Restricted Flow and Pressure: A Sign of a Blocked Filter

My shower is made by Kohler Mira, a UK based plumbing company. The Mira Vigour is a pumped electric shower which takes its cold water feed from an attic storage tank and hot water from a hot water cylinder. Hot and cold water are mixed and temperature is thermostatically controlled to a level set by adjusting a temperature control knob. An integrated pump in the shower boosts pressure, to cater for installations where there is low water supply pressure. Over the last couple of weeks, I noticed the flow of water from my shower had decreased. When I switched to cold flow, pressure didn't seem to be affected. The last straw was when we had brown water for a couple of days due to an issue with the supply and then flow stopped almost completely. I knew there was a filter in both the cold and hot feeds and since flow on the cold setting wasn't affected, this pointed to a clogged hot water filter being the culprit.

Download a Manual for the Shower

If I'm ever troubleshooting anything, I try to source an instruction manual or better still an installation or servicing guide. I found an installation guide for the shower here:

Mira Vigour Thermostatic Power Shower installation guide

This showed the inside of the shower and where the filter was located.

Steps to Cleaning the Filter

This is how I removed and cleaned the filter.

Step 1. Disconnect Electrical Power

Identify the electrical breaker or fuse which supplies power to the shower and switch off or remove respectively. Don't rely on using the pull cord switch on the ceiling to disconnect power, because switches can be faulty. However it's a good idea to turn this off also. Check the shower is powered down and doesn't function.

Turn off power at the electrical panel

Turn off power at the electrical panel

Step 2. Shut off water

Turn off the water supply to the shower using the valves in the feed pipes. These will be one of three types:

  • Quadrant or ball valves. These are normally turned off by turning the handle through 90 degrees so it's at right angles to the pipe
  • Gate valve. They usually have a red knob and are turned off clockwise, just like a tap. Sometimes these can seize, so it's a good idea to "exercise" all valves once a year by turning off and on again to prevent this happening
  • Miniature in-line valves. This type has a slotted screw in the centre. Turn off with a screwdriver by turning the slot through 90 degrees so it's perpendicular to the pipe.
Turn off the water supply. These are quadrant valves or ball valves and usually set to the off position by turning the handle perpendicular to the pipe.

Turn off the water supply. These are quadrant valves or ball valves and usually set to the off position by turning the handle perpendicular to the pipe.

Alternatively, gate valves may be used for controlling flow. These are turned off like a tap by twisting the wheel knob clockwise.

Alternatively, gate valves may be used for controlling flow. These are turned off like a tap by twisting the wheel knob clockwise.

Miniature in-line valve. This valve is in the on position.

Miniature in-line valve. This valve is in the on position.

Step 3. Remove the Shower Hose

This can get in the way when working. Also when you remove the filter and vent the hose, the contents will run out all over the place, possibly ending up in the shower electrics, so it's wise to unscrew it first (anti-clockwise).

Remove the hose so it isn't hanging down or dripping water.

Remove the hose so it isn't hanging down or dripping water.

Step 4. Remove the Temperature Selection and Flow Control Knob

First remove the knob. Mira have a tool for pushing the collets up on the intake manifold for releasing pipes when replacing a shower. In their installation guide, this doubles up as a tool for removing the knobs. They also say to turn the knob fully clockwise to the cold setting. I used a scraper and twisted it rather than levering. I repeated all round the perimeter so the knob wouldn't jam. Use something flat like this rather than a screwdriver which could leave dents or marks in the base of the knob. Hold the knob as you remove it so its three sections don't separate or fall on the hard shower tray or tiles.

Use a flat tool such as a spatula or scraper to lever off the knob.

Use a flat tool such as a spatula or scraper to lever off the knob.

Mira Vigour flow control and temperature setting knob.

Mira Vigour flow control and temperature setting knob.

how-to-clean-the-filter-in-a-mira-pumped-electric-shower
These screws hold on the cover.

These screws hold on the cover.

Step 5. Unscrew the Screws Holding on the Cover

Next remove the screws holding the shower unit's shell, two at the top and one at the bottom. Mira recommend not removing them totally, either in case they could go astray or because unscrewing them would enlarge the holes in the gasket through which they pass. Again hold onto the shell it so it doesn't pop off and hit the deck.

Inside the shower unit. The cable supplying power can be seen. The brown core is live and blue is neutral. These are European Union (EU) and UK wiring colours.

Inside the shower unit. The cable supplying power can be seen. The brown core is live and blue is neutral. These are European Union (EU) and UK wiring colours.

Wiring Colours in the EU and the UK

Wiring colours in the EU

Wiring colours in the EU

Step 6. IMPORTANT! - Check Power is Off

BEFORE PROCEEDING, CHECK POWER IS DEFINITELY OFF!

Using an electronic, non-contact voltage tester or phase tester screwdriver, confirm power is off at the point where the power cable is connected to the shower. This is extremely important because any water exiting from the filter housing when the filter is removed (e.g. if you didn't remove the shower hose) could potentially splash over the circuit board and terminals, resulting in serious shock and death.

A non-contact voltage tester will glow when its tip is placed close to the live core of the power cable at the point where it is connected to the shower. The blade tip of a phase tester screwdriver must actually be touched to the screw of the terminal into which the live cable is screwed (or touched to the copper core of the cable itself). Also you must place your thumb or finger on the metal area at the top of the handle of the screwdriver to earth it. If power is present, a neon tube in the handle will glow orange.
Both live and neutral should be checked in case the shower was fed by a cable that was connected incorrectly at the electrical panel (reversing live and neutral). Before using either of these tools, it's essential to check they are functioning properly, you understand the basic hazards of working with electricity and have experience of working with electrical appliances.

Using a Fluke Non-Contact Voltage Tester

A Fluke VoltAlert 1AC II Non-Contact Voltage Tester, like this one available from Amazon UK can be used for detecting mains voltages. You just need to hold the tip close to a power cable, socket outlet or electrical terminal and when the tip glows red and the unit beeps, you know there's voltage present. Note that this is a UK tester for testing 230 volts and not suitable for voltages in the US

Fluke VoltAlert tester

Fluke VoltAlert tester

A phase tester screwdriver can also be used for testing for the presence of power. The blade tip must contact the live electrical conductor and you must touch the metal pad on the end of the handle of the screwdriver to earth it.

A phase tester screwdriver can also be used for testing for the presence of power. The blade tip must contact the live electrical conductor and you must touch the metal pad on the end of the handle of the screwdriver to earth it.

Step 7. Remove the Filter

This is the filter/cap assembly, held on by a Philips screw. The o-rings hold it on quite tight, so after undoing the screw, pull it out gently, holding it top and bottom between your fingers and thumb, with a hand on each side so it comes off evenly. Wiggle slightly, to ease it off, but don't use excessive upwards or downwards force.

Mira Vigour filter, held on by a Philips screw.

Mira Vigour filter, held on by a Philips screw.

Step 8. Clean the Filter Baskets.

The hot water filter basket was quite dirty just as I suspected. I cleaned it in hot water and used a cotton bud to scrub the inside. I didn't want to use anything more aggressive for scraping in case it damaged the screen.

Filter baskets from a Mira shower.

Filter baskets from a Mira shower.

Step 9. Replace the Filter

After cleaning, replace the filter into the filter housing on the shower. It was a little difficult to force the o-rings back into the shoulders they seat into in the filter housing on the shower and I didn't want to deform the plastic, so I used the palm of my hand to push evenly all over. Alternatively use your two thumbs around the edges. Check the filter is fully back in place. You'll know this because the standoff for the Philips screw will have butted tight up against the plastic on the housing.

Make sure the o-rings are properly seated and the filter is pushed into the filter housing.

Make sure the o-rings are properly seated and the filter is pushed into the filter housing.

Step 10. Turn on the Water

Turn on the water at the shutoff valves. Wait for a minute and check no water is leaking from the filter housing.

Step 11. Replace the Cover

Check the black rubber gasket, located in a groove in the edge of the upper section of the shower, hasn't come free of the shell and push it back into place if so. Replace the lid. Push gently on the front cover while tightening the screws so they align properly with the plastic tags on the cover. Don't over-tighten the screws to avoid cracking the shower cover, potentially allowing water to get into the unit.

Step 12. Replace the Temperature / Flow Control Knob.

First replace the outer flow control knob. Next replace the the inner temperature control knob, ensuring the pointer is turned fully clockwise to the cold setting so that it aligns properly with the shaft. Push the knob into place.

Step 13. Restore Power

Restore power and check flow is ok by turning the flow control knob anti-clockwise.

Confirm flow is now constant on hot and cold settings by turning the temperature setting knob over its full range from cold to hot.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2021 Eugene Brennan

Comments

Urwa from East County & Cooking and Baking Expert on April 12, 2021:

These steps are very useful to clean the filter. Thanks, eugbug

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