Heat Exchanger - Single vs Multipass

[markl1420]

Does anyone have an opinion on single vs multipass heat exchanger? I was about to buy a multipass and the company told me it would agitate the wort too much. So I was wondering what everyone else is using? (I am putting in a 10bbl system).

Thanks!

[brewmaster 2011]

i would get a multistage heat exchanger. the begining with city water. second stage with glycol

[brewmaster 2011]

i would get a multistage heat exchanger. the begining with city water. second stage with glycol.

[markl1420]

i would get a multistage heat exchanger. the begining with city water. second stage with glycol.

Don't know if that's the same thing but I am a rookie. The manufacturer asked me if I wanted single pass, which uses more water and a higher GPM or a multipass which uses less of both. The single pass also has in and out on the front of the frame, where as the multipass had in on one side and out on the back.

[brewmaster 2011]

link some photos of the heat exhanger. i will tell you if it is a single stage of double stage.

[yap]

two different things...

two stage refers to passing through one section with one coolant and a second section with different coolant. it is essentially two HX's in series. usually the first has city water to cool and the second stage uses glycol to cool.

multi-pass is different. it refers to a HX that is set up internally differently. There is only one coolant flow so it is a single "stage" system. its tricky to explain but basically there are a couple of diverter plates inside that force the flow to go through the HX in "sections". think of it as running three standard hx's in series with the outflow of one being the inflow to the next. i used to have a picture of it drawn out but cant find it now. google search may yield something for you..

as far as what is better/worse, i don't think either way is any more or less gentle on the wort. mine is a multipass and i experimented with removing the diverters so that it ran like a "normal" HX and it did not cool as well.

I believe the advantage of a multipass is that it cools more effectively with a little less water usage, but I believe it is also slower so the water savings may not matter... plus time is of the essence when knocking out....

hope that helps..

[markl1420]

Thank you. That was my understanding also. So definitely single stage since only inputs are water and wort. I was leaning towards the multipass because it seemed to cool better with less plates but they were trying to make me think I would oxidize the wort.

Another question. How often do you take it apart to clean? I was think inline cleaning most days and a tear down cleaning once a week. Any thoughts?

two stage refers to passing through one section with one coolant and a second section with different coolant. it is essentially two HX's in series. usually the first has city water to cool and the second stage uses glycol to cool.

multi-pass is different. it refers to a HX that is set up internally differently. There is only one coolant flow so it is a single "stage" system. its tricky to explain but basically there are a couple of diverter plates inside that force the flow to go through the HX in "sections". think of it as running three standard hx's in series with the outflow of one being the inflow to the next. i used to have a picture of it drawn out but cant find it now. google search may yield something for you..

as far as what is better/worse, i don't think either way is any more or less gentle on the wort. mine is a multipass and i experimented with removing the diverters so that it ran like a "normal" HX and it did not cool as well.

I believe the advantage of a multipass is that it cools more effectively with a little less water usage, but I believe it is also slower so the water savings may not matter... plus time is of the essence when knocking out....

hope that helps..

[yap]

not sure how you would oxidize wort. should be a closed system. most everyone uses single pass. mine was purchased used for cheap cheap so that's what I'm dealing with.

as far as cleaning, backflush with PBW after every batch, flush with sanitizer before every batch. shouldn't need to tear down more than 1-2 times a year unless you run a lot of hops into it...

[markl1420]

Thanks again Scott. I saw you have a 7bbl system. How fast are you able to cool a batch?

not sure how you would oxidize wort. should be a closed system. most everyone uses single pass. mine was purchased used for cheap cheap so that's what I'm dealing with.

as far as cleaning, backflush with PBW after every batch, flush with sanitizer before every batch. shouldn't need to tear down more than 1-2 times a year unless you run a lot of hops into it...

[CPESystems]

The nice thing about using a dual pass heat exchanger is that the cooling water coming out will be a lot hotter and you can use it for your next batch or for CIP or ...... If you are cooling from boiling you could get 150 F water coming out of the heat exchanger and it is free energy.

[gitchegumee]

Yap is on the money with regard to single/multi pass vs. single/double stage. And you will not oxidize anything. Almost everyone uses plate heat exchangers with excellent results. You may want a second opinion by a reputable heat exchanger supplier (like Mueller, Thermaline, APV); whoever is leading you to single pass for the reason of oxidation or turbulence (the latter of which you want, btw--That's why the plates are stamped with chevron patterns.) is steering you wrong, IMHO. Multipass essentially lowers the flow rate past any given plate (and therefore reduces the pressure loss) through the heat exchanger; both the water and the wort. It increases contact time at the expense of contact area (for a given temperature). I have seen many multipass exchangers on 10 bbl systems, especially on higher end systems. Your heat exchanger supplier will be able to take your wort temp IN (~100C), your wort temp OUT (20C?), your cooling water temp IN, your cooling water temp OUT (80C is usual), the time rate of wort flow--1000 liters in 30-45 minutes is usual, and finally the flow rate of water--which is usually 1.2 times the wort flow rate. You want more hot water in your HLT than cooled wort coming out. You will want a two stage heat exchanger if you require wort significantly cooler than your cooling water (assuming you don't have a cold liquor tank--which is the other option). As for disassembly, it should never be done as frequently as once a week. If you keep your heat exchanger really clean, keep out hops, clean every brew, and filter your CIP cycle, you should get away with once the first 6 months for an inspection, and then once yearly for an inspection--at MOST. You should never have to tear down for cleaning. Only as an inspection of your cleaning efficacy. Best of luck!

[yap]

Thanks again Scott. I saw you have a 7bbl system. How fast are you able to cool a batch?

cooling for me is a bit slow but it is a function of my inlet temp and flow rate moreso than the HX. my city water flow is not where i'd like it to be and ground water temp is high in the summer. I am running a small second stage using glycol but it doesn't keep up if i run at full flow so i have to throttle it back...

with all of this it takes me ~1.5 hours to KO 7 bbls. definitely not ideal, but when spring comes we will (hopefully) be getting a bigger chiller for the second stage. this should get us to under an hour....

as gitch said have somebody who knows what their talking about size a system for you based off of the parameters at your location... mueller has an online tool that you can use as a start but i wouldn't purchase based off of that alone...

[markl1420]

Thank you everyone for the help. This has been very helpful

[Ted Briggs]

do the math

A proper heat exchanger will provide you with:

1-Wort cooled to your fermentation temp. -65-70f
2-a full, but not overflowing hlt ready to mash in the next batch. -170f
3-Do both in a timely manner. -45mins or less, pump full open.
Its just a matter of building it right. The known controlled variables will tell you the answer.

A CLT and a 2nd stage will allow for more flexablity in output temp ie doing lagers and ales. A CLT will also controll one of the variables, (which vexes me on my current system) fluctuating water supply temp. And there are other benifits too, such as water treatment/filtration.
In short get a 2 stage properly speced to your needs.

I havent used a multipass before, except to board a spaceship...

[BelgianBrews]

I have worked with a single stage and two stage HX. My preference is for single stage, assuming it is sized appropriately to KO in 40-50 minutes. The main reason I prefer single stage is temperature fluctuations in ground water (assuming you use ground water for one of the stages). With a single pass utilizing my cold liquor tank my KO times are consistent from batch to batch. This means my hop utilization is more consistent, as is my trub transfer. Being that I don't have money for an inline DO meter, I aerate based on sight. When I was using a two stage HX my KO times in the summer were 10-20 mins longer than they were during the winter. With a single pass my aeration level is more consistent.

Also, my return water on my single stage is 168-170 making it perfect for sparge water.