Overall based on 12 reviews
Recommended by plumber
PracticalLawyer, 2. May 2014
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This sentinel 400 was recommended to me by the heating engineer who had come out to replace a broken boiler pump. I was advised that there was too much rubbish (he didn't actually use that word!) in my heating system. It was simple to administer and I now look forward to it doing its job in sorting out my sludge!
Give it time
Rayzor, 29. Sep 2013
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Left this product in systen for two weeks and it made a marked improvement to heating system. I gave cool spots in radiators a few taps with rubber mallet to help loosen sludge and after a week they had gone.When I flushed sytem out there was a good amount of black sludge came out. Just give it time.
De-sludged!
RIck100, 27. Apr 2013
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We had a noisy boiler, Our plumber fitted a new pump and suggested we de-sludge. I am a bit sceptical about such things but thought I would give it a try and bought two bottles of X400. With trepidation, we drained some water off, poured it in and crossed our fingers. It's 3 weeks since we put it in and the system needs draining down again but it's worked a treat. It took a few days but the boiler is now unbelievably silent so I'll be following up with X100 & X200 to complete the job.
Did not work for my system
Neilb1898, 9. Mar 2013
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Hi I constantly have problems with sludge in my system in spite of using gallons of sentinel products throughout the last few years. I have power flushed the system 4 times in the last three years have fitted at least 4 pumps and as many Mid position valves, changed all the downstairs pipework to plastic the latest sequence of attempts was to power flush over 2 days using sentinel X800. This seemed to work well with the extra push provided by the power flush pump but as soon as I went back to the normal pump I was unable to get a proper flow once again I have now put in some X400 and still so far 3 days in the circulation is no better. So I have no confidence in any of the sentinel products, I always put inhibitor in and have had an Addey Magna clean filter in for all of the 3 years yet I still get pump & valve failures due to sludge. Neil
Sentinel X400
Deckindad, 24. Jan 2013
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I purchased this product to disolve a sludged microbore system which could not be powerflushed. I double dosed and found that the system during it's cleansing had already started to perform better.
Works great for me
PigletJohn, 18. Dec 2012
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It must vary according to the kind of water and sediment you have, but in my experience it is fantastic at loosening black iron oxide sludge from old open-vented systems. On one 30-year-old system I drained and gave it plain water flushes and fitted a Magnaclean first, and waited until the water appeared to be clear. I then added X400 and within days was getting enough sludge out to fill several jam-jars. I later converted it to fully-pumped and got a lot more out of the HW circuit that had not been dislodged by the gravity flow. Radiators heated much more quickly and evenly, and the boiler was quieter - unsurprisingly when you see the amount of sludge that came out. The boiler was still bonking due to limescale, and I subsequently added X200 which took some weeks to quieten it and wash away the hard limescale.. The customer who says he got little sludge out must have been lucky enough to have a relatively clean system. You can clean radiators more effectively if you close all but one so all the flow goes through that one to wash away the sediment. Then close that one, and open the next. This might take all day but I think improves the clean. If you have a system filter, keep emptying it at least weekly at first. You will be able to see when there is little new sediment appearing, and reduce the frequency of emptying. Very good price at Screwfix.
Definitely works given time
Markymarkmark, 28. Mar 2012
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We have a big 3 storey house with 18 radiators most of which are 20 years old. Simply added 2 containers of this to a partially drained system and allowed to circulate. It took 6 weeks over winter, running the system normally, for a change to be noticed in the poorly performing radiators. Drained the system completely after a few more days, flushed through for half an hour, filled and drained again, before adding 5l antifreeze/inhibitor plus one container of inhibitor and the difference is truly impressive. I have had to rebalance all the radiators since they were simply too hot upstairs and this has allowed the ground floor radiators to benefit from the balance of heat. We need the heating on for less time now and it is quieter and quicker to heat up.
Slight improvement
duncsuk, 1. Mar 2012
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Although my system was not blocked, I decided it was due a clean, as it was ~5 years since last done and the boiler had started 'hissing' a bit. Ran it for a couple of weeks in the system and although the water came out slightly dirty, I'm not convined this really helps clear the sludge in the bottom or radiators .. but would probably help clear a blocked system. System does seem better for it .. and now has Sentinel X100 and X200 in it.
Sentinel X400
Fatboy15, 26. Nov 2010
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I put this product into my central heating system and left it for the advised 28 days. I cleaned out system before re filling with Sentinel X400. After 28 days I drained it all down and guess what? the water that came out was virtually clear! My advice, dont waste your money on this product, it doesnt work. My radiators are hotter than they were but are still cold at the bottom meaning the sludge is still in there. Any increase in performance is probably down to the water flushing and the inhibitor I used FERNOX MB1
one that works
leebee, 3. Oct 2008
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Very easy to use, makes so much difference to the system, I dont get woken up with the boiler banging any more and the radiators are hotter. I had to turn the thermostat down too which will save me money.
cool stuff
harish, 18. Aug 2008
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do not economise here as this product is no nonsense
It worked for me
Carnaby77, 31. May 2008
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My CH had suddenly gone from OK to 'something wrong' within a week. A few days later with everything else shut down I could just get a single downstairs radiator lukewarm after an hour. Clearly there was a major blockage somewhere - big plumber's bills loomed. Drained system and refilled using X400. It said it could take 4 weeks - after that period there was almost no improvement. Then suddenly after a couple more days there was a dramatic change. Left it in for another week then drained and flushed. The contents were jet black! After multiple flushings the water ran clear and I refilled with inhibitor. No big plumber's bill.
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