Main Combi 30 HE : Hot water through taps, but not through shower

[bigospedros]

Hopefully this is in the right forum, if not, please feel free to move it.

I've recently bought a house and the installed combi boiler was a Main Combi 30 HE. We've been here for around 6 weeks and all was working well, until today.

When we turn the shower on upstairs, the boiler doesn't kick in any more, hence all we get is cold water.

However, if we turn the hot water tap on at either the kitchen sink or the bathroom sink, the boiler kicks in as normal and we get hot water.

Can anyone advise me on how to fix this ?

NB : I am no expert on DIY so be gentle!

 

[Mbear]

Defo defo sounds an issue with shower and not the boiler.

Sounds as though the shower isn't drawing the hw from the boiler and in turn the boiler is obviously not firing as it doesn't detect a demand.

 

[bigospedros]

hmmm, the shower is kind of all built into the wall ... how can I work out what's wrong with it ? I don't think there's any pump or anything involved. Maybe a thermostat issue?!

 

[moogwai]

have you tried just turning hot water on to the valve to see if it fires up then?
try fitting double check valve to hot water pipe to shower....the cold water might be to powerful for the valve to balance out the water pressures.

 

[bigospedros]

*wooooosh*

sorry, I did say I was no expert!

I assume you mean I should take the shower to bits and check the various parts?

 

[moogwai]

*wooooosh*

sorry, I did say I was no expert!

I assume you mean I should take the shower to bits and check the various parts?

no mate,can you gain access to the pipes feeding the shower? if you can identify the hot feed then put a check valve on that pipe,easily obtained from plumbers merchant.
do you have the instructions for the shower valve? it should tell you how to strip down the valve...i have had cases when a little bit of swarf/dirt can mess with the seals inside the valve causing a similar problem to what you are havin and giving the valve a good clean solved the problem. but as a diyer i would try fitting the check valve first as it may be easier for you to do.
if in doubt...get a plumber in...dont want you flooding the house!!!

 

[bigospedros]

before getting the tools out, I thought I'd try de-scaling the shower head and pipe and guess what?! It now works as before. I'm guessing it was all a bit clogged up, meaning the pressure was too low to kick the boiler in.

 

[moogwai]

lol.....good stuff mate,glad you got it sorted,you didn't mention the shower head was scaled up!!

 

[bigospedros]

i didn't know it was!