Cleaning central heating with partial plastic piping ?

27 Jul 2006
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United Kingdom
I will soon be replacing some radiators and then plan to run a cleaner like X400 through the system
I’ve just checked, and it looks like my Builder chose to use some plastic pipe for the long run to the radiators in our extension rather than copper (in the ceiling, not down to the actual radiator, of course)
I’m assuming therefore, that there are some plastic to copper push fit connections in the roof somewhere
Sentinel X 400 states it’s okay for plastic so am I safe to assume that the push fit connections won’t be caused any issue running it through the system ?

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Lot of people use plastic pipework now due to ease of installation. Especially new build where copper pipe theft can occur when site unmanned. Unless you specify copper pipework at the build stage. Prefer copper myself due to longevity . Mice and rodents have been known to chew on plastic, especially out in the sticks. Sentinel x400 should be fine. Might be an idea to see if your pipes are clipped properly and insulated. I have worked on heating systems with a mixture of copper and plastic pipe, and the plastic pipes have blocked due to old radiators deteriorating and sludge in the system. Had to replace the plastic with copper to solve the problem.
Thanks for the comprehensive reply, @Andy165
I managed to pull a spotlight down when I understood the route the pipes would take and yes they are lagged, but as they appear to cross timbers, I don’t think they look to be clipped from what I can see which is limited


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Meant to say, this was a 4x4m extension on the back of our house, so wasn’t a new build house
It was 10 years ago, but I’m still a little bit annoyed that the builder didn’t ask as like you. I’ve preferred copper all the way wasn’t Hard up for 30 quid of copper
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Fire away, no issue with using cleaner and plastic. Just remember to flush it clear really well and then use a good inhibitor.

Any other reason to clean the system other than just changing the rads?
Thanks @Madrab
The boiler is a little noisy when running and some of the radiators do take a while to warm up also
There was a leak that I only found recently which was the reason why my pressure kept dropping (behind tf1 where it connects to the return, fitted by plumber in a really awkward place when boiler went in) so it’s not had inhibitor in for some time as a result (my bad)
So thought a good time to give it a clean too as will need to do some pipe work also

Was planning to use x400 rather than x800 unless anyone thinks there’s a better chemical to use ??
The reason for asking is a system should really only be cleaned if the system condition warrants it. If the system water is anything but straw coloured or cloudy then it may need cleaned but if it isn't then cleaning should be avoided as it resets the natural balance that CH systems can reach.

X400 is fine, just give it a week in a scheduled running system.
Thanks again @Madrab
Definitely not straw coloured as mentioned due to a lack of inhibitor so think it warrants it
So x400 mentions leave in system for 3-4 weeks I think
I assume anything up to that time is fine then yes , and running it around daily ?

I left X400 in mine for 2-3 weeks. 25+ year old boiler.
Too long and it stops working I believe.
Drained (very dark), filled with water, ran for a few hours, drained (straw) and then refilled with X100 inhibitor.
Also fitted a magnaclean on the boiler return.

Possibly worth removing and flushing the rads you are not replacing as well.

My understanding is X800 more suitable for pros.
More aggressive. Works faster. Avoids revisits for plumber/heating engineer.
thanks @mcprinter
Any thoughts or preference between the cleaners from fernox sentinel and Adey or are they all much of a muchness ?
I’ll be doing the slower approach and not power flushing
thanks @mcprinter
Any thoughts or preference between the cleaners from fernox sentinel and Adey or are they all much of a muchness ?
I’ll be doing the slower approach and not power flushing

No idea on the cleaners sorry. Probably all similar.
Screwfix had an offer if I bought two Sentinel products so went for that.
Seemed to work for me. Pretty sure my old boiler is quieter.

Doing it yourself, you can take your time.
I parked Mrs Mc in the lounge with an electric oil rad. :)
Will definitely be taking my time as 4 new radiators to fit so some new pipe work needed before topping up to test before banging the cleaner in
Will advise my better half to stick a couple of extra jumpers on just in case
I assume anything up to that time is fine then yes , and running it around daily ?
Yes, run it for a couple of weeks, then drain and flush, you can always repeat it if necessary. Cleaners is usually a personal preference - X400 is fine. Get yourself a little booklet of litmus paper and test your mains and then make sure once the system is flushed and clean that the system is PH neutral.

A mag filter is always a good addition and helps to keep things clean after the fact as there will undoubtable be some residual solids floating about and the filter should catch them.
Thanks @Madrab for the advice on the paper tests…good call
Do you have a preferred cleaner ?

I’ve got a fernox tf1 already although it’s been fitted in a mega awkward place and was the source of needing to constantly top up the system due to a leak where it connects to the pipework and the nuts are virtually impossible to get a spanner on

I got it done somehow and replaced the rubber seals which were knackered but not convinced it won’t leak again at some point
I’ve got a fernox tf1 already
Apologies, missed that comment. No preference no, I've used a few, X400 is perfectly fine.

TF1 - if it's the black fibre plastic conical one then change it, they can be a nightmare. The Omegas are good filters, Spiro MB1's or any of the other metal bodied filters are my preference. I don't like the fibre plastic bodied filters.

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