Low flow rate from sealed domestic system

[heliboy]

Hi - new here and after some help!

Had poor water pressure for showers etc so upgraded the house to a sealed system. Problem is that the pressure is fine for about 10-20secs in the shower bath etc then drops right back. After switching off for a while the same thing happens again if you re-try - great for a few moments then poor again.

I have noticed that the pressure is the expansion tank drops right off. If I charge it to 3 bar (3.5 on placard) it holds until I turn on the taps and I can watch it drop as the flow drops off. When the taps are off it doesn't re-pressurise back to 3 bar (or seem to go up at all!).

The system has been like this since the start. We have a water softener with a PRV upstream of the system and the sytem itself has a PRV too. Both rated to 3 bar I think (mains is 6bar). Am I correct in thinking that they shouldn't cause too many probs (although the second one is redundant - but it also contains the strainer).

Did bypass the water softener itself while trouble shooting (though not the associated PRV) and prob still there.

I have disconnected the expansion tank and pumped it up while disconnected, so it looks like the membrane is still intact.

I have also cleaned the strainer (which I had hoped would solve the prob - but no).

Can anyone give me any pointers as to why the flow rate might be dropping off.

 

[Agile]

Based on what you are saying, I dont think you understand your system. Nor do I from what you have said eiher.

Who designed and fitted this system ?

What was it meant to do?

Tony

 

[heliboy]

It provides mains pressure showering and is suitable for use in new build or refurbishment schemes for domestic or commercial applications. PremierPlus is available in five capacities, from 100 to 300 litres, in both Direct and Indirect models, and can supply up to three bathrooms.

http://www.santon.co.uk/306.htm

Moved to unvented domestic water system - to do away with cold water storage tanks and provide mains pressure hot water so no need for shower pumps.

Plumber who installed turned out not to have a great deal of experience with unvented systems, but was under the umbrella of someone who did who then came and signed the work off (and insisted on a couple of changes such as the tundish leading to an external (visible) drain rather than just using existing downflow pipes)

'Design' as such was as per the installation instructions

http://www.santon.co.uk/docs/Prem_Plus_-_Issue_7_-_36005803.pdf

Originally lots of to-ing and fro-ing about blaming the water softener for reducing the incoming flow rate, then corroded pipes from the water board - who took 4 months to come and 'test' and declare that wasn't to blame and so on. I'm pretty sure it wasn't in a malicious pass-the-buck to get out of anything, I just think he didn't know what the prob was (and while an external factor could be to blame admittedly didn't look too hard). It is an early Victorian property and the pipework to the property we replaced was in a shocking state so it wasn't a leap to suspect the water boards pipework in the street.

Unfortunately I let the whole thing drag on a bit between infrequent contact and its been so long now I would have a hard time pushing him to sort it (even if I could get hold of him).

But its not rocket science so I'm hoping with a bit of knowlege from the ether I can track down the prob myself

 

[heliboy]

And just to add -

Now I have replaced the expansion tank - it seems to hold pressure fine (the coupling wasn't that tight when I removed it; but I don't see how that would affect the pressure in the 'air' side of the membrane. And it's not as though it was leaking so that may well be a bit of a red herring)

It hasn't solved anything though; now I no longer get a temporary surge of 'good flow'through the taps before it drops off - it just starts with the poor flow to begin with!