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Central heating water black?

(8 Posts)
Qwebec Thu 28-Jan-16 16:56:52

Our central heating is a 60 YO hot water system. The water tanks (not sure are they connected?) were changed 2 years ago and wealso converted from mazout to electric for the energy source not long after.
Last week we changed some pipes and had to empty the water from the system.

The water came out black!

I've been looking up to see if it was fine and found opposit opinions. In North America (where I live) the sites seem to say it's no big deal put fresh water in basta or leave it as it is, it's normal.
On the french sites they said you need to get a specialist in to clean it properly, it can damage you system and limit it's life expectancy.
Some said change the water every year and others said keeping the old water is best (less oxygen in the water)

I'm quite confused, what is the best way to treat a hot water system so that it lasts for ever a long time? Am I supposed to do something about the black water?

Klaptout Thu 28-Jan-16 16:59:25

I don't know the answer but a poster by the name of Pigletjohn will certainly know, I hope he sees this thread.

specialsubject Thu 28-Jan-16 17:49:20

your phone has really minced this post - mazout? Basta?

but...the water will normally be black from corrosion products, and if it hasn't been been cleaned in years that's to be expected. Is there any corrosion inhibitor in the system?

are the radiators etc also 60 years old? What size are the pipes? IF you have tiny pipes powerflush won't work. You can get chemical cleaners which are gentler on older systems.

Qwebec Thu 28-Jan-16 18:16:07

I'm not in the UK so maybe I did not use the proper words to make myself understood sorry
Mazout:looked it up does fuel oil make more sense?
basta: that's it

We are only here since 2 years, they emptied the water when they changed from fuel oil to electric and we did it last week.

I think the whole system is the age of the house, the pipes the go around the house with hot water and the ones with the cooled water are about the width of a tennis ball and the ones that lead to the radiators were copper (they seemed newer but we changed them because they were badly installed and had oxidated) and are now partly PVC are about the width of a finger.

Corrosion inhibitor? I don't think we have this, how do we get it in the water? Do they sell in in hardware stores or is it a specialist job?
Chemical cleaners, can I buy it or do I need to get a pro?

Thank you so much both of you after a few hours of searching I was getting more and more lost.

specialsubject Thu 28-Jan-16 18:27:01

aha - apologies. Fuel oil does make sense, I only know 'basta' as 'enough'...

switching from oil to electric heating would be a really bad idea in the UK, but that obviously does not apply in the States where energy prices are very different. At least I hope so!!

again, UK only but corrosion inhibitor (Fernox is one brand) is sold in our hardware stores and you just tip it into the system through a header tank or other access point. Don't do that until it is cleaned though. IMPORTANT: check what the situation is with this and cleaner now that you have plastic pipes as I only know about copper.

the chemical cleaners are also sold in hardware stores. If you are able to drain the heating yourself then you can use it. The idea is that you put the cleaner in, leave for a time from days to weeks, then empty it out, refill the system, empty again and then refill. You do need to know your system and where the drainage points, but as you've been changing pipes that doesn't sound a problem. Hope that helps.

minipie Thu 28-Jan-16 18:35:39

Yes, sounds like you have corrosion from the inside of your radiators. this will build up in all systems over time, slower if you add corrosion inhibiter to the water. It's not a disaster but will reduce the life expectancy of your boiler.

Here in the UK plumbers would, I believe, recommend they do a power flush or magnacleanse to get rid of most of the corrosion. then you can install a magnet thingy near the boiler to "catch" future corrosion, and put corrosion inhibitor in the water.

Qwebec Thu 28-Jan-16 19:19:13

I'm in Canada and where i live electricity is relatively cheap but petrol, diesel and fuel oil are heavily taxed, I split my heating bill in half by switching.

Ok so I need a cleansing product that is safe for PVC, a corrosion inhibitor and a magnet thiny grin.

Fantastic! I was dreading that since no one seemed to have done it in 60 years the pipes might be in a worse state than I initially thaught!

Waah!I'm relieved I thaught it would be an other expensive repair.

I'm never sure how to say thank you on MN, the is only so many ways and I keep repeating myself, but you all have my eternal gratitude and lots of internet cake
cake cake cake


specialsubject Thu 28-Jan-16 19:47:22


oops, forgot the magnet thingy - it's a Magna Clean here and it really is a great idea. We have a 30 year old system with a new boiler. Gave it a chemical flush and had the magna-clean installed. Loads of gunk for the first month with emptying almost daily. Now - almost nothing. It can be done.

educational re fuel tax - I've learned!

hope the fix goes well.

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