Condensation back into boiler

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Scotty

Condensation back into boiler

Post by Scotty » Mon Feb 14, 2011 10:05 pm

I've recently installed a powerful kitchen extractor hood above my boiler. It extracts the steam very well but for it to be effective, the boiler has to sit directly underneath the hood and due to the fan not extracting all of the steam, some steam condenses back to liquid and drips into the boiler.

I can move the boiler to avoid drips but the steam extraction isn't as good. The question is, will this cause a problem with the finished beer? I see breweries with enclosed coppers and a chimney and I suspect that steam will condense on the dome walls.

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Normski
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Re: Condensation back into boiler

Post by Normski » Tue Feb 15, 2011 12:06 pm

Hi Scotty

Yes this will cause problems. I cant remember the name of it, but you dont want it dripping back into your boiler. If i remember it gives, off tastes.
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Scotty

Re: Condensation back into boiler

Post by Scotty » Tue Feb 15, 2011 12:10 pm

It's something to do with hop volotiles if I remember correctly. It's not a lot but probably enough. I still cannot see how a brewery cannot have condensation dripping back in with enclosed coppers though.

adeybambam

Re: Condensation back into boiler

Post by adeybambam » Tue Feb 15, 2011 1:11 pm

Its DMS that you are trying to get rid of. I did a bit of searching about this recently. The general view from people much more knowledgeable than me is that it won't cause any problems a bit of condensation getting back in. DMS boils off at about 40oC so over a lengthy boil the DMS will have all boiled off. Anything that does condense and drip back in will then be boiled back off so nothing to worry about really, providing the condensation is minismised.

Hence why breweries can have enclosed coppers. The other point is that it is possible that the surface of the extractor hood (or chimney in a brewery enclosed copper) will be above 40oC from all the steam so DMS wont condense on it anyway.

boingy

Re: Condensation back into boiler

Post by boingy » Tue Feb 15, 2011 1:45 pm

Your biggest worry should be what the condensate has been in contact with before it drops back into the boiler. Any crud, grease, insects and leached chemicals will all end up back in the beer. The shape and open nature of a cooker hood will mean you get loads more condensation compared with a brewery enclosed system.

I'd suggest experimenting with mounting the hood at a very slight angle so that it is still basically horizontal but just tilted enough to make most of the condensation drip off one corner, where you can collect it or divert it away from your boil. The less condensate in the beer, the better.

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Re: Condensation back into boiler

Post by Kev888 » Tue Feb 15, 2011 5:19 pm

I did some poking around the internet a while ago, as I'm testing extraction methods myself. From this probably less than scientific research I believe that:
# DMS is actually quite easy to drive off, and so seems likely to be boiled away even if a small percentage returns once or twice as condensation
# In theory the heat should kill off most organic things that fall back in, but if you cool whilst its still dripping in that would not necessarily be so,
# Cack being dragged in by the condensation could still influence flavour of the brew, alive or not,
# if the extraction system contains any non-food grade stuff the steam may leech chemicles out and drip tem into the boiler.

I tried a small waste pipe that could be cleaned reasonably easily but that got blocked with hops in bubblier recipies. Now I've got a 6" flexible pipe on there instead - it curves immediately across and then down, so the only bit that condensation drips back in from is the very end that I can clean. It does seem to fill with quite a bit of liquid but otherwise works better than previous attempts.

However its not a complete solution because I find you have to start the boil without it; the start of the boil seems to create more foam/bubbles and until they have died or been stirred down, connecting the pipe just propagates the foam out of the boiler and along the pipe, taking half my hops with it. Similarly, you have to break its seal with the boiler towards the end of the boil, to get the IC in, add hops and so on, so steam is still pouring into the garage and condensing on everything for the last 15mins of the boil and even after until its cooled enough.

So a powered extractor that it could suck in steam rather than having to be clamped tightly would be a big advantage if the condensation could be sorted... Maybe theres a way to have a detachable cleanable, food grade hood with a fall in the pipe leading from it and all the extraction gubbins downstream.

Cheers
kev
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smdjoachim

Re: Condensation back into boiler

Post by smdjoachim » Tue Feb 15, 2011 5:39 pm

Use a fan to blow the steam towards the extractor

Scotty

Re: Condensation back into boiler

Post by Scotty » Tue Feb 15, 2011 7:00 pm

Thanks for the info chaps.

The fan was ok but overwhelmed by the amount of steam and the amount of condensation was difficult to manage. Boingy, the hood is already at an angle but it didn't do much good.

The only solution I can think of is making a stainless steel hood with a chimney which will enclose the boiler just like a proper copper. As you say Boingy, the heat of the enclosed system should help. It's either this or something similar or destroy my shed in record time.

techtone

Re: Condensation back into boiler

Post by techtone » Tue Feb 15, 2011 7:24 pm

I've had the same but no related issues and don't worry about it. A few drops out of a few litres evaporated is nothing. As with you the top of boiler is too close to the extractor so the steam is centralised in one area rather than dispersed. I switched from the fabric filters to metal which helped but not 100%. As it only starts to happen after about an hour for me, I have thought about easing off the boil half way through to let the extractor dry out but probably not worth bothering about.

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Re: Condensation back into boiler

Post by Kev888 » Tue Feb 15, 2011 7:31 pm

Scotty Mc wrote:Thanks for the info chaps.The fan was ok but overwhelmed by the amount of steam and the amount of condensation was difficult to manage. Boingy, the hood is already at an angle but it didn't do much good.The only solution I can think of is making a stainless steel hood with a chimney which will enclose the boiler just like a proper copper. As you say Boingy, the heat of the enclosed system should help. It's either this or something similar or destroy my shed in record time.
My enclosed system works well on the whole but is a pain at times because at least with my setup/process you can't keep it enclosed all the while. So you've achieved a better system then I have if you can reliably extract the steam without that kind of restriction. Just a pity about the condensation really, its annoying that its hard to quantify the dangers/chances but I'd imagine if it were fairly clean and not made of lead or something then what with the steam and heat in the boiler it should be reasonably safe.

I'm tempted to try something like it myself actually, maybe a hygenically designed, cleanable hood coupled to a pipe angled downwards slightly (I guess like the top third of the classic copper FVs they have in breweries) would work, at least if housed in the pipe was the same sort of powerful extractor you've found to work. Hmm, another one for the ever lengthening 'to do' list. Just out of interest, did your extractor system have anything saying how powerful it was?

EDIT: just had a potentially good idea - use a cone shaped hood with sides steep enough and a rim wide enough that condensation runs down to the rim and drips off 'around' the boiler, not into it? Could even make a small gutter or something, and possibly heat it so that condensation doesn't want to form easily to begin with. Copywrite Kev888; now all I have to do is to remember not to tell anyone before I patent it. Oh, bugg...

Cheers,
Kev
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Re: Condensation back into boiler

Post by Jim » Tue Feb 15, 2011 7:47 pm

The same thing happens to me when I boil up. Like others have said already, it's not a problem.
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unclepumble

Re: Condensation back into boiler

Post by unclepumble » Tue Feb 15, 2011 8:11 pm

If you put plenty of insulation on the outside of the hood and Insulate the ducting off it, there is less chance of the steam condensing until it gets to the cold air outside.

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Scotty

Re: Condensation back into boiler

Post by Scotty » Tue Feb 15, 2011 8:18 pm

The other problem I have with steam is that engulfs my shed and ends up sticking to the roof and walls. This ends up going mouldy and eating into the wood so extraction is a must if I want to continue brewing.

I have just had a look at the fan and the lower part of the casing is full of water which isn't good.

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Re: Condensation back into boiler

Post by oz11 » Tue Feb 15, 2011 8:19 pm

I use clothes pegs to clip a clean towel over the extractor fan grill. This soaks up the steam and doesn't drip back. If it gets over saturated I can cover the boiler while I change to fresh towel.

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Re: Condensation back into boiler

Post by Kev888 » Wed Feb 16, 2011 1:34 pm

Jim wrote:The same thing happens to me when I boil up. Like others have said already, it's not a problem.
Probably this is closer to being the solution than I/we realised then; if returning condensation isn't a problem in practice (and I'd trust Jim's experience more than any theories), and if the extractor setup extracts the steam well (which my passive pipe setup doesn't at times) then I think this is something I'll definately be trying in the future.

The casing being full of water sounds a bit undesirable though - could a small well placed hole maybe let it drip out before it collects in any quantity?

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Kev
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