Safe pH range in central heating water

[Trevor Rix]

(1) What would the expected pH be for a central heating system estimated to contain less than 2000 litres of water that was yesterday dosed with 50 litres of Trade-Chem C100+ inhibitor?

(2) The pH for the system water is 6.0 compared to the incoming mains water pH of 6.7. Is that expected or acceptable?

(3) And what would be a safe pH range for the water in such a system?

(4) Is there any method other than pH testing to determine the concentration of Trade-Chem C100+ inhibitor in a system?

This is another chapter in a long running saga regarding my ETA biomass boiler. The previous threads were ...

"Pressure drops when 650 litre buffer tank is filled with water but no drop with air"

"Wear And Tear Causing Leaks?"

"Jet Range by Wolseley - DN20 Isolation Valve"

 

[ShaunCorbs]

What’s the materials in your system eg steel, copper, aluminium etc

 

[Trevor Rix]

What’s the materials in your system eg steel, copper, aluminium etc

Steel (presumably) - ETA Hack 70 boiler, ETA 650 litre buffer tank, ETA expansion vessel, Fernox TF1 Tees.

Copper - pipes.

Aluminium - not known but possibly within heat exchangers?

Plastic - Upanor underground insulated pipes, Fernox TF1 filters.

 

[ShaunCorbs]

This should help

 

[Trevor Rix]

Thanks. But what is a safe range for my system? Is 6.0 pH acceptable? I think not.

 

[Harvest Fields]

Thanks. But what is a safe range for my system? Is 6.0 pH acceptable? I think not.

Look at the table

 

[ShaunCorbs]

Ph of 9-10 ish

Atm you could be causing harm to your steel side

 

[Trevor Rix]

How would I achieve a higher pH than 6.0?

 

[ShaunCorbs]

How would I achieve a higher pH than 6.0?

need somthing alkaline to raise the ph

 

[Trevor Rix]

Is this normal practice after adding what should be more than adequate inhibitor?

 

[ShaunCorbs]

inbh is around 7.0

 

[ShaunCorbs]

@Rob Foster

 

[Brambles]

Trevor,

You really need to achieve a PH of 7. If you are not achieving that with the correct dilution - there is a contaminant in your system. If the system is a recent instal, the contaminant may be residual citric acid from a system cleaner. Generally tap water is PH neutral or slightly alkaline unless it has been drawn from peat bogs, or other acidic strata.

PH scale is logarithmic so a PH of 6 is 10 times more acidic than that of PH7

To neutralise tap water, fill the system with water that has passed through a neutralising filter ( about £60)

 

[Trevor Rix]

inbh is around 7.0

Sorry, I don't understand. More detail please.

 

[Trevor Rix]

Yesterday the system was power flushed with Trade-Chem C600 cleaner, following visible rust in the water and a pH of 4.65. Then refilled and 50 litres of Trade-Chem C100+ added.

 

[Ric2013]

Sentinel's suggestion is that if the cleanser hasn't been removed then it's a question of the system not being flushed properly (and inhibitor doesn't really work properly if the system contains dissolved metals so you may as well...) but that if your supply water is not neutral enough then it is usually easiest to 'simply' ship in water from elsewhere. Which is obviously easier in a domestic system when you only have a couple of hundred litres at most.

In your case, Shaun's suggestion of adding something alkaline sounds more feasible.

 

[ShaunCorbs]

JBL pH-Plus

 

[Ric2013]

My only concern would be that this could make the water harder? But I suppose that is exactly what happens when acidic rain runs through a chalky rock and becomes neutralised so it's probably the same thing. Good shout, I reckon.

Ideally you'd probably use distilled water, but that might prove expensive...

 

[ShaunCorbs]

My only concern would be that this could make the water harder? But I suppose that is exactly what happens when acidic rain runs through a chalky rock and becomes neutralised so it's probably the same thing. Good shout, I reckon.

Ideally you'd probably use distilled water, but that might prove expensive...

true but then your still to high for a steel buffer / boiler around 8-9 would be the middle

 

[chris watkins]

This should help
View attachment 39391

VDI 2035 (sheet 2) is the German standard for water in heating systems, you may have seen this quoted be manufacturers. I believe that we should be following this now, no longer can heating systems just be filled from the mains & if lucky some inhibitor added.

From what you have told us Trevor your system should have a PH of between 8.2 - 10 so you will need to raise it, swimming pool & hot tub suppliers have products which can be added to raise it.
The attached doc is very good & explains the whole of VDI 2035 & it is shown on Shaun's post attachment.
Water Treatment - Vietec HEATING

 

[Trevor Rix]

Thank you everyone for your information Much appreciated.

 

[Ben-gee]

That’s a really interesting read.

Has anyone here ever filled a system with anything other than the mains water available at the property? (With the addition of inhibitor)

 

[chris watkins]

That’s a really interesting read.
Has anyone here ever filled a system with anything other than the mains water available at the property? (With the addition of inhibitor)

I know Andrew Millward does he got a cheap de-ionisation filter off internet & runs filling mains through it.
I don't do enough to warrant that but for £1.80 for 5Litres at Tesco I was thinking of refilling my mates system after all it would be cheaper than inhibitor.
It seems to be all all about getting the air out quickly (fitted an air separator) & getting the PH right.

 

[Trevor Rix]

Does anyone have access to the data sheets for Trade-Chem C100+ (C100S) inhibitor and Trade-Chem C600 power flush please? Also Trade-Chem step by step instructions on how to use the C600 power flush? I have been refused.

 

[Riley]

You have been refused??