Chemical Flush or Power Flush of Heating System?


I’m hoping for some experience or guidance here to help me with my property problem:

I’ve got a heating system with a gas boiler with a mix of microbore and more normal pipes. This seems to be a legacy of Irish late 70s, early 80s build with original pipes, and a few pipes due to a mid-00s extension that look of more usual diameter.

I’ve a LOT of sludge in my radiators and system. I’d like to clean it out but I’ve been advised that the standard “powerflush” would not be suitable with microbore. That it will just clog the system, and/ or pressure rupture my system.

I’ve gotten further advice that it IS ok to do this powerflush as long as you have a chemical additive to the water put in a week or so in advance.

I’ve gotten still more advice that just a low velocity chemical flush (after chemical has been in system a week or two) is the best option.

Has anyone been through this situation in a recent house move, refurb project - and if so, have you any advice to offer?

Or if anyone knows a good specialist in Dublin on this I’d really appreciate it.

Early “Googling” on this suggests there are a lot of chancers out there who could do more harm than good to my heating system! 8-


Interested in this exact same thing as well!


I don’t myself know the answer to your question. However I engaged a gas installer fairly recently who is seen as an expert in all aspects of gas installations (he used to run an online forum in this area for one thing). He carried out a radiator system flush for me using some specialist gear. I must confess that I do not know if the flush included some chemical elements as I was more focused on what he was doing in terms of the new boiler and heating controls that he was installing and the flush was an afterthought. However he is an articulate person who is well versed in all areas of boiler installation and I think that he could be a good source of advice. Also as someone who lives outside Dublin but carries out a good deal of installation work in Dublin, his quotes seemed to be cheaper than installers here which was a bonus. I can send you a PM with his details if you like.


Onioneater - that would be appreciated. Thank you.

I’ve heard some bad experiences of systems being fully blocked and insufficiently cleaned, so I was looking for any seasoned-Pinsters experiences/advice.


I’ve just heard one advertised on de radio.

Coincidence ?


Big data is listening everywhere!
There are a lot of companies out there offering variants of these flushes.
I guess I was more hoping to hear Pinsters experiences, or things to avoid doing that don’t work well, and approaches that do work well with a sludge-filled microbore system.


If your house was built before the mid 70’s it’s possible you have some gunmetal pipes, these are thicker and feel ‘heavy’ to the touch, unpainted ones are black or a very dull blue, and what you refer to as microbore might be copper. Gunmetal corrodes from the inside as is more prone to this if parts of it are buried in concrete. Ironically flushing or changing the water causes faster corrosion by introducing more oxygen into the system.


Thanks for the info. Thankfully it looks like I have very small bore copper pipes down to a few radiators. Doesn’t look like I’ve gun metal at all - which helps.