Simple automation question

[ChrisfromAbby]

I've got a manual HERMS set up using low pressure propane, but I'm considering automating (just) the HLT to simplify maintaining the temperature there.

I've been following discussions about using the Honeywell VR8300A3500 with a Pilot burner (Q314A4586) and thermocouple (Q390A1061) but realized some important little parts were left out of the discussion. Things like the NG to LP conversion kit, the pilot tubing and the 24v transformer. Little parts, but they add up. Already doubled the cost of the valve.

Then it occurred to me - how is this valve set to the temperature I want? Can someone explain this step and equipment to me? Do you need a separate PID controller? Or is there an analogue control method (thinking of my furnace and water heater temperature dials ). I'm using STC1000 temperature controllers already for my keezer and my fermentation chamber, but I think this situation would required a PID if it were to be digital?

Chris

 

[ChrisfromAbby]

Anyone?

 

[ChrisfromAbby]

After digging around I've learned that I will indeed need another piece or two of equipment. However not being a real electronics or computer guy I need some clarification.

It seems a controller is needed. The valve works on 24v so I'll need a controller with a 24v output. The controllers that seem to be most recommended are the Johnson Controls A419GBF, the Ranco Controller and the Love controls. It's not clear however what specific model is needed.

Do they all work on the same input and output voltage? None had a transformer built in to convert 110v to 24v? I'll need to put the transformer in line between the controller and the valve, yes?

Is there a preferred controller for a HLT? Specifically, which model??? I am familiar with using an STC1000. Would one of those be sufficient for controlling a furnace valve, or do I need a PID controller?

Chris

 

[RufusBrewer]

If I understand the players involved, the Honeywell device will light a burner when it is told to do so. When installed in a furnace that turn on signal comes from the thermostat.

In your case you need something more complicated than a thermostat.

Typically home brewers use a PID. The PID tells the Honeywell to open the gas valve. And the Honeywell will close the valve if there is no flame.

Depending on the model you have, it can create a spark to light the furnace. Or it will use a pilot lamp to get the burner aflame.

 

[ChrisfromAbby]

I read in one thread that PID may not be as desirable for the HLT as valve will keep turning off and on rapidly (causing it to wear out quickly) as opposed to a simple on/off heat controller?

Chris

 

[jrcrilly]

You won't be able to use a PID in PID mode to control the gas valve. You'll have to use the on/off mode, which would be the same as using an STC1000. The PID controller will look cooler and have dual displays but of those aren't important to you, you may as well use an STC. The 24 VAC comes from a transformer you add; might cost $10-$20 dollars. You'll route the 24VAC through relay contacts in the PID or other controller. You COULD get away with using one of the pre-wired controllers you mention, which switch AC power, by powering the 24VAC transformer from the 120VAC output. It would be better to keep the transformer powered up and switch the output through relay contacts, though.

 

[ChrisfromAbby]

THANK YOU!

That is exactly the sort of information I was looking for.
:rockin:

Chris

 

[ChrisfromAbby]

Sadly, the STC only comes in 24VDC or 110VAC versions not 24VAC. Is it bad form to wire the transformer between the 110VAC controller and the valve? Does it just cause a delay?

Any advice on which specific model of valve to use. HONEYWELL VR8300 or 8200? There seem to be several within each series.

Chris

 

[NoH20]

You can use a PID, but get one that can perform relay (Auber makes one, about $40). Put it "on\off" mode and you're all set. Get a 24v converter and run that to the PID then the PID sends 24v to the gas valve when necessary.

Todd