Appliance Repair Questions? Ask a Technician for Answers ASAP
Hello, I can help you with this.I will just look out the manual for your boiler, and the shower, and will post again shortly.
Please could you tell me the model of your Mira shower?
If you turn your Mira temperature control to the maximum hot setting, and run your test again, does that make any difference?
Of course. This isn't an interactive chat session, and you can continue posting for hours, days, or weeks - as long as you need to :-)If you post again and I'm not immediately available, please be patient - I will get a notification and will respond as soon as I'm able.
Your approach is logical - kudos.The shower-to-max-hot experiment is a valid one that often reveals odd faults. Although I don't like eliminating anything before the real fault is found, it tend to agree with you that it seems more likely that it's a boiler fault.The back-to-back 't' symbol on the boiler display (alternating with 't') is supposed to mean that the boiler is filling the internal DHW tank. This tank is intended to reduce delivery time when an outlet is opened, so I wouldn't expect to see it while a demand is being satisfied. However, if the flow sensor stops detecting flow, rightly or wrongly, the boiler should then revert to heating the internal tank. Otherwise the DHW demand should override all other demands.So, it's possible that the flow sensor is faulty, but I'm still thinking.Meanwhile, what's the hardness value of your local cold water supply?
OK. So it's unlikely that the DHW heat exchanger has scaled up.It seems like it's either a flow sensor fault, or the control board. Lets hope it's the sensor. Do you have the means to test its resistance?
I'll look it up. Bear with me.It's an NTC thermister and I'll have to look up the likely value too...
Resistance at room temperature : 14.7K OhmsResistance at 80C : 1.7K OhmsI'll attach a couple of diagrams to help you locate it. You'll need to power off and remove the outer casing.
I was just giving you the range - you don't have to make the boiler hot.
However, I've found a different range, so am ambivalent.That other range is (33.5k Ω- 500 Ω). Let's see what yours measures and go from there.The diagram took me a while to extract to a suitable file size.It should be attached now.
I hope you return sooner than Captain Oates!I'll look out for your reply later on....
I've been pondering, and another possibility to add to the list is low burner pressure.This needs to be tested and set by a Gas Safe registered engineer, as it's possible that your gas meter is at fault instead of the boiler.The problem wouldn't show itself in CH mode as the temperature differential is smaller, so the boiler tends to module down and you wouldn't notice anything.
Hello Michael, I humbly apologise - I've just noticed that you replied!I hope you had a productive visit from the Worcester engineer.