An HVAC question

The efficient way is to reject the heat to outside, but that normally requires cheap and noisy roof-mounted units, which neighbours would have the right to object to.

For a silent method of getting rid of surplus heat, it could be used to heat water, which could be offered to the neighbours to heat their homes.

While that would be fine in the cold UK winter, the summertime is the present problem.

Perhaps outside water-cooled tower system, (watch out for Legionnaires disease though), which can be kept fairly quiet, and reject the heated water to a storm-water pipe or channel with permission from the local Council Authority.

I would be asking other HVAC firms in the area if they could improve the situation, and if so at what cost.

Get any offers in writing, of course, and ensure you watch carefully for the "hidden extras" which like to creep into any construction project..

You say <"The store is in the UK">, and I realise that the weather in different parts of the UK is quite variable, so the proper calculations need to be done before alterations are commenced.

The cost of electricity is a major running cost for a supermarket, and any means of minimising those electricity costs would be greatly appreciated by the owners.

Kind Regards....

They probably bought off on someones less efficient design.. now they are stuck with it. I 'think' traditionally (due to the historical evolution of in store refrigeration units.. ) that they would exhaust the heat back to outside or at least an area behind the refrig units where the customers can go, thus making it more comfortable for the shoppers and less comforatable for the workers. SO maybe the kickpanels are missing or not installed correctly, or their inefficienct redesign of their store did not incorporate a back area sealed off from the cooler shopping areas? Maybe they didn't use exhaust ducts to outside to save money, maybe they are not installed correctly.

Mom n pop stores in 1940's did not envision the massive refrigeration we have now.

IE The cold drink cooler just sat there right in the store with no plan for exhaust heat on hot summer days, much like the home refrigerators.

In their case they might be stuck with it now that they have spent their money already on whatever they got.. if not they can install more ac and try to seal off the venting from the heat exhaust from the units to outside or at least to a back area , maybe rearrange how they cold units are setup so that they could all exhaust to same duct to a outside (or at least back area). Sometimes in one story stores its simply a duct UPwards to the roof outside. Zoundz like poor planning !

I seems to me that the condenser should be installed in a duct that could be selectively vented to the indoors or outdoors...Clint

In the US larger parallel refrigeration systems (typical of supermarket operation) use heat reclaim where the compressor discharge gas passes through a coil in the conditioned air stream for the initial stage of heating. Thermostatically controlled to by-pass the heating coil and go directly to the roof mounted condenser or a water pre-heater to the gas or electric fired water heater. Whatever the store you entered has it appears the controls need some adjustment.

Note: To accommodate a good neighbor policy air-cooled condensers can be esthetically hidden and noise abatement techniques used.

Here in Florida we use the heat reclaim system to control the humidity in the store. As you said the hot gas is run through a coil in the conditioned air ductwork after the evaporator coil. This puts heat back into the air to allow it to absorb humidity in order to reduce condensation on cool surfaces in the store especially in areas where there are refrigerated cases. This seems counterintuitive to saving energy but it allows the medium and low temperature refrigeration systems to to do less work removing latent heat from the air they are working with and also reduces the amount of ice that forms on those evaporator coils. Balancing the heat reclaim system is difficult to get right at first. Your maintenance contractor should beable to make adjustments to the system and get the air there feeling right. But be patient it takes time.

...at the very least, move the condensing units to the roof to get that heat load out of the building.

I did an extensive remodel of a large chain supermarket in 2006, and we moved a lot of the freezer and medium temp cases around. These units do not have the typical compressor / evaporator coil on the units themselves, as you might see in your home. The cases are freon piped to a compressor room where the, hence the name compressors are located and the coils are located on the roof. The units have fans on them, but do not discharge heat directly from them.

This is for your typical large type supermarket. Now if you are speaking small mom and pop type store then it is possible that the units are self contained and if that is the case then disregard what I said.

May be a HVAC imbalance situation where the zone where the equipment is now located is not sized to handle the load of these freezers/ medium temp cases.

Where is this located, what state? If this is a large chain store I am sure they are aware of the problem and are working on it.

Dave

The store is located in SE England and it's a very large store belonging to one of the largest chains in the country. I phoned their HO and asked them why they did their refit this way and they more or less told me to Foxtrot Oscar so I left them to their dumbness. I was just curious is all. Thanks everyone for your input.

The reason is that these stores have large areas of refrigerated equipment. The heat removed from the building would have to be replace. Summer time that would be fine but in the winter. That means a bigger HVAC unit to cover the heat loss. The freezers and refrigerated displays are continuously being open and closed. Heat from the isle goes into the freezer say then we take it out and dump it back into the isle. The only adjustment to the HVAC is to make up for the heat of the equipment. The other way the area would become too cold.

You may find a little psychology coming into play here. Hot isle with lots of different ice creams and cold beverages? A lot of which are bought on impulse.

may I suggest a sub cooler and a complete re routing to combine the neareswt coolers ,what the hell the compressors are old anyway