Megaflo - White sand / grit / limescale from cold taps !

27 Nov 2009
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United Kingdom
Hi, after much research into my problem I have drawn a big blank so hopefully someone can help !!

I have a megaflo HE and it's about 5yrs old, had a drop in water pressure and then large quantities (easily a bucket full :eek: ) of very fine white sand / grit from all of the cold taps except the kitchen taps but not the hot taps, this also fills the toilet cisterns !.

I have contacted Heatrae sadia who have not heard of this (but sent me the megaflo installation guide) and google draws a blank, 2 plumbers (megaflo experts !) have no idea? My neighbour had this problem a few years back and also drew a blank, he drained the system and re-balanced the megaflo and it 'cured' itself.

Would I be right in assuming that this is limescale from the bottom of the megaflo that is being pushed back through the cold water inlet and the combination valve, hence back through the cold water taps but not the kitchen one that is direct off the mains?

Any advice / experience of the would be appreciated !
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If its coming from the megaflo then it must be incorrectly installed, otherwise its coming from your water supply in which case you need to contact your local water authority.
why would you think its connected to the megaflo?
You don't say theres any evidence of this on hot water side.
Suggest you may want to call in suitably qualified plumber/engineer to clean inlet control group OF THE CRUD THAT HAS COME IN THROUGH THE COLD MAIN
Thanks for the responses guys much appreciated. I have spoken to the water board and as the main kitchen tap cold water is clean they say it is nothing to do with them. My (limited) understanding of the megaflo system is that the incoming cold goes into the cold water combination valve in the airing cupboard then splits to the megaflo inlet AND to the remainder of the house cold water taps? The 'crud' is very white like silica sand and very uniform in colour, I just assumed from the above that it was a sort of fine limescale that has been back syphoning via the megaflo cold water inlet thought the combo valve that feeds all the other cold taps in the house ??? Is that possible??

If this is a build up in the pipes would it all come out of them all of a sudden ? and the pressure of the hot water is affected the most hence I suspected the megaflo.

The installation was done by a large contract plumbing company on a housing development of around 100 houses so yes it may be installed incorrectly but unlikely ?

Thanks again for your assistance
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I have the same thing, and my neighbour also had this happen to him a while ago, I have enough fine sand like limesacel to fill a big bucket!

it has messed my wall mount shower and two toilets will not fill, I have cleaned my washing machine filter a few times also,

I had a plummer out that does the whole de-scales thing and he didnt have a clue....

ANy help would be most welcome?
get unvented register engineer out and check inline strainer,on combination valve. pressure reducing valve ,& check valve.
hot cannot be siphoned to cold taps from cylinder if check valve is operating correctly,
unless its been installed wrong :eek:
i believe the sandy stuff is lime scale.
if it was from mains inline strainer would block.
is cylinder stat working correctly,too high a temp,will scale cylinder ect
any way for safety you need unvented engineer out.
Your cold water in your kitchen should be fed from what is called a balanced supply-ie the feed is taken after the control set on the megaflo
to ensure you get ballanced water pressures between hot & cold
Find yourself a local plumber who is unvented certified (G3),get it serviced
then contact your water supplyer as some one has already said.
good luck.

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