"Quality product used on its own with a power flush or added to the system with X100, brings a scaled/blocked boiler back to life ( unless the boiler is beyond repair), I personally wont use any other product."
"It is not as quick as the acid cleaners, but is much easier and safer to use. I have had damage to skin and clothes from spillages of acids, and you have to rinse and flush them out very thoroughly.
X200 is mild and seems harmless, and you don't have to drain it out or rinse it - you leave it circulating in the system permanently.
It works faster if you add it in summer when the radiators are all turned off, then it is more concentrated in the boiler HEX and hot-water system because it does not mix with all the water in the radiators.
It may take a month or two to achieve its best
You may need two bottles if the system is very large or scaly."
"Our boiler was tripping the thermal cutout and was only able to run a 15 minute on 15 minute off duty cycle because of it. I suspected it was choked with limescale and wasn't able to transfer the heat properly so I put a litre of this into the six radiator system and left it to work.
At first it seemed to have had little effect but after a few weeks it had really made a difference, now the system can run for a good hour and a half without issue.
Not exactly cheap but well worth it for the ease of results."
"I found this very easy to add into the heating system - Drain an amount of water from the system whilst isolating the header tank then add to the header tank and refill the system. So far it appears to be working well."