Renewing inhibitor - thoughts

[Knappers]

So I get the question occasionally
"Should the inhibitor be replaced on a regular basis?"
And I'm not sure exactly how I feel about it.
Yes if you've got an open vented system, lost water, had work done or have to top up the system occasionally or are not sure of any of the above.
However otherwise my general opinion is ...no
Why drain the system and introduce lots of fresh oxygenated water only to treat it, surely in a sealed system with repeated heating and agitation from the pump there won't be much corrosion happening.

Apart from the manufacturers of inhibitor does anyone reccomend regular dosing or include testing inhibitor levels on a service?

Happy to be educated here...

 

[Deleted member 32524]

I suggest every 3 to 5 years. Nobody does it apart from one or two.

 

[king of pipes]

Every 5 years is my advice . Kop

 

[Knappers]

Can't hurt I guess.
Would you just dose, drain and dose or make a job of it and do a chemical flush with sludge remover or similar?
I don't push it and am usually a bit unenthusiastic when asked.

 

[Welder]

You could always do a test!
Adey do an analysis test that's actually quite cheap in the scheme of things which will give you a broad chemical analysis of the system constituents.
Once you know those you can choose to do something or nothing but at least the customer knows...

 

[Knappers]

I wish I was that professional

 

[townfanjon]

This thread will cause problems with us Viessmann guys lol . They dont want it in their boilers .

 

[Ric2013]

The inhibitor manufacturers say it doesn't wear out too!

'Although Sentinel X100 Inhibitor provides long-lasting protection for systems, unforeseen circumstances can sometimes compromise the level of inhibitor in the system – there may be a hidden leak or your customers may remove a radiator to decorate and then top up the system with fresh water.'

Which, it would seem to me, means that if no water is lost then it'll last and last. Evaporation from an uncovered (surely not!?) F&E is possible, but only if the important parts of the inhibitor are prone to evaporation. My hunch would be to say they are probably less volatile than the 99% of water in the system.

For what it's worth, I witnessed an F&E with no lid and no ballcock dry up entirely. The loss of a half-full cistern took around a year, so that's 2-3 gallons (9-13.5litres) a year. If the inhibitor was more volatile than the rest of the system, then it's been lost, but if it evaporates at the same rate as water, then that system only lost a small percentage of the inhibitor. Of course, if the inhibitor evaporates less, then all that was lost is distilled water.

I suppose it is worth considering that as the water lost by evaporation will leave behind its dissolved solids, the inhibitor will have an increasingly hard job to do as the top-up water adds yet more dissolved minerals, thus making the system water increasingly hard.

 

[Welder]

This thread will cause problems with us Viessmann guys lol . They don't want it in their boilers .

You're right. That issue, seems more to be about the pathways in the hex than anything else. Hexs are getting so small (cos it's the major cost in a boiler) anything and everything blocks it and of course with many being ali they are not very robust mechanically with a hostile water in them. The better boiler manus seem to be learning lessons and finally settling for st/st.

The dichotomy there tho is plastic pipe. As barrier pipe is gas permeable you are always letting air into the system and of course we all know oxygen kills systems. Even when deaeration is fitted it simply means one is always topping up with fresh oxygenated water.

 

[Jones82]

Why would you not want inhibitor in the system? What’s different about Viessmann boilers? Surely the inhibitor reducing corrosion and hence sludge can’t do it any harm. Also it doesn’t say not to add it in the manual in fact something along the lines of water hardness should be considered and an appropriate treatment added?

 

[townfanjon]

Why would you not want inhibitor in the system? What’s different about Viessmann boilers? Surely the inhibitor reducing corrosion and hence sludge can’t do it any harm. Also it doesn’t say not to add it in the manual in fact something along the lines of water hardness should be considered and an appropriate treatment added?

Ive been through this with them, they just want clean water in their boilers , no inhibitor is used in the boilers in Germany .
I have just put some in a pals 100 because the towel rail was rusting and infecting the rest of the system ,I am hoping it will help .
Apart from that I dont put it in .

 

[Jones82]

That’s surely nonsense, most towel rails, designer rads etc are European made, they must have similar systems to us. So just as likely to rust

Reason I’m interested is we’re refurbing a house with an existing vitodens 100. The house is all ideal school radiators the big old cast iron type and I wouldn’t even think of not putting inhibitor in

 

[Knappers]

I think there's a bit of a legacy issue here, old vented systems especially those with microbore.
Now with sealed systems is it such an issue, it's an easy sell but prob not the problem it's made out to be imo.
Side note - I'm yet to see any decent studies or scientific proof that scale reducers work and their effective range but they're required by many manufacturers?
Do think it's about time boiler manufacturers started building-in magnetic filters tho

 

[Knappers]

That’s surely nonsense, most towel rails, designer rads etc are European made, they must have similar systems to us. So just as likely to rust

Reason I’m interested is we’re refurbing a house with an existing vitodens 100. The house is all ideal school radiators the big old cast iron type and I wouldn’t even think of not putting inhibitor in

Would be interesting to compare two similar systems, with and without after say 5 years.
The biggest headache I get is with flake in the system, when i get there i don't know if it's due to poor cleansing of the system from new or if some Muppets added sludge remover and left it...