direct fire MT or HERMS??????

let me start by saying that there is alot of information out there on HBT about both of these systems. I 'think' i have read most of it over the past couple of weeks. i do have a ? about the reason for choosing one over the other.

I have a brew tree (3 tier all gravity feed), all keggels, the MT and BK have false bottoms in them.
i really want to build a single tier with a pump (maybe 2) but 1 to start. my ? is this--HERMS i would need to pump my wort from the MT through a HEX that is in the HLT and back into the MT. with direct fire MT i would have to recirculate the wort with a pump to prevent scortching.

Direct fire seems much easier.... so i'm not sure why people go with the HERMS. is it because, down the line, when i want to automate, it is easier to have 1 furnace/ pilot valve on the HLT and not need 1 also for the MT?


thx for all of your help, as you can tell, i need it

I'm not an expert but I'll take a stab at it.

It is easier to maintain correct mash temp by recirculating through a large volumn of water i.e. your HLT. If you are direct firing your mash, you will probably have larger temperature swings as you are applying heat directly to the bottom of the mash.

If you are recirculating through a coil in your HLT, you just need to maintain the temp of the HLT water. The wort passing throught he coil will assume the temp of the surrounding water. If by chance your HLT water gets too hot you can simply shut your pump off until the temp is corrected.

Hope this helps.

They both work well, just do your homework there are alot of discusssion on this topic here at HBT. Read as much as you can since almost if not all questions about it have already been answered some twice. When I built mine I took my own advice. Read till it hurts, pretty soon you will get tired of researching have all you parts and you will be posting pics for others to follow. Good Luck! Can't wait to see your new stand.

thanks for your help! are there any other reasons to go herms over direct fire MT than it is more of a stable way to hit your mash temps?

I personally use direct fire my MLT. I feel it gives me another level of involvement with my beer, no just setting it and walking away.

have u ever thought of using a pid controller for the gas on the MT? or is that only for HLT??

I had a herms and switched to direct fire with a stirrator. Steps took too long with the herms, and after I figured out the correct design and speed for the stirrator my temp control is better, less than 1dg top/bottom in a converted keg. I just added a honeywell controller and valve with standing pilot to the MT to reduce the hands-on during mashing.

I built an all electric BCS460-controlled HERMS with a standalone heat exchanger (HEX). The HEX is only 2 gallons, so it reacts pretty quickly when temp changes are needed for step mashes. That said, I can't increase temps as quickly as a direct fire MT, but since the thermal mass is low, it's quicker to react than a combination HLT/HEX (where you're trying to heat HL plus the wort). One benefit of a HERMS is there's zero chance of scorching the grain.

dblott1 said:

thanks for your help! are there any other reasons to go herms over direct fire MT than it is more of a stable way to hit your mash temps?

Click to expand...

I prefer a direct fired RIMS. Mine is a semi-automatic configuration. I have no trouble at all hitting the strike temps, ramping up or maintaining temps. I do not agree that a HERMS is necessarily a more stable way to hit your mash temps vs direct fire. There are a lot of variables that can affect the performance of either system, so IMO a blanket statement that either system will inherently provide superior performance is not of much value. It all depends, as usual.

jdieter,
where did you get your honeywell valve and standing pilot? where they expensive? do you have some sort of PID?

if i'm gonna do a gas valve and a pilot with a PID is it just more functional (more options for the same equip) to put that under the HLT than under the MT. meaing i can control the temp for the the HLT for all my water needs as well the mash tun via a HEX (all with 1 pump and gas valve) or am i missing something?

Honestly I built my electric system specifically for the eherms capability. Once I started wrapping my mash tun with reflectix, etc - I was getting 1-2 degree temp loss over 60 minutes in the dead of winter. I have since pretty much abandoned the idea of an eherms and direct fire if needed.

dblott1... got the gas valve off an ebay store, it's a Honeywell VR8200A2132 very common and should be easy to find, I think the valve, pilot and thermoucouple assembly were around $100 The controller is a Honeywell UDC3000 which is capable of pid control, however I use it as an on/off control. To get true pid control I would need to modulate the flame, i.e. as the error (difference beween setpoint and process temp) decreases the flame output would decrease. I simply turn the burner on and off via the honeywell valve. If I'm making a step change I run the burner flame quite a bit stronger than when controlling at a constant temp. A pid would be ideal but I would need to automate the burner flame control knob with a command and position feedback device, so I still have to be hands-on anytime I make large step change to make the temperature rise at a reasonable rate and also not overshoot the setpoint.