Low cold water pressure in new shower

[kwieme]

We have just had a bedroom converted to a bathroom and are having trouble with the pressure in the new shower. We have a combi boiler and cold water tank (which I understand is only about 50 cm above (although in a different room) then the shower head. The hot water comes out of the shower with great pressure, but is scalding hot. When we attempt to adjust the temperature (we have a mixer but not thermostatic) to be cooler, the pressure either pulsates or cuts out altogether. We have been advised by our builder that the problem is that the hot water pressure from the combi is overpowering the cold water pressure from the tank. He has suggested two alternatives - one is to fit a pump after the cold tank to boost the pressure and the other is to take the cold water straight from the mains. He said with the first alternative the risk is that we may run out of cold water in the tank (although we had a pumped electric shower previously, so I don't really understand this) and with the second alternative the risk is that the cold pressure from the mains may be too strong for our existing pipes (we live in an old Victorian terrace) which are used to much lower pressure and it could cause leaks.

Based on the limited information I have (apologies for not understanding more of the technology), can anyone make a recommendation as to which is the better option (or if there are other options)?

Thanks in advance.

 

[ChrisR]

[code:1]take the cold water straight from the mains[/code:1]

 

[kwieme]

Thanks for such a prompt reply. Can you guess as to whether there is a strong or weak chance that taking cold water from the mains may cause leaks in other parts of my house?

 

[ChrisR]

Same methods would have been used for joining all the pipes without regard to purpose, so slim risk. You may need to alter the inlet nozzle inside the WC valve - no big deal.

Whether your supply is up to providing C as well as H at the same time is another matter.
Does the kitchen sink cold tap "stop" the hot at a separate tap?

 

[kwieme]

I have no idea, but it is on the list of things to check before undertaking the work.

Thanks again!