DIY HLT

[Garry]

I found an old Burco boiler in my oul' fella's shed ages ago. It was fairly battered looking but the inventor in me wanted to make use of it. It's been an on/off project for the last few months but I'm finally finished it.

The boiler is unusual in that the external skin is galvanised steel. It's fairly manky looking but we'll sort that out later. The internal skin is stainless steel and still shinny (ish).

I stripped everything off it first and gave it a bit of a clean. (I know, it doesn't look it!)



I fitted a new 3kw element. Then fitted a REX-C100 PID, a solid state relay and 12V transformer to power the relay. The transformer is just some old charger I found in the man drawer.





I drilled a PT100 probe into the kettle.



Here's my wiring diagram.



I then fitted a 1/2" brass ball valve and fashioned a dip tube from some fittings I found on the garage floor.





I graduated the inside of the boiler with a cheapo dremel. It's rough but does the job  Fair play to all you guys who posted up the etching tutorials lately. I just didn't have the patience.





I made a lid out of some 80mm thick insulation. It's over-kill but that's what I had in stock. I covered the boiler in a layer of foil insulation.  It covers up the ugly galvanised steel nicely. I'll add more insulation to the sides when I get a chance.





I tried it out on Saturday. I think it took 35min to get 25l of strike water up to 75°C. The PID over-shot a fair bit, but it was better when I did the sparge. I think it will take a few goes before it trains itself.

So that's my 3 tiers finished. What am I supposed to do with myself now? RIMS, HERMS, arduino.........

[Cambrinus]

Nice one Garry!

[Beerbuddha]

Fair play you know your stuff 

[LordEoin]

any reason you have a constant current to the transformer instead of having it click on when the PID wants?

[Garry]

any reason you have a constant current to the transformer...

It works, leave me alone 

.....instead of having it click on when the PID wants?

My brain is frying trying to figure out how to do that! Tell me how?

[donnchadhc]

Is there a need for the transformer, won't the PID send a 12V pulse to the SSR without it?

[Will_D]

Most PID controllers like the STC-1000 drive a set of relay contacts so you can switch what you want with them. They are know as voltage free contacts.

A Solid State Relay, just like a mechanical coil relay needs a low voltage to cause it to work.

So the transformer is powered all the time just like Gary's drawing

[LordEoin]

it only needs to be powered when you want the SSR to switch. At least that's how I wire mine, which is why I'm wondering.

[Will_D]

I would stick with Garys original.

Transformers/power supplies are NOT designed to be switched on and off continously!

Every switching causes a surge of current through the primary windings - not good.

If you have ever switched on big transformers then you will hear the "thunk" as the traffo draws an initial surge of current. That is why large inductive loads (like motors and traffos) have special fusing requiremnts!

[LordEoin]

They're not designed to be mastic'd to the bottom of a Burco boiler either, but reason accepted. you win a cookie!

[Garry]

I see what you mean now Eoin. I think I'll stick with what I have. I'd be afraid I'd fry the PID with the 240V on top of what Will says. Anyway, when you have a 3kw element on for a few hours, a 12v transformer isn't going to make the meter turn much faster.

It's interesting reading Will's post. I actually blew my solar-pump power supply during the weekend. I assumed it was the pump that went because everyone says they are shít. But it was the power supply. I'm thinking now that maybe I was switching it on/off too much? Or maybe it was a crap power supply.

[cno1]

Is there a need for the transformer, won't the PID send a 12V pulse to the SSR without it?

I would have though the the transformer was not required either. Does the PID not output not produce a 12V DC output that would be sufficient to operate the SSR? Essentially having it's own internal Transformer?

Maybe I'm missing something, can someone tell me why the Transformer is required?

[LordEoin]

The PID doesn't push electricity, it just flicks an internal switch to complete the circuit.

[Garry]

Is there a need for the transformer, won't the PID send a 12V pulse to the SSR without it?

I would have though the the transformer was not required either. Does the PID not output not produce a 12V DC output that would be sufficient to operate the SSR? Essentially having it's own internal Transformer?

Maybe I'm missing something, can someone tell me why the Transformer is required?

This PID controller is just a relay. I wouldn't trust it on it's own to power a 3kw element, that's why I'm using the SSR relay. It's the SSR relay that requires the 12v supply.

There are many different types of PID controller out there. Maybe some have an internal transformer? This particular one doesn't. I bought this one because I've seen it pop up a few times on other brewing forums. It's also very good value.

[donnchadhc]

Ah, no internal transformer, makes sense.