Urn lagging surprise

[Bribie G]

For the last five years I've been lagging my urn during the BIAB mash by:

Floating a circle of bubble wrap on top of the mash then fitting the lid
Slipping over a cheap old non-feather Big W sleeping bag
Wrapping the whole thing in metallised rubber foam and securing with bungee cords.



I can count on losing around 1.5 degrees per hour, or over 2 degrees for a 90 minute mash

Yesterday I'd busted the zip on the sleeping bag and couldn't get it to sit right on the urn, so I just draped it over the top of the urn and fixed with a bungee cord right round the bottom of the urn below the tap, with the bag quite loose and voluminous. To my surprise I only lost one degree over 90 mins.

I think what's happened is that previously with the sleeping bag tight against the urn and the rubber sheet strapped tightly, heaps of heat was escaping via conduction into the fabric, somewhat defeating the purpose.

Procedure now changed.

 

[GABBA110360]

I cover top of my mash as much as I can with old flano sheets folded doubled etc.
then wrapped with a doubled thickness doona
heat predomantly rises so your onto to it bribie.
I only loose 1-1.5 in winter for a full volume mash.

 

[buckerooni]

good post, it's always good to get real observations about this kinda stuff. noted!

 

[Ducatiboy stu]

I have a peice of polystyrene foam ( from a broccoli )

Be surprised how much heat escaped thru the top

 

[donald_trub]

I'm doing 20L batches in a Techni Ice mast tun... I think it's 40 litres.

I've been unimpressed with the amount of heat loss I get over an hour, so I'm thinking of covering the top of the mash with foil. Will this work, or are there better ideas? Currently about half of the mash tun is empty due to head space.

 

[Ducatiboy stu]

Grab a broccoli box lid. Much better than foil, Been there..blah blah

 

[donald_trub]

Thanks. Off to raid the green grocers!

 

[marksy]

I use a 40L eski and for a single batch put foil on top of the grain bed, an old thick towel, and one of the 50L plastic tubs upside down. Shit be real warm in there.

 

[Diesel80]

For me, ghetto style 1x picnic blanket ratchet strapped to the 80L aluminium kettle (BIAB) and another just laying over the lid.
With a double batch it does the job fine and easy to remove.

Not so good if you need a blast of heat to correct something so I normally let it ride and try make sure temps are good to go.

Having said that, gearing up for my first brew in about 2 years and haven't seen my blankets lately! :blink:

Cheers,
D80

 

[Bribie G]

One of the best lagging methods I've ever seen was the guy who just popped the Crown Urn carton over the urn upside down, lost about 1.5 degrees over the mash.

Of course I'd long thrown mine away. :unsure: