Megaflow tank air bubble refill

6 Jan 2017
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United Kingdom

I have looked on this site for the answer to this question but couldn't find it.

My hot water pressure feels like its getting low.
System is 7 years old and has never been touched apart from the normal yearly gas cert.

All system is outside.

I wondered if it was to do with internal air bubble. I understand to recharge air bubble is to shut off cold water combination valve and then open hot water tap in doors. After that then open PRV on tank.

What I'm not sure of is when I shut of cold water combination valve and open hot water tap in doors there is no hot water flowing. I thought the idea was to open hot water tap to empty tank, but nothing.

Anyway I went to PRV and opened that and it literally dripped to the tundish with gargling noises.

Any ideas to help me understand / steer me to the correct path would be highly appreciated.

Thank you
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If its anything like mine be prepared to stand there for a long while. I'd consider using a heavy stiltson wrench or something to save the boredom
Does that mean that no water should come out of hot water taps?
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You should open the lowest hot water tap on the system, and water will flow out of it while the TPRV is held open
I suppose what I'm asking is it normal not to have any hot water flow whilst cold water combination valve is closed?
Thanks for your reply. Sorry what do you mean by lowest hot water tap? How would I find it etc ??
All your searching should have found plenty of instructions telling you that an annual service is required on an unvented.

But you have never bothered in seven years!

Surely the planes you were involved with during your career receiver regular servicing in accordance with the maker's schedule?

How my system is behaving at the moment: -

If I turn off cold water combination valve and run hot water tap in kitchen no water comes out. So I think to myself megaflow needs charging. Go to megaflow PRV turn it fully etc but nothing happens, no gurgling etc. Any ideas would be much appreciated.

I have started another thread with ref to how the system works etc.
Nody, Nody, Nody!! There's every chance your unvented cylinder has never been serviced properly. I've not seen any of these Micky mouse service contracts cover servicing a UVC. Get a Plumber with a G3 ticket in & get it serviced correctly. Your filling group needs cleaned or replaced.
Re-establishing your bubble is a DaftyDIYers job, but not servicing the unit.

You have been thank you

I have?? Oh well, thanks for your expression of gratitude & I hope you get sorted out.

You do need a thick skin for these forums mate, so don't take it to heart. The Plumbing trade has always been full of banter & wind-ups, most of the Pros on here are Top Drawer tradesmen. So if you can take a bit of ribbing, you'll get a helpful answer.

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