Funky Hill-Phoenix case install with a dark future

[icemeister]

A customer bought a 16 ft run of used Hill-Phoenix "multi-temperature" case and is in the midst of having it installed by the Miami-based outfit he bought it from. I was there on a service call for a walk-in freezer problem today and got moment to check this deal out and I got a real bad feeling in my gut over this one. :(

First of all, I've never before seen full-sized market case with a low-temp coffin bottom and a 2 deck medium-temp top like these two eight-footers. I've run across self-contained stuff kinda like that from Masterbilt or Universal-Nolin, but not Hill. No nameplates, no numbers, no clue as to what they are. Anybody know?

Anyway, to the fun part........

I noticed looking at the cases and the units on the roof that they have two 2 HP R404A LT unit for the coffin sections and one 2 HP R22 MT unit for the upper MT decks. OK so far.

I then noted that the LT coffins have R22 VZ TXVs. :eek:

I noted that the LT coffins are set up for HG defrost. :eek:

........and they've got each LT unit piped into the side inlet tee after the TXV. Classic three pipe HG defrost. :eek: :eek:

.....and three units have Embraco hermetics. :eek: :eek: :eek: !!!

I'll have to get pics of this deal. And the installation is atrocious to say the least.....enough to make Payson's company look good. ;)

[Edited by icemeister on 07-02-2005 at 05:42 PM]

[R12rules]

Quite possibly the crew is clueless about what they are dealing with.

This would be especially true if the outfit is from either an Auction House or a Used Equipment Supply.

If your outfit is the one this client uses regularly to service their stuff ... I would document the project and aproach the customer with your findings.

He will either choose to have them complete the project and THEN threaten suit when it doenst work as promised in the contract ... or he will have you fix it all and THEN he will sue them for what you had to do to fix their mess.

I doubt these guys would understand what your talking about if you approached them individually.
Nor do I beleive their supervisor would comprehend either.

I have experience with these types and it is sad to say the least.
The call is up to you. Just cover your "6" so this cant return and bite you.

[icemeister]

I'm just going to stay out of it unless the customer calls me to fix it after these guys leave. I've done all of this customer's service for 12 years, they're good payers and good people.

[bigdmike]

ice i've came across this problem a few times.but never seen a case that is low temp on bottom and med temp on top.anyhow i've had to convert a case from hot gas to electric defrost and vise vsrsa.i've also had to replace powerheads or txv's to get the flavor correct.maybee they will get it correct before the job is complete.if not you will have a nightmare on your hands,but will make some $$$ getting it correct.

[icemeister]

These cases are fairly current Hill-Phoenix that were in a Publix store in S Florida. (They're probably specials made up for Publix) The bottom section looks like an OMZ single-deck FF. What really makes me nervous about this installation is the single compressor 3-pipe hot gas defrost setup. It's already doomed to failure right there. :(

[gas-n-go]

Ice I do publix work on the westcoast and I have not seen what your describing in any of thier stores. They are currently purchursing selfcontained stand up cases that maintain three different temps for thier aprons displays but these are new cases not old and i dont think they are made by hill but you may be looking at an experimental piece of equipment that they tried. If you can get me any data on these cases or a picture or something more to work with i can ask around and try to get some imformation for you

[icemeister]

Well......I got the call from the customer that the installation is done and after nearly a month of mucking about, the installer hasn't got things working right.

This is a pic of the cases in the store. They're relatively new Hill-Phoenix, but no dataplates to be found. The bottom section is basically an OMZD coffin frozen food while the top is a cut-down dairy case.

http://i10.photobucket.com/albums/a103/bart_989/AztecaHillCases8-12-05.jpg

Here's a shot of the skid-mounted units on the roof.....a nice little package deal, but wait, there's more. :eek:

http://i10.photobucket.com/albums/a103/bart_989/Azteca-Unitsonroof8-12-05.jpg

As I mentioned in my earlier posts, this is set up with single compressor hot gas defrost. Here's a look at the case piping as installed. Note the HG line teeing in after the TXV and the ice in the bottom of the case. If you look closely there's a fan delay/termination Klixon wire-tied to the suction header. This guy was shutting off the fans during defrost. :(

http://i10.photobucket.com/albums/a103/bart_989/AztecaHillCasePiping8-12-05.jpg

This is one of the LT units. The piping is all 3/4" and 3/8" soft copper......must be an A/C guy. ;) Note the 4# capacity 4" x 10" accumulator and the lack of a CPR valve. These compressors were very happy that I came to shut them off.

http://i10.photobucket.com/albums/a103/bart_989/AztecaLHFFUnit8-12-05.jpg

My first approach to this one is to get the evaporator fans running constant, set up proper defrost termination and install CPRs. I'd like to upsize the Accumulators as well, but I'm going to save that for round two. :D



[Edited by icemeister on 08-14-2005 at 06:11 PM]

[Freezeking2000]

How is the hot gas working? No wonder it is iced up!

[icemeister]

Originally posted by Freezeking2000
How is the hot gas working? No wonder it is iced up!

The coil as was clean as a whistle..........there was ice everywhere else, though. ;)

Fans on during defrost with a 50ºF discharge air termination should help that issue.

I've only played with this mess for a couple of hours so far. The HG appears to work OK at clearing the coil but I'm more afraid of wiping out the compressors at this point.

There's severe overloading due to the lack of a CPR valve, both during defrost and pulldown. The floodback is something that I haven't got a good handle on just yet, although it was obvious during my short analysis that it'll be a problem for sure.

[bigdmike]

Ice, is there not a seperate set of fans for the med temp section. Cutting fans off during defrost on low temp is how it's sposed to be.But if the fans are for both med and low temp sections then hmmm good question bout the fans.The line that tee's just past the txv should have a check valve in it.The check valve in liquid line up at unit,what the heck is that for.Hot gas should enter the suction line and return through the liquid line.I would run the unit as low temp and add a epr for the med temp.Hmm i'm gonna read your original post and study it some more.

[frosty-ne]

Icemeister

I agree with you about fitting cpr but I have never heard of running the fans during hot gas defrost? is the fan delay working correctly after defrost holding fans off till coil frosts? the hot gas line should be insulated although the pipe work looks a mess and is that a check valve in the liquid line at condensing unit?

Regards
Frosty-ne

[bigdmike]

Man this is a difficult situation ice.wish i could be there to help ya!looks like a challenge.

[icemeister]

The MT top sections are totally separate from the bottom LT, and they're not really a problem at this time. The two 8 ft MT case sections are tied to the third condensing unit pictured on the roof.

The evap fans on a closed LT case must shut off during defrost, but not on any open LT case I've ever seen.

The check valve at the condensing unit is the liquid return check you're looking for. I would have installed it in the case.

The direction of flow would indeed be the reverse of what I've got here if it were a parallel rack system with tradition 2-pipe HG defrost. With the 3-pipe setup HG in after the TXV is better.

[icemeister]

Originally posted by frosty-ne
the pipe work looks a mess and is that a check valve in the liquid line at condensing unit?

In reality, the piping is much worse than you can imagine from what I've shown here.

That is a check valve.......that should be in the case.

[icemeister]

Originally posted by bigdmike
Man this is a difficult situation ice.wish i could be there to help ya!looks like a challenge.

The good things here are that the customer is good to work with, they're not pressuring me, they pay on the spot and have five more stores with a similar problem. ;)

I could save myself a lot of grief here if I just added some Calrod heaters, but a HG defrost setup like this one is definitely a challenge.

[bigdmike]

Good luck Ice.

[frosty-ne]

Icemeister

Regarding the defrost if you run the evap fans on a defrost would you not cause icing or frost in the supply/return air flues and effect product temp as well as lose hot gas temp are you sure you have not seen this used on pack systems and not on single condensing units? is there also pressure switch for condenser fan to maintain high enough head pressure on defrost? I have never seen one of these MT/LT case set ups before a good challenge for you icemeister!!!, I would still insulate that hot gas line as well.

Regards
Frosty-ne

[icemeister]

Open frozen food & ice cream cases, whether they are hot gas or electric defrost, always run the evaporator fans during defrost. The above-freezing warm air (up to about 50ºF) during defrost insures that all accumulated frost is melted off the flues, ducts and the pan.

Closed cases like glass door reach-ins always shut the fans down for defrost and restart on a coil-mounted t'stat.

Pack systems?????......Are you from the UK? ;) We call them parallel racks on this side of the pond.

The only single-compressor HG defrost systems I've seen in my nearly forty years at this biz has been with walk-in systems like those offered by Kramer (ThermoBank), Recold (Vapot) and Dunham-Bush. If my father were still here, he would surely have some examples of other systems to tell me about in his forty years experience.

I have not seen, yet alone worked on a FF case with HG defrost on a single compressor. It's the larger coil volume than a walk-in system that's concerns me now. I'm looking at a lot of liquid hitting the pump (post defrost) after filling up that tiny accumulator.

The head pressure aspects will likely be dealt with later on after the bugs are worked out......good point.

The MT/LT thing isn't really a problem as they are totally separate systems......and the MT is behaving itself so far. :D

The HG line is in fact insulated from the roof level to the case. maybe I'll clean that up at the end of all this.....if there is one. ;)

[frosty-ne]

Icemeister

Sorry I meant to say rack systems yes I am from the UK. I also have never seen HG defrost on a single system since I was an apprentice and that was on a walk in cold room and that was vey rare and yes you had to still be careful with an accumalator/ floodback before you ran out of hot gas, you could fit heaters to suction accumalator to assist with boil off of liquid

[frosty-ne]

Icemeister

Yes I am from the uk but have worked in Canada and was fully licensed for refrigeration and gas (Boilers) so I really enjoy reading your posts as I would like to return to Canada (Citizen) if i can get a decent job or even the US I have been out of the supermarket game for a while but used to commission racks (packs)

[icemeister]

I completed Phase 1 of this remedial project by rewiring the evap fans to run constantly and got rid of the fan relay and 3-wire Klixon stat in the case. I burned in a couple of CROT-6 Sporlan CPR valve and set them at about 35#. I haven't reconnected the OEM termination t'stats just yet, but once I get things running smoothly I intend to do that.

No more frost and ice leftover after defrost and no more compressor overloading either during pulldown or post-defrost.

One thing I don't like is during defrost the HG continually feed to the evaporator and the pressure pegged my lowside gauge at about 5 minutes into the cycle.

I'm thinking about adding a HG regulator on the HG feed like a Sporlan ADRI to limit the evaporator pressure to around 80-90#.......kinda like an HPR on a Manitowoc.

Any thoughts or suggestions?

[condenseddave]

Absolutely throttle the evap pressure during defrost.

The biggest hurdle you're going to face is what to do with the liquid returning from the hot gas. BIG acumulator or.....

Do they need free heat somewhere???

[icemeister]

You're right on about the returning liquid during defrost. I put the CRO valves ahead of the accumulator to get the benefit of the flashoff and hopefully get a bit more out of their very low liquid holding capacity of about 4 lbs.

The compressor suction goes to saturation within a minute or so after defrost initiation......no great for the pump, but not slugging it in. The discharge gas temps stay pretty hot.....no lower than 140-150ºF with 150-160# discharge pressure while in defrost so I'm not terribly worried about busting up a pump......just yet. ;)

The accumulators need to be larger for insurance. The HG need to bet throttled back to limit evap pressure during defrost and thusly slow down rate of return of the defrost liquid to the pump.

I've even given to thoughts of building a Thermobank. :D

[Freezeking2000]

I have seen this exact set-up as you describe run for years with just the accumulator for a heat load.............................some things make me go hmmmmmm?

[condenseddave]

Originally posted by icemeister

I've even given to thoughts of building a Thermobank. :D

Hey. Dan Kramer did it, so can you.:p

[icemeister]

Originally posted by Freezeking2000
I have seen this exact set-up as you describe run for years with just the accumulator for a heat load......

But not with a Bristol compressor I'll bet. ;) :D

[icemeister]

My latest thoughts are to add a heat exchanger in the suction line just ahead of the CPR and accumulator and pipe the HG through it. I came across some old D/B stuff that used what they call an HCX heat exchanger for three-pipe systems. Refrigeration Specialties makes a "Deluxe" heat exchanger which is essentially the same shell-and-tube arrangement as the old D/B setup.

The heat-X will flash off returning liquid, the CPR is downstream of it so it will hold back even more. With a HG regulator limiting evap pressure I should be good to go, no?

I'm just thinking out-loud here for anyone that's following this. ;)

......and starting to sound like Poodle Head Mikey. :D:D

[condenseddave]

I'll sell ya a couple used Goodman outdoor units cheap.:p

3.5 tons EACH!:D

[frosty-ne]

Icemeister

The heat exchanger seems like a good idea using hot gas through it but thinking aloud as long as it is only de-superheating the gas? and as long as there is enough superheated gas to clear the coil under worst conditions? Does it not seem a catch 22? have you seen this used before with hot gas through heat x ?

Regards

Frosty-ne

[icemeister]

Originally posted by frosty-ne
The heat exchanger seems like a good idea using hot gas through it but thinking aloud as long as it is only de-superheating the gas? and as long as there is enough superheated gas to clear the coil under worst conditions? Does it not seem a catch 22? have you seen this used before with hot gas through heat x ?

With the added heat-x I would expect the defrost time to increase somewhat because some of the heat content of the HG flow would be given up re-evaporating returning liquid. Most of that lost heat will be the superheat, but in reality, that's not what is doing most of the defrosting of the coil......the latent heat does that. Hussmann's Koolgas defrost isn't superheated.

The heat-x will flash off a lot of liquid to add to the suction flow. The CPR valve will still only allow the same flow so as to maintain my 35# compressor suction. The result is that the flow of HG to the case and therefore the liquid flow return will be reduced accordingly.

At the same time, the suction gas entering the compressor will (hopefully) be superheated instead of saturated or slightly flooding. This will provided higher discharge gas temps, ie hotter HG during defrost and will help protect the pump as well.

I would expect the defrosting of the case to less aggressive, but kinder and gentler to the compressor.

Dunham-Bush used to call this a Heat-Cycle HG Defrost. It was marketed from the late fifties until around 1980 or so when I worked for D/B at W.Hartford,CT. I got to see a couple of new jobs that weren't experiencing any troubles, so unfortunately I didn't get an opportunity to play with them. Later when I worked for a supermarket chain I got to see a thirty year old R22 walk-in freezer with the D/B Heat-Cycle HG defrost system installed with no accumulator. It still had the original Copeland compressor.

[frosty-ne]

Icemeister

I have worked on racks with coolgas defrost but the saturated/condensed gas was going back into the liquid line with a differential valve fitted in the main liquid header, you seem to have it well sussed anyway icemeister the Kramer thermobank seems a good idea but must be a lot more cost wise? are they very reliable? also if you seen the heat x D/B system on thirty year old system without accumulator it must be ok.

Regards
Frosty-ne

[icemeister]

Originally posted by frosty-ne
.......if you seen the heat x D/B system on thirty year old system without accumulator it must be ok.

That system had a Copeland semihermetic. The ones I got have Bristol/Embraco tin cans. It's a good thing to have accumulators in this case..........kinda like belt and suspenders (or as you blokes say, braces) :D

[thegoodhumorman]

Seeing as how I am thinking of recent nightmares thought I would just have to drag this one from the grave-
I have seen another Hill (okay a few) phantasm that
had Med temp reachins atop the OMZD bottom, with HG.
Can't say how well it worked but
Looked real good in my rear view mirror!