Safe pH range in central heating water

[Trevor Rix]

Yes, point blank refused. Apparently the Trade-Chem policy is to only supply such information to their existing customers. Why the secrecy?

 

[Riley]

Then if I were you I’d buy another cleaner??

 

[Trevor Rix]

Unfortunately I am constrained by the choice of chemicals already made by the supplier/installer of my biomass heating system. I am suspecting that the power flush conducted this week may not have been done properly, so I want to research both the power flush and inhibitor as thoroughly as possible.

Does anyone in here have a Trade-Chem account?

 

[Riley]

I think you’re doing too much here if you suspect it’s wrong I’d be getting the company back

 

[Rob Foster]

I must have missed this one. Of course the chemical condition of ch water is important. As always the system must be tested watertight first...otherwise you will waste expensive chemicals, then drained...examine the drained water I do, then do,it again until clear. Run the whole thing up,to maximum and see what happens, drain. Then put in your preferred inhibitor as specified by the boiler manufacturer..as this is the most expensive component, use the test paper to indicate correct...photograph it...the metadata on your phone will date it anyway. Job done. I have worked with Sentinel etc often ...its good stuff but its universal and you must satisfy the boiler manu that its been done correct or your engineer nobody else. By the way Screwfix sell the same stuff under a different name way cheaper. Thats my take on this
Rob Foster aka centralheatking

 

[Jones82]

Informative thread.

I've always wondered about the presence of cleaner in the system, from what I understand I could test this with simple litmus paper? So if cleaner was present in the system the ph would read acidic? And likewise the presence of inhibitor should read alkaline?

This would make testing for inhibitor so much easier, instead of having a manufacturer specific tester... or lack of and just doing it by eye, I can simply test some drain water with litmus paper! Very interesting

 

[Trevor Rix]

At this point I don't even know if the Trade-Chem C100+ inhibitor is alkaline or acidic.

 

[Jones82]

Logically it must be alkaline.... I think

 

[ShaunCorbs]

best thing to do is test it get some ph test strips

found it

http://www.thebiomassstore.co.uk/Graphics/files/C100+ Inhibitor with Biocide & T4 SDS(2).pdf

ph 9-10

 

[Trevor Rix]

Well, I have a situation this week that 50 litres of C100+ inhibitor added to fresh mains water of 6.7pH, tests at 6.0pH.

To me that suggests that the system may not have been completely flushed clean after using C600 power flush? Prior to the power flush the water was visibily brown rusty with a pH of 4.3.

 

[Trevor Rix]

It has been suggested to me that a thorough power flush of a dirty system with cleaner can't be done in one day. Maybe more like several days to a week?

 

[ShaunCorbs]

It has been suggested to me that a thorough power flush of a dirty system with cleaner can't be done in one day. Maybe more like several days to a week?

naa depends how many rads and how bad

 

[Trevor Rix]

It's a biomass system with a 650 litre buffer tank and 100 metres of underground pipe to two properties. The circuit in question is separate to any radiator circuits, that is separated by heat exchangers.

 

[Rob Foster]

It's a biomass system with a 650 litre buffer tank and 100 metres of underground pipe to two properties. The circuit in question is separate to any radiator circuits, that is separated by heat exchangers.

So its a normal domestic set up not...why did you not state this
huh...I think I would rather watch the tennis centralheatking

 

[Trevor Rix]

The suggestion is that one day was not long enough for the power flush cleaner to do its work. Plus the time it takes to thoroughly flush out the residues.

 

[Trevor Rix]

So its a normal domestic set up not...why did you not state this
huh...I think I would rather watch the tennis centralheatking

Throughout my threads I have never said that it is a normal domestic system. It is a biomass 70kW ETA boiler system burning woodchips. Please read.

 

[ShaunCorbs]

no defo no one day wont say two either 3-4 and if its steel pressfit pipe around the buffer you need to watch your ph and air levels

http://www.nwssp.wales.nhs.uk/sites...ing systems - rapid corrosion and failure.pdf

 

[Trevor Rix]

There are no steel press fit pipes in the system.

 

[Jones82]

Depends on the system, its always good to run the cleaner with heat for as long as the manufacturer recommends. Sometimes up to two weeks and I think a minimum of 2 hours if I remember right.

What you've got to remember Trevor rix is the engineer who's quoted for your flush is trying to anticipate all outcomes, him flushing the system leaves him wide open to any future problems... so its good he's giving you honest information and a realistic price. It means hes going to do a good job!

But of course, when in doubt always get 3 quotes

 

[Trevor Rix]

The cleaner was run with heat for around 2-3 hours.

The current problem is that I can't obtain the information as to how long the manufacturer recommends the cleaner should be run for (see above).

The power flush cleaning and refilling of the system with inhibitor was done by the original supplier/installer of the whole system, free of charge, because of the numerous problems that I have discussed in my four threads in here. No one else has done any work on the system.

Therefore no prices involved and no quotes required.

 

[ShaunCorbs]

whats the problems eg sludge or just colour of the water?

 

[Trevor Rix]

whats the problems eg sludge or just colour of the water?

The problem prior to the power flush cleaning was the colour of the water - dirty brown, brown sediment in the bottom of the sample jar when left to settle, and a pH of 4.73. When the two Fernox TF1 filters were flushed the contents were dark black.

The problem now is that the pH is 6.0 compared to the incoming mains water pH of 6.7. I will take another sample from the drain near the bottom of the buffer tank when the system is cool and the pump has been switched off for a couple of days.

 

[Brambles]

Trevor,

A couple of points:

Unless the Manufacturers Instructions (MI’s) from ETI have changed, the ETI boilers I have installed have all required the primary circuits to be on softened (ion exchange) water with a PH above 7 preferably higher. Your MI’s will define how ETI require the primary water to be treated (or otherwise).

I think that a call to ETI technical explaining the issues that you are experiencing would give you an insight into a range of possible solutions. Whenever I have had an issue with their equipment, the advice has always been excellent.

In general terms, to achieve ETI’s MI the complete psystem is pre-commissioned, immediately after installation. If there are extensive runs of pipework from the boiler house to remote heat exchangers, this is normally with a citric acid clean, neutralised and then, if stainless steel, passivated.

If you are getting a low PH, it is likely that that is just a snap shot in time - the PH will rise and fall as the oxidation process, from green rust to hydrated iron oxide to red rust and then magnetite takes place. This is a constantly ongoing fluctuating process as the steel corrodes.

The type of inhibitors you are referring to are to stabilise systems that are fundamentally clean. An inhibitor added to a system that is actively corroding is unlikely to stop that process.

The chemistry in every system is different - but for domestic systems a “one solution fits all” system is generally cost effective and a satisfactory long term solution. For larger / small commercial systems that philosophy also generally holds - provided that the system was properly pre-commissioned after installation.

However, once the chemistry of oxidation has become well established in a larger system - it normally needs the primary water to be analysed and a bespoke flushing regime developed and executed. That may involve a further acid clean to remove the various iron oxides and salts. Thereafter, once the system is stable it can to reflushed set up in accordance with the MI’s

It is not as simple as just dosing an acidic water with alkali to increase the PH. The PH is an indicator of what is going on in the system.

Be aware ( if it has not already been mentioned), the use of inhibitors in boiler primary systems is, in my experience, very much a UK thing. Elsewhere, it is often common to use untreated water produced by Reverse Osmosis as the stable solution in a clean system. Hence the ETI MI referring to the use of softened water ( albeit artificially softened water is not without it’s problems in complicating boiler water chemistry)

 

[Trevor Rix]

Brambles, thanks very much for your comprehensive input. Just to be sure we are taking about the same boiler, my boiler is an ETA Hack 70, not an ETI.

ETA HACK 70 to 90 kW - ETA Heiztechnik GmbH

 

[Jones82]

My apologies for jumping to conclusions Trevor Rix