PicoBrew Zymatic

HomeBrewTalk.com - Beer, Wine, Mead, & Cider Brewing Discussion Community.

Help Support Homebrew Talk:

ShaLaH

Well-Known Member
Joined
Oct 28, 2011
Messages
190
Reaction score
14
Location
Brooklyn
Yep, writing on the wall for years and all of their crap finally caught up to them... This quote from the article is the best news I've heard in years "And yesterday, the founder team (Bill Mitchell, his brother Jim Mitchell and Avi Geiger) was let go, along with the customer service team. " Not everyone at PB was horrible, but two guys in particular had a hand in its failure.

It's no big deal though, my Zymatic has been running issue free since I started my own maintenance and cleaning regimen along with a few needed mods. It does mean that I'll need to accelerate my RPi development...
As I've mentioned before, I'll gladly donate to the RPi development cause. I'm actually topping off the glycol in the hex loop today, thanks to your very detailed instructions. Really appreciate it.
 

danyo

New Member
Joined
Jan 2, 2017
Messages
3
Reaction score
0
In the same boat as you and Pile. I got the Zymatic in late 16 and while I love it compared to biab on a stove but it has fallen short mostly due to Picobrew's resistance to opening the system up and being open to self repair. I'm working on a replacement API since I've had so many brew days ruined from it just refusing to cooperate with wifi and observed actual pico server outages and crashes. Though this wont be possible with the new gen Z since it looks like its going to do self firmware updates and ssl. The way the API works is really going to piss anyone off with a programming background. Their http requests violate RFC2396 by throwing non ascii characters into the request (wiresharked) requiring an http server that doesnt implement this. Out of the box Kestrel and (I assume IIS) throw bad http requests when the Zymatic hits them. Its constantly pinging back home for no good reason and rather than fire and forget for data recording appears to keep some kind of retry buffer that eventually just crashes the unit. Bring this up to them and BAN HAMMER. If you get a chance can you post some of the part details from your teardown/repair. We need something like an actual service manual and parts manifest for this thing because I really don't feel like having a $2K investment subject to the whims of Kevin.
I have been trying to get this to work:
github hotzenklotz/picobrew-server
I can run the server and the Zymatic does connect to it as seen in the log. When I try to load either recipe or cleaning the Zymatic has some error causing it just to reset and the screen goes blank. What have you found is the best way to get around the non ascii characters?
 

Mike Howard

Supporting Member
HBT Supporter
Joined
May 22, 2018
Messages
399
Reaction score
150
Location
Texas
What I plan on doing is building software to mimic the software currently running on the Zymatic. I have a first pass right now and it sorta works. I say sorta because the way they implemented the stepper arm is a joke. The rest of the software is very basic, turn on a pump, turn on a heater, turn off both, etc... nothing sophisticated about that.

I'm currently working through bugs that align the stepper arm to the correct step filter hole at the correct step. Once I get a system that will work, I plan on releasing it to a few folks for testing and then later I'll give it to anyone who asks for it. If you want to donate that's up to you.

That should be a stop gap as I then continue to modify the code with enhancements, bug fixes etc.... The ability to completely get away from the PB motherboard, the internet and any parts that are not readily available is my goal. Stay tuned....
 

ShaLaH

Well-Known Member
Joined
Oct 28, 2011
Messages
190
Reaction score
14
Location
Brooklyn
What I plan on doing is building software to mimic the software currently running on the Zymatic. I have a first pass right now and it sorta works. I say sorta because the way they implemented the stepper arm is a joke. The rest of the software is very basic, turn on a pump, turn on a heater, turn off both, etc... nothing sophisticated about that.

I'm currently working through bugs that align the stepper arm to the correct step filter hole at the correct step. Once I get a system that will work, I plan on releasing it to a few folks for testing and then later I'll give it to anyone who asks for it. If you want to donate that's up to you.

That should be a stop gap as I then continue to modify the code with enhancements, bug fixes etc.... The ability to completely get away from the PB motherboard, the internet and any parts that are not readily available is my goal. Stay tuned....
Quick question Mike, I topped off the glycol yesterday, thanks for the instructions! I still wasn't able to run a clean cycle without getting Fatal Error #1. When I put hot water in the keg, however, the zymatic ran the clean cycle no problem. How do I get around this to brew without adding hot water to start a brew cycle?
 
Joined
May 2, 2020
Messages
8
Reaction score
4
Looks like it's time for me to open up my Zymatic too. I'm up to 99 brews, but Fatal error #1 won't let me get to 100.

For those adding a glycol reservoir, do you circulate through the reservoir, or is it enough to just hook it in so that gravity fills up the lines?
 

Mike Howard

Supporting Member
HBT Supporter
Joined
May 22, 2018
Messages
399
Reaction score
150
Location
Texas
Quick question Mike, I topped off the glycol yesterday, thanks for the instructions! I still wasn't able to run a clean cycle without getting Fatal Error #1. When I put hot water in the keg, however, the zymatic ran the clean cycle no problem. How do I get around this to brew without adding hot water to start a brew cycle?
You didn't get all of the air out of the HEX would be my guess. It sometimes takes a bit of work to get all of the air out. You need to massage those lines really well if you are not adding a reservoir. Keep the unit at a 45 degree angle and massage the tube going to the RIMS unit and the one at the sensor that should be open now.

Sometimes the RIMS unit and the HEX can contain a lot of air. Just keep working it until you are sure all, or mostly all, of the air is out. When I first did the procedure it took awhile. You can also take the unit from 0 degrees to 45 to 90 and back just to get the air at the top. A reservoir would solve your issue if nothing else works. ALso, make sure your connections for the three temp sensors are connected in the right spots, if you removed them.
 

Mike Howard

Supporting Member
HBT Supporter
Joined
May 22, 2018
Messages
399
Reaction score
150
Location
Texas
Looks like it's time for me to open up my Zymatic too. I'm up to 99 brews, but Fatal error #1 won't let me get to 100.

For those adding a glycol reservoir, do you circulate through the reservoir, or is it enough to just hook it in so that gravity fills up the lines?
The reservoir needs to be added just prior to the glycol pump.

This is how mine is set up:

1588444249965.png
 

Attachments

danyo

New Member
Joined
Jan 2, 2017
Messages
3
Reaction score
0
The reservoir needs to be added just prior to the glycol pump.

This is how mine is set up:

View attachment 678466
You didn't get all of the air out of the HEX would be my guess. It sometimes takes a bit of work to get all of the air out. You need to massage those lines really well if you are not adding a reservoir. Keep the unit at a 45 degree angle and massage the tube going to the RIMS unit and the one at the sensor that should be open now.

Sometimes the RIMS unit and the HEX can contain a lot of air. Just keep working it until you are sure all, or mostly all, of the air is out. When I first did the procedure it took awhile. You can also take the unit from 0 degrees to 45 to 90 and back just to get the air at the top. A reservoir would solve your issue if nothing else works. ALso, make sure your connections for the three temp sensors are connected in the right spots, if you removed them.
Hi Mike, I just had the tubing rupture between the heater and the T / temp sensor.
I was working through issues connecting the Zymatic to a local server. The screen went blank after trying to load a recipe. After 30 seconds I heard the pop. The heater must have been on and I know the circulating was off.
Would you be able to send any specific steps you use to refill? Also interested in adding a T and additional tubing to aid in air removal.
 

Attachments

TREY206

Member
Joined
May 2, 2020
Messages
13
Reaction score
6
Yep, writing on the wall for years and all of their crap finally caught up to them... This quote from the article is the best news I've heard in years "And yesterday, the founder team (Bill Mitchell, his brother Jim Mitchell and Avi Geiger) was let go, along with the customer service team. " Not everyone at PB was horrible, but two guys in particular had a hand in its failure.

It's no big deal though, my Zymatic has been running issue free since I started my own maintenance and cleaning regimen along with a few needed mods. It does mean that I'll need to accelerate my RPi development...
@Mike Howard New member here. I just want to say thank you for all the knowledge and guidance. Every google search Ive done about my zymatic seems to lead back to you. Could you please share how to tear down the zymatic with me? I was able to get a scope camera in the housing to see a giant air bubble in the hex tube. Everything else has been working well until now with the FE1. Since I cant pm you yet let me know what I need to do to communicate. Thank you again.
 
Last edited:

Mike Howard

Supporting Member
HBT Supporter
Joined
May 22, 2018
Messages
399
Reaction score
150
Location
Texas
Hi Mike, I just had the tubing rupture between the heater and the T / temp sensor.
I was working through issues connecting the Zymatic to a local server. The screen went blank after trying to load a recipe. After 30 seconds I heard the pop. The heater must have been on and I know the circulating was off.
Would you be able to send any specific steps you use to refill? Also interested in adding a T and additional tubing to aid in air removal.

Bummer, but not the end of the world. I've actually heard of that happening more than once. Thing is, after several years the tubing needs replaced. Mine was in very bad shape on my 2015 model when I first cracked into the lower end. Could be the RIMS heater is now bad also, but luckily I found a replacement after having mine short out. In this post I talk about the RIMS heater.

I responded to your PM
 

Vandammified

New Member
Joined
Apr 16, 2020
Messages
3
Reaction score
3
The reservoir needs to be added just prior to the glycol pump.

This is how mine is set up:

View attachment 678466
Mike, I am very appreciative of all the information you have provided about the zymatic! I am a long time lurker, first time poster and felt compelled to post this. Luckily I have not had troubles with my zymatic but in the future I am sure I will be referring back to your posts to fix issues as they come up. I am planning on adding a reservoir before beginning to have issues with the dreaded FE#1. Thanks again!
 

rmklaw

Member
Joined
Feb 3, 2015
Messages
23
Reaction score
10
Mike: I am amazed at the wealth of knowledge that you are sharing with the group. We should all unite to have the Picobrew investors turn over the servers and make available parts to you so you can get compensated.
 

Trevor Mack

Supporting Member
HBT Supporter
Joined
Jun 16, 2018
Messages
167
Reaction score
46
Location
Boston, MA
It sure is great tech just some wrong business and software integration decisions along the way. Hopefully with enough community interest we can truly unlock the potential of all the machines out there with or without PB support.
 

TREY206

Member
Joined
May 2, 2020
Messages
13
Reaction score
6
Honestly, I just want to make sure Zymatics live forever...regardless of what my position is on Picobrew and its employees, I absolutley love the machine.
@Mike Howard Just want to say thanks again. With your help and a run to the tractor supply store for, glycol and clamps, it took less than 2 hours to be fully operational again after a week of troubleshooting and cursing. If you ever get that RPI server software going. Ill glady throw some compensation your way. GO HAWKS!
 

Bryce Aston

New Member
Joined
Oct 26, 2019
Messages
2
Reaction score
0
Howdy guys. Owner of a pico c and been cruising FB marketplace and Craigslist for a pico z. Found one for $450. What ?s should I ask owner before purchasing.

Thanks in advance
 

TREY206

Member
Joined
May 2, 2020
Messages
13
Reaction score
6
Howdy guys. Owner of a pico c and been cruising FB marketplace and Craigslist for a pico z. Found one for $450. What ?s should I ask owner before purchasing.

Thanks in advance
I would be very careful at this point. The machines are registered to the owner and there may be issues getting it transferred now. I would make some calls or send some emails to see if any support staff are still around.
 

Trevor Mack

Supporting Member
HBT Supporter
Joined
Jun 16, 2018
Messages
167
Reaction score
46
Location
Boston, MA
I would be very careful at this point. The machines are registered to the owner and there may be issues getting it transferred now. I would make some calls or send some emails to see if any support staff are still around.
I haven't been able to get any response from support. If you were going to buy (I was also talking to same individual, but with shipping across the country I'd rather get a 3 vessel or single all in-one with higher volumes) I'd ask for Picobrew login information and change the account password after confirming the machine is linked once you transfer money.
 

Mike Howard

Supporting Member
HBT Supporter
Joined
May 22, 2018
Messages
399
Reaction score
150
Location
Texas
I would look into a BrewBoss system before buying a picobrew brewsystem. I love the Zymatic (and glad I cancelled out of the Z), but its just a countertop appliance that's fun to play with. If you want a brew system, get a BrewBoss. I have the 20 gallon and couldn't be happier.
 

Trevor Mack

Supporting Member
HBT Supporter
Joined
Jun 16, 2018
Messages
167
Reaction score
46
Location
Boston, MA
I would look into a BrewBoss system before buying a picobrew brewsystem. I love the Zymatic (and glad I cancelled out of the Z), but its just a countertop appliance that's fun to play with. If you want a brew system, get a BrewBoss. I have the 20 gallon and couldn't be happier.
Yeah brewboss, SS, Spike and Grainfather are all in my "investigate" list for an upgrade to for larger batches. Regardless I'll keep my Z1 and look to modify to run automated offline if PB doesn't come through with a good solution for that (doubt the leaked embedded webserver will save recipes, show logging, etc).
 

Sebastian Weetabix

Well-Known Member
Joined
Sep 29, 2019
Messages
188
Reaction score
203
Location
Florida's Left Coast
Howdy guys. Owner of a pico c and been cruising FB marketplace and Craigslist for a pico z. Found one for $450. What ?s should I ask owner before purchasing.

Thanks in advance
Someone is willing to sell you a $2400.00 PicoBrew Z For $450.00 and that ain’t a giant red flag?
Just sayin’
 

Ryder P Moses

Supporting Member
HBT Supporter
Joined
May 9, 2020
Messages
4
Reaction score
1
@aangel The cause for the FE#1 could be low glycol and the cause of the gurgling, however the pumps that Picobrew uses are diaphragm pumps and after sitting for a very long time the silicone pump valves can get stuck. Can you just run a circulate without heat? If while running a circulate you can't get flow get back to me and I'll help you get it running. There is almost nothing we can't fix, even if we need to replace a pump head....
I’m in the same boat. I
I have a complete step by step procedure, with photos, that I have been working on with the help of about 10 or so others on here who have followed the procedure and added modifications/clarifications for each revision. I'd be happy to provide that info to anyone who needs to top off their glycol. Just shoot me a PM and I can get it to you.

For the glycol, I use this one from AMAZON, but I have three draft chillers so I need large quantities. As GP said, USP, Food Grade is what you need.
This is super helpful. Is this the same stuff just in a smaller container?

Propylene Glycol - Food Grade - USP - Kosher - 18 oz net wt in a 1 Pint Safety Sealed HDPE Container with Resealable Cap Propylene Glycol - Food Grade - USP - Kosher - 18 oz net wt in a 1 Pint Safety Sealed HDPE Container with Resealable Cap:Amazon:Industrial & Scientific
 

Ryder P Moses

Supporting Member
HBT Supporter
Joined
May 9, 2020
Messages
4
Reaction score
1
I also have a small leak in the tee with the syringe lure lock fitting on it. Any one know it this is an off the shelf part that can be replaced?
 

Ryder P Moses

Supporting Member
HBT Supporter
Joined
May 9, 2020
Messages
4
Reaction score
1
I... did not ask picobrew until earlier this evening, as it turns out. That would have been a good idea.

Interestingly enough, what it appears they did was take some kind of small 1/4" polycarbonate "T" and just attach a needleless injection site to the middle leg of the "T". Now I just need to find a source for the needleless injection site & the polycarbonate "T". Project for tomorrow!

In the mean time, I've ordered one of these which I plan to add to the "beer out" tube. I've been having issues lately with my "beer out" quick disconnect getting jammed with tiny pieces of grain and I'm hoping this will help with that.

I'm pretty sure this is the same inline filter that they use on the "beer in" line to the Zymatic - just with a clear nylon bowl rather than black glass filled polypropylene.
what did you end up getting? Would you mind posting a link?
 

Thorrak

Supporting Member
HBT Supporter
Joined
Feb 7, 2016
Messages
2,429
Reaction score
1,330
Location
New York, NY
what did you end up getting? Would you mind posting a link?
I never managed to find the luer lock needleless injection site/polycarbonate T, unfortunately. I did order a filter, but I found that with the filter attached to the "beer out" tube there wasn't enough pressure to keep the zymatic working as expected. Eventually I gave it up.
 

Mike Howard

Supporting Member
HBT Supporter
Joined
May 22, 2018
Messages
399
Reaction score
150
Location
Texas
@Ryder P Moses as long as you use a food grade glycol you'll be fine.

As for the luer connector, just remove it and replace it with a stainless steel connector or replace the entire out line....I've never actually used the luer fitting so I removed it long ago.
 

Vandammified

New Member
Joined
Apr 16, 2020
Messages
3
Reaction score
3
Mike, I am very appreciative of all the information you have provided about the zymatic! I am a long time lurker, first time poster and felt compelled to post this. Luckily I have not had troubles with my zymatic but in the future I am sure I will be referring back to your posts to fix issues as they come up. I am planning on adding a reservoir before beginning to have issues with the dreaded FE#1. Thanks again!
Yesterday I had my first FE#1 but the brew went fine after restarting the machine. I think I may finally have to refill the glycol. @Mike Howard may I please have a copy of your instructions on how to do this procedure? I have tried to PM you but as I am a new member I cannot seem to send out a PM to you. Thanks!
 

Ryder P Moses

Supporting Member
HBT Supporter
Joined
May 9, 2020
Messages
4
Reaction score
1
I never managed to find the luer lock needleless injection site/polycarbonate T, unfortunately. I did order a filter, but I found that with the filter attached to the "beer out" tube there wasn't enough pressure to keep the zymatic working as expected. Eventually I gave it up.
I ended up trying:

PendoTech PDKT-104-03 Adapter Tee, 3/8" Hose Barb x 3/8" Hose Barb x Male Luer Fitting, Polycarbonate
by Cole-Parmer
Learn more: https://www.amazon.com/dp/B00PR05X0A/ref=cm_sw_em_r_mt_dp_U_8QDWEbQTYV3F4

The hose barbs are a little big but I was able to connect it without too much trouble. I've only done a clean run with it but so far so good.
 

Peksi

Member
Joined
Sep 1, 2019
Messages
6
Reaction score
0
@Ryder P Moses as long as you use a food grade glycol you'll be fine.

As for the luer connector, just remove it and replace it with a stainless steel connector or replace the entire out line....I've never actually used the luer fitting so I removed it long ago.
Mike, thanks for all the very informative content in the thread. Could you send me the instructions for refilling glycol (sorry but I was unable to send a PM)? I have a Z instead of a Zymatic but am also facing the max temp difference error and running out of other possible solutions. Perhaps the Zymatic instructions are helpful in figuring out what to do with the Z!
 

Mike Howard

Supporting Member
HBT Supporter
Joined
May 22, 2018
Messages
399
Reaction score
150
Location
Texas
Mike, thanks for all the very informative content in the thread. Could you send me the instructions for refilling glycol (sorry but I was unable to send a PM)? I have a Z instead of a Zymatic but am also facing the max temp difference error and running out of other possible solutions. Perhaps the Zymatic instructions are helpful in figuring out what to do with the Z!
I can certainly send you the procedure, but I am not sure it will help with a Z over a Zymatic. Gaining access into the bottom end of the Zym is really a pain, but I think the Z is fairly easy as it is all in the top. I would jump over to the Picobrew Z Thread and put your symptoms and what you have tried there and maybe you can get some answers. I am in that thread as well so will help with whatever I can. I can't imagine a new Z is already having the low glycol condition unless something didn't get connected right.
 

Vandammified

New Member
Joined
Apr 16, 2020
Messages
3
Reaction score
3
@danyo I noticed that you are also on the Picobrew Server Github page (hotzenklotz/picobrew-server). I saw from a thread there you could get a recipe uploaded to the zymatic but have you been able to run a recipe? I can get a recipe from my server uploaded to the zymatic but when I go to run it I get an attribute error.
 

dyrtmonkey

New Member
Joined
May 21, 2020
Messages
1
Reaction score
0
so, i'm in the Seattle area and Pico is doing a sale at their excess inventory warehouse tmrw. i picked up a zymatic bnib. the firmware on it is 1.1.16. The most up to date firmware i can find on the website is 1.1.14 and i'm wondering if this is something anyone that is way more technologically inclined then i am would be interested in? or should i just update to 1.1.14? I ran a brew and the only weird thing that happened was that it turned my 60 minute mash into a 90 minute mash. Any ideas?
 

Yaowei

Member
Joined
May 26, 2020
Messages
5
Reaction score
1
@Mike Howard Thank you for the useful information in this thread. My Zymatic had repeated fatal error #1 for some time now, and appear to have large gap between the wort temperature and heat temp. I’ve tried the deep clean cycle, it does help a bit but still have the FE #1 from time to time. I‘ve read about your comments on refilling glycol along with other procedure and seem to resolve the problem. Could you please send me some more information on how it should be done? Thank you in advacnce.
 

cheesemonster

Well-Known Member
Joined
Dec 28, 2016
Messages
60
Reaction score
35
@Mike Howard Thank you for the useful information in this thread. My Zymatic had repeated fatal error #1 for some time now, and appear to have large gap between the wort temperature and heat temp. I’ve tried the deep clean cycle, it does help a bit but still have the FE #1 from time to time. I‘ve read about your comments on refilling glycol along with other procedure and seem to resolve the problem. Could you please send me some more information on how it should be done? Thank you in advacnce.
Refilling the glycol is a rather messy operation that requires a lot of disassembly. You have to be reasonably skilled at repair IMO. I did it to mine but I also have a lot of repair experience and worked as a professional repairing laboratory equipment which is pretty similar. I think for all you people running Z's it would benefit from a small glycol reservoir up inside it. If I still had mine, I'd mount a stainless tank with a non airtight cap on it, put 2 barbs going in and out, and make it so I can top it off from a hole in the side of the machine. This also degases the gycol for you for free.

With error 1 if you are sure you cleaned the HEX well it could very well be low glycol. You can notice this when you turn it on. The glycol pump is always on and it makes a lot of bubble and swishing noise when there's air in the loop.

Cleaning the HEX might take a lot of cycles to get it to the point where it is not gunked up. If you see stuff on the step filter screen that means there's still stuff coming out of it, and I'd continue that before doing glycol. Also please please please make sure you are using propolyne glycol, not ethylene. It is pretty likely a hex losing glycol is losing it in your beer. Wouldn't want toxic material coming out.
 

Yaowei

Member
Joined
May 26, 2020
Messages
5
Reaction score
1
Refilling the glycol is a rather messy operation that requires a lot of disassembly. You have to be reasonably skilled at repair IMO. I did it to mine but I also have a lot of repair experience and worked as a professional repairing laboratory equipment which is pretty similar. I think for all you people running Z's it would benefit from a small glycol reservoir up inside it. If I still had mine, I'd mount a stainless tank with a non airtight cap on it, put 2 barbs going in and out, and make it so I can top it off from a hole in the side of the machine. This also degases the gycol for you for free.

With error 1 if you are sure you cleaned the HEX well it could very well be low glycol. You can notice this when you turn it on. The glycol pump is always on and it makes a lot of bubble and swishing noise when there's air in the loop.

Cleaning the HEX might take a lot of cycles to get it to the point where it is not gunked up. If you see stuff on the step filter screen that means there's still stuff coming out of it, and I'd continue that before doing glycol. Also please please please make sure you are using propolyne glycol, not ethylene. It is pretty likely a hex losing glycol is losing it in your beer. Wouldn't want toxic material coming out.
Thank you for your advise. I do have some prior experience in repairing laboratory equipment, but I haven't try to take apart the Zymatic yet. And there is periodic swishing noise when the machine is on, which consistent with the possibility of the glycol being low. My Zymatic seems to choke up with error 1 when ramping up from lower temperature (around 120F), once it get up to 130 (by putting in very hot tap water), it seems to be OK from 130F on if the increment is set to be 10 degree.
 

cshelden

Active Member
Joined
Feb 5, 2012
Messages
43
Reaction score
0
Location
OKC
Thanks for the write up on Glycol, that was my issue. I actually found the correct Glycol at Tractor Supply of all places. If I keep the unit I'll do a reservoir. Instant fix on #1 and the graphs look much better!
 

Yaowei

Member
Joined
May 26, 2020
Messages
5
Reaction score
1
@cheesemonster @Mike Howard Could you please let me know briefly about the tools required to disassemble the Zymatics to refill the glycol? I'm planning to do that this weekend and just want to make sure the tools I have in hand are sufficient. Thanks!
 

cheesemonster

Well-Known Member
Joined
Dec 28, 2016
Messages
60
Reaction score
35
Mike might know better as he has probably done this more recently, but from what I recall you need to have a Philips screw driver, and for the front there's nuts that are pretty far up to keep the machine top on to near the display. I think the nuts might be 5/16 or 3/8. I forget if you have to remove that part though I think you can take the whole lid off with top. A long extension is good. Also a hex key set because one of the bolts holding the drip tray and case on is hex. In addition if you have it a pex clamp cutter but some strong cutters would work as well to remove their pex style hose clamps. Get some hose clamps too because you are going to have to replace those clamps. The hoses to the in and out ports on the machine on the inside need to be removed to get the lid totally off. The heating element is all the way in the bottom along with glycol pump. I found it easiest to fill a cup with glycol and run the 12v pump with extra hose to get all bubbles out. It is kinda a pain. Be careful too because the sheet metal in there is unfinished and sharp. It can cut you.
 
Top