Combi boiler and mixer shower

[jonpeck]

Hi Long story short I have just moved into a property and I am not sure weather there is an actual problem or not. The Issue is the shower is not adjustable as there is just one constant temperature and it runs out after 6/7 minutes but goes scalding hot then stops all together. No cold water comes out. Also no hot water comes out the tap. So surely it should just run cold as it runs out of hot water? Or is the mixer valve at the boiler or shower not working? There is also a 25 gallon water tank in the loft. dsss

 

[Dotty]

You sure you have a combi? What boiler is it?

To me it sounds as though your boiler was installed by someone who didn't do the necessary checks before he hung it on the wall.

Sounds as though you might have the pressure but your flow rate is pants.

 

[diamondgas]

Sound like you need a plumber ... I don't know any combi that'll give "scalding hot" water 🙂

 

[jonpeck]

My apologies its a Potterton suprima 50l, which after reading a few things are not the best in the world. I will try my best to explain the system start to finish. The boiler only has a knob for the temperature. There is a water tank, a shower pump that works and its correctly hooked up. Also a 35 gallon water tank in the roof. Hope this helps.

 

[Scott_D]

If you run your bath does it fill properly?

 

[jonpeck]

I will test this in the morning. The boiler seems to fire up fine and my heating is spot on. I just still cant get my head round the fact when it runs out of hot water there is no cold even coming through. Also If I need to get into behind the shower controls they are puttied in. I'm just trying to get a general idea of the problem so I can get in touch with my landlord. There are pcbs inside the boiler which can fail.

 

[PlumbBobBob]

i would say the reason why the water runs out is because the pump has drained it all. the 35 gallon tank is too small imho. you need at least 50 gallons, the tank is feeding the hot water cylinder and​ the cold feed to the shower.

 

[jonpeck]

This is what I presumed just have to tell the Mrs to stop taking forever in the shower! And quick calculation means it will run out in 7 Minutes with normal flow.