Cleaning / Flushing a Central Heating System - Advice please

[paulfromswindon]

Hi,

I have to replace the mid-position valve, and a couple of rusty rads in my system. Since the system (I suspect) has never been serviced in it's ten-year life, I want to take the opportunity to give the system a good clean-out.

What would be the easiest way to do this?

I'm assuming that I need to get a decent cleaner (anyone recommend a good one?), and put it into the system a few days beforehand. I may get some Fernox system cleaner, which would then have to be followed up with a neutraliser and the system flushed out twice. (or would the less powerful Superconcentrate Restorer do the job on a 10-year old system?)

What is the most efficient method of flushing out the system, in the absence of a power-flusher? Do I need simply to refill the system, run it for a while, then empty it again? Or it it better to attach a hose somewhere and get a more powerful flow of water running through to push the crud out? If so where would you usually tap into the system?

Advise would be much appreciated. Apologies if there is already a guide to cleaning heating systems out on this site, I haven't managed to find it yet.

Many thanks

Paul

 

[ArtfulBodger]

If you have rads going rusty then this is a very good indication of what your systems like inside. Throwing a couple of litres of chemicals and flushing through won't achieve much IMHO.

Hire a power flusher for £50 and be prepared to spend a day getting all the contaminates out of it.

Be aware that you must turn your open vented system into a temporary closed system while flushing.

 

[ChrisR]

Agreed. Flushing mayreveal other rusty rads. I've just changed ALL the rads on a sytem like that - they were all pretty dire. Rads aren't all that expensive though. (B&Q are pretty cheap!)

 

[paulfromswindon]

Thanks guys, I think I will hire a power-flusher - a couple of q's

1) Do you feel I should change all the rads, or just the ones that show signs of rust? The rusty ones look like they have rusted from the outside (not sure how though in a dry room). Except, that is, for one, which has a bad rust area running down from the bleed valve, which does kind of suggest to me that perhaps the bleed valve was seeping at some point. More to the point, if the water from the rad itself has rusted the outside of the radiator, I suspect there is no corrosion inhibitor in the system (The system is 9-10 years old, and I have no idea if it has ever been serviced)

2) Where in the system do you normally connect the power-flusher?

3) Should I still shove some cleaning chemicals in a couple of days beforehand?

Thanks for your help so far guys, much appreciated

Paul

 

[kevplumb]

1 wouldnt hurt
2 across the pump connections (remove pump first )
3 no

 

[oilman]

I'd say the answer to 3) would be "wouldn't hurt". A non-acid cleaner is a detergent type product that will get some of the debris into suspension. Put it in a couple of weeks before you flush. Don't put an acid cleaner in and leave it. Even the one used during powerflushing will take the zinc out of the surface of brass fittings.

 

[kevplumb]

good point oilman

 

[paulfromswindon]

Thanks very much for your help chaps, it's been really useful, and I'll be acting on your advice.

Cheers

Paul

 

[ChrisR]

Fernox "Heavy duty restorer" is best left a week or so and Sentinel X400 several weeks. They have "flocculating" agents to get the particles into suspension and "chelating" agents which are oxide grabbers which get what they can into solution. Plus a bit of Fairy liquid praps.

 

[ArtfulBodger]

Fernox "Heavy duty restorer" is best left a week or so and Sentinel X400 several weeks. They have "flocculating" agents to get the particles into suspension and "chelating" agents which are oxide grabbers which get what they can into solution. Plus a bit of Fairy liquid praps.

Fairy liquid? that rings a bell, isn't that used to try and remove stubborn air locks or am I thinking of something else?