Rads expandin ????

[Sanke]

Hi all
Both my brother & father had Ferroli combi boilers fitted about two years ago. Both systems were flushed prior to installation. They are both now having problems with filters inside the boiler blocking (pressure on my brothers fluctuates from 0.5 to over 3bar) and have been told that the rads are now getting hotter so expanding more and so letting rust/crud etc flow around the system and hence into the boiler. Plumber who fitted them now wants to reflush & charge £350
Has anyone had experience of this ? Is this normal after a combi has been fitted on an existing system ?

 

[buffy27]

Hi all
Both my brother & father had Ferroli combi boilers fitted about two years ago. Both systems were flushed prior to installation. They are both now having problems with filters inside the boiler blocking (pressure on my brothers fluctuates from 0.5 to over 3bar) and have been told that the rads are now getting hotter so expanding more and so letting rust/crud etc flow around the system and hence into the boiler. Plumber who fitted them now wants to reflush & charge £350
Has anyone had experience of this ? Is this normal after a combi has been fitted on an existing system ?

don t know much about the spec of that boiler [very few combi s in ireland]..but there is rust forming most likely with the arrival of the new boiler so issues with water reacting with metal is the source of all evil.the components of the boiler may lend to this ?? not certain[the combi lads will know though] were the old boilers swapped for a similar complications... [oxygenated water causing havoc...]
the expansion of the rads??? don t get that....it would be minuute dimensions from the previous temp. water used on the old boiler.i am interested in the outcome of this one!!

 

[stevetheplumber]

Hi all
Both my brother & father had Ferroli combi boilers fitted about two years ago. Both systems were flushed prior to installation. They are both now having problems with filters inside the boiler blocking (pressure on my brothers fluctuates from 0.5 to over 3bar) and have been told that the rads are now getting hotter so expanding more and so letting rust/crud etc flow around the system and hence into the boiler. Plumber who fitted them now wants to reflush & charge £350
Has anyone had experience of this ? Is this normal after a combi has been fitted on an existing system ?

obviously not powerflushed properly the first time rads should have been hammered to remove any rust

 

[Kip]

obviously not powerflushed properly the first time rads should have been hammered to remove any rust

Not true, rust can occur again over two years, what rust is, is a reaction isnt it. You remove any loose partings of rust the reaction is still happening, over two years more rust is bound to flake from the inside of rads and pipework so it has nothing to do with it being flushed properly or not because it may well of done.

 

[radswilldo]

How old are the rads, are they panel or convector?

 

[stevetheplumber]

Not true, rust can occur again over two years, what rust is, is a reaction isnt it. You remove any loose partings of rust the reaction is still happening, over two years more rust is bound to flake from the inside of rads and pipework so it has nothing to do with it being flushed properly or not because it may well of done.

a properly flushed system which is sealed and filled with inhibitor as it should be wouldnt rust in 2 years theres three nails in a jar of inhibited water in my localmerchants have been there several years with out rusting

 

[P4ULT]

just a thought you say the pressure fluctuates from 0.5 to 3 bar could it be the expansion vessel needs recharging.

 

[migoplumber]

pault has it right, the expansion vessel needs checking/replacing before you do any more flushing.
whilst you may have rad rust issues, they do not relate to the problem you currently have and i come accross on a weekly basis.

 

[Kip]

a properly flushed system which is sealed and filled with inhibitor as it should be wouldnt rust in 2 years theres three nails in a jar of inhibited water in my localmerchants have been there several years with out rusting

Yeh but thats just sat there, not heating up, not moving. As things move and heat up reactions happen, the inhibitor is to help 'prevent' it.

 

[Plouasne]

If the iron (nails, radiators, etc) are in water without FREE Oxygen, there will be very little rusting, hence the reason for putting inhibitor in the heating circuit, once the free oxygen in the water has been driven off, and vented, there will be very little rusting

Curtsy of Wikipedia

Iron corrosion

For iron rust to occur the metal has to be in contact with oxygen and water, although chemical reactions for this process are relatively complex and not all of them are completely understood, it is believed the causes are the following:
Electron transferring (Reduction-Oxidation)
One area on the surface of the metal acts as the anode, which is where the oxidation (corrosion) occurs. At the anode, the metal gives up electrons.

Electrons are transferred from iron reducing oxygen in the atmosphere into water on the cathode, which is placed in another region of the metal.

Global reaction for the process:

Standard emf [disambiguation needed] for iron rusting:

Iron corrosion takes place on acid medium; H+ ions come from reaction between carbon dioxide in the atmosphere and water, forming carbonic acid. Fe2+ ions oxides, following this equation:

Iron(III) oxide hydrated is known as rust. The concentration of water associated with iron oxide varies, thus chemical representation is presented as . The electric circuit works as passage of electrons and ions occurs, thus if an electrolyte is present it will facilitate oxidation, this explains why rusting is quicker on salt water.