HVAC Make Up Air (Repair Garage)

In Boston in the winter, an air-to-air heat exchanger might help. These take part of the heat out of the air you're exhausting and put it in the make-up air, so the furnace doesn't have to provide as much heat.

Here's a link that may help http://www.ventusa.com/ Usual disclaimers - I haven't even read the whole page. There are many other manufacturers.

Yeah you need to heat the garage....I would use a squirrel cage blower....You might want to consider a fresh air intake for a portion of the return air for forced air ventilation even when exhaust fan is off...

Well with out knowing the CFM of the exhaust fan it is difficult to give you an answer.

If the CFM of the fan is low nothing needs to be done. I have yet to see a roll up garage door that seals tight. So air will be drawn in around them. If the CFM of the exhaust fan is relatively high. If there is no means for the air circulate thru the building it may cause the fan motor to labor. One means would to be to put small louver vent in each garage door. With several small vents spread out it would help to move the fumes better.

Better choice to me would be to put a variable drive on the exhaust fan. So in winter the can control the circulation with out dumping too much heated air to the outside.

First, I suggest you install a reliable CO alarm system. Second, we need to know whether the engine exhaust is vented directly to the outside (which it should be). If this is the case, you need to supply make-up air for the engines that are running in the garage. If the engines are mostly idling, the calculation is simple. If you have several dynamometers in the garage and are testing powerful V8 motors, the solution will be different. An air to air heat exchanger will help your heating load.

You will be needing to install a makeup air unit which consists of a centrifigul fan and heating element mounted in a casing along with a damper in the unit's air intake opening. Your local mechaical code will need to be consulted and followed. The outside make up air must be heated to at least room tmeperature...the unit's built-in controls can accomplish this. Better to size it to deliver slightly more air than the amount exhausted. This will give you a slightly positive indoor air pressure, minimizing cold drafts for the outside. Your local building department will require you to have a licensed contractor. Pick a good one and he can help you satisfy the code authorities plus sizing the unit correctly saving you money and future head aches.

Good luck.

Lou Bindner

Ok 1st, Run the exhaust extractors and the room air extraction through a heat exchanger, this will remove nearly all the heat & the bonus for you is that exhaust gasses are hot so will give you more free heat. 2nd is with the right heat exchanger you can control the air temp to the room, if you have an exchanger that works by transferring the reclaimed heat to a hot water cylinder then you have free hot water so even in the hot summer time you can still benefit, if the exchanger is fitted with a temperature control you can use the device to just remove stale air & bring in fresh, if you take it a step further you can add a chiller to the ductwork, if the waste oil burner could be used to heat water you can put a radiator within the intake duct to further heat the air.

Bazzer