Mira Sport Max. Low Flow Problem.

[Harry Bloomfield]

Duh!

The OP has simply stated no blockages, but hasn't explained how he has tested this, so the possibility remains, that either the hose, or the head might be restricting the flow. Instead of carrying out the suggested checks, and coming back to the forum, the OP seems to have simply disappeared...

 

[D Park]

Thanks to those who have replied however, I did make it clear in my original post that the obvious options have been eliminated. The shower head & hose are in perfect condition & the water pressure is fine. Electric shower low flow faults are frequently caused by solenoid problems. I'd encourage anyone who wishes to verify this to look it up on Google. The symptoms are exactly as described. The shower runs normally for a few minutes & then cuts off. The low flow light is on & it takes a while for the unit ro reset.
Also, why shouldn't I try to fix it myself if I can? A replacement solenoid costs about £10 whereas a new Mira Sports Max weighs in at around £350! A no-brainer really.
What I'd really like is to hear from anyone who services Mira showers on a regular basis. Mira obviously encourage in-built obsolescence & are not prepared to offer any hints on compatible alternatives for discontinued parts. For example, to my uneducated eye, the 10.8Kw heater tank looks identical to the later models but the Mira computer says "no". Has anyone got actual experience of fitting replacement heater tanks?

 

[BlueLoo]

Go on eBay and get a "spares and repairs" unit for 10£.

Canabalise it for parts.

I bought two and made one good one to replace my old unit.

 

[Johntheo5]

Thanks to those who have replied however, I did make it clear in my original post that the obvious options have been eliminated. The shower head & hose are in perfect condition & the water pressure is fine. Electric shower low flow faults are frequently caused by solenoid problems. I'd encourage anyone who wishes to verify this to look it up on Google. The symptoms are exactly as described. The shower runs normally for a few minutes & then cuts off. The low flow light is on & it takes a while for the unit ro reset.

When you say it runs normally for a few minutes and then cuts off do you mean it stops heating and the flowrate looks normal or the low flow light comes on with a reduction in flow rate?. on mine it would run very hot before the low flow light illuminated and will normally cut out on the TCO which is set to 48C before this occurs. You said in post #1 that the pressure is fine, can you, with shower hose&head as normal, with power switch to cold, turn the temperature control to fully cold (max flowrate) and run the water into a container held underneath the shower head for exactly 30secs, do the same with the temperature control at fully hot (minimum flowrate) and again run the water into a container, measure both with a 1L container, X 2, to give the flowrates in LPM.
Schematic below of my 9.8kw (at 240V) Mira Sport.

 

[D Park]

Thanks for your reply. I'm confident that the water pressure is not the cause of the problem. The shower operates normally for a few minutes then the water cuts off completely & the low flow light comes on. There is no variation in flow rate or temperature prior to cut off. I've already replaced the TCO a couple of years ago & when the old one packed in, the water flow would continue but the power to the heater tank would be off & hence, no heat.

My opinion is that the solenoid coil is the most likely culprit. This is a recognised problem with electric showers. The coil, when working, lifts a plunger within the flow valve allowing water into the heater tank. If the coil is not working correctly then the flow valve closes & the water cuts off. If the coil is okay there should be resistance of about 3.5ohm. I've tested the existing coil & it was just about okay however, that was after the shower had eventually reset. What I need to do is test it again just after it cuts off. Low or no resistance will indicate the coil is not producing the magnetic field required to shift the plunger. If however, that is not the problem then the whole flow valve assembly will probably need replacing.

What's bugging me though is a problem I frequently encounter with appliances which are perfectly capable of being serviced or repaired & that is that the parts are no longer available. There must be loads of Mira Sports Max showers of this particular age still around but the manufacturer in their wisdom has decided to discontinue the most important ones. That was why I was asking if anyone who repairs or reconditions Mira showers on a regular basis can confirm from experience that parts for later Mira Sport Max models are compatible. For obvious reasons that is a question which the Mira people are not prepared to answer.

 

[Johntheo5]

Yea, could well be the solenoid coil but it should read ~ 3.5K ohms???

 

[D Park]

Yes, the reading should be 3.5K ohms. Sorry for any confusion.

 

[D Park]

Problem eventually solved. I was delayed in getting it sorted by a couple of other issues by which time the shower was not operating at all. I tested the solenoid coil & sure enough, a zero reading. Replacing the coil was a simple enough task. To be honest, my major difficulty was removing the bath panel to get at the water isolator. I did not want to work on the shower unit while it was on the wall so I disconnected the water inlet & power supply & took it off the wall so I could get at it on a bench. The replacement went so quickly I could have easily just turned the water off at the stop tap instead of messing about dismantling the bath panel.

The shower is now working perfectly. A new lease of life for a part costing just £10.

My previous remarks are still valid though. If there is anyone out there who services or reconditions Mira showers on a regular basis I would appreciate any tips regarding inchchangability of parts. Specifically, are any of the current Sport Max parts compatible with older models despite what the Mira people say?

 

[jeff the gasman]

For evans sake. The chap said it's not the head. A simpleton can check it.

Time how long the shower takes to fill a bowl with head attached.
Remove head
Time how long the shower takes to fill a bowl with head removed.
Is there a significant difference?

Duh.

It could be the head though couldn’t it!
























HaHaHa.