Runs hot then cold max airboost 10.8

Hi My mira max airboost 10.8 shower has started running normally then cuts out and runs cold then runs hot again 30 secs later and repeats this cycle. Fault is intermittent.
Asked 6 years ago by Ewen
In addition the flow rates seem to be ok, the pipes etc seem ok too and temperature does change with dials.

Thanks

Answered 6 years ago by Ewen Tweedie

The things to check first are:

1 That the main valve coming into your house is fully open.

2 Then check that the valve on the line to the shower is fully open.

If these valves are not fully open then there may not be enough water getting to your shower to cool it properly, it overheats the safety device cuts in (TCO) and turns the power off to the elements until it cools down and it all starts again!


Make sure that the shower head is clean and clear, that the hose isn’t kinked (this can happen just behind the hand set where it is difficult to see) also check the inside of the hose although it can look OK on the outside it could have collapsed internally


The other possibility is a faulty flow/stabilizer valve not allowing the correct amount of water into the shower.


There is a link below that explains the above.

www.youtube.com/watch?v=m0xrObqfGqg

Answered 6 years ago by Barrie Seabright

Hi Mr Seabright,
Thanks for the info. I have checked both the head and hose which were replaced c 12 months ago and can't see any kinks. There is seemingly good flow through tge components. The pressure is reasonable from the shower.

After a week or two of non use I have now used it the last 2 mornings with no issue.

When there was issue I don't recall the flow pressure changing. I also don't recall the temperature increasing more than the setting. I.e. it was at a comfortable level then ran cold then returned to same level.

Could there be another fault with the cut out switch?

I am yet to open the unit to inspect is there something I should look out for on the flow valve? The video implies it is a sealed unit so unlikely to see if it is blocked.

Thanks

Ewen

Answered 6 years ago by Ewen Tweedie

Barrie isn't in at the moment, however if youi have carried out all the checks he suggested and everything is OK, then the next thing would be to check the inlet filter is clean (This is very seldom a problem) After that the next most likley suspect is the flow valve.

Answered 6 years ago by George Thomson

Barrie , George,
Thanks for your help. I have now taken off the assembly as the issue has started again.

As I say the flow rate seems good and temperature remains constant before cytting out, i.e. there isnt a surge of heat then it goes off. however there does appear to be some corrosion on the top of heating tank and TCO. I have attached images.

Could this be the issue instead?

Is this easy to replace? I can't seem to get the tco off as in your videos as there seems to be an extra nut at the back of the switch holding it to the heating tank.

Any further thoughts would be great or should I bite the bullet and replace the hole unit???

Answered 6 years ago by Ewen Tweedie

The corrosion could be caused by water getting in through the screw hole above. The TCO should just pull out after the earth cable is removed.
Make sure you do not push the bottom of the tco when fitting the new one.

Answered 6 years ago by Barrie Seabright

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