Condensate disposal from condensing boiler

[Dave]

Is there any reason not to run the condensate from a condensing boiler directly into the SVP via a trap? Does it need to run through a tun dish?

[Andy Hall]

The boiler manufacturer's instructions should tell you the situation on this.

Most (possibly all) condensing boilers have an internal trap to prevent the escape of fumes through the condensate drain. Obviously it's very important to make sure that that never gets sucked out.

I did my installation by putting a washing machine trap, dedicated for condensate use and connected to the soil pipe. I fitted a plastic tundish below the boiler's condensate output at the bottom and piped that to the trap.

This gives me two air breaks and the ability to look at how much condensate is coming from the boiler. There was no specific requirement from the manufacturer to have the tundish, though.

If you are going to use one, it does need to be plastic.....

[Dave]

Thanks, I hadn't realised that some would have an internal trap (I'm expecting to use a Worcester Greenstar 29HE - unless someone here can suggest a "better"/cheaper boiler - I see now that it has an internal trap). Have you found it useful to be able to see/measure how much condensate?

[Lurch]

On Thu, 02 Dec 2004 20:18:33 +0000, Dave strung together this:

Doesn't the Greenstar range release the condensate in 100ml lots? If so you'd be hard pushed to be able to see how much is being pushed through with a tundish.

[Andy Hall]

I wouldn't say that it's necessary as such, but seeing how it varied with power level and temperature to begin with was interesting.

[Andrew Gabriel]

Agreed. I included a section of clear plastic hose in the condensate pipework for this purpose. Mine runs into a wash basin wastepipe, and I fitted a trap with integral air admitance valve to the washbasin so pressure differentials in the waste pipe can't suck the integral U-trap in the boiler dry.

Actually, first time I ran the boiler, I diverted the condensate waste into a bucket so I could see what sort of volume it produced. I got half a bucket in about half a day, but it wasn't a cold day. Still, I saved the energy it would have taken to boil away at least half a bucket of water (some of the condensate leaves the flue as fog rather than going down the drain).

[Philip Barton]

Why not have a diverter arrangement to a gallon container, and use the (pure) condensate for your iron/battery/anything else that needs distilled water?

Phil.

[Andy Hall]

Because it ain't pure. It's mildly acidic at around pH4, mainly consisting of carbonic acid from the CO2 from combustion..

This is why plastic components are used and stainless steel in the boiler.

You could perhaps descale your iron with it but that's about all.