Black C.H. Water

[alba2]

I decided to get a professional in as I also needed a faulty thermostatic valve changed. It was stuck open.

He looked at the dark brown water, run it through his fingers and said there was no grittiness, and said that the system did not need to be cleaned. According to him his system also has dark brown water like mine. He said that this was probably due to the Fernox inhibitor which he said he could smell when he ran off water from the radiator to replace the thermostatic valve. In his opinion it therefore did not need topping up.
I am confused now. Is he correct?

 

[phod]

It doesnt take much magnetite at all to turn the water jet black. You need to run the water out of the filter into a clear container and let it stand for an hour. See how much magnetite settles out of the water. Then shake the container and see how black it goes again. Its probably very fine magnetite and thats showing the filter is doing its job - collecting any circulating magnetite.
Now if black water is coming out of another drain off point on the system then that may be a bit more worrying.
Try draining a cupful out of another drainoff or out of a radiator bleed point and see if that is black too.

 

[alba2]

Phod thanks for your reply.

The colour of the water from the radiator was also back. The c.h. engineer had to drain the radiator down to replace the stuck open Danfoss thermostatic valve, so it was very obvious.

Everything I have read said that black or dark brown water is a problem. The engineer ran a sample I had collected through his fingers and said there was no grit so it was ok to be that colour. He said that Fernox could produce black/dark brown water, and that his own c.h. system was that colour. He obviously also saw the black/dark brown water draining from the radiator. It drained down and did not run clear. It was black/dark brown right to the last drop!

I am now totally confused. Here is a professional saying that there is not a problem, yet I read on the Internet and on various threads on this site that it is! Is he plain wrong or is there room for interpretation, ie the water can be black/dark brown as long as there is no grit in it?

 

[phod]

The black water is probably indicative of corrosion that happened but has now stopped. Your PRV problems and rads off for decorating would explain that. However theres a possibility the pH and conductance of your system water is outside the ideal range and is contributing to ongoing corrosion.

Without being able to test the water quality its going to be cheaper for you to just get it back to a baseline ie clean and re-inhibit. Add a chemical cleaner (x400) for a few weeks, then thoroughly flush it all out, and I do mean thoroughly. You drain it down. fill it again, let it circulate for 30mins then drain it out again, if its not completely clear water coming out down to the last dregs you repeat until it is - for your system it might take a good while if the filter is your only drainpoint as you may well have to crack open the nuts on the valves/rad tails of lower radiators to drain them into a container.
If you can work out a way so that mains water from the filling loop is directed through each rad in turn (by isolating boiler and other rads) before exiting at the drainpoint then all the better. Its no use if the water enters the filling loop travels 50cm and exits at the drainpoint...

Then finally fill it back up adding the inhibitor. Then at least you'll know the baseline of your system and what inhibitor it has in and how much. Then check the filter at increasing intervals - dont keep tinkering with it, just drain a pint after a month then 6mths then yearly. A well cleaned and inhibited sealed system should stay that way for a good few years if left undisturbed.

One last really important thing, if you are regularly topping up the pressure in the system then you have a leak and that should be fixed as a priority - the repeated introduction of aerated water into the system causes lots of corrosion.

 

[alba2]

Many thanks for your detailed reply Phod.

I am not regularly topping up. The pressure only drops very slightly over 6 months, ie about 0.25 bar. When I do top up at 6 months it is only a quick squirt.

 

[RTFB]

Refer to the boiler Installation Instructions. Your boiler manufacturer recommends filling a clean system with potable water and no inhibitors.

 

[alba2]

"potable water and no inhibitors" - that has really confused matters now!! RTFB.

This is a German manufactured boiler, and I have read somewhere that they don't use inhibitors in Germany, but they use some sort of deoxygenating system instead. I don't have the space to install such a piece of equipment because the boiler is in a confined kitchen cupboard space, and the UK norm seems to be the use of inhibitors.

The Spirotech MB3 filter will filter out any magnetite but I obviously have to protect the radiators from rusting. Sentinel inhibitor says that it can be used with any metal, so where is the harm to the boiler heat exchanger etc?

I will now have to get in touch with Viessmann UK on Monday and clear this up.

I really wanted to ensure the longevity of this recently installed system due to a really bad experience with plastic pipework in a new build, back in 1999. I also like to do things correctly, and what should be straightforward seems to be getting more complicated.

I have black/dark brown water, yet the system was supposed to have been dosed with inhibitor.
This week a c.h. engineer said that this dark water is not a problem, he could smell the inhibitor, and his system is just as dark.
I am now being told I should not use inhibitor with a Viessmann boiler.
I also note from scanning threads on this site that some c.h. engineers have said that they don't believe inhibitor is a good thing.
This is all so muddied (pardon the expression) and confusing! Where do I go from here?

 

[Doggit]

It'll be interesting to get Veismans views, but I've always suspected that they say no inhibitor, because being a German company, German system are all steel pipework, so no copper to steel corrosion issues. Check that out for me Alba.

The water in the system is going to be "pottable"by virtue that it comes from drinking water we all enjoy, so the final question is the inhibitor, and I think you're over worrying the situation.

It's more than possible that there is inhibitor in the system, and you're confused between the brownish colour of the fernox, and what you expect it to be, but at the end of the day, as Phod has said, add the x400, run it, drain and refill the system a couple of times, then fill with inhibitor. Believe me, you need the inhibitor in English system, so leave it out at your peril.

 

[alba2]

Thanks Doggit for your further comments. I may appear to be over worrying and I will admit I am a belt and braces kind of guy, however, we had a really bad experience in a previous new build property (1999) which does induce an element of concern. It was a plastic piped system and within a short period from moving in we had problems, as did all the neighbours in the complex. Hardly a year went by without 3-4 visits p.a by c.h. engineers due to our system constantly breaking down. Despite inhibitor it eventually clogged up and we had to get sections of pipe cut out and replaced. This was HEP pipe with an alleged barrier.

I always insisted on copper pipe after that. With this new build we had no option. All the properties had already been plumbed with HEP 2o piping. I hoped that the coating technology had moved on, but just in case, I actually bought the Spirotech filter and asked the builder to install it, as well as asking inhibitor b added and topped up as necessary.

We had numerous other problems with the new build and the system was drained and altered on a number of occasions. There was eventual friction due to dissatisfaction over the problems, and the quality of work in some instances. I saw plastic piping being pushed through walls and left in situ with uncapped ends before final connection. Wrenches were used to tighten fitments such that chromed valves were down to the brass. The boiler was repeatedly emptied through the pressure relief valve so that it became faulty. Fitments were slack, radiators leaked, showers and wc leaked. It was a long list. Given the problems we had, I was never absolutely sure that the inhibitor eventually had been dosed to the correct concentration, although a c.h. engineer who changed the faulty Danfoss thermostatic valve this week said he could smell it when he emptied the radiator.

Having moved a number of times over the years and with all the ensuing problems, I became quite knowledgeable about plumbing and electrics etc. I also do my best to read up on the technicalities. However, I am getting so much conflicting information even from the experts, on this one, that I must admit it is a bit perplexing.

I can't really determine what caused the black/dark brown water that is obviously throughout the system. The engineer this week said that although really dark brown it was due to the Fernox, (although I don't know if that is what is in the system) his system was identical. Yet everything I have read, and particularly on this site says it should be fairly clear and you should aim to achieve that. Is the c.h. engineer right? If Viessmann say that inhibitor should not be used, I don't know where I go from there, because I want to maintain the 5 year warranty on the boiler, but what about the radiators etc!! I am at pains to try and ensure the correct operation and longevity of this system.

 

[Doggit]

Fair enough Alba, you've had some bad experiences in the past, but as Phod and I have both said, if you're happy to spend the time and money on the chemicals, then that gives you a base line to work from.

Give Veismann a call, then decide on their recommendations. If you've got an ongoing problem with the Hep20, then at least you know you've eliminated all the other issues.

Let us know what Veismann say.

 

[phod]

Viessmann follow the German engineering guideline VDI2035 which says that inhibitor is not needed if the pH, conductivity and hardness of the water are maintained in specified ranges and that there is no external source of oxygen allowed to enter the system.

In an ideal world a sealed system with the oxygen removed will have very minimal corrosion.

But we dont live in ideal worlds like that. We have radiators being removed by decorators. We have leaks because of old pipework radiators and valves. We have pressure relief valves that let go. We have expansion vessels that fail. We have plastic and rubber components that are more permeable to oxygen than they really should be.

The pragmatic choice for most of us is to dose with inhibitor because we know systems are rarely perfect.

 

[alba2]

I contacted Viessmann today. It is correct that they do not approve of inhibitor. It seems that Viessmann UK are adopting the German approach. They said that their boiler warranty would be void if it was negatively affected by inhibitor. I wonder how many installers and home owners are aware of this. This would certainly deter me if I was in the market for a new boiler.

I also obtained an estimate of £720 excluding materials for cleaning, mains flushing and inhibiting our 12 radiator system, which I thought was overly expensive. I therefore now plan to do it myself.

 

[Agile]

I am sure that I could fly to Scotland and do the job for less than that.

But before you finally do anything, I suggest you ask both Sentinel and Fernox what their views are. And tell us.

Some of these manufacturer's decisions don't always seen very well thought out.

Viessmann are in effect being contrary to the BS to which we are expected to clean and dose new boiler installations.

Remember that most boilers use the same or very similar components and all the other makers not only recommend, but insist, that inhibitors are added!

Tony

 

[alba2]

I am sure that I could fly to Scotland and do the job for less than that.

But before you finally do anything, I suggest you ask both Sentinel and Fernox what their views are. And tell us.

Some of these manufacturer's decisions don't always seen very well thought out.

Viessmann are in effect being contrary to the BS to which we are expected to clean and dose new boiler installations.

Remember that most boilers use the same or very similar components and all the other makers not only recommend, but insist, that inhibitors are added!

Tony

Tony, thanks for your comments. We are ripped off here. Klondike pricing is still going on, unfortunately.

I found Viessmann to be unhelpful re the inhibitor. Basically "that's our rules, end of." Given their stance, I would be up against it, if I did have a boiler problem, and they decided to play the inhibitor card. Unless you could invoke the Unfair Contract Terms Act.

I have had two different c.h. engineers in the past week. One to replace a thermostatic valve and the other to service the boiler. Surprisingly they both played down the need for proper dosing with inhibitor. One said his system is just as black and it is not a problem as long as there is no grit etc. This led me to think through the whole process of inhibitor. My sister in law had an old system, which was left alone and never gave one bit of bother over decades.
With regard to my new system I am worried about the black/dark brown water, despite the fact that I have a Spirotech filter, and one of the above c.h. engineers assures me it has inhibitor. Should I just simply add inhibitor to a largely inert oxygen environment and let the Spirotech do its business? The alternative of draining down, cleaning, adding inhibitor and refilling with fresh oxygenated water, surely adds plenty of fresh oxygen that will contribute to a new phase of radiator corrosion, and set the original cycle in motion again!

Re inhibitor and the boiler warranty. perhaps it is not worth servicing the boiler annually to comply with warranty requirements under the circumstances. Modern servicing seems to result in nothing more than testing and tinkering, which could possibly slacken or upset things. It is not a tune up or whatever. Perhaps the saying "if it isn't broke don't fix it" applies! The annual servicing charge could be kept for when there is a boiler breakdown!