Shower pressure issue

[Vic8710]

Looking for some help with the shower pressure issue.

Issue had started after my boiler was replaced to a combi-boiler (worcester bosch greenstar 30i) about a year ago now. Hot water the shower is supplied from the combi boiler downstairs with cold water coming from the cold water tank in the loft.

The shower mixer that i had at the time (Mira pace) had started making a fairly loud noise and losing pressure every so often. Recently I decided to replace the shower mixer with (Bristan Sonqiue2 Bristan Sonqiue2 Thermostatic Shower Valve With Riser Kit Chrome - https://www.qssupplies.co.uk/bathroom-furniture-shower-taps/82475.htm) this had resulted in no weird noise being made by the shower but the water pressure being even worse. Initially pressure seems fine but about 30 seconds in it drops and then fluctuates.

Thanks in advance for your help with this as its driving me crazy.

 

[Aquarius]

So you have a combi boile and cold tank was left in? If this is the case, you have unbalanced supplies.

 

[Vic8710]

So you have a combi boile and cold tank was left in? If this is the case, you have unbalanced supplies.

Yes that appears to be the case, thanks for your reply.

 

[Timmy D]

Yes that appears to be the case, thanks for your reply.

Link mains feed to tank ball cock to tank outlets to balance the pressures and ditch the tank.

But, I wonder why the tank was left in. Lazy? Real low mains flow so the installer thought that the tank would supplement the hot mains and not be powerful enough to cause issues?

Can you measure the flow rate at your kitchen sink cold?

 

[spanner]

Unbalanced HOT / COLD wont mix . If Yuove the cold water tank still in place why not get rid of it to balance it.
Sounds like the unbalanced route taken through a new combi installation.