Black C.H. Water

[alba2]

I know this has been discussed a number of times, but I would really appreciate a reply specific to my system.

We are 2 years in a new build with a Veissmann condensing boiler and plastic pipework. At the beginning of the c.h. installation I requested the installation of an MB3 Spirotech Filter. I also kept asking for inhibitor to be added when there was any draining down of the system, which happened a number of times.

At the first year boiler service the c.h. engineer surprisingly did not know how to flush the filter so it was left untouched and the 2nd year service is now due. I did not want a repeat of the forst year so decided ahead of the service to flush the MB3 filter myself and was amazed at how black the water was. It was like impenetrable Guiness. I drained at least 3 litres and the colour did not change. I decided to stop as the system obviously required to be seriously flushed through.

I had problems with the builder concerning a significant number of non c.h. problems, which I won't go into.

I have a number of questions re the c.h. system:

1. Given the precautions I requested, why is the water so black?
2. I assume that the system will have to be thoroughly flushed out until it runs clear?
3. As the system is only 2 years old, what would be the best/cost effective method?
a. Just run it through with water only?
b. A chemical flush run over 4 days?
c. A full blown power flush.
all followed by inhibitor top up.
I don't want to go over the top and incur higher costs if it isn't necessary. On the other hand I want the system to be optimally functional and be protected such that it will last.
4. If 3b above, which products would you recommend?
5. I am a reasonably competent diyer, should I consider doing 3a or b myself?

In 1994 I moved into a new build with a similar system. It too had plastic pipework. We had loads of trouble with the system right from the off. The Worcester boiler and associated components kept breaking down and it got really silted up over a 10 year period, such that pipes had to be cut out and replaced and radiators flushed through etc. This may have been the early years of the HEP plastic pipe system. I assume it was due to osmotic action. Please convince me that with the new plastic piping this is not happening again!

Thanks

 

[Doggit]

If the system is completely plastic, then it shouldn't be black, as this is normally down to the copper reacting with the steel rads.

You can add a system cleaner, leave it for a week with the CH running normally, and then drain it down and refill it a couple of times.

A full blown power flush is an expensive waster, so I wouldn't bother.

Fernox if you want a known name, Screwfix if you're changing it every year or two.

What's the name on the plastic pipe.

 

[DP]

If the system is completely plastic, then it shouldn't be black, as this is normally down to the copper reacting with the steel rads.

I always thought it was oxygen in fresh water reacting with metal radiators
On occasion using a non barrier pipe for heating system allowing air ingress through pipe wall also a cause

 

[45yearsagasman]

Does your plastic pipe have a barrier? What make of pipe?

 

[alba2]

Thanks for your help.

It is difficult to see the markings on the pipes in situ, but what I could see was Hep 2o, ISO 15876-2, Class 5/6, Bar KIWA Class 2/10. Can I assume that this is kosher, or are other details required?

All the pipes to and from the boiler are copper, but I know that the c.h. is plastic throughout.

I don't understand why the water is so absolutely black, it is like ink. Could it be down to lack of or insufficient inhibitor or is there something else going on? We are in a 100% soft water area.

From your comments and reading other threads I intend to dose the system for 4 weeks with Sentinel X400, then run mains water through until clear, followed by 2 litres of Sentinel x100 inhibitor (we have 10 radiators and 2 towel rails). Or should I run mains water through to clear as much as possible before dosing with X400?

Would this be the way to go considering the system is just 2 years and 2 months old? Or should I simply run mains water through until clear and dose with 2 litres of Sentinel X100.

There is no low drain point in the system. Rather than detach a radiator valve, could I flush the system through the Spirotech MB3 filter? It is about 100 cms above floor level, on the return, just below the base of the Viessmann boiler.

If I do all the foregoing should I be confident that the system is fully protected and will not be impaired?

How often should I repeat the above if ever?

 

[Steelmasons]

Oxygen ingress would indicate an orange colour.

 

[Doggit]

If you've got cold spots om the bottom of the rads, then they'll need taking off, and a hose attached to one end, and flushed through; the X400 is going to help shift some of the muck in the rads, but I doubt if it'll get it out without taking them off.

If you use the cleaner to flush the muck out of the system, you'll leave all the heavy stuff at the bottom of the pipes and the rads.

The pipes okay, so the problem lies elsewhere.

 

[mcmoby69]

Cheap rads and towel rads?

 

[alba2]

It's good to know that the pipes are ok.

Of the 10 radiators 7 are Kermi. There were 3 small radiators changed/added to the system and I can't identify the brand. There is no indication of brand on the towel rails. Even if the 3 small radiators plus 2 towel rails were cheaper, would sufficient inhibitor compensate?

There are no cold spots on any of the radiators.

Am I wrongly assuming that a 26 month old system should not require a power flush or the radiators individually flushed at this stage in its life?

Following your comments and reading other threads, my plan (please advise if wrong) was to:

1. add 1 litre of Sentinel X400 to the system, then after 4 weeks, drain and run water through until hopefully clear.

(a) I am not sure if this 1st step is absolutely necessary. Should I just drain and run water through until clear? What do you think?
(c) If I do use the Sentinel X400, is it necessary to drain and run water through the system first, or can I just add the X400?

2. Add 2 litres of Sentinel X100 inhibitor, then re-check the system via the Spirotech filter in 6 months, and hope that all is well.

3. The Spirotech filter is 100cms above the floor and just under the Viessmann boiler. If I attached a hose to the drain point on the filter and brought the hose down to floor level (I can run it outside) would this be an ok method to drain the system down? I ask this because there is not a drain point in the system?

I, however, still remain puzzled why there is such very black water in a system that is only 26 months old. It may or may or may not be relevant but for 4 months of the 26, the system was switched off, because we were not in the property due to repairs. Some radiators and pipework was removed and replaced during the repairs. Previous to this there was a lot of messing with the system due to the pressure release valve leaking. (I suspect due to frequent inappropriate draining through this valve) This led to components being replaced including the heat exchanger because that was mistakenly thought to be the problem for pressure loss. Two extra radiators were later added to the system, and so on. Through all this I kept emphasising the need for inhibitor to be added to the system after the interventions. There was a lot of incompetence which I won't go into, and it may be that either insufficient or no inhibitor was added at the final stage of re-commissioning. I hope this latter possibility is the explanation for the black water.

Finally, given my experiences with another plastic pipework system from 1999 onwards, I am seeking reassurance that if I undertake steps 1-3 above that this new system as I described it should be ok now. What do you think?

 

[Doggit]

Sorry, Alba, must have got confused with another post in thinking there were cold spots.

Okay, You have a problem, and I'm not sure if anyone her can completely tell you the reason for it, so all you can do, is go through the normal remedial steps, and see if that cures it.

Keep in mind the following points though, as you seem to keep going over them.

If you put a hose on the system, then water will just find the path of least resistance, and not flush the system out.
If you use the Spirotech as your exit point, you'll still have dirty water in the system below this point. You should have a drain point on the lowest point of the system - so try and introduce one if you can, or find the lowest accessible drain point if you can't.

Fill the system with the X400, and run it for a couple of weeks (it's still a newish system) but 4 if that'll make you feel better.

Drain the system down and refill it a couple of times, then fill with the X100, and then just check the cleaner every 3 months.

The rest is just speculation, and will give you ulcers

 

[alba2]

Thanks Doggit

I didn't intend to put a hose on the system. I just intended to open up the filler valve and the Spirotech drain tap at the same time and let the water run through the system to hopefully eventually see clear water. I don't feel the system is sludged up, it is more a question of black water that could/would obviously lead to sludge in time.

I know Sprotech say not to fill the system through the unit, but my logic in using it as a drain or flushing point, is because it is partially used for that purpose anyway. In terms of draining or flushing at the lowest point in the pipework, I thought that if I added a length of plastic pipe to the drain point on the Spirotech then dropped it down to floor level and outside at that same level, that would in effect be simply extending the return loop in the circuit and taking it down to the lowest level thus being an effective method of drainage. Am I missing something here, and is my logic flawed?

My other question is that given as you say it is a relatively new system do I really need to use the Sentinel X400? Should I not just run the system through with mains water as per the above? I am not worried about the cost of the X400, it is more a question of "if it isn't broke don't fix it" sort of thing. Or to be absolutely sure of avoiding future problems should I bite the bullet and go the whole hog and get a professional power flush. Although I do worry about this creating leaks. Due to other problems we had all our sub floors re-laid with engineered wood and tiles atop throughout, at significant expense. I am quite paranoid about all this having to come up again in the near future, should there be blockages!!

 

[Doggit]

I know Sprotech say not to fill the system through the unit, but my logic in using it as a drain or flushing point, is because it is partially used for that purpose anyway. In terms of draining or flushing at the lowest point in the pipework, I thought that if I added a length of plastic pipe to the drain point on the Spirotech then dropped it down to floor level and outside at that same level, that would in effect be simply extending the return loop in the circuit and taking it down to the lowest level thus being an effective method of drainage. Am I missing something here, and is my logic flawed?

Very flawed I'm afraid, but that's how we learn.

My other question is that given as you say it is a relatively new system do I really need to use the Sentinel X400? Should I not just run the system through with mains water as per the above? I am not worried about the cost of the X400, it is more a question of "if it isn't broke don't fix it" sort of thing. Or to be absolutely sure of avoiding future problems should I bite the bullet and go the whole hog and get a professional power flush. Although I do worry about this creating leaks. Due to other problems we had all our sub floors re-laid with engineered wood and tiles atop throughout, at significant expense. I am quite paranoid about all this having to come up again in the near future, should there be blockages

You have black water, so it's reasonable to assume you've got a problem, the question is how serious. You're using the X400 as a basic precaution, but a power flush shouldn't be necessary, and if the systems getting hot, then you don't have a major problem now, and the inhibitor will stop one developing. The power flush shouldn't break any joints, but I just think it's an unnecessary step. You can always go for it 6 months down the line if the initial steps don't prove effective.

Give the steps we've suggested a go, and then report back for any further advice if necessary.

 

[alba2]

Thanks again Doggit. Much appreciated.

Would you mind answering 2 supplementary questions?

Can I simply add X400 to the system as is, or does the system have to be run through with mains water first?

I like to understand how things work. Why was it a flawed method of attaching a tube down to floor level on the Spirotech, and opening up the filler valve to flush through?

 

[Doggit]

Yes, just add the X400 to the system as it is, and that'll be fine.

The central heating is a sealed system, so the pump exerts a positive pressure one side, and a negative pressure behind it, but because it's sealed, the water can only get pushed round the system, but if you attach a hose to the system, and then open a valve somewhere, the fresh water will find the path of least resistance, and the shortest distance between those to points; everything outside of that path will still be black.

 

[alba2]

Thanks again Doggit. I appreciate you coming back.

Thanks also to the others who contributed. I appreciate your input.