Heuch Refrigeration

Frost heave can be found in walls, floors and any other areas associated with freezer rooms and colder environments, both constructed and natural.

Frost heave (sometimes referred to as ice heave, slab heave and concrete heaving) occurs when sub-zero ambient temperatures penetrate the earth or a structure and freeze pockets of moisture. As these pockets freeze, they expand. This potentially enormous pressure has to go somewhere, so it pushes the earth or structure outwards toward the point of least resistance. When considering ground based frost heave, this is usually up to the surface, and creates little mounds. Areas that exhibit Freeze-Thaw-Refeeze cycles can be particularly persuasive and cause slab heave.

 Why is frost heave important?

A bit of frozen moisture doesn’t sound like much, but it has the ability to seriously damage floors, building foundations, roads and driveways. Much in the same way that a little steam doesn’t sound like anything to worry about, until you contain it, then it can drive a train, or electricity producing turbines!

Moisture is always drawn to the cold. So when a pocket of ice forms under the soil, underground moisture is drawn to it, freezes and adds to the pocket. This is a problem that the people of Canada (for example) have to deal with on a seasonal basis. The frost heave often pushes sideways and damages the foundations of their houses and basements.

In the commercial sector, if the floor of a freezer isn’t heated, the frost heave will lift and crack floors, create a very uneven surface, prejudice walls and structures and make for a very unsafe work environment. It can penetrate poorly sealed walls, freezing and bulging, damaging the structural integrity of the very walls themselves.

 How to spot frost heaves.

It starts with a bit of a sinking feeling. Often, businesses we visit will comment that the foundations of their building are sinking, but a quick inspection points out that actually, the floor is lifting! Sometimes the floor heating has failed, and other times it hasn’t been installed at all.

Early signs to look out for include:

• The corners and edges of the freezer room appear to be sinking.
• Uneven spots in a once very flat freezer floor.
• Cracks in the concrete that are only getting worse.
• Bulging or warped walls of the freezer room.

 How to fix frost heave

At the first moment you suspect frost heave is occurring, check that your floor heating is working!  If the walls are the problem, check that your freezer room has been vapour sealed correctly and effectively. Is there forklift damage to the external skin of the cool room panels? Do the door jambs need repair?

 Floors:

If your floor is electrically heat traced, check the circuit breaker to make sure it’s still working. If it can’t be reset, check for a second circuit. Often a second heater is laid in the concrete to add a level of redundancy and peace of mind.

If the floor relies on outside air ventilation, check that the pipes or channels supplying air flow aren’t blocked or supporting nesting rodents and their families.

If your floor uses hot gas or reticulated glycol from your refrigeration system to heat the floor, this will need reviewing by your refrigeration services company.

The bad news is that if these have failed, the heating was poorly installed, or never installed, then the fix may become expensive.

The first step is shutting the freezer room down to let the ice pockets thaw and the floor to settle. This can take weeks in some cases and obviously disrupts productivity, and is only a very temporary measure. The results are variable and there is no guarantee this action will not in itself cause consequential damage.

To fix the problem from here, you might have to have the freezer floor re-laid. Getting a contractor in to tear up the existing floor and insulation, lay floor heating and re-pour a concrete floor. But once it is done, is something you no longer have to have in the back of your mind.

Walls:

Have a coolroom panel professional inspect the joins and penetrations in your walls. They will be able to detect if your vapour seal is adequate, and identify where the moisture is getting in.

If it’s caught early, and the vapour seal is repaired, the room might be able to simply returned to service.

If not, the coolroom panels may have to be replaced.

The best fix, like almost anything, is PREVENTION! 

Notice the pallet racking leaning due to an uneven surface caused by frost heaves.

 How to prevent frost heave.

Best prevention is to have a regular maintenance program by knowledgeable techs and make sure floor heating is being looked at and included in your programmed maintenance service.

If you are going to be buying or leasing a new facility, check with the current occupants/landlord to find out if the freezer room has floor heating, and make sure that it works!

If you are having a new freezer room built, discuss the floor heating methodology with your supplier.

• What floor heating system are they offering?
• What backup method if offered?
• How is it being installed?
• Can it be repaired or what redundancy is included?
• How much energy will it consume? Remember this heat energy is required 24 hours a day, 365 days a year!
• Is waste energy reclaim used?
• How much floor insulation will be laid?
• What type and specification is the vapour barrier system?
• How will the installer implement the vapour barrier?
• What insulated cool room panels joining system is proposed?
• When will these steps happen in the construction program? Planning inspection visits during construction is a good idea.

A little vigilance and a little investment now will save you many times the expense in down times in productivity, lost storage space and will ensure a safer workplace for you and your colleagues, as well as giving you the invaluable gift of peace of mind!

Heuch can help make an assessment and develop a cost effective programmed maintenance schedule. 

Talk to Heuch’s engineering team when considering your next refrigeration system expansion.

Further references: www.ashrae.org; www.astm.org; www.bradyips.com.au; ASTM D5918-06