Service life of a megaflo: What can one reasonably expect?

[Synec]

We have a Megaflo that was installed some 12 years ago. We are in a hard water area and we have some measures in place to reduce limescale - but not a water softener. The Megaflo was serviced about 15 months ago. Now we have low pressure (drops rapidly from 2.7 bar to 0 on HW out) through the megaflo with a steady 2.7 bar going in (there are pressure gauges on both sides). We have been in touch with local unvented specialists and chatted to the plumber about the problem over the phone. We have also spoken to Megaflo direct (my wife specifies hundreds of Megaflos as a consultant engineer). The common view is that there could be a blockage in the CW feed to the base of the tank caused by scale, discounting a blocked/ dirty PRV cartridge which the plumber will do to exclude it as a cause. The plumber commented that he has been unable to find a good method of cleaning the downward curving feed pipe in case of low level blockage. He also admitted to having recently replaced his own Megaflo at home for the same problem after 13 years. Accordingly a replacement Megaflo along with a water softener is now recommended. Before we take this step can anyone comment on the difficulties of clearing a blockage in the location described and is a dozen years' service in a hard water area par for the course for these stainless steel (and expensive) wonders?

 

[SimonG]

They will last as long as they last. Its overdue a service so that imo would be the place to start. If it does need replacing then replace it with something other than a megaflo. Over priced tat. Far better cylinders on the market for a much better price.

 

[Killy Bing]

I dont even spec megaflow i don't see the point, the bubble can fail and then the novelty is gone!
i do spec oso super series or on a budget gledhill

if you really wanted the hastle (and it bloody well would be)

you could have it removed , poke something into the cold inlet to clear it and see.
at that age i wouldent even bother tbh.

change it for a regular unvented and have the water softener.
harveys are a very nice one.

p.s ehy does she spec megaflow again?

 

[Ray Stafford]

Its not just the time, its also the usage. The degree of scale build up is a function of four factors:

1) The hardness of the water
2) The throughput of water
3) The temperature to which it is raised
4) The design of the vessel and other components both in terms of scale adhesion, and in terms of performance resilience once scale build up starts.

Passage of time (ie 12 years) only gives a clue to 2), but doesn't answer it. 12 years of a little old lady living alone is very different from 12 years supplying hot water to a catering business, or even a family home with several teenage girls living in it.

 

[SimonG]

Coupd fill it full of vinegar. Probably Sarsons though for the best results.

 

[Synec]

Its not just the time, its also the usage. The degree of scale build up is a function of four factors:

1) The hardness of the water
2) The throughput of water
3) The temperature to which it is raised
4) The design of the vessel and other components both in terms of scale adhesion, and in terms of performance resilience once scale build up starts.

Passage of time (ie 12 years) only gives a clue to 2), but doesn't answer it. 12 years of a little old lady living alone is very different from 12 years supplying hot water to a catering business, or even a family home with several teenage girls living in it.

1. Hardness of water is slightly hard (according to Essex & Suffolk water)

2. Throughput of water over the last 10 years on average is:
8 showers + 2 baths a week
1 adult and 1 male child under 12 ordinarily + 1 adult at weekends
3 dishwasher loads/ week
3 washing machine loads

3. 60 deg

4. I can't really answer except to say that it is a conventional megaflo installation with a system boiler and Honeywell S plan. The water treatment provision at the outset was an inline scale inhibitor on the supply side of the MCW stopcock.

I'd be interested to hear why Megaflos are regarded by some as overpriced tat, why some others may be better and which those may be.

Thanks for the answers so far.

 

[AWheating]

Ermi will do it with brick acid I think he drinks it

 

[rpm]

Coupd fill it full of vinegar. Probably Sarsons though for the best results.

Any truth in White vinegar works better on limescale than brown? Anyone know?

 

[SimonG]

Any truth in White vinegar works better on limescale than brown? Anyone know?

I was just going back to an old physics experiment. Sodium bicarb, red food die and vinegar. Diy volcano. Would expect the same result on limescale. I would expect white vinegar to work better.

 

[BLOD]

Synec,
I live & work in a very hard water area and have found that limescale prevention devices don't really stop the formation of limescale, they just change the nature of the limescale that gets deposited. I have no scientific evidence of this, it's just my own observations.

You'll probably have a bucket load of limescale at the bottom of the cylinder - the easy part is removing this. The difficult part is clearing the diffuser right at the bottom of the cold inlet, and on megaflos this can be a pig of a job !
I've found sulphamic acid works well and is not as agressive towards metals or as dangerous to use as certain other acids.

I'd definately try to clear it , a megaflo should last at least as long as it's guarantee - 25 years ?

 

[wetdrip]

Any truth in White vinegar works better on limescale than brown? Anyone know?

Purchase a bottle of Acetic Acid 33% solution from you local chemist.Cost around £5-£6.
It'll remove staining from inside the WC bowl with ease, too.

 

[Ermintrude]

Any truth in White vinegar works better on limescale than brown? Anyone know?

Ones almost a keytone - not full moxidised and other is acid.

 

[Ermintrude]

Get about 20g of sodium dichromate iv from your local school. Bomb that in the cold. Cap off hot and heat .

 

[josh]

Megaflo are poo.


Stop specifying it and use something cheaper and better so basically any other cylinder without the internal air gap.

 

[Ermintrude]

Most consultants will spec a main 24kw if some one tells them. I would think your baffle looks like a massive white cornflake, your coil a wet loo roll and base of cylinder - toothfaries grotto. A decent water softner will gradually lift out the smeg. Coca cola will do job just fine. 20 l two days! With a circuit pump Tell your mrs to grow some and spec a decent cylinder. ACV ! If she didn't know of them she should return charter-ship and get back to school!

 

[lame plumber]

warranty is not to leak, doesnt mean it wont block full of crud though

 

[Synec]

Synec,
I live & work in a very hard water area and have found that limescale prevention devices don't really stop the formation of limescale, they just change the nature of the limescale that gets deposited. I have no scientific evidence of this, it's just my own observations.

You'll probably have a bucket load of limescale at the bottom of the cylinder - the easy part is removing this. The difficult part is clearing the diffuser right at the bottom of the cold inlet, and on megaflos this can be a pig of a job !

I've found sulphamic acid works well and is not as agressive towards metals or as dangerous to use as certain other acids.

I'd definately try to clear it , a megaflo should last at least as long as it's guarantee - 25 years ?

Agreed re limescale and that has been our experience of the deposits on the immersion element, old T&PR valve, tap outlets generally and the bath - easier to remove but still present. Another plumber, a company whose retail side I have used before has commented that it is the hot side at the top of the tank that they have found to be more of a culprit than the supply side. Sound sensible and any recommendations for cleaning that?

 

[Ermintrude]

Coca cola

 

[Synec]

As I recall, it is more usual for the contractor to select and propose the HWCs and for her and her company to comment on the proposals as most schemes are d&b these days. The recent choice of Megaflos for large scale residential appears to have been driven by client preference for Heatrae Sadia as a supplier. Neither of us are too fond of ours and the integral bubble is really not that great an idea in our experience.

 

[Synec]

Coca cola

In the end it was not Cocacola but formic acid (conventional retail kettle descaler) and patience. I am glad to say that it was completely effective. Thank you and all the others for their responses, especially the facetious ones.

Better than £1000+ for a new cylinder as recommended by plumber.

 

[Alex Pelton]

this is what you need

http://www.fernox.com/files/Fernox/Content/PDF/English/DS3 2kg new.pdf

 

[Synec]

Good morning Mr Pelton,

thank you for that advice, it looks like absolutely the right candidate for the job. Now that the problem has been solved and we have full hot water flow I will know what should be done the next time. It is a shame that a Heatrae Sadia recommended plumber did not seem to be aware of this approach and simply recommended replacement; yet another company to avoid in future, I suppose. For myself I shall proceed with installation of a suitable water softening system in order to try and avoid the problem recurring.

Thanks again.

Synec