1st Lager attempt, fermenting temp concerns

Hello all, I'm currently at day 4 of my first attempt at making a lager (a Munich Helles.) I'm fermenting it in an unplugged, empty freezer in the garage (waiting until I have time to add a tower and turn it into a keezer). I ordered an STC1000 but it hasn't arrived yet, so I'm using the weather forecast and the freezer insulation for temperature control right now.

I have two probes setup and I've been checking the ambient temp inside the freezer and outside (in the garage) several times a day since I started. The freezer has been holding steady at 51F since I put the carboy in there, so I think the freezer is doing what I wanted. (The garage temp has been swinging between 35 and 45 (night/day)). Its day 4 and the freezer temp has dropped to 44F, and the bubbles from the blow off have slowed down to 1 every 1.5 to 2 seconds.

I don't have a temp probe in the beer, but the freezer inside temp has been pretty stable at 51 until now. On day 1, I cooled my wort to 54 and pitched a 3L starter of WLP833 that I decanted down to 500mL of slurry. It had a very aggressive start with 1 bubble per second at my blow-off tube in under 2 hours! I've never had an ale take off that fast before, is that a feature of lagers?

I think the heat of fermentation has been keeping it warm, but I'm wondering as fermentation slows down, if it will cool off too much to finish fermenting completely?

Should I put a heating element in the fridge to bring the ambient temp back up and hold at 51 for another two days? My other option is to bring it down to the basement which is at a constant 61F right now. Or, I could do nothing and just leave it and RDWHAHB. If I take the do nothing approach and it cools down to the 30s, how long should I wait to rack it to secondary? Any other suggestions?

You need to take a temp or you wort to see where you ar at if it is too cold heat it up. Lager is not the best thing to brew until you can control the temp. Hope it ll works out for you.

Where are with your gravity readings? When it's time for the DR it sounds like your basement may be perfect for a 2-3 days....then back in the freezer for lagering.

Anyway, I would try to keep that freezer space in the mid 50's until DR. The mass of the fermenter will help with minor temp variation.

Are you able to read the freezer temp without opening the door? If so, you could use a low wattage light bulb to bump that temp up a bit since it looks to be well insulated.

helibrewer said:

Where are with your gravity readings? When it's time for the DR it sounds like your basement may be perfect for a 2-3 days....then back in the freezer for lagering.

Anyway, I would try to keep that freezer space in the mid 50's until DR. The mass of the fermenter will help with minor temp variation.

Are you able to read the freezer temp without opening the door? If so, you could use a low wattage light bulb to bump that temp up a bit since it looks to be well insulated.

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Thanks helibrewer, that was a great suggestion. I don't have any lightbulbs with small enough lamp sockets to put in there, but I did put a heating pad (set to low) on the far side of the freezer opposite the carboy and thermometer probe. The ambient temperature climbed back up to 52F within a half hour so I turned it off and the temp has stayed 52 for the last 1.5 hours. I have a couple of those Poulder thermometers with long leads that I use for mashing, so I don't have to open it to check the temp. I think you're right about the thermal mass of the wort overcoming any small flux in ambient temps. Its still happily bubbling away.

My OG was 1.052 but I haven't taken any gravity readings since I pitched, I was going to wait the five days and check it before doing the DR. I'm still fairly new and rather paranoid about infections, so I try to resist opening the fermentor as much as I can.

I have a bedroom closet that stays about 68F, would the basement at 61F be a better location for a diacetyl rest?

If you can't warm the fridge up move it to the basement. It might be a little early to warm it up but it's getting too cold to ferment out there. I use a 15 watt light to warm mine up.