Refrigeration Sizing

[utcheme75]

I am in the process of purchasing a new walk in cooler for a liquor store and need some assistance.

1) Which insulation is better ,foamed in place urethane, extruded polystyrene or expanded polstrene for a cooler temp of 35-38 F? I ve heard the salesman side of which is better but I want to hear it from an engineer.

2) What sort of HP and BTU is recommended for a cooler area of ~800sq ft with an 8 ft ceiling. The floor is concrete. Outside ambient temp of 85 F and cooler temp of 35 F? Condensing unit will be remote (outside).

3) The cooler is going to have 25 30"doors. Is there a door manufacturer out there that is better than the rest? I have ran into names such as Gemtron, Anthony and Ardco.

Any info that you can provide will be appreciated.

Thanks
Nick

[Peter_1]

BTU, °F,...if possible place SI units between brackets.

Insulation, PU is far better but why foamed in-situ? You will never reach the density of 40 kg/m³ (hard , IP units)
Better use PU panels, made in the factory and assembled on site very fast.
Foaming in-situ is a technique of the sixties.

Take 100 W/m³ for the heat load as an estimate for a well insulated room (so, with PU)

Doors...I can recommend you EU manufacturers but this will help you not further.

[US Iceman]

Insulation: If you ask for the R value of the panel from each manufacturer that gives you a good indication of which one is best. Let's assume the walls are 4" thick. Each manufacturer can tell you their own R value for a 4" thick wall. You want the highest R value you can get. The higher the R value, the less heat will leak into the cooler. Same thing applies if the walls are a different thickness.

Panels that are "foamed in place" are usually better in my opinion. Factory foamed-in-place is what I meant. I just saw Peter's comments and thought I would clarify that.

Capacity: This is an estimate only. The actual numbers depend on a great deal of things. One of them being the 25 glass doors you want to use. With some rules-of -thumb I normally use, you might require around 3 Tons of cooling (36,000 Btu/hour). It could be a little more or a little less.

Doors: My experience has been with the Anthony or Ardco doors. Both are acceptable. You should be aware they have different versions for energy use. Some versions are better than others. Usually the less efficient doors are cheaper. Doors are a one time cost, but energy is something you continually pay for.

[Peter_1]

Click on the right side menu http://www.pu.bayer.com/db/pu/pu_cms_internet.nsf/0/DB352F94FA6E336AC1256F770042BAA2?open&ccm=010010020070010

[rickmor]

I've read that extruded polystyrene holds its R-value longer than PU, at least that's the claim of EPS manufacturers. So even if PU has a higher initial R-Value, in the long term EPS saves more. Is there any truth to this?

[Peter_1]

I should say: sales-talk.
PU outperforms PSE far more regarding R-value.
What about mices eating PSE?
Water absorbing capacity of PSE?

[old gas bottle]

one thing to consider in our country now anyway,is the fire rating of cold rooms,most insures require PIR as apossed to polyurathane,polystyrene is a no no,even with a retardant added,not sure on the US requirment,bar that you only need 80-100mm panel thickness,use a insulated floor [same as walls]if poss as apossed to streight down onto the concrete, avoid glass doors if poss [poor insulation] and fit strip curtains over doorways, the kit is basic stuff. cheers.

[Samarjit Sen]

Provide PU. This is far more efficient.

[Andy W]

Does any one still use polystyrene panels for "new" installations? the reason that I ask is a customer of mine had a large coldroom installed last year (not by me) which consisted of 200mm polystyrene panels for a 4oC veg cold room, he has had problems with it from the start, the evaporator been undersized for the room, the unit twice oversized for the evaporator amongst other problems. I need to know if polystyrene is still recommeneded or used as an insulation and how is it classed for fire safety etc, any help on this one appreciated or links to any sites would be great.

Thanks, Andy.

[Peter_1]

Is the used PSE the white, very light (with bubbles) one or the green, more dense one?

[old gas bottle]

whites the polystyrene peter,used for years because its light and effecient,also easy to use and quite strong, the only places i know where it is still used is farms and similar,reason for that is there mainly rural and lots dont even have insurance on the coldroom structure,ever since 911 ploystyrene was black listed by most major insures,mineral fibre was a replacement [like loft insulation]but the panels were too heavey and needed supporting,ployuranthane still is fairley common,PIR has the best fire rating, to dispose of polystyrene costs lots of money thats why farmers get cheap jobs done!

[Peter_1]

I asked this because you have expanded (mostly white, the bubbel one) and also the extruded PSE (green or yellow)
The extruded is used in Belgium for isolation between the outer and the inner wall of a house.

[Samarjit Sen]

Dear Andy W,
Puf panels are very much in use and have gained quite a reputation. All new Cold Storages or Cold Rooms are with puf panels with +40kg/m3 density. For a 4 Deg. C job, your customer could have used 100 mm thick puf panels. We use 200 mm thick panels for much lower temperature may be for a -40 Deg. C job.

If you can provide with the datas such as the product proposed to be stored, the total load and the per day loading of the product, dimensions of the Cold Store, I may be able to assist you in getting a suitable design and reccommend the equipments.

With regards, Samarjit Sen

[Andy W]

Is the used PSE the white, very light (with bubbles) one or the green, more dense one?It is white with crumbly bubbles.

[Andy W]

Why would polystyrene insulated panels be used over polyuretane foamed panels, is it down to cost or fire safety. I have got to get back to my customer with some answers. Regarding calculating the cold room, I calculated the room as well as my wholesaler calculated it using his software and we both arrived at 9 kw, the evaporator is giving us 6.5 kw and the condensing unit 15kw! This installation was bodged from the start just unfortunate that I have got to do the ground work and collation of data for the customer which I wont get paid for (but he is a good customer of mine) so he can decide what action to take.

[Toolman]

Does any one still use polystyrene panels for "new" installations? the reason that I ask is a customer of mine had a large coldroom installed last year (not by me) which consisted of 200mm polystyrene panels for a 4oC veg cold room, he has had problems with it from the start, the evaporator been undersized for the room, the unit twice oversized for the evaporator amongst other problems. I need to know if polystyrene is still recommeneded or used as an insulation and how is it classed for fire safety etc, any help on this one appreciated or links to any sites would be great.

Thanks, Andy.

Polystrene is very common in Aussie , the thicker the better 200mm for a coolroom will reduce the required equipment size and its far cheaper than polyurethane , and thats all that matters to 90% of buyers . No-one in this thread has mentioned or asked you about load conditions .Do you expect to cool the product in 24hrs or 24 days thats another factor to what size to make the equipment . If your customer has a crappy equipment setup dont use the clown who put it in for him . Ask for heat load calculation sheets that show what equipment you need to cool a certain quantity of stock in 24 hrs , if the product is coming in HOT . That sheet should show coolroom construction detail etc ( wall thickness , and if Polystrene or Urethane ). I have quoted many jobs that will work but MANY customers will go for the cheapo and wrong alternative by others , like your customer with Large unit and small evaporator :cool:

[Andy W]

Thanks for the info guys, I have prepared for my customer an heat load calculation for the cold room using adacam software, my wholesaler has calculated the same job with mistral and give or take a few watts we are very close in our calculations, I have also given him a photocopy of the evaporator design data and condensing unit data so he can clearly see it all in black and white, it is now down to him what action if any he wants to take against **** Turpin Refrigeration Ltd, to do the job properly as I will not bodge a job is going to cost him more than he thinks.

[knighty]

It's kind of off topic... but I just removed 3 freexers at work a year back and replaced them with 1 larger one....

2 of them had cork for insulation, nailed into wooden pannels about a foot thick... it took 5 of us to move the door from one of them it was so thick and heavy !

(for people from outside the UK who might not understand "cork".... it's hard to explain, it's made from wood and it floats... oftern used for notivce bords that you stick pins into)

[Samarjit Sen]

Cork used to be a very good insulation material. Due to the rise in cost, peaople started avoiding cork. There has been other insulation materials such as glass fibre, which basically is a hot insulation. Polystrene used to be originally used as a packaging material. If you want to use it as a insulation materials then it should have a minimum density of 22 kg/m3. Butthem termites and rats love to eat the material. Polyuretahne was introduced long time back, but were not aware of it. Now it has come back and is a very good insulation material. We do a number of Cold ooms from - 45 Deg. C to + 5 Deg C abd prefer to use puf panels.

[winfred.dela]

Regarding insulation panels:

For your temperature (35-38F), it would be enough to use 4 inch Polysterene because it will be cheaper and will be structurally sound.

Due to better R value, you may use a 2 inch or 3 inch polyurethane but it maybe more expensive and you need more ceiling and wall supports to make it sturdy.
Of course you may use also a 4 inch Polyurethane but will be a lot expensive.