UK Plumber Forum

[zeeman]

Hi

I am new to this forum and I'm hoping someone can help me out with an issue I'm having.

I have recently installed a new bathroom in my house, this includes a new thermostatic mixer shower. The issue I have is that when I turn the shower on the combi boiler fires as it should and runs as it should, it will then go off and the shower will go cold, the boiler then fires up again and heats the water. I checked the status on the boiler when this happens and the 'flow' light goes out when the boiler cuts out so I assume there isnt enough flow going through the shower to keep the boiler fired?

So far I have checked the following:

Checked all isolation valves are fully opened.
Checked the filters in the shower inlets are clean.
Checked the hot water taps in the other rooms and all function properly.
I have also run the shower with the hot water tap in the bathroom sink opened as well and when doing this it functions ok.
Also the flow restrictor has been removed from the shower head.

This leads me to believe that the issue is there is somehow not enough hot water flow going through my shower? If I am correct is there anything I can do to fix this?

Thanks

[REDSAW]

yes, turn your boiler hot water stat down.

[zeeman]

Thanks REDSAW for the quick reply. I had tried turning down the hot water stat and it made no difference, however after your comment I decided to find a manual for my boiler online and have a further look. Turns out when my boiler is set to heating and hot water the boiler control stat is used and the hot water stat doesn't do anything. After turning this down it seems to have worked so thanks for that as I have tried everything apart from the simple thing....doh.

Am I right in saying I have to have my hot water temp above 60 degrees?

[RPM]

Thinking REDSAW has it covered but welcome to the forum.

[REDSAW]

Thanks REDSAW for the quick reply. I had tried turning down the hot water stat and it made no difference, however after your comment I decided to find a manual for my boiler online and have a further look. Turns out when my boiler is set to heating and hot water the boiler control stat is used and the hot water stat doesn't do anything. After turning this down it seems to have worked so thanks for that as I have tried everything apart from the simple thing....doh.

Am I right in saying I have to have my hot water temp above 60 degrees?

55 will do-giving 45 at outlets
anymore is just putting boiler in hi-demand, you couldnt put your hand in 45 degrees so why that high!

[zeeman]

Perfect thanks redsaw. My boiler doesn't have the temp on the stat setting as its quite old. I will test the temp at the taps and get to around the 45 mark. Not sure where I saw that but sure I saw it somewhere because of bacteria growth and build up? Not to say its true though lol

[REDSAW]

Perfect thanks redsaw. My boiler doesn't have the temp on the stat setting as its quite old. I will test the temp at the taps and get to around the 45 mark. Not sure where I saw that but sure I saw it somewhere because of bacteria growth and build up? Not to say its true though lol

probly me on another thread!
bacteria exsists at bellow 55deg which should result in a 10 temp drop at furthest outlet giving you 45deg.
if you use hot water everyday then i doubt it will ever exsist at all lol

[REDSAW]

BTW, try running it with the shower head off for 10-15 mins or longer than it takes until boiler normally knocks out. it could be an easy fix just buying a greater flow shower head !!!

[zeeman]

Will do this tonight when I get back in REDSAW. I have been looking through the manual and schematics and I am struggling to grasp the concept of whats happening. The boiler is a Camray 5 90a external oil fired. It has a hot water stat and a boiler stat and it has a summer or winter setting . Summer is for only hot water, winter is for both water and central heating.

I have attached parts of the manual. I have played around with the hot water stat but after I run the hot water tap for some time (as you do when showering) the temp always goes back up to above 60 degrees, whether its full up or or full down which makes me believe the boiler stat is what it is going on? But if that is the case to get the desired hot water temp then my central heating temp would be too low?

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I will try the shower head off tonight and see what happens there. Im just trying to understand exactly how my boiler should be working in case there is a fault somewhere else.

Thanks

[zeeman]

BTW, try running it with the shower head off for 10-15 mins or longer than it takes until boiler normally knocks out. it could be an easy fix just buying a greater flow shower head !!!

Hi REDSAW . Sorry for the late reply I just got back last night.

I have just tested the shower with the head off and it works perfectly boiler keeps fired and continuous hot water.

Thanks

Can you recommend a shower head with high flow rate or point me in the right direction of what I am looking out for? Thanks again

[zeeman]

Just an update on the situation and closure to this thread.

I received a new high flow shower head which I ordered from Amazon yesterday. Installed it and hey presto no issues. I ran the shower for 20 mins and in that time the boiler cut off but it cuts back in before the water temp drops so the water is at a continuous temp for the 20 mins I ran it. The pressure has also improved with the new head.

Thanks for all your help REDSAW, can't believe it was something so simple