EMB ERJ 145 ER/LR
Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Gate; Flight Crew Returned To Departure Airport; General Declared Emergency
Aircraft
We got on the aircraft about an hour and half late due to a late inbound. The APU was up with the PACK 2 on. I noticed about ten minutes after we got on; that the PACK was pushing a lot of cold air into the cockpit; about as much as when both PACKs are on. I asked the flight attendant if the cabin temp was OK and to make sure it wasn't too cold. I put in the numbers for the weight and balance and we could only use runway XX because of our weight and temp. The captain double checked the numbers and I informed ground that we were restricted only to RWY XX; they said ok but it will be a few minutes because they had to switch runways and coordinate with approach control. We taxied out to the runway and were talking to ground about the fast moving thin but intense weather that was approaching from the west moving east northeast. We waited a few minutes short of the runway for tower's call. Tower cleared us to line up and wait; take a look and request a heading for departure and said there was cell 1.5NM off the end off the end of the runway. Captain said it didn't look good and I agreed and we taxied clear of the runway.We waited about twenty minutes and the weather had cleared and we could depart to the west. In that time I made a comment about how cold it was in the cockpit for only having one PACK on but we both thought that it was just a good PACK. We departed to the west switched over to Departure and were climbing through 8;000ft when I smelled something and heard a slight pop. It was an electrical smoke type smell but no visible smoke. I looked at the Captain and asked if he smelled something and as soon as he confirmed my question the flight attendant (FA) called and said there was smoke in the cabin. I; the First officer; was Pilot Flying and the Captain was Pilot Monitoring. He turned the PACK 2 off immediately and we performed the Fire/Smoke memory items together. He requested we return to our departure airport. He then performed the Fire or Smoke QRH followed by the Air Conditioning Smoke QRH. He briefed the FA and she said the smoke had dissipated. We kept the PACK 2; Bleed 2 and the Recirculating Fan deselected. Then ran the normal checklists. Once the FA called I engaged the autopilot then slowed the rate of climb in anticipation of returning. We were cleared to turn direct and to expect a RWY XY approach. We were only 20NM or so from the airport so I slowed to 200K to give us more time to run the QRH and all normal checklists. We landed over weight at less than 200 fpm rate of descent. We taxied clear of the runway and; after the fire marshall inspected and cleared us; we proceeded to the gate and deplaned. I feel the entire crew did an excellent job in all phases of the flight and our training was a big contributor.
When the Flight Attendant reported smoke in the cabin and the flight crew smelled an electrical odor they returned their EMB-145 to their departure airport where they landed safely and were declared free of hot spots by CFR.  They taxied to and deplaned at the gate. An unusually vigorous air conditioning pack had raised early suspicions.