Problems with leaking Megaflo

aitch-aitch

Every 4 years or so we have had our Megaflo replaced as it starts leaking from the area where the imersion heater element is.

We get our water from a borehole and have to treat it with chlorine to remove very high levels of manganese and iron. According to the plumber something in our water is attacking the metal around the seals in the tank (it could be the manganese if it's not being removed properly or perhaps the chlorine?)

Anyway so far we have managed to get Heatre Sadia to replace the megaflo free of charge but I'm not convinced they will do that again.

The leak started again this morning and the plumber is coming out but he is already making noises that we won't get a free replacement and he doesn't think there is much he can do. Hence this post....

1. Is there an alternative to a hot water tank (we don't have mains gas and currently heat the house / water using an oil fired Stanley (similar to an Aga). I'm thinking on the lines of instant hot water / combi boiler but as I said we can't get mains gas.

2. Is there a better hot water tank anyone could recommend.

3. Any advice appreciated.

Thanks in advance.

MX5huggy

You can get oil combi boilers http://www.grantuk.com/products/oil-fired-boilers/ are one supplier. Not that I think this may be a good idea your water could destroy a combi in double quick time.

Maybe a copper cylinder would be better?

Maybe your water needs more testing and treating, soften it?

aitch-aitch

MX5huggy wrote: »

You can get oil combi boilers http://www.grantuk.com/products/oil-fired-boilers/ are one supplier. Not that I think this may be a good idea your water could destroy a combi in double quick time.

Maybe a copper cylinder would be better?

Maybe your water needs more testing and treating, soften it?

mmm I was thinking maybe copper cylinder as we don't seem to have any problem with the pipes leaking.

alanobrien

Megaflo are made from duplex stainless steel so manganese or chlorine alone are not causing your problem. I suspect its cholide iron attack initiating crevice corrosion, this is quite common with heat exchangers etc in industry, i see it regularly in my job. If my suspicions are correct then a copper cylinder will resolve the problem.

aitch-aitch

Thanks for your response to my post about megaflo. The plumber came on Tues and has shown me the damage.

Basically there was what looked like rust around the hole where the immersion heater fits into the tank and also underneath the rubber seal on the metal of the immersion heater itself. The rubber seal itself was not damaged. When he cleaned this up there was a small amount of pitting on the metal. Do you think that fits in with your diagnosis?

aitch-aitch

alanobrien wrote: »

Megaflo are made from duplex stainless steel so manganese or chlorine alone are not causing your problem. I suspect its cholide iron attack initiating crevice corrosion, this is quite common with heat exchangers etc in industry, i see it regularly in my job. If my suspicions are correct then a copper cylinder will resolve the problem.

I have googled cholide iron and nothing comes up - does it have another name or did you mean iron chloride (sorry last did chemistry in 1986!!)

alanobrien

aitch-aitch wrote: »

I have googled cholide iron and nothing comes up - does it have another name or did you mean iron chloride (sorry last did chemistry in 1986!!)

I meant chloride ion attack. Out of interest i spoke with our chief metallurgist about this and he suggested either galvanic corrosion (due to the differential caused by the copper pipes) or crevice corrosion as per my first thoughts. Both types tend to initiate at high stress centres such as threads and flanges etc. some more info here;

http://www.corrosionist.com/what_is_chloride_stress_corrosion_cracking.htm