Poor hot water flow rate

[Spider99]

Hello, I'm looking for some help with my hot water system.

My hot water is powered by an air source heat pump, which I think is equivalent to a pressurised, unvented system. There's a large hot water heater/storage tank in my downstairs bathroom, fed by the cold mains feed at an inlet pressure of 4 bar (the pressure is restricted to this by gauged restrictor). My mains feed pressure seems high from what I've read.

However the flow coming out the taps seems slow. I've measured the cold water in the downstairs bathroom and it takes 7s to fill a litre container, but upstairs it's about 11s. The hot water is worse about 10s and 14s.

Now, I've read the way to increase poor water flow is to install a buffer tank. But surely that's exactly what my hot water tank is acting as? So I can't understand why the hot water flow is worse than the cold.

In the process of doing up the upstairs bathroom and would like to put a new shower in, but I want to get to the bottom of this first. The shower upstairs is more of a trickle at the moment.

Any ideas what would cause these symptoms?

 

[Agile]

You need to measure the dynamic flow rate at an appropriate point.

To get an idea the kitchen cold tap fed directly from the mains is often used.

Tony

 

[Spider99]

Sorry, I didn't mention in my first post. My mains feed comes in to my downstairs bathroom - so the tap I took the measurement from downstairs is straight off the mains. 7s to fill a litre... So about 8.5l/min. How does that compare to normal? I think my mains pressure unrestricted is 7-8bar.

My house was only built about 6 years ago, it's been like this since I've owned it (1year) but not sure if it has always been like this.