Freezer Floor Heave / what is preferred underfloor heating design & technology?

Hello Everyone,

we have a freezer floor which is 21 m2 inside meat factory, it's operation temperature is -18 C, it kept rising till it reach 25 cm, where we decided to stop it from working.

i have done some google and i have found the reason of ice building up below slab, so i suggested to repair the floor and install underfloor heating system, which i have no experience in such systems.

what i have found that we can install electric heating system or heating system using water mixed with glycol that operate by heat pump or gas boiler

for these tow different systems i have some questions:
1) what is preferred underfloor heating system using electric heaters or water with glycol? (pls let me know what are advantages and disadvantages)

2) what is the required energy flow by the system (i have read that it is 30W/m2, but i think it is little, am i right)?

3) how can we check and do necessary maintenance for the system if it would be covered with concrete?

4) does underfloor heating system affect the efficiency of freezing inside the room, or make losses for freezing unit?

5) what is the preferred for the floor, to use tiling or epoxy coating?

6) for the layers, i have read that floor layers order should be as following: (vapor barrier, slab of concrete 10 cm, insulation layer 15 cm, heating system, concrete slab 15 cm)? is the order right? any additional layers?

thanks for everyone who help little experienced man :D

Hi, Suhaib :)

Welcome to RE forums....

No need to ask the same question in different forums ...only making confusion .... that is the reason for deleting.

We are not paid for our work here (we are working in some other place to provide our daily bread) and sometime you need to be patient until you get some answer ...

Quote:

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Originally Posted by Suhaib

Hello Everyone,

we have a freezer floor which is 21 m2 inside meat factory, it's operation temperature is -18 C, it kept rising till it reach 25 cm, where we decided to stop it from working.

i have done some google and i have found the reason of ice building up below slab, so i suggested to repair the floor and install underfloor heating system, which i have no experience in such systems.

what i have found that we can install electric heating system or heating system using water mixed with glycol that operate by heat pump or gas boiler

for these tow different systems i have some questions:
1) what is preferred underfloor heating system using electric heaters or water with glycol? (pls let me know what are advantages and disadvantages)

2) what is the required energy flow by the system (i have read that it is 30W/m2, but i think it is little, am i right)?

3) how can we check and do necessary maintenance for the system if it would be covered with concrete?

4) does underfloor heating system affect the efficiency of freezing inside the room, or make losses for freezing unit?

5) what is the preferred for the floor, to use tiling or epoxy coating?

6) for the layers, i have read that floor layers order should be as following: (vapor barrier, slab of concrete 10 cm, insulation layer 15 cm, heating system, concrete slab 15 cm)? is the order right? any additional layers?

thanks for everyone who help little experienced man :D

---

I will try to answer some of your questions:

1. undefloor heating system depend on your facility ... if you have installation with warm glycol water you can use that one ... now that will be quite expensive to install ....my suggestion is to install electrical trace heating (http://www.flexelec.com/) , but double for safety ...

2. I am not sure about but you can ask manufacturer about ...

3. it will be covered with concrete and you have to do checks during installation before you cover heating cables with concrete

4. no

5. depend on your use ...sometimes tiling ... but maybe in the freezer room epoxy is better

6. from bottom to the top ...

0. dry and healthy soil
0.0 it is also possible to make one slab of 70-80-100 mm to flatten the floor
preparation for vapor barrier - but total price is rising -

1. good poly sheet vapor barrier - must be also on the vertical walls ...
2. heat tracing (my advice - double one working and one spare)
3. polystyrene insulation 300 mm
4. covering paper
5. finished reinforced concrete 100-150 mm
6. epoxy or tiling cover

... you will be surprised when you start to remove frozen soil under your freezer room ...maybe you have to dig 2+ meters to come to not frozen soil.

try to avoid cold bridge between floor and insulation panel walls - wall panel must go down to polystyrene layer ...

to be honest, this is job for professional company ... to give you warranty ...

Hope this will be of some help to you;)

Best regards, Josip :)

Quote:

---

Originally Posted by Josip

Hi, Suhaib :)

Welcome to RE forums....

No need to ask the same question in different forums ...only making confusion .... that is the reason for deleting.

We are not paid for our work here (we are working in some other place to provide our daily bread) and sometime you need to be patient until you get some answer ...




I will try to answer some of your questions:

1. undefloor heating system depend on your facility ... if you have installation with warm glycol water you can use that one ... now that will be quite expensive to install ....my suggestion is to install electrical trace heating (http://www.flexelec.com/) , but double for safety ...

2. I am not sure about but you can ask manufacturer about ...

3. it will be covered with concrete and you have to do checks during installation before you cover heating cables with concrete

4. no

5. depend on your use ...sometimes tiling ... but maybe in the freezer room epoxy is better

6. from bottom to the top ...

0. dry and healthy soil
0.0 it is also possible to make one slab of 70-80-100 mm to flatten the floor
preparation for vapor barrier - but total price is rising -

1. good poly sheet vapor barrier - must be also on the vertical walls ...
2. heat tracing (my advice - double one working and one spare)
3. polystyrene insulation 300 mm
4. covering paper
5. finished reinforced concrete 100-150 mm
6. epoxy or tiling cover

... you will be surprised when you start to remove frozen soil under your freezer room ...maybe you have to dig 2+ meters to come to not frozen soil.

try to avoid cold bridge between floor and insulation panel walls - wall panel must go down to polystyrene layer ...

to be honest, this is job for professional company ... to give you warranty ...

Hope this will be of some help to you;)

Best regards, Josip :)

---

Dear Josip,
i would really like to thank you for your very kind response, actually after i posted this thread here and no one answers, i thought that i posted it in the wrong division or i had written too much information that no one likes to read, that's why i re-posted a short thread in technical division, But thank you again for your time and the answer.

here i have some question if we can discuss a little bit please;

1) you have told me that heating system comes under insulation layer, which is the opposite of what our consultant / contractor put in the design, can you please help me to understand why is heating system should come under insulation layer in freezer?

2) for insulation layer, should it be 300 mm (or it is preferable to have this thickness) even though that we have heating system, at the design we have 15 mm..

3) for heating rate, i have contacted a contractor which claims that 30 w/m2 is enough heat for freezer. but, the one that install UFH with water / glycol system claims that at least we need it to be 60 w/m2? how can i decide the right?

thank you again Josip for you help,, i really appreciate that. sorry but i have no experience in UFH system for freezer, only what i read on internet or the help i get from this forum, our contractors / consultants do not have the good experience also, that's why i have to lead this project here.

Hi

See Also these fills
Attachment 14740Attachment 14741

Hi, Suhaib :)

Quote:

---

Originally Posted by Suhaib

Dear Josip,
i would really like to thank you for your very kind response, actually after i posted this thread here and no one answers, i thought that i posted it in the wrong division or i had written too much information that no one likes to read, that's why i re-posted a short thread in technical division, But thank you again for your time and the answer.

here i have some question if we can discuss a little bit please;

1) you have told me that heating system comes under insulation layer, which is the opposite of what our consultant / contractor put in the design, can you please help me to understand why is heating system should come under insulation layer in freezer?

2) for insulation layer, should it be 300 mm (or it is preferable to have this thickness) even though that we have heating system, at the design we have 15 mm..

3) for heating rate, i have contacted a contractor which claims that 30 w/m2 is enough heat for freezer. but, the one that install UFH with water / glycol system claims that at least we need it to be 60 w/m2? how can i decide the right?

thank you again Josip for you help,, i really appreciate that. sorry but i have no experience in UFH system for freezer, only what i read on internet or the help i get from this forum, our contractors / consultants do not have the good experience also, that's why i have to lead this project here.

---

... no need to ask the same question in different forums ... that makes only confusion ... furthermore all of us here are volunteers (struggling for our daily bread in some other place) and sometimes you need to be patient and wait ... answer/s will come when we found a free time to visit RE forums ...

Generally is not waste of the time, because answer/s you get here are good if not the best and the most important free of charge ... actually priceless ;)

... other solution is to hire contractor/consultant which sometimes can give you a very expensive, but wrong advice ... like in your case above ...



please download this document and then we can discuss anything further ...

https://www.gccaonline.com/eweb/docu...vingFloors.pdf



1. we have to protect water vapour coming out of soil from freezing ... first we install vapour barrier to reduce ingress of water vapour as much as possible ... then we install heaters to protect that vapour to condense and freeze due to ingress of cold from above .... in the soil under that circumstances we have only some small and constant amount of water vapour ... but if in that area we increase relative humidity (due to ingress of underground water) or reduce the temperature (cold ingress from freezer room) it will start to condense and without heaters by time will start to freeze ... insulation layer without help of heater is not enough on the long run ... so between very cold (frozen) room above and heating system must be a layer of insulation ... otherwise heating system with power of 30 or 50 or 100 W/m² cannot fight against freezer room evaporator ... if you install heating system directly under your reinforced slab and above insulation layer it should be almost the same power as a freezer unit ... wasting of energy ... what do you think is this logical?


2. the thickness I suggested to you was for (-50*C cold room) ...it is one time investment ...but the minimum should be 200-250 mm ... this is up to you ... I am trying to give you a good advice ... (like: to install two electrical tracing systems - duty and spare)


3. check this please ...http://www.thermon.com/catalog/us_pdf_files/CPD1038.pdf



Hope this will be of some help to you.


Best regards, Josip :)

If the fill beneath the floor is already frozen there would be cause for additional heat.

There is only cause for sloping anything if you are pushing air around: some condensation could come out of that air and needs to be at least inclined to move even if the air is not moving..

The heat source should be close to the soil because that is what you are trying to keep warm. The vapor barrier wants to be close to the soil because that is where the moisture is coming from. Any intense heat source would then represent a challenge to the integrity of the vapor barrier so with electric particularly you want something like a concrete layer between the cable or elements and the vapor barrier.

The insulation goes between the heat source and and the cold space. If you figure that the bulk of the underfloor grid, in area terms, is going to be 8 to 10-deg. C and the cold store at Minus 25 C. and the normal resistance to heat transfer for say 125 mm of relative rigid insulation you will calculate something considerably less than 15-Watts/M^2. Should be more like 7 to 8.