Unvented cylinder - second shower low flow

@Madrab and @flameport

It would appear I can get a new cartridge for the multibloc inlet. see this: http://www.unventedcomponentseurope...for-multibloc-inlet-control-group-rpcw11.html

Could I simply shut off the water supply to the cylinder, then remove the current cylinder and put this in its place? Or again, is this something that an engineer needs to do?

It could be the reducing valve or something else but it needs to be confirmed what the fault is first.

It's a safety device and needs a qualified engineer to service or replace.

Madrab said:

It could be the reducing valve or something else but it needs to be confirmed what the fault is first.

It's a safety device and needs a qualified engineer to service or replace.

Click to expand...

Hi Madrab

I spoke directly with technical support at RM Cylinders and they gave me advice to inspect and clean the cylinder as part of the monobloc. This was pretty straightforward but did not show any specific issue with the device. The gauze was clean, the spring operational and no bits of gunk of other blockages that I could see.

So there must be another reason. Someone else I spoke with at RM said it could be an airlock between the cylinder and the en-suite in the loft (only one floor up), however I don't think so because it happens with both hot and cold which means there would need to be identical airlocks in both pipes. Anyway, as part of servicing the monobloc, this pipework was of drained down and then refilled.

The thing that confuses me is the fact that when main bathroom taps are open, air is drawn into open tap in the loft (i.e. negative pressure).

If anyone can think of a next step to investigate this that would be great - I feel I am running out of options. The next thing I will learn about is the difference between dynamic and static pressure. I know that static pressure is higher than 4 Bar (with flow approx 30 l/min) but perhaps as soon as water is moving this pressure crashes down - could this be possible? Perhaps I still need to get hold of a pressure gauge that can fit onto a bath tap after all

Any help hugely appreciated.

Thanks,
W

Wesley, no disrespect intended but you really should have a qualified engineer working on the controls and safety devices of your un-vented system. Have you ever seen an un-vented cylinder explode, with a young family I'd honestly be using someone that understands and is qualified to work on the system.

The pressure after the PRV needs to be checked as that's really the only thing that could be causing this issue you are seeing, if all balanced feeds are after the valve and the distribution pipes have been routed correctly.

Madrab said:

Wesley, no disrespect intended but you really should have a qualified engineer working on the controls and safety devices of your un-vented system. Have you ever seen an un-vented cylinder explode, with a young family I'd honestly be using someone that understands and is qualified to work on the system.

The pressure after the PRV needs to be checked as that's really the only thing that could be causing this issue you are seeing, if all balanced feeds are after the valve and the distribution pipes have been routed correctly.

Click to expand...

Hi @Madrab

Yes I totally agree. I have a qualified plumber coming on Thursday to do the cylinder service and to try to help fix the issue. In the short term, with the safety backups in place (temp/pressure release valves - one in multibloc and one from cylinder into tundish) I was happy, under instruction directly from the manufacturer, to check the PRV cylinder and replace without any fear of the, in all honesty, unlikely issue of cylinder explosion.

I appreciate and agree with your concern and I would not endeavour to do anything more complex without lining the pockets of the local engineering community of course.

Thanks!
W

Heh heh ... and I totally understand the wry comment re the pocket lining. Should it be a requirement to be qualified to work on these systems, given the ramifications of incorrect DIY work then it's probably safer for the masses and someone, in an office somewhere, in their wisdom has required that legally it needs qualified personnel to work on them. Again it comes down to that word 'competent' and the only way to show that these days is to have a bit of paper saying so.

You're probably right about being able to check the PRV without issue, especially if a person understands its operation and the risk would probably be minimal. Should the manufacturer be directing anyone to test safety devices without confirming their qualifications?? Well that's another question.

All that being said, I would still be getting the original person that performed the work back in as it's obviously not fit for purpose and should be guaranteed.

Hi All,

Well I got an engineer round and it turned out to be the PRV after all. A few turns of the screw inside to adjust it, then a check of the static pressure at the shower upped the pressure enough to give us better results in the loft bathroom.

It pays to be persistent!

Thanks to all for your replies - I now have a boiler question that I will start as a new topic (my Worcester Bosch 24i is too loud on ignition but then, after a while, modulates down to a manageable noise- I want to prevent the first loud stage if I can as it wakes everyone up. I think it's more fan noise than combustion.More details in the thread).

Thanks to all.

Pete

Hi all,

We are facing a very similar issue. When BOTH the hot and cold 1st floor bath taps are run, all water supply in the 2nd floor loft cuts off, even the toilet doesn't refill after a flush! At this point, air is drawn when taps are opened at loft and then after 1st floor bath taps are closed, loft taps sputter for a few seconds. We have a mains pressure system boiler with an unvented cylinder, boiler is located in ground floor utility, cylinder is located in cellar.

There was a solution mentioned, could I get more clarification please?

Please note, if only either hot or cold 1st floor bath taps are run separatly, the corresponding hot or cold supply in the loft is reduced but fine.

Thanks