Soft water and combi boiler

[danmickread]

Hi, i am no expert. I have some central heating knowledge, but i have bought a water softener and am reading many different articles/comments on filling your central heating system up with soft water. Some for and some against. I have a baxi duo tec 28 which has a combi care scale inhibitor on the cold feed to the boiler.
Now Firstly does the combi care do the same job as a softener or at least try to, if so that would mean the central heating and hot water would be softened or not anyway?
I bought the softener as anyone does to elimenate limescale, so i assumed i would drain down and fill the central heating system with soft water as well in order to stop limescale build up in my central heating pipes and boiler. I then read that in no instance should soft water be used to fill the central heating system up as soft water is more corrosive because of higher ph levels and increased levels of sodium, or something like that so its no good for your boiler. I then read that it is ok providing you use a corrosion inhibitor such as sentinel x100. So if i use hard water you get limescale if i use soft water i get corrossion correct? Which is worse.
What i am mainly confused about is if i install a softener but leave hard water in the central heating with inhibitors, or put soft water in the central heating with inhibitors either way soft "corrosive" water with no inhibitors will still pass through the boiler and pipes for my hot water. Is the correct?
Also inhibitors such as the sentinel are for use in indirect systems, is a combi boiler an indirect system, what does this mean?
Any help on this would be greatly apprecciated.
Thanks Dan

 

[REDSAW]

welcome,

what does your boiler man'ftr guide say?.

 

[stevetheplumber]

Hi, i am no expert. I have some central heating knowledge, but i have bought a water softener and am reading many different articles/comments on filling your central heating system up with soft water. Some for and some against. I have a baxi duo tec 28 which has a combi care scale inhibitor on the cold feed to the boiler.
Now Firstly does the combi care do the same job as a softener or at least try to, if so that would mean the central heating and hot water would be softened or not anyway?
I bought the softener as anyone does to elimenate limescale, so i assumed i would drain down and fill the central heating system with soft water as well in order to stop limescale build up in my central heating pipes and boiler. I then read that in no instance should soft water be used to fill the central heating system up as soft water is more corrosive because of higher ph levels and increased levels of sodium, or something like that so its no good for your boiler. I then read that it is ok providing you use a corrosion inhibitor such as sentinel x100. So if i use hard water you get limescale if i use soft water i get corrossion correct? Which is worse.
What i am mainly confused about is if i install a softener but leave hard water in the central heating with inhibitors, or put soft water in the central heating with inhibitors either way soft "corrosive" water with no inhibitors will still pass through the boiler and pipes for my hot water. Is the correct?
Also inhibitors such as the sentinel are for use in indirect systems, is a combi boiler an indirect system, what does this mean?
Any help on this would be greatly apprecciated.
Thanks Dan

your getting confused the water in your heating system isnt affected by lime scale its the hot water side that can scale up
all systems should use inhibitor in the heating water

 

[birdflue]

The combi care does not soften the water it just stops the scale falling out,
Fitting an ion exchange softerner will give soft water, this is not a problem on the cold supply to a combi as the hot water will be produced by the secondary heat exchanger which is stainless steel.
Soft water is corrosive to aluminium, some boilers have aluminium heat exchangers in which case the manufacturers dont recomend filling primary system with soft water
If however the boiler has a stainless or copper primary heat exchanger then filling with soft water is not an issue

 

[danmickread]

The combi care does not soften the water it just stops the scale falling out,
Fitting an ion exchange softerner will give soft water, this is not a problem on the cold supply to a combi as the hot water will be produced by the secondary heat exchanger which is stainless steel.
Soft water is corrosive to aluminium, some boilers have aluminium heat exchangers in which case the manufacturers dont recomend filling primary system with soft water
If however the boiler has a stainless or copper primary heat exchanger then filling with soft water is not an issue

Ok thanks, the earlier comment said that the CH isn't affected by limescale, why is this? And if so then there is no need to worry about putting soft water in the central heating system is there? There isn't soft water in it at the minute, nor prob in the majority of houses that live in hard water areas. As long as there is adequate inhibitor, it should be fine right?
One other thing isnt it everything that carrodes, not just aluminiun, for example your radiators as well thats why you get the black sludge build up in rads if no inhibitor. So on the DHW side with soft water through it doesn't that carrode pipes and fittings and stuff as well.

your getting confused the water in your heating system isnt affected by lime scale its the hot water side that can scale up
all systems should use inhibitor in the heating water

Right so hard water in the CH with inhibitor will stop all limescale build up, so its like having softwater in it anyway (in terms of no limescale) but with less corrosive properties.

 

[stevetheplumber]

the water in your heating system is recirculated and is basically chemically inert with the addition of inhibitor it becomes totaly inert causing no corrosion i know of open vent systems over 30 years old that have never had inhibitor which show very little sign of corrosion its all in the design

 

[Riley]

This thread has done a Lazarus I suspect that its sorted by now

 

[Dotty]

Unregistered eejit deleted.

Thread closed.