– Urgent – Blast Chiller Problems – Urgent –

[ectofix]

I have absolutely no experience on that creature…and – I stepped away from serious refrigeration work five years ago.  Our supposed “HVAC” shop does all that (***cough***).  ‘Scuse me…

 

So, no help from me.  Sorry.

 

You’ve certainly gotten allot of input about this already.  They can be a bit cruel in their critique(s) and intimidating over there at HVAC-Talk, Olivero.  Been there and done that.

 

You have the right attitude about it though.  They can EVENTUALLY help you.  Just stick with it.  The solution will hit you when you weren’t expecting it.

 

Maybe fixbear can chime in.

[olivero]

Cool, appreciate the input

 

They are a bit rough but I do understand them, having to help rookie after rookie after rookie can be a bit annoying, I am sure some guys out there think its all just fun and games and then eventually get hurt or hurt someone, that’s why I sometimes will answer a bit angry or rough, some people just don’t get that it’s serious work.

 

Either that or they just are like that, either way

[fixbear]

You never mentioned the refrigerant in use.Perhaps R404. .  Regardless, the suction line superheat being 40 degrees tells  me the evaporator is starving. Type of metering system? TXV, balanced TXV or cap tube? Being it has a sight glass i’m thinking a balanced TXV. Check the charge and see if it has rusted though and lost it’s charge. The sight glass should be after the dryer, so that’s not the restriction  How long did you let it run after adding refrigerant. It takes 20 min. for the system to stabilize. Seven and 1/2 HP is a lot of compressor for so small a box

   You should also feel the hot gas defrost line near the evaporator to make sure that the valve is not leaking. Once you check those items install temp probe and suction gauge. Open the TXV 1/2 turn and see if it has a effect. It probably won’t , so you will have to replace the charge and chect the liquid screen in the valve inlet..

[olivero]

I am just happy you showed up.

 

Its 404A yes, correct, also TXV yes, correct and yes once again with the SG after the drier, impressive.

Its also water cooled

Well, I have been working on it pretty much all day, tricked the door open so it still runs with the door open and now I can mess with the system and see effects.

 

Looks like it was starved and that was all it was, might be slightly undersized though, opened the TXV, water regulating valve as well as the 2 balancing valves on supply and return are now cranked all the way open and now I am starting see what I want.

 

Suction pressure is hanging 15-17 PSI, SH is about 20-40* as it pulls down it gets less.

High side is about 250 with a SC of about 11*

 

When I started in on this unit I had absolutely no clue about it at all but looks like we are getting somewhere now. Suction pipe is below 32* Pretty much the whole time and after a while will go down below 0- probably in an effort to make that box 36* come hell or high water

 

well… buddy… it’s not gonna happen when the door is open all the way

 

IT can go down to 36* and 0* I am doing all this with the unit trying to go to 36* not sure how its gonna all work when it tries to go to 0*, should I worry about that? Chefs use the 36* setting way more than freezing.

 

after opening the TXV all the way I am seeing bubbles in the SG again, probably added about 2 lbs. on top of the 1 lbs I did the other day. I will weigh it when I am done but just guessing about 2 lbs.

 

Adjusting the TXV definetley had an effect, brought it from 60* SH to 20*-40* SH.

 

Gonna turn it back on now that I let it warm back up and see what I got, hopefully its good. So far its improving. *furiously knocking on wood*

[fixbear]

olivero wrote:

 

having to help rookie after rookie after rookie can be a bit annoying

It is our obligation as seasoned tech’s to train and help those starting and even proficient in the trade. .All of us have had that one machine that frustrated us to death.

[fixbear]

Thank you for telling me it’s water cooled. Now, is it a txv or balanced TXV? Sounds like TXV and that you overrode it so it no longer regulates. Is it a Alco, Sporeland or Danfoss valve? You have to be very careful with this size machine opening the metering as when you add staving refrigerant you can flood back the compressor. That would be like 4 to 5 grand gone.

Looks like it was starved and that was all it was, might be slightly undersized though, opened the TXV, water regulating valve as well as the 2 balancing valves on supply and return are now cranked all the way open and now I am starting see what I want.

Where are these at, water side or refrigerant side? Something caused this and you still don’t have the ideal 10 degree superheat. You say that the condenser unit is downstairs, Make sure to visualize the lines the whole way for damage. sometimes workers hit them and crush causing starvation.  If that is all well, change the charge on the valve. be cautious to set the calibration back to where it was before you changed it as you can destroy to compressor. also makes it easier to put the charge on.

 

As a side note on this one, I had a cooler that was starving like this that drove me crazy. Finally went to change the expansion valve (soldered in) and saw that someone previous had replaced it with soft solder instead of braze. .Now I have to correct by cutting  back due to solder..Can’t do that on the evap due to distributor. It also had a lot of solder glop hanging and in the drain pan. Ok, lets just try rebuilding the valve. Pumped it down and disassembled the valve in place only to find it was full of solder. This cooler could never have worked right from the beginning yet was 6 years old. Just love a AC guy who thinks he can do refrigeration. Can’t tell you how many I’ve been called in to trouble shoot for over the years.

[olivero]

Yup, water cooled but the location is opposite, Condensing unit is upstaits, chiller is downstairs. 

 

Its a Alco TXV, TI series. 

 

Just ran the unit again in freezing mode, took this reading when it was almost at set point of 0*

 

SP: 5 PSI  Suction pipe temp: -19*F

SH 15*

 

LP: 247.2 PSI Liquid Pipe Temp: 90.5*F

SC: 12.5*

 

When I ran the unit in cooling mode (36* box temp) yesterday, here is what I got, the unit ran for about 20-30 minutes as I had the door open all the way. Box temp was about 40*

 

SP: 17.5 PSI          SPT: 11.1*F

SH: 32.9*

 

LP: 273 PSI            LPT: 98.7*F

SC: 11.6*

 

This looks good to me, What do you think?

[john]

I lurk over there and really dislike how some folks act. Lots of posts on the web suggest the younger generation is the disrespectful group with a keyboard behind the screen– clearly they haven’t visited over there. 

 

I’d argue that with great users like you (fixbear, ectofix, olivero, and izzygreen, just to name a few) and our techs here, we rival their knowledge base in commercial kitchen equipment. 

 

Speaking of, I haven’t seen alnelson or badbozo2315 around here lately. I know bozo is active over there. Any thoughts on that?

[olivero]

Its true, I do agree.

 

I think helping the guy next to you out is the responsibility of knowing. Being the guy with the manometer in your hand trying to figure out WHY oh WHUY!!!!!!! this unit won’t do what It’s gotta can bring your understanding of rage to whole new highs

 

I like teaching what I know, I definetley don’t know a lot, only been in the trade for 3-4 years but I started from scratch with no official training or anything, so I know it can be done.

[fixbear]

Still wonder why the valve/feed changed.  If the bonding of the bulb was loose it would over feed. I still think the charge has lost some gas. do you see variation in suction temp like the valve is throttling? It should be varying a few degrees as it hunts. If you have the adjustment screwed all the way out, it is not working on the spring. What’s your compressor full load amps and running amps? Tells you if your near capacity.  Something had to change.

 

How big is the liquid receiver?  Just trying to determine if it could have just been a volume loss that caused it. Water cooled have a very even head pressure compared to air cooled.

 

   Now the big design question.  What is the elevation from the bottom of the evaporator to the suction line on the condenser and the diameter of the tubing. I ask because of oil return.  Milk tank installers were my worst on this.  If you have a high rise one need to place traps every 3 ft to keep the oil returning right. and not choking off the suction. The oil only returns on the tube wall from velocity. Every shut down it drains back to the evaporator without the traps. Makes for a abnormally long equalization.    I imagine this unit must have a suction receiver on it for oil feed and slug protection.

 

FYO the charge is what opens the feed. the spring closes that you can adjust closes it. The coil back pressure works against the charge that senses the tail coil.  With a bypass TXV a tube is added from the end of the evaporator tail coil to make more accurate sensing and load limiting.