Power shower problems triton

[Tel1981]

Hi all, I have a triton power shower. When switched on with the temp set to hot, the pump runs dry, if I reduce the temp, cold water will flow. Increase the temp and it will run dry for a minute or so, eventually hot water will flow. If the shower is used regularly it's fine, but if not used for more than a day, the problem occurs again. The hot supply is taken from the top of the tank, I have installed a check valve in the hot pipe recently but seems to now be worse. It should be noted that I have an old back boiler, so I believe that makes my system low pressure or gravity feed.
any help greatly appreciated,

 

[steadyon]

If its always been a problem I'd suspect the hot feed. It may be from the top of the tank, but is it from an Essex or similar flange to remove air?, or at least downward from a horizontal section at the top of the tank. Resolution is get the manufacturers instruction and re-run pipe work to comply.

If a recent problem I'd suspect the filter(s) and / or non return valve(s) are choked, with lime scale or sand / grit. Resolution is remove and clean.

 

[Tel1981]

Thanks for your reply steady on. It has been a persistent problem since we bought the house, but becoming more of a problem. I will try to upload some pictures of the tank where the joint is made. The pipe work to shower is the 15mm with isolation valve. From what you have described I think this maybe where the issue is.

 

[Tel1981]

It appears I can't do technology anymore, and can't upload pictures lol. But the joint is to horizontal section of 22mm from top of tank, he has used a 't' and installed 15mm pointed upwards from here. Sounds like this maybe the issue. A bit concerning that the son of the previous owner was supposed to be qualified plumbing/heating engineer, and carried out most of the work in the property. I'm always finding bodge ups and worse. Lol

 

[SimonG]

The t should point downwards.

 

[Tel1981]

Ok thanks Simon, the other thing I notice is the top of the shower unit is approx 65cm below the tank base, manufacturer states it should be 75cm, is the 10cm gona mess me up or is the t the main issue here. As the bathroom has recently been lovingly retiled I don't fancy repositioning the shower.