Auto Service Garage Ventilation

[carlosgw]

In a large service area (say at a car dealership) 1.5 CFM per square foot is quite a bit of air. In a northern climate a reduction in the heat load could be significant.
If we use a heat exchanger to recover 60% or so of the exhaust heat I think the payback would be less than 10 years vs. just using a gas fired make-up air unit to heat the ventilation air.
However - what if we used a CO sensor to control the ventilation air? In this case I do not think there is any point to paying extra for heat recovery because I think that the ontrol will keep the air flow low enough that the payback would be way too long.
I have no data to back this up. Does anyone have any data or practical advice?

 

[ChrisConley]

Your service area requires the constant 1.5 cfm/ft2 to meet ASHRAE 62. We frequently use CO control to temporarily increase the ventilation rate if CO levels are building up. Controlling exclusively on CO means that other contaminents could build up.

Depending on how many service bays you have (how many large overhead doors) you could also do a calculation to determine a reasonable number to use for natural ventilation. Then augment the natural ventilation number with a 'smaller' HRV.

Also, as far as cost recovery goes, depending on how cold your northern climate is; I'd say that your payback on Heat Recovery would be much less than 10 years. I've worked on a number of similar applications where HR's simple payback was under 5 years.