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Discuss Safe pH range in central heating water in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

Apologies, that’s because I was typing whilst watching tennis highlights! My reference was to ETA biomass boilers - their MI’s refer to using only softened water in the primary circuit, dosed (where required) with up to 30% glycol.

If you look in the Warranty section of the ETA manufacturer’s instructions - unless it has changed recently - it clearly sets out the water quality criteria to maintain the warranty. I have only fitted three Hack 30/70’s - but I am sure that the same criteria applied as per the smaller boilers in their range of which we have installed over 40.
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Brambles, your post has prompted me to look at the ETA Hack 70 user manual. I am not sure how relevant it is to my topic? Page attached.

ETA HACK_User_Manual_page 37.jpg
The original commissioning was overseen by an expert from the UK sole importers of ETA boilers, so I assumed that it had all been done properly.

As far as I am aware only standard mains water was used which is relatively hard in my area. Plus Trade-Chem inhibitor.

I only have a ETA Hack 20/90 manual to hand, your manual my be different. If you look in section 3 ( Warranty) it sets out all the criteria that are required to maintain the as sold warranty for the wood chip boiler. That includes, but is not limited to, using only softened water in the primary circuit and filling with water of a PH 8 / 9.

With respect to Trade Chem, I have never seen it as a recommended inhibitor by any boiler manufacturer. That is not to say that there is anything wrong with it.

A call to ETA will quickly resolve all of the issues raised in your thread
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Quote below from the warranty section of the user manual. But, it was mentioned in this thread that in the UK softened water is not commonly used?

"Water is the intended heat-transfer medium. For
special anti-frost requirements, up to 30% glycol
may be added. Softened water is required for
the initial fi ll-up of the heating system and for
refi lling after repairs. For the initial fi ll-up of
boilers up to 90 kW, the value of 20,000 lt°dH
for the system volume in litres multiplied by the
hardness (in degrees of German hardness) may not
be exceeded. For boilers over 90 kW, the limit is
30,000 lt°dH.

The pH value should be set between 8 and 9.
Addition of hard water should be minimised to
limit limescale build-up in the boiler. Set enough
shut-off valves to avoid bleeding large amounts of
water during repairs. Any leaks in the system must
be repaired at once."
The issue with artificially softened water from a traditional ion exchange water softener is the magnesium and calcium ions are replaced by chloride ions. That is not ideal in a boiler, because it makes the water a better electrolyte ( one of the three components that helps corrosion).

Water softened by reverse osmosis does not have that issue.

Having said that, I think that is preferable to having acidic water circulating long term in the system.

I only raised this point that from my own experience to maintain the manufacturers warranty - we pre-commission ETA boilers (and occasionally need to acid clean) then use softened water.

Generally, in heating, if you deviate from the MI’s in ether installation or operation, always get a concession in writing from the manufacturer.

Apologies if this is now getting off topic
Brambles, your input is most welcome. Helps me understand the issues and decide what to do next. I think I will phone Innasol as you suggest.

chris watkins

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?
Define power flushing?
That is the common problem, how many times do you need to completely drain & refill the system for example to dilute / remove the cleaner?
It is all about the amount of time & effort an engineer wants to put in against how much a customer wants to pay.
In my case it's not about the cost because the I am not paying. It's all about having the job done properly resulting in this expensive system being in a safe condition not subject to corrosion.

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