Boiler rooms need to be ventilated even when the outside temperature drops below zero, which means bringing in freezing air. These are typically unmanned areas, so it is acceptable for them to be colder than usual. However, very low temperatures could cause issues to the process equipment, such as freezing pipes or condensation.
What is the best way of ensuring the internal temperature at low level doesn’t drop too low? There are different options, depending on the building.
Heat recovery for big differences in temperature
If the boiler room is very high, there can be a large temperature differential between low and high level. In this case, you can use a mechanical ducted system to move heat from the high level down to the low level and mix it with the incoming cold air, raising the temperature above freezing.
This can be an expensive system, but if the difference between the temperatures at high and low level is high, or if the temperature drops below freezing often enough, it can be the most cost effective and energy efficient solution.
This system also provides the solution to heating the low level of the boiler room when the boiler is stopped for maintenance, which typically happens once or twice a year. In most cases, the mass of the boiler and construction of the building mean that the accumulated heat at high level is sufficient to raise the temperature at low level while the boiler is not operating.
Heating low level air
When the boiler heat load is too low to allow for a temperature differential big enough for a heat recovery system to be cost effective, the alternative is to heat the air at low level. This can be done by heating the inlet air as it comes in, so that the internal temperature never drops below the desired level, or by installing a small heating system at low level.
Designing the problem away
Another alternative would be to design the system so that the inlet louvres are not near areas where they could result in freezing pipes or create condensation problems
Every power generation plant has its solution
Energy efficiency is an increasingly important consideration when designing or updating a power generation plant, as it can significantly cut down on operating costs. In this respect, heat recovery can provide an excellent solution if the conditions are right and the temperature differential between high and low level is sufficiently big.
Every power generation plant is different: its shape and size, its orientation and the weather conditions in its location will affect its internal climate. To identify the most efficient and cost effective solution, it is important to consider all these factors.
Graeme Clark is a Senior Consultant for Colt UK and specialises in the design and product application of energy efficient HVAC and smoke control systems.