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Thread: Recirculating from heat exchanger

  1. #1
    Join Date
    Feb 2017
    Location
    moseley. west midlands, uk
    Posts
    8

    Recirculating from heat exchanger

    Hi,


    My system is not too big, we make about 460litres in a batch, but our plate heat exchanger doesn't really do the job of getting it down to the right temp. It depends on the water from the tap, which seems to be really variable, a few months ago when it was really cold it worked perfectly, a little too good, I had to keep switching it off, but the last two times we have brewed the weather has been hotter and it hasn't managed it, so I've had to recirculate it.

    As a makeshift solution I recirculated it through the fermentor but I think this might have caused some hot side aeration. I think it was around 35 -40 degrees when it went through. The beer tasted pretty bland, not bad but just not much flavour, this was a new recipe with a different yeast and different hops, so I am unsure if it was due to recirculating the wort or not.

    I think I should recirculate the wort through the boiler instead and pump it directly into the beer using a pipe or an inlet so as to avoid any hot side aeration, do you think this is a good idea? When home brewing I didn't care at all about hot side aeration and did fine, now I don't think I am big enough for it to have a massive effect do you think it should be a concern? In the book prinicples of brewing science it says that it is, but I have read elsewhere it is over rated especially on the small scale.

  2. #2
    Join Date
    Aug 2017
    Location
    Calmar Iowa U.S.A.
    Posts
    37
    As long as your water temp is not higher than your desired wort K.O. temp you should be able to chill to appropriate levels. Does the pump that you use have a vfd? If so, just slow down the speed that the wort flows through the heat x. If you don't have a vfd put a valve inline on the wort outbound side of the heat x and choke down the flow that way. If that doesn't work consider pre chilling you water.

  3. #3
    Join Date
    Feb 2016
    Location
    San Francisco, CA
    Posts
    84
    I second the "restrict flows with ball valves" solution – this is the setup we've got where I work. I wasn't sure the first time they showed me the system, but it's easier than you might think, almost "set it and forget it" after you've got things dialed in (we tweak it once or twice per eight US barrel knockout). Too cold? Restrict the chill water. Too warm? Restrict the wort.

    We do have a CLT, which helps a lot. If you've got the space, I don't think it would be a very big draw on your glycol system, it can literally take all day to bring the next batch of tap-temperature water down to temp. We definitely end up restricting the cool water a lot more often than the wort, probably a good investment if you've got the space/cash available.

  4. #4
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
    Posts
    1,813
    Size your HX for the warmest water you'll be using for cooling. Now get a VFD controlled pump so you can slow down or speed up the flow through the HX if it's under- or over-cooling. If you use a valve to limit water flow, put it on the inlet side of the HX to minimize risks of water leaking across to the wort side.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

  5. #5
    Join Date
    Feb 2017
    Location
    moseley. west midlands, uk
    Posts
    8
    Thanks, I did try restricting the amount going into the pump, it only got it down to 35. The pump is pretty basic so I can't control the speed of it. Don't really have money for CLT at the moment, but that would probably do the job no doubt.

  6. #6
    Join Date
    Aug 2010
    Location
    Enterprise, Oregon
    Posts
    1,813
    Never restrict the flow into a pump. If you need to slow things down, use a valve after the pump. Restricting the flow to the pump will cause cavitation, which can rapidly destroy the pump.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

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