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  1. #1
    Join Date
    Jan 2014
    Posts
    8

    Preheat coil in dishwasher exhaust

    Our food service managers purchased and had installed a new Hobart dishwasher. As I understand it they fill the 3- 40 gallon tanks with hot water before starting it. Then as the machine requires more water (about 74 gph) it fills with cold water that first goes through a coil in the machines exhaust. The claim is that this coil will heat 52 degree entering water to 120 degrees before it goes into the tanks. There is a heater in the machine that will bring the water up to and maintain 180deg. I got involved when the coil froze and burst. That problem will be solved. The question here is has anyone had experience with these preheat coils? I was looking at the unit and I checked the discharge of the exhaust fan without while the water was bypassing the coil and the temperature was 100 deg. It's hard to get 120 deg. water with 100 deg. air. Did we get sold a pipe dream or are these coils working as promised else ware?

  2. #2
    Join Date
    Oct 2008
    Posts
    843
    Quote Originally Posted by Randyv View Post
    Our food service managers purchased and had installed a new Hobart dishwasher...

    .....It's hard to get 120 deg. water with 100 deg. air. Did we get sold a pipe dream or are these coils working as promised else ware?
    Randy, I don't have any knowledge of such a feature you're describing. Then again, Hobart has been doing some newer, presumably innovative design ideas as of late.

    Some of OUR newer machines have "Opti-rinse" emblazoned onto their descriptive title - using some fancied up rinse arm nozzles, to conserve water I suppose...while another machine (a pan washer just installed last week) that we now have - all of a sudden doesn't require any form of exhaust for the steam that a typical 150°wash/180° rinse cycle generates. So I guess the "going GREEN" bug has prompted Hobart into doing some design renovations the past few years.

    Was your machine recently installed so that it may be still under warranty? If HOBART installed it, they DO have an 18 month standard warranty if Hobart DID the installation.

    If you've verified that all utilities are working per the manual's stated standards AND that your situation doesn't fall into any "disclaimed" operating parameters the manual may stipulate (i.e., unusually cold weather may cause lower air temp, which may affect the efficiency this 'feature'), I'd certainly get Hobart involved for a warranty service call.
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  3. #3
    Join Date
    Nov 2013
    Posts
    32
    Quote Originally Posted by Randyv View Post
    Our food service managers purchased and had installed a new Hobart dishwasher. As I understand it they fill the 3- 40 gallon tanks with hot water before starting it. Then as the machine requires more water (about 74 gph) it fills with cold water that first goes through a coil in the machines exhaust. The claim is that this coil will heat 52 degree entering water to 120 degrees before it goes into the tanks. There is a heater in the machine that will bring the water up to and maintain 180deg. I got involved when the coil froze and burst. That problem will be solved. The question here is has anyone had experience with these preheat coils? I was looking at the unit and I checked the discharge of the exhaust fan without while the water was bypassing the coil and the temperature was 100 deg. It's hard to get 120 deg. water with 100 deg. air. Did we get sold a pipe dream or are these coils working as promised else ware?
    Is your dishwasher a CLE ? Hobart now has an energy recovering system as an option on a few different styles of machines called " Advansys " . Ive only come across one of these units so far as they are fairly new . Ive never actually took a temp reading of the air , but next time i get a call i shall . I think the principle of it does work , as the exhaust is very hot . As to Hobarts claims of what temp can be acheived is open to debate . You would think certain factors would effect it , such as if the machine is constantly running , acatually temp of water filling coils...etc ect...

  4. #4
    Join Date
    Jul 2002
    Location
    SE Texas
    Posts
    462
    This is what the specification sheet says for the Advansys CLer Conveyor Type:

    The Energy Recovery System captures escaping heat and steam from the exhaust air and uses a heat exchanger to recycle it into energy. This free energy is used to preheat the incoming water supply before it enters the booster heater. The ground temperature water passes through a heat exchanger positioned directly in line with the machine’s unload exhaust system to capture the energy from the exhaust air and ware leaving the machine to elevate the temperature of the water to 110° before it enters the booster heater.
    With your chrome heart shining in the sun, long may you run.

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