Hot supply not hot hot

27 Sep 2020
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United Kingdom
had a new combi 30kw boiler installed in my loft about 4 years ago but the hot water supply to my mira excel shower located in the ground floor is not super hot even at maximum, I have not noticed this issue in the summer month’s only in the winter months but was wondering if this could be a pipe insulation issue which may need upgrading rather than a boiler issue, any advice would be most welcome thanks
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Sounds plausible. Combi’s are notoriously poorer hot water delivery in the colder months.
Compare flow of shower to HW output of boiler. Pipe lagging will reduce heat loss by a (relatively) tiny amount so not significant. You might need a flow restrictor.
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Turn the flow down. Does it get better? If so get a shower head which is designed for less water flow. Some incorporate air to make it feel like more.
Complete diagnosis - turn shower on full, no other gas appliances, and measure the gas flow rate at the meter. It's either here in FAQs or gooogle it. If it's >=32kW, it's not the boiler at fault.
Best to do it when CH is OFF and COLD.- CH flow pipe shouldn't get warm.