Shower 'hottest' setting is cold

13 May 2016
Reaction score
United Kingdom
Hey all,

I bought my house 2 years ago, gutted it, renovated, and have only just had the time to look into the problems: I had a brand new Worcester greenstar 29cdi classic and a new Mira Agile ERD shower fitted, the plumber who installed both is qualified and has many years of experience, has previously worked for my parents many times so I have no reason to doubt his skill or knowledge.

The issue im having is that the hot water from the shower is not hot enough, the radiators get very hot, the hot water from the taps get hot. It does get very hot as in scolding hot if the radiators are on but then immediately drop in temperature to just hot.

I'm wondering why my showers hot water temp isn't as hot as should've been expected to be, it also fluctuates in temperature wildly and the only way to adjust temperature of water is to actually adjust the power from the shower whilst keeping hot at maximum. I had an issue with a leaky shower to which Mira sent a technician to my house who himself stated was fairly cold.

I've got the shower manual, ive adjusted the range of hot and cold and believe me I maxed this things temperature out! and still not hot enough!

What can I do at this point short of calling out a plumber?
Sponsored Links
If it works when you reduce the flow rate then it sounds like your Wooshitter Bodge isn't keeping up. If the radiators are getting hot when the hot tap is run, then you have a diverter valve issue (nasty plastic diverters in these boilers IIRC, not built to last). If the radiators aren't warming up with the hot tap running then it sounds like the flow rate through your shower is simply too great for the boiler to keep up. Could also be that the cold is pushing the hot back - either way, flow restrictors fitted to the shower supplies should cure it
Thanks for your reply, Its strange as i know it is more than capable of supplying sufficient hot water as i have been burnt from the hot water from the taps if the radiators are on (as you say i think i can actually hear hot water being diverted from the rads to the taps, it then seems to adjust the water temp down for sink usage to a much lower temp), it just wont supply anywhere near that temperature to the shower at a decent flow rate, it will on an incredibly low pressure / speed, but is completely unrealistic to shower with such a pitiful pressure of water.

I'm wondering, is my boiler big enough to handle the amount of hot water i need to supply a decent hot shower? has the boiler's internal maximum and/or minimum been adjusted incorrectly? is it probably best to ask a plumber to take a look?

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links