Guide
Cold room refrigeration system: integral or remote, and how it is sized
Updated
The plant is the part of a cold room that decides whether it holds temperature on your worst day, what it costs to run, and how much of the installation price is pipework and access rather than refrigeration.
The three arrangements you will be quoted
- Integral monoblock
- A single packaged unit that mounts through the wall or over the door, with everything inside it. Fastest to fit, least site work, no interconnecting pipework. Rejects heat into the room it is mounted in, and puts the noise and heat where the unit is.
- Split system
- Evaporator inside, condensing unit nearby, joined by pipework installed on site. More flexible about where the heat and noise end up, at the cost of pipe runs, refrigerant handling and an extra siting decision.
- Remote condensing plant
- Condensing unit sited away from the room, often outside or on a roof, sometimes serving more than one room. Best for heat rejection and noise, most site work: pipe runs, supports, an electrical supply at the plant, and often access equipment to install it.
There is no universally right answer. A small florist's chill room in a shop with an outside wall is a monoblock job. A kitchen chill and freeze pair in a basement is not, because the heat has to leave the building. Ask each installer which arrangement they have priced and why, and make sure two quotes you are comparing are for the same arrangement.
What actually sets the duty
- The temperature you must hold, and the ambient it has to hold it in. A plant room that reaches 40°C in July is a different design problem from a cool warehouse.
- What goes in and at what temperature. Storing already-cold product is a light load. Pulling down warm product is a heavy one, and it is the commonest reason an undersized room never quite gets there.
- How much product and how fast. Daily throughput matters more than the room volume for pull-down duty.
- Door openings. Every opening is a load. A door open through a service period is a large one, which is why strip curtains and air curtains exist.
- Heat from inside. Lighting, fans, people working in the room and any equipment all add load.
- Defrost. Below freezing, the evaporator has to be defrosted, which puts heat back into the room and water into a drain.
Running cost is part of the price
The cheapest install is not the cheapest room. Thinner panels and a plant sized to the paper minimum will hold temperature on a mild day and struggle on a hot one, and it will run harder for the life of the room. When you compare quotes, compare panel thickness and plant duty alongside the price. If one quote is much cheaper, the difference is usually in one of those two lines or in an exclusion, see the cost drivers.
Refrigerant choice is not just a technical detail
The refrigerant affects your ongoing duties. Leak-check frequency and record-keeping are driven by the carbon dioxide equivalent of the charge, so a system with a lower global warming potential refrigerant can sit in a lighter compliance band for the same physical charge (gov.uk). The UK is also phasing down hydrofluorocarbons, and gov.uk advises users to ask their supplier about lower global warming potential alternatives (gov.uk, F gases). Ask what refrigerant is proposed, what the resulting leak-check band is, and whether the plant is subject to any current or future restriction.
Ask for the design conditions in writing: room temperature, ambient, pull-down assumption and door opening assumption. If a quote does not state them, it has assumed them. Get quotes that do.