Recharging the Megaflo having a problem!

31 Aug 2012
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United Kingdom

I have the drips from the pressure relief valve on the megaflo which tells me i need to recharge the air gap.
When i close the water supply to the megaflo, open the lowest HW tap i get only around 5 seconds of water flow before it stops ( manual tells me it should take up to 20mins ). When i open the pressure relief valve there is a few drip's and no gargling sound?

Can anyone suggest if i'm doing this wrong or what the problem might be?

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which prv are you opening ? it should be the temp & pressure relief valve on the side of the cylinder not the one on the combination valve

Yes its the temp & pressure relief valve on the side that i have tried. ( the one that has the polystyrene insulation ).

Like i said i turn the water off,open the lowest HW tap and i only get about 5 sec of water then nothing. I go to the valve and nothing happens, no water or gurggling.
Hey budgie (flash back to the 70s) it may not be the airgap, faulty pressure reducer or back feed from the mains can cause the tprv to drip, what do you mean by polystyrene insulation?
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Hi Picasso,

the T & P relief valve has some polystyrene insulation.
I just found it strange that i only managed to get 5 seconds of hot water after i turned the cold water supply to the tank off.
I am doing everything as i should according to the video.
I have tried both the main water supply cock under the sink and also the local one near to the megaflo tank.
With both methods i only get about 5s of water flow not the 15 to 20min they say on the video?
It only seems to leak whilst the water is being heated.
I think i will need a to get someone past to have a look.
I saw a video of some explosion's with these tanks, i dont want that!!!
Here's a thought...
My Megaflow is on the ground floor an the lowest HW tap is higher than the bottom of the megaflow tank.

Could this be why i cant get anything out of it when i turn off the cold water to recharge the air gap?

Should i use the drain cock instead of the HW tap?
The only correct way to recharge air gap is to drain unit completly via drain off cock , simply opening the T&P will not replenish air gap due to cylinder unable to drain it's contents , if the hot supply rises up off the top of megaflow then simply open a hot tap above cylinder , opening a tap below cylinder will not allow for any air to be admitted in order to drain tank.

Open drain off along with T&P.
Sorted, had to use the drain cock, the lowest HW tap is Higher that the tank.

Thanks a lot guy's for the help.

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