Generator in the garage - Thoughts?

[Watts Happening]

Lets start by saying I fully understand this wouldn't be considered the safest way to go, I'm aware of the risks involved across the board.

Solar is my primary, but we're coming into winter and who knows, let's say a big storm comes through and knocks out power for a week, solar production is terrible and I generally heat my home with mini splits so I need power. I have an unvented 30k btu natural gas heater but don't love the idea of using that as a main heat source, it's got all the protections and I have carbon monoxide alarms etc.

So, in the interest of maintaining a low profile, I'm considering the idea of running something like my Champion 2500w Dual Fuel inverter generator in the garage. I've already got (2) 2.5" holes on one wall that were previously used for an outdoor shop vac I had plumbed into the garage on a switch. Am I crazy to think I could add an exhaust kit and plumb the exhaust out one of the holes, while also adding a small computer fan to pump air in through the other hole?

We have no HVAC or otherwise any normal way for any fumes in the garage to enter the house beyond the man door, which leads into a laundry room that has another door before getting to the living room. I'd clearly have multiple carbon monoxide alarms set up both in the garage, in the laundry room and in the living room.

Anything else? Or purely just a terrible idea? Thoughts as a whole?

 

[pvgirl]

You need to make sure you get enough fresh air for the generator, I'm not sure a 2,5" intake will pull in much air, hopefully it's not too close to the exhaust. You also gotta worry about removing the heat the generator produces, as well making sure the exhaust is insulated well enough It doesn't burn down the house. Multiple CO alarms also good to have.

 

[42OhmsPA]

Following along since I've considered the same concept numerous times.

I'd start with the generator in an enclosed box lined with steel and covered in noise blocking insulation.
Then I'd open one of those holes up for intake, drawing outside air from down low with one of these.
AC Infinity CLOUDLINE PRO S4, Quiet 4” Inline Duct Fan with Speed Controller – EC Motor Ventilation Exhaust Fan for Heating Cooling Booster, Grow Tents, Hydroponics https://a.co/d/4cf99r6
Plumb the exhaust in SS above and away from the inlet.

As you already mentioned multiple CO detectors, ideally some type of air quality monitor to trigger generator shutdown.

 

[Zapper77]

Have you looked at...Generator Shed?

 

[CoolWill]

Sure, it CAN be done. It is done in industrial settings all the time. The problem is that if it's done badly, nobody wakes up for breakfast. I have full confidence that I could do it safely. But I'd never recommend someone do it. But if someone were to do it, the most important thing would be carbon monoxide detectors in the bedrooms and living areas.

 

[OffGridForGood]

I have actually done this last winter, with a Champion Generator - piped the exhaust to the automotive exhaust line (existing) out of the shop. My shop is NOT connected or near my house (next door) so I was not as concerned about CO gases.
As @pvgirl noted, you need enough make-up air to keep up with the exhaust the generator is pushing out - no way a 2.5" opening is going to keep up.
In my shop the inlet air louvre is 12" x 12' - but no fan. just natural convection.

If I were to do it again, I would pipe the air intake from the exterior directly to the generator air intake and seal it up, not use room air for combustion. I would go bigger than 2-1/2" though, at least 4" diameter and keep the intake run as short as possible. The generator running makes a good about of heat to warm up the space around it- if that is part of what you are after. (good in winter, bad any other time).
CO detectors for sure, perhaps positive pressure for the garage space to ensure the exhaust goes where you want, could be a good idea.
I can tell you one thing, running the generator under load inside the shop is loud.

 

[Watts Happening]

I should clarify some things:

The generator in question is quite small, a 2500w champion just like a Honda 2000. I think the 2.5” hole would move WAY more air than that thing could consume, plus a garage isn’t exactly air tight. The exhaust output is probably 3/4”, maybe 1” at best.

It would be sitting on a 3/4” thick steel table, exhaust exiting through well insulated piping etc, obviously thermal concerns there will be handled.

The heat it puts out is desired, this is only a worst case scenario in the winter. We produce far more power than we need in the summer.

I understand it makes some noise, but I’d only be running it at about 60%, just helping us not deplete the battery bank.

I think with multiple layers of carbon monoxide alarms, doors shut, exhaust existing the garage by 10-15 feet (plumbed through a large car muffler to further eliminate sound without inducing back pressure) and a few other mitigating ideas like only running when awake and able to address any issues, it could be done safely.

 

[Zapper77]

I should clarify some things:

The generator in question is quite small, a 2500w champion just like a Honda 2000. I think the 2.5” hole would move WAY more air than that thing could consume, plus a garage isn’t exactly air tight. The exhaust output is probably 3/4”, maybe 1” at best.

It would be sitting on a 3/4” thick steel table, exhaust exiting through well insulated piping etc, obviously thermal concerns there will be handled.

The heat it puts out is desired, this is only a worst case scenario in the winter. We produce far more power than we need in the summer.

I understand it makes some noise, but I’d only be running it at about 60%, just helping us not deplete the battery bank.

I think with multiple layers of carbon monoxide alarms, doors shut, exhaust existing the garage by 10-15 feet (plumbed through a large car muffler to further eliminate sound without inducing back pressure) and a few other mitigating ideas like only running when awake and able to address any issues, it could be done safely.

I've seen people weld a threaded pipe fitting to the exhaust port.

 

[Watts Happening]

I've seen people weld a threaded pipe fitting to the exhaust port.

That’s how I plan to do it. I don’t want to rely on clamps

 

[Rednecktek]

When I put my 6500w generator in my pump house, I welded a short length of pipe around the exhaust port so I could weld on some flexible exhaust pipe, ran it through a hole in the side of the pump house, and threw a car muffler on there. It gets warm in there when I run it but it works fine.

As small as yours is, getting some kind of ducting from the exhaust port to the hole in the wall will go a LONG way to making it feasible. A 2.5" hole should be plenty of make-up air. If there is some way to mount an exhaust fan in the ceiling that would be even better, and handy when you're working in the garage on paint or stain or welding or any other kind of stinky project.

 

[Hedges]

RVs have generators in a compartment. Is it 100% sealed from living space?

Onan had "Vacuflow" generator, with blower not pushing air over engine, rather sucking and exhausting outside. That maintains negative pressure in the compartment and carries away any blow-by, smoke from oil on the outside, etc.

 

[Delmar]

Aristotle: nature abhors a vacuum. Any exhaust gas will easily get replaced via every small opening in the garage.

I have toyed with the idea of using a gas water heater, with the burner removed, as both a liquid-dampened muffler and source of hot water. Around 50% of the usable fuel energy is wasted in exhaust heat.

 

[Rocketman]

RVs have generators in a compartment. Is it 100% sealed from living space?

In my MotorHome the generator (Onan diesel 7500w) is separated from the living area. (But I can’t say it is 100% - those *#%!$&@ mice keep finding ways in up there).

Because it pushes the exhaust out the side of the RV we do notice the exhaust smell coming in through the windows. To prevent that we got a Gen-turi - it is basically a chimney for the exhaust to put it above the rig. It works very well.

You may want to consider something like that - but your use case is so infrequent and your generator so small - it probably doesn’t make sense.

 

[Watts Happening]

In my MotorHome the generator (Onan diesel 7500w) is separated from the living area. (But I can’t say it is 100% - those *#%!$&@ mice keep finding ways in up there).

Because it pushes the exhaust out the side of the RV we do notice the exhaust smell coming in through the windows. To prevent that we got a Gen-turi - it is basically a chimney for the exhaust to put it above the rig. It works very well.

You may want to consider something like that - but your use case is so infrequent and your generator so small - it probably doesn’t make sense.

I'm thinking just weld a threaded bung/male pipe onto the exhaust output then make a transition to high quality flexible exhaust for a short section, then once outside back to hard pipe and through a muffler to really tone it down a lot.

 

[rodrick]

Plumbed correctly it’s a non issue as long as the exhaust isn’t pointing to a living space, remember carbon monoxide is heavier than air and will seek out low areas

 

[CoolWill]

Plumbed correctly it’s a non issue as long as the exhaust isn’t pointing to a living space, remember carbon monoxide is heavier than air and will seek out low areas

Not true. Carbon monoxide is lighter than air. It will rise. If you filled a balloon with it, the balloon would float. That's one reason why running an engine inside is so dangerous: The poisonous CO rises to the bedrooms up stairs. It's also flammable. You're thinking of CO2 that's heavier than air, which is a suffocation hazard rather than a poisoning and explosion hazard.

 

[curiouscarbon]

given that the proposed use case is an emergency, if the ducting is implemented well with good seals, and if people are aware of the risk of CO accumulation during emergency operations, and there are multiple (redundant) decent CO alarms in the area, the risk would seem to be relatively minimized.

disclaimer: never set up or operated a fuel generator in a static configuration or indoors.

if a sealed duct can be set up from outside, to the gen inlet, and from the gen exhaust to outside, and tolerate the temperatures involved, this would help mitigate the indoor risk.

with preferential use of heat pump implying generator backup becomes essential for heating, this project makes sense to me. regard for safety has been clearly expressed.

sprinkle the CO sensors anywhere a human might go, seal up duct well, and it makes sense for emergency.

also the muffler sounds like a nice touch.

 

[Shimmy]

Beware of exhaust back-pressure. Those little generators tend to have issues with extending exhaust line; it may not show up at first, but over time they get gummed up and fail.

 

[Quattrohead]

If the garage is attached to the house I just would not do it at all. So many people here in Florida die from this scenario every hurricane.

 

[JJJJ]

We have a wood stove and a four inch air intake from a nearby source. Naturally a stove uses a lot more oxygen but this reduces air intake from other areas.

Safety with carbon monoxide includes dry wood and a clean chimney.

And of course the needed detectors.

The back of my garage has an exit door. I open it from time to time to help remove simple garage smells. My concern in this case would be to check the seal on the garage door. Gases are very opportunistic and can sneak through the smallest cracks