Mira pumped Shower - no water on hot days (Ed.)

[philc47]

I have a Mira sportsmax shower. When it’s a hot day, it doesn’t work… still has power, when press the on button I hear the pump start to come on, but no water. So feels like a thermal cutout - but seems a bit sensitive… yes it’s been warm weather but there is no exposed pipe work in direct sunlight so seems a bit odd. If I were to try again late evening/in the morning it’ll be fine

Thoughts? There is a long run of (insulated) pipe work in the loft but again it doesn’t get “that” hot in the loft

 

[Johntheo5]

Are you sure its a pumped shower?, I had a Mira Sport for 16 years and it was mains supplied, it may be the solenoid coil thats breaking down. If you can use a M.meter isolate the power to the shower, remove the cover and check the coil resistance, should be around 3.2K ohms.

 

[philc47]

Well not the pump then - but the noise it should make when it comes on. It does that but no water comes out. I’ve replaced the full shower and the exact same thing happens - works fine until it’s a particularly hot day, then stops until it’s cooled down

 

[Johntheo5]

The TCO should only cut off the power to the heating elements at ~ 48C, water outlet temperature, but the water should continue to flow, if this is what you mean, then you have a flow problem, my mains temp just now is 18.5C, so a 8.5kw shower requires a flowrate of 5.7LPM to give a showering temp of 40C and the TCO will operate (48C) at a flowrate of 4.1LPM, corresponding flowrates are..... 9.0kw,6.0LPM/4.4LPM, 9.5kw,6.4LPM/4.6LPM., suggest turning the temperature control to fully cold and let the water flow into a container for exactly 15 secs, measure this with a 1 liter milk bottle or whatever, X 4 to give the flowrate in LPM.

 

[philc47]

Thanks will check that out!

 

[philc47]

Okay so I’m significantly over this flow rate, so my actual mains feed isn’t the issue - it’s early morning so everything nice and cool. However could there be something (valve, stop-tap etc) that’s swelling in the heat perhaps that’s killing the feed to the shower? There is a stop tap in-line on the pipe in the loft that leads to the shower, and a strange fitting I’ve not seen before just after it that's possibly a reducer or something

 

[Johntheo5]

Post a photo of the fitting.

 

[philc47]

Used to have a header tank/water cylinder - that’s all been removed since (can see at edge of insulation where it’s been capped off) - shower feed is off to the right side

 

[Johntheo5]

Don't know what that is, check that the isol valve wheel goes ~ 3 full turns between shut and open, I would remove that fitting and just install a bit of pipe in its placee except that this device shows up something special. Is this supply just dedicated to the shower??

 

[philc47]

Yeah that’s what I’m thinking. Yep only the shower now the header tanks out of service. Thanks

 

[Johntheo5]

I have posted a view of it on plumber.uk, should find out, hopefully, shortly.

 

[Johntheo5]

It appears to be a "verifiable" temperature controller of some sort or other so just remove it, all electric showers can deal with water up to 28C.