shower goes intermittently cold - is it the pump or mixer?

[aaronmorty]

Hi ,
Searched forum but couldn't find this one - apologies if has already been answered. I have a showerpump fitted to a thermostatic mixer in the shower. Sometimes the shower starts off hot but goes cold after a few seconds/minutes. If you turn off the mixer tap and then wait a second before turning it back on, often the water is hot again but again only for a short time. Sometimes I have to turn the tap on and off 3 or 4 times during the course of a shower, sometimes 20 times, sometimes I just cant get any hot water out at all. I'm wondering if it's the mixer tap or the pump?
Thanks
Aaron

 

[spraggo]

Hi ,
cant get any hot water out at all. I'm wondering if it's the mixer tap or the pump?
Thanks
Aaron

If you have the open vent system with a header tank in the loft, check that the vent pipe is not extending below the water level causing cold water to be syphoned down to the shower.

Regards

spraggo

 

[seco services]

what pump is it ?
how's it connected to the hw cylinder ?

you don't give a clear veiw of what it is thermostatic mixer in the shower,mixer tap.

is it a shower mixer or mixer tap combined shower ?

 

[aaronmorty]

Hi
Thanks for quick replies. It's a salamander pump with a Triton Sentiment thermostatic concentric mixer (so just a shower mixer rather than a mixer tap combined shower).

 

[seco services]

have the checked the pump filters ?

 

[TicklyT]

How is the pump connected to the hot cylinder?

If it is just teed into the outlet near the open vent, it could be drawing air down the vent instead of water out of the cylinder, airlocking the pump. Check any valves in the cold feed to the bottom of the hot cylinder are fully open, as that can exascerpate that situation.

The full solution to that problem is to fit a Surrey or Essex flange to the cylinder to feed the pump, as advised by pump manufacturers.