DIY Doctor UK DIY Forums

We had a leaking Alpha combi boiler repaired this week, a new diverter valve was fitted and the leaking stopped.

However, since then, we cannot get the shower water hot enough, a three year old Mira thermostatic shower, which has always worked perfectly. Water from all other taps in the house is nice and hot.

Thinking that the shower problem must be related to the boiler repair, we have had the engineer back in today but he is adamant that it must be a faulty shower and could only suggest that we call in a plumber. Before I do so, does anybody know if the problem could still be boiler related?

Thanks.

There has to be a possibility that some debris from the boiler repair has ended up blocking the filters in the Mira shower. Of course, until they are examined no one can be sure.

Remove the shower head and turn the shower on full hot. Note the flow level. Turn the temperature to full cold and compare the flow level to before. If the hot is significantly less it may be a blocked filter.

Thanks, will check this in the morning.

Done as suggested.

I don't have the proper instruments but on full cold the flow is approx twice as much as on full hot. Not sure if relevant but the engineer yesterday reduced the overall flow rate, saying it was too high - the shower pressure/flow has dropped significantly and the water system makes a hell of a racket when the shower is on. The shower this morning was hotter but not what it was before the boiler repair.

Its a Mira Excel by the way.

I have spoken with the engineers supervisor who has agreed to look at it on Monday but is adamant that it has nothing to do with the boiler repair. He may be right but I'm not a great believer in coincidence!

regiom wrote:Not sure if relevant but the engineer yesterday reduced the overall flow rate, saying it was too high - the shower pressure/flow has dropped significantly and the water system makes a hell of a racket when the shower is on.

Altered the overall flow rate of what?

regiom wrote:I don't have the proper instruments but on full cold the flow is approx twice as much as on full hot.

They should be practically the identical. A difference indicates either a blocked inlet filter on the shower or the boiler flow rate is insufficient to feed the shower. Either way, I would point the finger at the heating guy. After all, it did work before. Why don't they just clean the filters as an act of good will? It is an easy job on the Excel as it doesn't have to be removed from the wall.

Is it a built in or exposed valve?

Altered the overall flow rate of what?

I assume the boiler flow rate.

Is it a built in or exposed valve?

Exposed valve.

Thanks plumbbob, I'll ask if they'll check the filter. Should I also ask them to increase the boiler flow rate in order to get more water up to the shower, since the flow/pressure has reduced dramatically?

regiom wrote:Exposed valve.

Good. Takes 10 mins to check the filters. Just make sure the manual is to hand otherwise they will be removing the valve thinking that's how to get at the filters!

regiom wrote:Should I also ask them to increase the boiler flow rate in order to get more water up to the shower, since the flow/pressure has reduced dramatically?

If the hot to the taps is ok then there was no need to adjust it. You only restrict the flow if the boiler can't keep up with the water flow. Reducing the flow could starve the shower of hot making the problem worse.

Many thanks plumbbob, much appreciated.