Questions/Issues with new UVC System

[Spinny]

What is a bit odd is that the original lead pipe provided 22 l/m and we raised the flow problem (regarding the shower being weak and becoming very weak when a tap was turned on) with the builders plumber. His response was to suggest it could be the PRV and he removed the original Gledhill PRV and replaced it with the Caleffi PRV. However it made no difference to the performance of the system when he did that. He never said whether he found any blockage or damage to the Gledhill PRV, just whisked it away to his van. I suspect he would have shown me the damage had he seen any. The PRV was changed about a year ago now. It lead to the mains supply being declared as 'the problem'. Now that is fixed but we still have a problem.

[Spinny]

12 minutes ago, John Carroll said:

 

Exactly, I'm happy now.

There is one "foolproof" method of checking if the problem is with the PRV and that, as you suggested, is to remove the PRV and install a spool piece but this ia a bit messy as the balanced and EV connections must be removed and the spool piece made up,  easier IMO to remove the balanced cold at the PRV, make up a connection and install the PG here, then check this pressure with shower on (HW) only and/or other HW users, this will also show, if the PG reads say 2.6/2.8bar,  that the problem is downstream of the PRV.

Problem DOWNSTREAM of the PRV ? Do you think the problem could be in the cylinder or in the pipework downstream of the PRV ? How would that work ?

[John Carroll]

No idea but I think you will just have to methodically plod through logical checks, one could also say that the chances of two PRVs being faulty are tiny, one strainer might get full of debris but hardly the second one.

[Spinny]

2 hours ago, John Carroll said:

 

... easier IMO to remove the balanced cold at the PRV, make up a connection and install the PG here, then check this pressure with shower on (HW) only and/or other HW users, this will also show, if the PG reads say 2.6/2.8bar,  that the problem is downstream of the PRV.

I think this is what the utility tap gauge already shows anyway though, because it is connected to the balanced cold coming from the PRV. Connected via copper pipe and about 4m of 16mm MLCP.

[John Carroll]

That makes sense allright as there is/should be no flow in that balanced cold with any hot flow only, so what is your next step as it points to a restriction upstream from or at  the PRV. 

 

You have 6M of 25mm MLCP + ??M of what type/size of remaining piping to the PRV?

[Spinny]

The full pipe route to the PRV is as follows:

32mm barrier pipe mains supply

Right angle connection to approx 1m of 22mm copper pipe with lever stop tap

22mm connects into and out of water softener connector currently set to bypass

short piece of 22mm copper pipe with right angle bend

connection into 6M of 25mm MLCP running under floor

1.5m of 22mm copper pipe to connect from MLCP to the PRV

 

So the full route from the 25mm internal bore mains to the PRV is 20mm internal bore with the exception of the press fit connectors at each end of the MLCP which have internal bore of 14mm.

 

The PRV is about 1.5m vertically higher than the mains pipe (just 0.15bar) as everything is on the ground floor.

Edited Thursday at 06:56 by Spinny

[John Carroll]

Friction loss tables would indicate that the dP through that pipework should be well < than 0.25bar at 11.6LPM, (one table shows a loss of < 0.1bar), add the elevation loss of 0.15bar gives a total (max) loss of 0.4bar, a 1M dP should give a flow of 18.34LPM and still leave ~ 1.8bar after the PRV.

 

[dpmiller]

might the strainer in the PRV be blocked?

[Spinny]

3 minutes ago, dpmiller said:

might the strainer in the PRV be blocked?

How do you actually check that, do you have to drain down or remove the PRV ?

There is a photo of the Caleffi PRV above.

[Nickfromwales]

8 minutes ago, dpmiller said:

might the strainer in the PRV be blocked?

Can be the case, aka commissioning debris.

 

4 minutes ago, Spinny said:

How do you actually check that, do you have to drain down or remove the PRV ?

There is a photo of the Caleffi PRV above.

If you search on YouTube you should see how to strip / clean / reassemble the PRedV. Quick and easy, just unscrew the body from the valve to expose the gauze filter.

 

Note, turning the water off and draining down via a tap would be ‘advantageous’ in terms of staying dry. Have an old beach towel to hand to deal with a bit of residual water in the local pipe and valve itself. 

[John Carroll]

1 hour ago, Spinny said:

How do you actually check that, do you have to drain down or remove the PRV ?

There is a photo of the Caleffi PRV above.

 

You shouldn't have to drain down the UVC, just shut the mains supply to it, open a hot tap and any cold tap off the bananced cold, the water should then stop fairly quickly as there is/should be a check valve in the combination valve set.

[Nickfromwales]

5 minutes ago, John Carroll said:

 

You shouldn't have to drain down the UVC, just shut the mains supply to it, open a hot tap and any cold tap off the bananced cold, the water should then stop fairly quickly as there is/should be a check valve in the combination valve set.

Yes, sorry, when I said drain down I just meant turn off mains, open all taps fully until nothing comes out, then you’re ’drained down’.

 

Cylinder will remain full.