Confused about acidic condensate

PuppetMaster_2

Hi,

I'm currently getting quotes for a new central heating system. I was told by one engineer that the condensate from a gas condensing boiler is acidic and if sent down an old cast iron waste stack, it will corrode it. To get around this, it would either need it's own plastic piping or pump it up into the plastic guttering. Is this really true? What about the concrete drains underground?

On reading around the consensus seems to be the acidity is about 4.5pH, but I'm not sure if that's strong enough to corrode metal. Anyone else have any more knowledge on this?

Thanks!

jblack_2

That's a new one on me. I've seen/done plenty in to cast pipe. It's just a PITA to drill:D.

J

Wherryman

The engineer was about correct according to the
BRE Installation Assessment Procedure Appendix C:
But it is only a guide.

http://www.idhee.org.uk/ExceptionsGuide.pdf

Canucklehead

Hi

It will eat cast iron if there is no other water running down the same lenght of pipe ie basin/sink waste. It will just take a long time.
As an installer I will not run a boiler condensate waste through anything but plastic waste pipe before it gets to plastic or glazed earthenware pipe.
It can be neutralised with a cartridge type filter fitted to the pipe under or near the boiler, but must be changed at the yearly service .
One day we will catch up with Germany and neutralise the condensate before it gets into the drains as it will start to eat the water treatment works.

Corgi Guy.

savcab

http://www.heatingcentral.com/boilers/plumbers/high-efficiency-boiler-tips

The water condensate is drained into a discharge pipe or into an external drain. Plastic and clay drainage are the most effective in dealing with the water which has an acidic properties and contain traces of nitric and sulphurous acids. Cast iron as well as cement and concrete products show the least resilience to this water and will get damaged over time.

it all depends on the circumstances, sometimes they like to take the condensate to a pit filled with lime chips to save putting it into a drain.

Razor

Corgis view on this is that it is acceptable to discharge condensate into cast ironware as long as it is not the highest connection on the stack, doesn't really take into account the fact that just because there may be a basin waste discharging above it may be an unused basin!
I would use a neutraliser before the stack to be on the safe side.

andrew-b

A pH of 4.5 isn't particularly acidic. Vinegar has a pH of upto 2.4 (i.e. more acidic). Now how many moneysavers use vinegar as a cheap cleaning product?! The discharge pipe should have sufficient fall for the condensate not to be left as standing water in the pipe so it's even more unlikely to chemically react. Corrosive effects on cast iron i suspect would take a long time - similar to the effects of acid rain down cast iron drainpipes. I suspect corrosion by other means is more likely to occur before corrosion from boiler condensate has time to take effect!

All these neutralising products in my mind are a bit of gimmick capitalising on our interests in preserving our environment - when in reality i don't believe it's really causing huge problems. There are much more acidic or alkaline products being poured down our drains from dishwashers, washing machines, kitchen sinks etc on a daily basis that most people wouldn't give a second thought to!

Andy

Razor

I have seen condensate pipes wrongly run in copper leaking after about two years they say run it in plastic for a reason!

Canucklehead

Good morning: Requirements for condensate waste disposal are detailed in BS6798, Part H and boiler manufacturer's installation instructions. A Vaillant EcoTEC plus 837 combi can produce 2.9 l/h condensate..majority of new boiler installs are combis so it makes one wonder what the actual volume of condensate waste water going into the system annually is and what impact does it have?Will the regs change in the future and mandate the neutralization of boiler condensate waste using a device such as this? Watch this space.;)

HTH

Canucklehead

PuppetMaster_2

[FONT=Verdana,New Font Name,Helvetica,Geneva,Swiss,SunSans-Regular]Thanks for everyone's input! I think I'll make sure it's going down plastic piping, just to be on the safe side.

I found a product called Condensafe to neutralise the acid. No doubt their report is biased, but it makes for interesting reading:-

"There are several problems that occur when acid goes down the drain as micro-organisms used in the biological purification process are sensitive to acid conditions. The activity of these organisms practically ceases at a pH of below 5. This is not a problem for an odd house or two but week by week, the amount of acid condensate put down the drain is growing at a rate in excess of half a million litres per week. At this conservative rate, in two years time we will be adding 50 million litres of acid at pH4 to our drains each week. The environmental consequences are huge and, until now, little interest has been shown in solving the problem."[/FONT]