freezer floor construction

[jayjay]

Hi all.
I'm thinking about build a new freezer. I'm not going to build the unit till next year, but I need to pour a slab that it will sit on this year. The question is should I get involved in the expence of insulateing the floor, possible heating the floor etc. Or should I pour the slab 6" lower then the finished floor and plan on installing a freezer panel floor?
Thanks

[Josip]

Hi, jayjay :)


Hi all.
I'm thinking about build a new freezer. I'm not going to build the unit till next year, but I need to pour a slab that it will sit on this year. The question is should I get involved in the expence of insulateing the floor, possible heating the floor etc. Or should I pour the slab 6" lower then the finished floor and plan on installing a freezer panel floor?
Thanks

What about to tell us about size of your freezer L x W x H (meters,feet), and some more info about type and quantity of freezing goods ;).....

Best regards,Josip :)

[Toolman]

I looked at all your previous posts they are all to do with possibly the same freezer room.
If you are taking the advice given in earlier posts and starting again GOOD to here . Leave a set down in the slab to allow for the new room to be constructed so the floor is 4" - 5" below the rest of the building then concrete is poured inside the room and made level with floor outside the freezer room . his is the correct way to build a freezer with a concrete floored room .
Oh Yes of course I forgot Heating under the insulation or airflow under the insulation and out the end of the room via PVC piping laid down .

[NH3LVR]

As far as floor heating forget it why would you do it ? This is the correct way to build a freezer with a concrete floored room .
Toolman; Are you saying we should not put heat under a Freezer floor:confused:

[jayjay]

Josip- Size is about 18' wide 40' long and 13' high. Not sure what will be stored. I have 3000 sf freezer on site and 4000 sf fridge. this is an unused space that I'm going to try and rent. Possibly Ice cream so temps may be in the -20F to -30F.
Toolman Unfortunitly I can't afford to do anything to the other unit. I have mentioned in the past. They just keep stuggling along. As I learn more about refrigeration the floor seems to be one of the most important.
This unit will be about 2 feet away from the older one with a 12 inch brick wall between.
Do you have a detail of the floor? The space is 24" below where I want the finished floor so I Can do almost anything now. Heat? insulation? vapor barrier? thermal break? I don't want to get crazy with it because it may never be a freezer.
As always thanks for your help

[old gas bottle]

well it does need a floor heater for sure,you need to put a concrete sub floor in it with a smooth finish or put sand on top ,then the heater mat,[the previous to stop damage] then 100mm at least insulation and finaly the finish depth of concrete,that will depend on the weight of trafic but at least 100mm re-enforced. and dont forget that the wall panels go in on the sub floor then the rest inside the finished box.

failure to fit one will result in frost heave wich has been covered in previous posts.

[Josip]

Hi, jayjay :)


Josip- Size is about 18' wide 40' long and 13' high. Not sure what will be stored. I have 3000 sf freezer on site and 4000 sf fridge. this is an unused space that I'm going to try and rent. Possibly Ice cream so temps may be in the -20F to -30F.
Toolman Unfortunitly I can't afford to do anything to the other unit. I have mentioned in the past. They just keep stuggling along. As I learn more about refrigeration the floor seems to be one of the most important.
This unit will be about 2 feet away from the older one with a 12 inch brick wall between.
Do you have a detail of the floor? The space is 24" below where I want the finished floor so I Can do almost anything now.

Thus 5,5m x 12m x 4m, nice small ice cream storage with (-20*F/-28*C) temperature, but....

....do you know or you don't know:confused:.....

....if you plan to rent it as ice cream storage you should invest some more money now (renting such of low temp storage is also under higher prices;))....later on it will be to expensive to transform it to freezer storage...

....yes, the execution of freezer room floor is very important....you have to do it properly for purpose or forget about freezer storage....


Heat? insulation? vapor barrier? thermal break? I don't want to get crazy with it because it may never be a freezer.
As always thanks for your help

you need: bottom slab with heating system...installation of walls and ceiling panels.....vapour barrier, insulation...normal slab...installation of racks....

why to get crazy....make it right or forget....all you need is (not love:)), but right decision and money....the rest is quite simply...let's say;)

....anyhow you must decide what you want and then we can help much more.....

Best regards, Josip :)

[jayjay]

Can I just leave the floor a bit lower then install a insulated floor panel above it and not use any heaters?Seems like if that will work it will be the least expensive for now.
My other unit has no heat it looks like trenches were dug every few feet under the slab. I guess to allow air to flow. No problem yet.
What did toolman mean by no heat?
Any detail of all the different methods? This way I can get my sub slab moving along.

[NH3LVR]

Can I just leave the floor a bit lower then install a insulated floor panel above it and not use any heaters?Seems like if that will work it will be the least expensive for now.
My other unit has no heat it looks like trenches were dug every few feet under the slab. I guess to allow air to flow. No problem yet.
What did toolman mean by no heat?
Any detail of all the different methods? This way I can get my sub slab moving along.
If you use it as a freezer, eventually the ground will freeze below it and heave the floor, no matter how much insulation you put in it. If it only runs a few monthes of the year you might get away with it. But it will freeze down 20 feet or so, despite the insulation, in time.
There are several ways to put heat under the slab. Liquid heated by the compressors, warm air blown underneath are common.
You might put tubing under the slab, which could be hooked up later.

[jayjay]

Thats what I was thinking just run some pex and deal with it latter. Can't some type of heat exchanger from the compressor do it?

[Toolman]

Toolman; Are you saying we should not put heat under a Freezer floor:confused:


yes sorry forgot that bit , have editted my earlier posting to mention heating or ventilation :o:rolleyes:

[hendry]

added to others' comments ....

underfloor ventialtion may be of cheaper option; floor heating could be expensive when maintenance is NOT simple jobs.

forced ventilation is necesary.
never trust natural ventialtion because it sucks!

you should study the AS standard of carpark's ventilation design to design good ventialtion for your underfloor.

from top down, you need

1] point loads of your racking system if ther is any;
2] floor hardener if you ar allowing heavy vehicle moving around;
3] concrete which its thickness subject to above;
4] 2 layers insulated panel;
5] vapour barrier;
6] structure floow slab;
7] ground beams;
8] underfloor ventilation void;
9] turfing/vapour barrier for ground soils


hope that helps ... :)

[jayjay]

Thanks for info everyone but nobody has a simple detail of a section of the whole floor assemblie?
I can't find AS standard of carpark's ventilation design?

[Toolman]

Get a professional coolroom builder to put together a price and spec for you so they do it , thats there job its a bit like a coolroom builder doing the refrigeration work themselves they will stuff it up and once its stuffed up its very hard to fix !!

[jayjay]

i'm a builder so if I have specs its no big deal. As I said before it may never be a freezer so I would like to keep the investment down. If I used a freezer with a panelized floor do I still need heat in the floor? Can't I just keep the panels off the slab and let the air move around it.

[TXiceman]

If you do not address the underfloor heat or ventilation, you will be dealing with some bad problems of floor heaving later on.

You need to hire a refrigeration consulting engineer to prepare you a specification and check the construction. It will be money well spent in the long run.

Ken

[hendry]

Thanks for info everyone but nobody has a simple detail of a section of the whole floor assemblie?
I can't find AS standard of carpark's ventilation design?

i think it is AS1668 pat 1 & pt2 ...

i get th eproject architect to produce the sectional details from my explanantions.
they are better in the details esp. esthetic views.

[Josip]

Hi, jazjaz :)


Thanks for info everyone but nobody has a simple detail of a section of the whole floor assemblie?
I can't find AS standard of carpark's ventilation design?

Is this of some help;), of course you can install electrical heating system if you want...

Best regards, Josip :)

[Josip]

i think it is AS1668 pat 1 & pt2 ...

i get th eproject architect to produce the sectional details from my explanantions.
they are better in the details esp. esthetic views.

I do not agree, (only partially;))....architects should support always good technical solution......I have many examples of bad designing (making good outlook) done by architects...but that is another long story;)

see this...


Architects are becoming worse by the day!

We were ordered to put the condensor on lower studs, on a 44m high building because it was above the walls and he thought it was a bad view! I had to get a kilometer away to see it! And this is just one thing, I can go on for hours and hours! But let's not!

Link is here:
http://www.refrigeration-engineer.com/forums/showpost.php?p=88391&postcount=4


Best regards, Josip :)

[jayjay]

thanks josip thats what I was looking for.
Can I use spray foam? Instead of rigid panels. Seems like it would work better there would be no joints

[jayjay]

Whats the best way to get the heat from my compressors and send it under the floor? If the units were inside it would be easy. with everything outside how should I do it?

[TXiceman]

Use a glycol system to circulate warm glycol under the floor. Recover the heat from the compressor discharge and/or condenser depending on the type condenser you have.

Ken

[jayjay]

How do I reover the heat from the compressor? I have air cooled condensers.

[Peter_1]

I wrote in the Cool&Comfort issue of the 3tht quarter of 2007 a Dutch article about freezer floors and the different ways of heating the underfloor.
Do you mind Josip I'm posting my figures I made for this article?
If interested, I can post the whole article but it's in Dutch of course and i was also translated for the French part of our country.

[old gas bottle]

best way in my opinion would to fit a plate exchanger on the discharge condenser line through a three way valve,this would have to have either a temperature or pressure control to maintain the correct head pressure,and as suggested hook it up to a glycol system,this may need heated back up to maintain the 6-9 deg C needed to match a heater mat.

getting comlicated isnt it !, just fit a heater mat in one two or more sections, it ,s not the norm because its the most expensive.;)

[Josip]

Hi, Peter_1 :)


I wrote in the Cool&Comfort issue of the 3tht quarter of 2007 a Dutch article about freezer floors and the different ways of heating the underfloor.
Do you mind Josip I'm posting my figures I made for this article?
If interested, I can post the whole article but it's in Dutch of course and i was also translated for the French part of our country.

:):), of course, please.....we can "read" pictures in any language;)....then if we need we can ask you about details....

Best regards, Josip :)

[Peter_1]

This is the link to the whole article and in attachments the pdf of the freezer floor my son made in Autocad
For the moment, I only have it in Dutch. It is the publisher who translate it.

http://www.megaupload.com/nl/?d=N1K8QVFS

[Peter_1]

best way in my opinion would to fit a plate exchanger on the discharge condenser line through a three way valve,this would have to have either a temperature or pressure control to maintain the correct head pressure,and as suggested hook it up to a glycol system,this may need heated back up to maintain the 6-9 deg C needed to match a heater mat.

getting comlicated isnt it !, just fit a heater mat in one two or more sections, it ,s not the norm because its the most expensive.;)

Old gas bottle, your idea is very good but I don't see why you need a 3 way valve. Just switch the pump on and off if you want to control the temperature of the underground.
But, if you install a PHE in the liquid before it flows to the TEV (heating up the underfloor with the energy 'stored' in the liquid) then this will give you a huge increase in liquid enthalpy.
Plot this once ion a log/p and you will see.

A heater mat is the smallest cost if you only look the initial cost.

We have a rather small (10 x 15 m or 30 x 45 ft) freezer running where the probes of the underfloor are connected to a supervising system. If you switch off the heating for 6 months (!!), then there's a temperature drop of +/- 0.6 (from 6.6 to 6.0)
So, the underground is radiating in this example enough energy.

[Peter_1]

Translation of the pdf :
Bovenbeton = upper concrete
2° laag folie = 2nd layer of plastic
2° laag PU = second layer PU-isolation
Onderbeton = lower concrete floor

Verwarming = heating

Alternatief luchtkanaal: second possible heating method with plastic tubes burried in the underground (in the text is an explanation why I don't like this solution)

Betonnet= concrete reinforcement mesh

Stootvoeg= expansion seem

Sandwichpaneel = Sandwich with tuna :p
Onderbreking staalplaat = steel of the underside of the panel is removed.

[Josip]

Hi, jayjay :)


How do I reover the heat from the compressor? I have air cooled condensers.

Not a simple answer...and not a cheap solution....on discharge line you have to install heat exchanger (desuperheater) to heat your glycol for underfloor heating, but...you need also storage tank, pump/s, controls...

check links to get a picture...

....http://www.doucetteindustries.com/desuperheater.html
http://www.doucetteindustries.com/ac_desuperheater.pdf
http://www.doucetteindustries.com/cads_desuperheater.pdf

not exactly what you need, but with some modification...almost perfect;) if you not forget to utilize that also for sanitary water...

you can google for more....

Best regards, Josip :)

[Peter_1]

Josip, how we do it here in Belgium most of the times, installing a normal PHE in the discharge or even better in the liquid line, connect it to a radiant heating system (PE tubes) http://www.zwembad.eu/images/1a30_1_b.JPG, burried in the under concrete floor.
A small collector http://www.sanutal.be/images/sanitair/collector1.jpg (image is for 3 circuits) for the different PE tubes, circulation pump http://www.stopet-verwarming.nl/images/8212139.jpg, small expansion vessel, http://www.koicymru.co.uk/img/blr4.jpg with control manometer and filling connection.

Insert on 3 places a probe (retractable afterwards in a spare PE-Tube going to the middle of the underfloor, bend the end of the PE with a http://www.seton-signalering.nl/upload/Vf214LPS1_2.jpg so that the concrete can't flow in the PE tube) so that you have a control of the temperatures of the underground.

What's the English name for the white plastic straps?

[Peter_1]

http://www.thermon.com/us/catalog/us_pdf_files/CPD1038.pdf
http://www.heatec.com.au/page9.html
http://www.irc.wisc.edu/file.php?id=119
http://www.fao.org/DOCREP/003/V3630E/V3630E08.htm fig 33 and 34

[old gas bottle]

see your point peter,i have never done this before and was just thinking outloud, but what happens when the reclaimed heat from the condenser is not enough,have you had any problems with the head pressure dropping to much?
other thing is,i think price is a consideration here.

[The MG Pony]

If you are worreid about "over condencing" you can use the VG48AC-1C Head pressur modulated by pass valve from Johnson Controls http://www.johnsoncontrols.com/publish/us/en/search.html .

I agree with Peter_1 that it is the best long term option that allows the greatest savings and flexibility, why waste primary energy when you can re-use the waste heat from the refrigeration system?

Peter, we call the wite straps "zip strips" or "tie straps" here.

[Peter_1]

You need +/- 15 to 20 W/m² (in our regions of course) underfloor heating capacity, so this is a rather small amount of heat.
So for a freezer of 6 x 14 m (18 x 40 '), I should install a +/- 15 HP.

This surface needs +/- 1.68 kW (= 6 x 14 x 20) underfloor heating (=5.460 BTU/h)

The refrigerant mass flow = 0.1433 kg/s (0.3159 lb/s) and I take the enthalpy difference of the liquid at 30 °C (86°F)and 12°C (53.6 °F) assuming that the PHE in the liquid works with a DT of 6K , compared to the soil temperature.
This flow gives us 4.200 W, so more then enough to heat the underfloor.

Adding this huge subcool will increase the COP from 1.67 to 2.16 or in other words, your compressor will absorb 30% less power for the same capacity.

With R404a at -30°C, condensing at 35°C (95°F)and 5°C subcooling at the condenser, discharge temperature = +/- 61°C (142°F)
This gives 23.26 kW (6.61 TR -79.366 BTU/hr) condenser capacity.
A desuperheater with a DT of 15K will add 4.4 kW (15.013 BTU/h) to the water (=+/- 20% of what's available)
So condensing completely is much more efficient because you add theoretically 5 times more energy to the water.

Just did rough calculations but it gives a good idea of the savings you can expect.

[Peter_1]

Forgot something, If you use PE pipes (the black ones which we call here socarex tubes) ,then you have to install a circulating pump which can pump sanitary water, so a stainless steel inner housing. Otherwise the pump will rust inside because the PE pipes don't have an vapor barrier and oxygen will come into the circuit.

[monkey spanners]

Peter, here they are known as cable ties.

[Peter_1]

Never use a refrigeration plant with the purpose to heat very hot water.
You must see this heat as something the machines gives you for free and you must use this in the best way for the compressors, not for your water requirements.
So increasing HP to increase water temperature is a waste of energy. If your client is asking to increase water temperature, this can easily be done with shutting of the condenser fans, refuse to do this and explain also why.
The savings he/she thinks they makes with the warmer water so that no electrical after-heating is needed will be more then lost due to the decreased COP (higher condensing pressures)

Don't worry about over-condensing in our countries, I have R404a packs running in winter at 9 bar (130 psi) and evaporating at 4.8 bar (70 psi) which gives theoretical COP's of 7.7 (!) with mechanical Danfoss TEV's.
There's of course no much energy left to heat water under these conditions. :D

[Peter_1]

Peter, here they are known as cable ties.
And this is a cable tie tree http://www1.istockphoto.com/file_thumbview_approve/160264/2/istockphoto_160264_cable_tie_tree.jpg

[jayjay]

wow! I need some time to digest all that info. I think I may look into all your first suggestions which was to find an engineer and have something designed. This is way over my head

[Peter_1]

Especially the cable tie tee, difficult to install :p

[old gas bottle]

good info there peter and something to offer the customers who care about the planet as oposed to just the cheapest solution.

deserves a thread on its own for referance, if cost effective condensing units were available with the PHE and controls built in it could be a real step forward,

[jayjay]

Fianally poured floor. Installed pex tubing for future heat. Took some time but got it done. Thanks for all info