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rich99 · Joined: 14 Apr 2008 Posts: 5 Location: Edinburgh

I have a Mira 415 shower working on a combination boiler. I have been in the house for 4 years and in the last few months have been having a problem getting hot water to the shower.
On previous visits to this website it has mentioned the problem may be down to the shower as it only happened every now and again where the water would go cold for 3-4 minutes and then get hot again but in the last couple of weeks when we turn the shower on the combi boiler does not even come on and I have to turn the hot tap on in the bath or sink which brings the hot water into the bathroom and it comes out the shower but with a reduced pressure. As soon as I swith the tap off the water goes cold and the demand light on the boiler goes off.
The shower seems to work at night but the heating is on so I am not sure if this is the difference.
The boiler has been checked by the gas board and supplies hot water to all the hot water taps in the house and the central heating radiators.
I have also had the waterboard check the water pressure and have been tol it is at 2 bar and only needs to be at 1 bar.
I have no plumbing experience and am reluctant to spend money on either getting a new shower or the current one repaired if it turns out to be something else especially as it seems to let hot water through some of the time.
I would greatly appreciate any advice or suggestions to fix this problem.

thescruff · Moderator Joined: 03 May 2003 Posts: 4659 Location: Bath

Have you got check valves on the shower feeds, if you have an isolation valve on the shower turn the cold off and try it.

You may need to strip the shower down and clean the bits

rich99 · Joined: 14 Apr 2008 Posts: 5 Location: Edinburgh

Thanks for that I will check it out although I am not sure where to look. I don't know if this helps or not but this morning I was in the shower, the central heating was on and the water was hot but the central heating went off at 7am and the hot water stopped.
Also the boiler type is a Worcester Bosch 240.

Like I say I am not sure if any of this extra info makes a difference to the answer.

AlanE · Posted: Tue Apr 15, 2008 6:55 am Post subject:

Could be defective diverter valve in boiler.

rich99 · Joined: 14 Apr 2008 Posts: 5 Location: Edinburgh

Sorry for my ignorance but would that not affect the hot water going to the taps also as these seem to work ok whether the heating is on or not.

AlanE · Posted: Tue Apr 15, 2008 8:35 am Post subject:

Diverter valve might well be operating ok with the increased flow from a tap.

I would go with checking shower is working ok first. Clean any check valves and filters at the inlets to the shower and descale the shower rose.

Next would check the diaphram in diverted valve as it could be getting perished and not operating correctly at reduced flow rates.

rich99 · Joined: 14 Apr 2008 Posts: 5 Location: Edinburgh

Thanks for the advice. I will try it out and let you know how I get on. Also I have been on the internet to find out more about the diverter valve and it seems there is one in both the shower and the combi boiler. Which one should I check?

poolcorgi · Posted: Tue Apr 15, 2008 10:06 am Post subject:

boiler

rich99 · Joined: 14 Apr 2008 Posts: 5 Location: Edinburgh

Finally got the problem sorted and it was indeed the diverter valve that was the problem with the washer on the valve having worn. It was replaced and everything is now working. Thanks for all the advice.