Shower unable to hold temperature

[lgs141]

Hi,

We have a shower (not electric) that can't hold its temperature.

If we set the temperature to anything below very hot (almost burning), the temperature is steady and doesn't change during the course of the shower.

If we set it to anything below that, after a certain period of time - ranging from 1 minute to 10 minutes - the water will go stone cold. We then either have to wait while the water warms back up or turn the shower on/off. This will continue to happen during the course of the shower so it is extremely frustrating and time consuming.

I've changed the head of the shower and have also changed the filter (is it called something else?) that the shower pipe connects to the shower unit with.

I have attached a picture of the shower. It is a Mira 415.

Does anybody have any insight as to why this might be happening?

The boiler pressure is optimal. This has been a problem since we moved in 6 months ago and the shower hasn't been changed. It might be worth noting that our bath hot tap only seems to produce warm water, as does the bathroom sink hot tap. Downstairs temperature is fine.

 

[lightning]

What boiler do you have, if it's a combi it could be scaled up plate exchanger, when you run the shower does the boiler fire up and then go off and fire up again

Paul

 

[lgs141]

We have a Vaillant turbomax vuw 242e.

I have just tested and noticed this

- The boiler does not kick in at all until I hit a certain point on the shower dial (about half way)
- Once I hit that point, the boiler kicks in but that specific temperature is very hot, almost burning
- If I lower the temperature ever so slightly, the boiler stays on (temperature still too hot, I'm not even sure if the temperature lowers)
- If I lower the temperature to a suitable level (about half of the setting the boiler needed to kick in), the boiler turns off a while after, maybe 30 seconds or so, and doesn't turn back on so the water goes stone cold

 

[muggles]

Turn it round to hot and run it, then feel the temperature of the pipe connections on the sides of the valve. Which one gets hot?

 

[picasso]

After you try muggles suggestion take the head off the shower and see if the boiler stays on and the temp stabalizes.

 

[lgs141]

The left pipe in the image is the one that gets hot. The right pipe is cold the entire time.

Picasso are you suggesting that I first turn on the shower, then remove the head while it is still active?

 

[picasso]

Only if you fancy getting soaked, take the head off and then start the shower, some shower heads are very restrictive and can cause the boiler to cut out.

 

[lgs141]

Oh sorry you meant the shower head... clearly I've had a long day, I thought you meant the head off of the shower unit itself.

I'll give that a try tonight

 

[St0rmer66]

Sounds like water flow switch diaphragm in the boiler has worn out to me!

 

[lgs141]

Tried another shower head, didn't make any difference unfortunately.