Questions about Panel Design - 2 elements in HLT

cookie · Joined: 17 Aug 2017 Posts: 1 Location: St. Louis, MO

I'm a new member to the forum, but I've been lurking around here for a few years learning and dreaming about my future electric brewery. Currently, I'm getting more specific in my planning.

I am considering building a 50A panel that is sort of a hybrid of the back-to-back panel and the 30+ gallons panel.

There would be one 4500W element in the boil kettle and 2 4500W elements in the HLT, however the HLT elements would be switched on and off separately. As envisioned, the panel could function as a "standard" back-to-back panel (simultaneously firing one element each in the BK and HLT) but also work as a "supercharged" single batch panel for 10 gallon batches (able to run 9000W of heating power in the HLT while the BK is switched off).

To explain, here is what I am envisioning:

Panel front: identical to a 50A back-to-back panel, except that the 2-way boil on/off switch would be replaced by a 3-way switch that turns on either the BK element or the HLT-1 element. The other element on/off switch would be a simple 2-way switch controlling the HLT-2 element. This way, no more than 2 elements can be powered simultaneously (HLT-1 and HLT-2 OR BK and HLT-2).

Inside the panel: on the boil element side, there would be no changes from the 50A back-to-back panel. On the HLT side, the SSR would be 80A and each HLT element would get its own contactor, protected by its own 30A fuse/breaker.

The questions I have about this set up are:

1. Is this even a feasible set up? Have I missed something that makes the entire thing impractical?

2. I have only seen a few builds around here that use this concept. Is going with 2 elements in the HLT just over-complicating things for a max 10 gallon batch size?

3. My biggest concern with this concept is the impact on PID performance. How would the accuracy of the PID be effected by controlling inconsistent output wattages? For example, if I autotune the PID using only one element and it learns how to control the temp with just one element, would I experience problems with overshooting when using both elements simultaneously?

**kal**

Welcome to the forum!

wscottcross · Posted: Tue Aug 22, 2017 2:23 am Post subject:

Some thoughts:
1. You could simplify it by going with a straight 50A back to back setup and split your water heating by using less water in the HLT and also use the boil kettle and just recirc through the HERMS coil. I actually do this and heat strike water in the boil kettle while the HLT is coming up to temp at the same time.
2. You could put a second element in the HLT and manually switch the cable. This is actually what I do, except that my second element is in the boil kettle because I'm doing 40+ gallon boils. Doing it this way, I put whichever PID is controlling the output being switched in manual mode and use that as a booster for the the PID that is actually doing the temp control. Since I'm boiling, I end up with both PIDs in manual mode and just swap cables a couple times while brewing. Clearly labelling the cables helps a ton and the twist lock connectors are really easy to swap.
3. You could manually switch cables (or wire as you described above) and have the HLT PID autotuned with only one element. Use the second element to boost your HLT heatup rate and set a temp alarm for when you're approx. 10 degrees away. Then switch off the second element and the PID tuning should be appropriate to reach final temp without overshooting.