megaflow, twist or stick

[Johntheo5]

The instructions for recharging could possibly be a bit clearer as it doesn't specifically state that the T&PRV should be left opened until all the water has ceased draining from it. Presumably the water cannot be seen draining into the tundish since they mention gurgling.
Also interesting to see that the bubble only lasts 6 to 8 weeks (post #1) "without" the baffle.

"To recharge the air volume:-
Turn off the heat source to the cylinder via programmers / immersion isolation switch(es).
Turn off the water supply to the cylinder by turning off the isolating valve on the 3 bar pressure reducing valve if fitted at this point or at the 8 bar pressure relief valve if fitted there. Turn the handle so that it lies at 90° to the direction of flow. See figure 17 page 27.
Open the lowest hot tap.
Hold open the temperature / pressure felief valve until water ceases to run from the tap and gurgling noise at the valve stops.
Close the temperature / pressure relief valve.
Turn on the isolating valve at the cold water combination valve by turning the handle so it lies parallel to the direction of flow, when water flows from the hot tap, close tap.
The air volume will be automatically recharged as the unit refills. If after following the above actions water still discharges from the expansion relief valve, further advice should be sought from a competent installer or the Megaflo service department."

 

[vulcancontinental]

I suggest stick with Megaflop as it’s the easiest, cheapest option.

There seem to be two issues with them, one I haven’t encountered myself, that of the disintegrating baffle.

Have you had to replenish the air bubble in the past? If not just fit the replacement. If you have, stick an external vessel on then forget about the bubble (it disappears depending on the water quality in the area, in my hard water area the bubble lasted only a few months).

The only issue is you’ve lost the top section of the cylinder stored water as you can’t remove the drop tube.

 

[Johntheo5]

The drop tube effect is interesting, in a 250L cylinder and pressurized to 3bar there is ~ 47L between the bottom of the drop tube and the water surface (a 15L bubble ), which makes it a 235L cylinder?, when heated to 60C, 50L between the drop tube bottom and the water surface, is this ~47L of hot water still usable as the cold water replaces the hot or does it stay as a "plug" on top and cold water then enters the drop tube?. so in effect only 203L of usable HW?.

 

[vulcancontinental]

The drop tube effect is interesting, in a 250L cylinder and pressurized to 3bar there is ~ 47L between the bottom of the drop tube and the water surface (a 15L bubble ), which makes it a 235L cylinder?, when heated to 60C, 50L between the drop tube bottom and the water surface, is this ~47L of hot water still usable as the cold water replaces the hot or does it stay as a "plug" on top and cold water then enters the drop tube?. so in effect only 203L of usable HW?.

It's why I recommended the Oso cylinders which allowed removal of the drop tube so with an external vessel it could be fully flooded. I've learned they've dispensed with the tube a while ago due to the bubble issues.

 

[Johntheo5]

Just a clarification re recharging, the T&PRV, when opened, actually allows air to enter the cylinder and the water drains out through the (lower) hot tap via the drop tube, hence the gurgling.

 

[dilalio]

I have attended dozens of Megaflos.
Most have never or hardly ever been serviced.
Customers clueless about air bubble or baffle.
All have worked fine but improved upon my recharging them.
Not personally experienced a baffle break down but have acquaintances who have.
Fit the replacement but check pipework arrangement is as it should be.
Consider water treatment if in a hard water area (softener or Aquabion).
Consider a strainer on the hot outlet.
Remove grohe shower mixer, dismantle and clean and lube innards to see if you can ease it's operation.

 

[ianmcd]

installer and serviced properly every year, then the new unit's warranty will cover any future issues.

@Madrab I swapped one out in my sisters house, no problem getting the replacement, but no warranty on it whatsoever, they say that supplying a replacement covers everything and they dont provide a warranty on the new unit

 

[Johntheo5]

One might think, at the very least, that it should cover the remaining warranty period of the original cylinder.

 

[ianmcd]

One might think, at the very least, that it should cover the remaining warranty period of the original cylinder.

Nope once replacement is supplied warranty is cancelled

 

[Madrab]

@Madrab I swapped one out in my sisters house, no problem getting the replacement, but no warranty on it whatsoever, they say that supplying a replacement covers everything and they dont provide a warranty on the new unit

Oooooo, that's sneaky, I'd like to read through their warranty conditions because you wouldn't think that would be allowed, what the point then as it's their reputation too. I could see me really argue that one with them if the occasion arose.

 

[ianmcd]

Oooooo, that's sneaky, I'd like to read through their warranty conditions because you wouldn't think that would be allowed, what the point then as it's their reputation too. I could see me really argue that one with them if the occasion arose.

Look at many replacement things mate, if a complete unit is replaced then no more warranty