Need some help with mash temps on a RIMS system

[BrewinSoldier]

So I seem to be having an issue I definitely need to get fixed. I recently upgraded to a 30 gallon mash tun from Spike as well as their 30 gallon BK.

Prior to this, I was using my 10 gallon SSbrewtech insulated mash tun using the same 240v blichmann rims system which I believe is 3500 watts. On my 10 gallon system, it would keep my temps dead on throughout the grainbed. Now on my new system, if I have it set at say 152°, the mash bed it at 148-149°.

I'm curious what has changed. Is it because I'm not longer using an insulated mash tun? Maybe the element isn't powerful enough for the bigger batches? I would think at 3500 watts it would be but idk.

The temp probe on the RIMS is right where blichmann and everyone else recommends it(outlet of the rims).

I guess this brings me to my next question. If I raise the set temp of the controller to say 158°, and that brings my mash bed to the 152° I am aiming for, would that affect my mash? Should I care more about grain bed temps or temps of the wort that the RIMS is heating the wort up to(say the 158°)?

 

[mabrungard]

The ONLY thing that matters is the temperature of your wort. The bed temp is meaningless in the short term. If your RIMS has the power to bring your wort to your set temp, then the bed will eventually get there as long as the heat loss through the tun walls isn’t too great.

 

[BrewinSoldier]

The ONLY thing that matters is the temperature of your wort. The bed temp is meaningless in the short term. If your RIMS has the power to bring your wort to your set temp, then the bed will eventually get there as long as the heat loss through the tun walls isn’t too great.

Thanks Martin! Unfortunately I must be losing too much temp through the mash tun walls because the mash bed during my last 60 min mash just would not come up to temp. However, the wort coming out of the rims rocket outlet was at the set temp. Next brew day I'll check the actual temp of the wort entering the mash tun. I only checked the grainbed temp.