What shower system is this?

[Mozzbo]

Hi,
I've just moved into a house an there's a problem with the shower.
It's a 'rainfall' type shower head and the shower appears to be fed from the instantaneous boiler.
When the shower is switched on at the tap the water literally dribles out, but is warm.
After a couple of minutes, the flow increases but the water goes cold.
So, warm water, hardly any water flow cold setting/water, reasonable water flow.
Basically the shower is unusable.
I've attached sone photos of the shower, which appears to be licated behind a tiled wall!
Does anyone know what shower system this is and any ideas what could be wrong with it?
Thanks in advance.

 

[Ric2013]

I'm going to guess

1 That the boiler has something similar to this fitted or built in: CombiSave Device - Save water and money if you have a combi-boiler - https://teddingtonheating.com/combisave/

2 That the shower itself is a thermostatic mixer that will ALWAYS deliver water 10°C colder than the hot water it receives. One tap is the flow and one is the temperature?

3 That your boiler hot water set temperature is warm enough for taps, but not 10°C warmer than you'd like your shower temperature to be?

 

[Mozzbo]

I'm going to guess

1 That the boiler has something similar to this fitted or built in: CombiSave Device - Save water and money if you have a combi-boiler - https://teddingtonheating.com/combisave/

2 That the shower itself is a thermostatic mixer that will ALWAYS deliver water 10°C colder than the hot water it receives. One tap is the flow and one is the temperature?

3 That your boiler hot water set temperature is warm enough for taps, but not 10°C warmer than you'd like your shower temperature to be?

Hi thanks for the reply.
I can't see a CombiSave fitted (see photo).
The top tap on the shower is the flow, the bottom is the temperature.
Its as if theres not enough flow to keep the boiler activated.
With the temperature control set to its hottest, theres just a dribble coming out of the shower for around 2-3 minutes. The temperature of the dribble is warm but not hot.
After 2-3 minutes, the flow increases and the temperature goes cold. Grateful of any advice.

 

[Ric2013]

Well, if you think the boiler is switching off, have you tried leaving the shower running and seeing if the boiler is firing? You can often see the flame through a little window, or hear if the boiler is firing or not.

You'll should also be able to work out which of those pipes is the hot water to taps leaving the boiler (might be the one on the far right?) and you'll know at least if the water is leaving the boiler hot or tepid...

 

[Mozzbo]

Yes, the boiler fires initially but as soon as the water starts coming out of the shower head warm, the flow slows to a trickle for around 2 minutes. As the flow is so slow, the boiler then switches off. As the water cools, the flow through the shower head increases again and after a minute or two, the boiler fires again, the water gets warm and the flow through the shower head slows to a trickle again and the cycle repeats.
There's plenty of hot water to the hand basin and bath in the same room.

 

[SimonG]

Check filters in shower for debris.
[automerge]1585729019[/automerge]
It will be the cartridge in the shower.

 

[Mozzbo]

Would the cartridge likely be located behind the shower control taps, or could it be further down the line?
Is the cartridge purely a filter, could it be bypassed if I found it?
Thanks

 

[moonlight]

What is the hot water like in the rest of the house?

 

[Mozzbo]

Thanks, the hot water is fine through all the taps.

 

[SimonG]

Cartridge behind the chrome plate on the temperature control

 

[Ric2013]

Cartridge is thermostatic and regulates the temperature.

The filters are not the same thing as the cartridge.

Could be that the cartridge is initially allowing mainly hot water through, as it senses cold. As the hot water reaches it, it restricts the hot to allow more cold water into the mix. If the cold filter is blocked or there is a lack of cold flow for some reason, the cartridge will restrict the hot too, then, as you say, the boiler cuts out. Not sure if that is what is happening in your case, but might be.

Out of interest, what happens if you open a hot tap just enough to keep the boiler firing and then use the shower? Not sure why I'm asking this, but I have a half idea in my head which I'm trying to understand.