Help needed please - Pumped Shower Issue

[Ermintrude]

Nice thinking batman

 

[galaxy_plumbing]

had similar on combi where restrictor in shower head wasnt letting enough water through and boiler kept cutting as was overheating so cust had hot/cold/hot/cold shower. took me bit of time to find that restricting bugger. all fine once removed

 

[Shower Engineer]

I normally find removing the NRV's sorts this out. The springs in the NRV's are just too powerful for the gravity supplies to overcome. I hear what you say about the open end flow rate but you might find it is the same with most shower heads.
I would try a different head and if that doesn't work remove the NRV's.
Negative head kit will also sort it as would a momentary switch but both of these involve more cost.

 

[Plumbstar Tom]

drop the head into the shower tray and then turn on the shower. If it works then your problem is you are in a negative head situation.

Shower heads are all resrictive to some point as they need to spread the water out and through smaller holes.

Solutions are Negative head kit or increase the height of the cold water storage tank. Another shower head may help but will be trial and error

 

[cr0ft]

Hi again and thanks for all the replies. Same issue no matter where the head is. On gravity flow with the head on there is not even a drop coming from the head. Without the head there is a decent 4L/min flow. The shower head is all metal so I am going to drill the holes slightly larger with an HSS drill bit on Monday evening and see if that works. To me the obvious problem is the shower head. A negative head pump would sort it but as there is already 4L/min from the shower we should be able to get 0.6L/min through the shower head needed to start the positive head pump. Don't really want to buy another pump!

Will keep you all posted.