HERMS noob questions

[Sadu]

Hi everyone, I built myself a 10 liter electric brew kettle for making small batches. But along the way I figured it might be cool to use this as a HERMS coil for my bigger batches. It was a feat of engineering to get all the hardware below the 5 liter water line (the finished volume) with nothing touching the element.

Anyway, I'm unsure of the finer points of HERMS and are putting down a stout tonight. Was hoping someone could point me in the right direction.

First question. My mash temperature is 156f/69c. I was planning to set the controller to keep the HERMS water at mash temperature, then have the pump running permanently recirculating from the bottom of the mash tun to the top. Is this going to do what I want it to do or does the HERMS water need to be slightly warmer than mash temps? There is 5 meters / 16' of copper coil inside that little kettle so it should have pretty good heat transfer.

Second question. I do BIAB and my mash tun is a plain stainless kettle with no ball valves or false bottoms. I was going to put the input end of the hose under the bag (with a filter of sorts to keep the bag away from the hose opening) and put the output end at the top inside the bag, below the water line so it doesn't get aerated more than necessary. I realise I'll need to prime the pump before it will work.

Appreciate any advice.

 

[LandoLincoln]

I typically keep my PID for the HLT one degree above target temp for the mash, but your setup may require more. I'd start with 2 degrees and tweak from there.

 

[EmDubeu]

I set my hlt 7 degrees above mash temp. 50 feet of stainless steel tubing (1/2 id).

 

[Sadu]

I did a double brew tonight, stout and a maibock. The stout went like clockwork. Set the HERMS kettle a few degrees C above mash temps and it was the most stable mash I have had to date. Loved it.

Maibock not so much. The pump kept getting air bubbles and stopping. Since I don't have a ball valve on the mash kettle the pump has to suck up and out of the kettle then through the pump and push through the coil and up over the rim of the mash tun again.

I'm not sure if it's just my cheap 12v pump that sucks, or my cheap 1 amp power supply that sucks, or maybe too much hose or maybe I just need to install a ball valve so it's gravity feed to the pump. I burned my mouth a couple of times trying to restart the suction again.

Overall though, I really like where this is heading. Celebrating with a tasty doppelbock

 

[LandoLincoln]

You are asking a lot of that little pump. I'd get that valve installed ASAP.