No installation dinners. We bring Trainees on whenever we have a sufficient number to make a "class" (usually 4-8) and they've finished their background checks, and we bring them up to Probie usually at the December and June meetings with a little ceremony including the oath and badge pinning.
We do an awards dinner in November and a Christmas dance in December. The awards dinner is a joint event between the department and the Volunteer Firefighters' Association. All current and retired members and their spouse/guest are invited, along with some VIPs (City Council members, city management, etc.) The department gives service awards (5 year increments) as well as three special awards: an EMS Award (for most hours staffing the ambulance), a Utility Award (for most hours staffing the utility truck) and Firefighter of the Year. The Association gives thank you gifts/certificates to the Association officers and anyone who chaired an event committee (pancake breakfast, Christmas dance, etc.). The budge is around $5,000, split between the Department and the Association.
The dance is more of a fundraiser and is a big public event. We mail 4 tickets to everyone in town (and a few surrounding areas), which they can choose to buy for $2.50 apiece. A lot of residents buy the tickets as a donation but don't attend. No food, but we do a cash bar and have some snacks, and provide live music. There's also a big Toys for Tots drive with it.
We also generally do a retirement dinner for any long-term members who retire. For shorter-term members, their crew at least will usually do a dinner or something on their own, but the department usually only gets involved if its a 20+ year member.
Lastly, my crew does have a tradition of a Probie doing a dinner/party for the crew before or shortly after he/she gets off probation, the tradition being the Probie has to cook something (in other words, no catering or going to a restaurant). Other crew members will usually kick in some money or bring other food/drinks, depending on what help the host needs. I just did mine back before Christmas.