CH inhibitors - what is the difference?

peca27 · 12 Jul 2006

Afternoon all

I've just been speaking to a plumbers merchants + I've mentioned that i've been having trouble with my diverter valve (got a Vaillant 828 turboMAX).

He reackons pretty much all combi's get this problem sooner or later. His advice is to drain out the CH system + refill with inhibitor annually. Ok sounds fair enough, with all the crap floating around the CH system every time the valve switches to + from CH + HW your gonna have that very same crap eventually clog up the valve.

Question is i've seen a few types of inhibitor, what is the difference between the X-100, X-200, X-300 etc. They're all similar price, is it to do with the no. of rads + size of boiler?

He also said the best inhibitor out there is K100? does it make a difference which one u use........as in my case i've got a Vaillant 828.

Cheers in advance for any advice

Beans-on-Toast · 12 Jul 2006

The X range that you mention are all for different purposes.

X100 is the Inhibitor.

What do you want to achieve ?

Are you going to flush the sytem before you add the inhibitor ?

If so, you could add X400 Sludge Remover to the system at least 2 weeks before draing and refilling with X100 Inhibitor. The C/H needs to be on for this process to have any effect.

Installing a magnaclean filter may also be beneficial.

Agile · 12 Jul 2006

No amount of chemicals wil repair your boiler !

The diverter valve has failed ! It does this on virtually every boiler of your model usually between 18 and 36 months, just outside the guaranty.

The moving ball swells and sticks in either position.

The replacement has a "rugby" shaped ball and is less likely to stick.

Tony Glazier

Beans-on-Toast · 12 Jul 2006

Once you have had the combi fixed, it would be a good idea to clean out the system...............

peca27 · 13 Jul 2006

Thanks for replies

OK - I'll get the sludge remover in, run it daily for a few hrs, empty the system after a few weeks + refill with an inhibitor inc.

Agile - when u say the replacement has a 'rugby' shaped ball, what to do u mean by replacement? Are u saying that the replacement diverter valve i put in a few months ago has that 'rugby' shape + that all valves on the boiler (when installed) have the 'football' shape?

Beans-on-Toast - what is a magnaclean filter + how much would it cost approx?

Agile · 13 Jul 2006

The original diverter with round ball had "side holes" which were about 4 mm diameter.

The later type with the "rugby" ball had larger side holes about 6 mm.

I thought that was definitive until a few weeks ago when I hesitated to change one with a larger hole however as it was sticking I did change it only to find that although it had the larger hole it had the original round hole.

The answer is that MOST original types had the 4 mm side hole and ( so far ) ALL the rugby ball later ones have the 6 mm hole.

The question will arise what sixe side hole has your replacement got and what shape is the ball?

Did you buy it as current stock from a spares dealer?

Its easy to identify the diverter sticking because in one of the two modes you get cold DHW but the radiators heat up.

The other mode is DHW hot but no CH. But this is not noticed when the weather is hot and the CH is not in use.

Tony

Water Systems · 13 Jul 2006

peca27 said:
Afternoon all

I've just been speaking to a plumbers merchants + I've mentioned that i've been having trouble with my diverter valve (got a Vaillant 828 turboMAX).

He reackons pretty much all combi's get this problem sooner or later. His advice is to drain out the CH system + refill with inhibitor annually. Ok sounds fair enough, with all the rubbish floating around the CH system every time the valve switches to + from CH + HW your gonna have that very same rubbish eventually clog up the valve.

Question is i've seen a few types of inhibitor, what is the difference between the X-100, X-200, X-300 etc. They're all similar price, is it to do with the no. of rads + size of boiler?

He also said the best inhibitor out there is K100? does it make a difference which one u use........as in my case i've got a Vaillant 828.

Cheers in advance for any advice

Don't go to plumbers. Go to a heating engineer -there is a difference. You don't put in inhibitor ever year.

Fit a Magnaclean filter on the CH return first as it collects solids, use Fernox DS40 cleaner, flush twice, and install X-100 inhibitor.

Clear the filter after a week and each week until clear then once a year. Change inhibitor once every 4 years - can be poured into the Magnaclean filter, in two goes.

The 3-way valve playing up is a different problem, but a clean system would makes running matters better.

conorius · 13 Jul 2006

Vaillant should consider fixing these when in resonable proximity to warranty , as the damage to their previous excellent repution has got to be more expensive. I assume they intend to try keep the badge of " Excellent reliablilty" or is one years margins that important.

Agile · 13 Jul 2006

Vailant have a further problem with the 824/828 models.

After having the diverter valve replaced at about 18-36 months the unfortunate owners have/will find that the expensive air pressure switch fails after about 30 months.

Again the original part has been "modified" but its still as expensive.

I dont instal boilers as I repair them.

People choose Vailants because they think that they are reliable. My local Parts Centre tell me they sell about 10 diverters every week, thats 520 a year!

Tony

simond · 13 Jul 2006

There was a rash of air pressure switches but out of the 400 approx Vaillant units we have fitted over the last 36months so far none of the diverter valves have failed - we know this because we give a 3yr warranty.

In Germany it is considered not good form to use inhibitor because their systems are usually sealed & leak free and the chemical treatment is known to swell up seals. Apparently inhibitor sells as well there as a Paddy Hopkirk dog guard in Korea.

I guess this could explain why the German tolerances have been on the tight side. Or it could just be that UK systems tend to be sludged up.....

Water Systems · 13 Jul 2006

simond said:
There was a rash of air pressure switches but out of the 400 approx Vaillant units we have fitted over the last 36months so far none of the diverter valves have failed - we know this because we give a 3yr warranty.

In Germany it is considered not good form to use inhibitor because their systems are usually sealed & leak free and the chemical treatment is known to swell up seals. Apparently inhibitor sells as well there as a Paddy Hopkirk dog guard in Korea.

I guess this could explain why the German tolerances have been on the tight side. Or it could just be that UK systems tend to be sludged up.....

I have seen many sealed systems last well without inhibitor. I know of one system that never had inhibitor from start and now is 27 years old and not one rad has blow and the water has not been changed. It was a soft water area, and the old Stelrads were thick metal.

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CH inhibitors - what is the difference?

Water Systems

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