Buffalo Boiler Thermal Switch & Element

[FutureBrewer]

Hi all,

After a few successful rolling boils from my Buffalo 40 litre boiler, it's now having problems...

When approaching boiling point, it cuts out and the indicator light turns red. After a while, the power returns for a few minutes before cutting out again.


Power cut & red light of death!

Now, I put this down to a little bit of scorched wort on the element causing it to overheat, tripping the boil-dry protection/thermal switch.

But, even with a sparkling clean element and plain old water in the boiler, I'm still having power failure!

Time to get the screwdriver out...


Buffalo guts

On the underside of the element is a 120 degree thermal switch/thermostat that cuts the power when it reaches that temperature, then auto-resets itself when the element cools down.


Thermal p.i.t.a.

It's bolted onto the element, with a little thermal paste between surfaces (wiped off for this picture...)


Detached

So, questions:

Does the fault lie with the thermal switch..? Is it tripping before it should i.e. at a much lower temperature than 120 degrees? Or, is the element actually getting much hotter than it should for normal operation?

Should I replace the thermal switch (a few quid from China/Hong Kong Ebay dealers and a LONG wait...) and/or replace the element (£19.54 delivered from Nisbets.)

If, for instance, I leave the thermal switch detached (but obviously made safe with insulation tape, cable ties etc,) could the element run out of control and burn out in a dangerous fashion..?

Basically, I don't want it to go all Fukushima on me

Advice welcomed!

Cheers,
FB.

[FutureBrewer]

Update:

There aren't many parts to a boiler - how complicated can it be..?

Fault testing:

1. Remove and test resistance of element.

It's rated at 2600W so using R = (V x V) / P:

R = (230 x 230) / 2600

The resistance of the element should be 20.36 ohm - I'm getting 20.9 ohm.

So, by my reckoning, the element is fine.

2. Remove and perform continuity test on auto-reset thermostat.

Took the unit out and connected multimeter across the terminals. It's 'normally closed' until it reaches it's rated temperature of 120 degrees C.

Continuity fine.

With multimeter still across terminals, I put the surface of the thermostat into boiling water - and it remained closed, as it should.

Using a cooker hob, I heated the surface of thermostat (beyond 120 degrees C) and the switch opened. After a few moments, when the surface cooled, the switch closed again.

So, by my reckoning, the auto-reset thermostat is fine.

3. Continuity test on adjustable thermostat

Removed spade terminals to isolate unit and connected multimeter.

With dial turned fully clockwise, the circuit is closed. With dial turned fully anti-clockwise, the circuit is open.

So, by my reckoning, the adjustable thermostat is fine.

Hmmmmmm....

Now, the only other parts of the boiler are:

An illuminated power switch, and an indication lamp (which consists of two bulbs/neons) with four wires running to it. Two black for one bulb and two white for the other.

One of the black wires & one of the white wires each has a component beneath a sheath. The black wire sheath is marked "125°C HFT (2.0Ø) SAL" and the white wire sheath is marked "E205436" but the writing is soooo small , I may be wrong....

Just for the sake of experimentation, I took the thermostat off the bottom of the element, leaving it connected (but insulated & away from other surfaces...) and fired up the boiler with about 10 litres of water.

Within a few minutes the boiler power cut out again... This is without any direct heat applied to the surface of the thermostat!

The final thing to note is, and this is before I performed the above experiment, the end of the wires on the 'live' side of the thermostat seem to have been getting VERY hot. The insulation is brittle and breaks away easily and the wire beneath seems blackened. Could the fact that the terminal is getting hot be tripping the thermostat, rather than heat from the element..? If so, WHY is the terminal getting so hot..?

Any advice or comments welcomed even if it's to point and laugh at the man with the broken shiny

Cheers,
FB.

[Steve B]

Is it worth just bypassing everything. If the element works you will stull be getting a rolling boil with no worries about thermostats and switches.

[jmc]

Hi FB

I must admit I'd be tempted to do a test with thermostat bypassed / removed.

I have a much older Buffalo thats been working well for a year now (On AG #26)

Initially I had problems so I moved my temp sensor
see post : Buffalo Boiler 27L - help needed with electrics from last July.

Moving sensor to side works for me as I can now set dial to 50-60 and still have a rolling boil that's not mad.

I do have to clean element very carefully after each brew. Any slight build up & it cuts out.
I think this is due to separate temp sensor in-built into element.

As long as its clean I can do a 90min rolling boil, but I have to be careful to ensure no caramalising of wort ( I stir element regularly) and I wouldn't add sugar granuals or malt extract anywhere near the element.

Good Luck.

ATB John

[FutureBrewer]

Is it worth just bypassing everything. If the element works you will stull be getting a rolling boil with no worries about thermostats and switches.

True Steve... but I'd feel happier knowing what the fault is. And, who knows, this problem may be just around the corner for other Buffalo owners. This thread may be handy in the future.

Having said that, I might get frustrated enough to do what you've suggested.

I must admit I'd be tempted to do a test with thermostat bypassed / removed.

Hi jmc - I've tried it without the thermostat/thermal switch attached to the bottom of the element, and it still trips the power. The adjustable thermostat & sensor is working correctly (as far as I can see) and if it was giving a false reading, it would just switch the element off, as it does during normal operation. What I'm getting is different - the illuminated power switch goes out and I get a red indicator light... No mention of a red light in the instruction manual either.

I do have to clean element very carefully after each brew. Any slight build up & it cuts out.
I think this is due to separate temp sensor in-built into element.

Even with the element sparkly-clean, fresh tap water and the thermostat/thermal switch removed from the element, I'm getting the fault light/power cut. This is only a few mins into heating the cold water...

Cheers for the replies chaps - keep 'em coming...

Cheers,
FB.

[Aleman]

There seems to be a few buffalo boilers with this symptom, and the one chap I know who has resolved it replaced (had replaced) the thermal 'boil dry' cut out . . . it seems the one fitted was faulty and tripping out too soon

[FutureBrewer]

There seems to be a few buffalo boilers with this symptom, and the one chap I know who has resolved it replaced (had replaced) the thermal 'boil dry' cut out . . . it seems the one fitted was faulty and tripping out too soon

Hi Aleman - I came across the first post during research... cheers for the other one too

I thought that the boil-dry thermostat/thermal switch would be the cause, but on testing it (in isolation,) it seems to be operating normally.

Nisbets supply them as spares, but they're not available until September! Just to eliminate it from my inquiries, I'd better get a couple from China/Hong Kong Ebayers, even though that'll still take weeks

Cheers for the reply
FB.

[greenxpaddy]

Not had any problems with my mine

Have noticed that the thermostat is adrift though.

[Aleman]

Eliminate it completely and bypass it . . .if you are still getting the problem, it is working fine . . . If not . . . order something from China . . . Looking at your post in depth I would say your issue is the wiring overheating . . . it really should not be getting hot, if it is, it does imply a poor/loose connection . . . Or the Wire isn't high enough spec to carry the current. Ideally It should be using high temperature rubber coated flex similar to that used on an immersion heater . . . and at least 2.5mm sq

[FutureBrewer]

Not had any problems with my mine

Hi greenxpaddy - and long may it continue!

Also, as a fellow Buffalo owner, could you check this on your boiler:

According to the manual, step 6 of operation is - "Set the Temperature Control knob to the required temperature. The Heat Indicator illuminates and the appliance heats the water."

And, then step 7 - "When the water has reached the set temperature the Heat Indicator light turns Off."

Interestingly, my Buffalo (until recently, obviously) operated totally opposite to this... i.e. When switched on, but dial set to zero, the indicator light was illuminated green. When I set the dial to, say, 80 degrees C, the light went out and the boiler would heat the water until it reached that temperature (or thereabouts,) and the green light would come back on...

Is this how your one operates..? I'd be interested to know.

I'm beginning to think I've bought a 'Friday Afternoon' job..?

Eliminate it completely and bypass it . . .if you are still getting the problem, it is working fine . . . If not . . . order something from China . . . Looking at your post in depth I would say your issue is the wiring overheating . . . it really should not be getting hot, if it is, it does imply a poor/loose connection . . . Or the Wire isn't high enough spec to carry the current. Ideally It should be using high temperature rubber coated flex similar to that used on an immersion heater . . . and at least 2.5mm sq

Yes Aleman, I'm a bit concerned that the wires on the positive/live side of the thermostat seem to be overheating - and I'm thinking that this is what's causing the thermostat to trip... There is no evidence of overheating around any other spade connector or termination. Maybe, dirty/loose connector onto the thermostat is causing an overheating issue, perhaps..?

Maybe:

1. Replace thermostat/thermal switch (just for the hell of it!)
2. Beef up the live wire - replace with high-temperature rated cable.
3. Replace spade terminal on input side of thermostat/thermal switch with shiny/clean new one.
4. Test it, with fingers tightly crossed...

Cheers,
FB.

[greenxpaddy]

Yep the green light comes on when up to temperature

I would say that makes sense

[FutureBrewer]

Yep the green light comes on when up to temperature

Great - thanks greenxpaddy

That's good to know... They've got it wrong in the manual then.

Cheers,
FB.

[FutureBrewer]

UPDATE:

The boiler is back in action

For the sake of thread completion, and in case anyone else has a similar problem in the future, here's what I did.

Eliminating the obvious things first (as catalogued in my posts above) it definitely wasn't:

• The Element
• The Adjustable Thermostat
• The 120 Degree Thermal Switch

The thermal switch was operating correctly in isolation to the boiler but, looking at the live-side wiring (the left-hand terminal in the pic below) something was obviously going awry...


Hot cables

Melted insulation and blackened spade terminal. Not good. Not good at all...


Chargrilled spade terminal

So, looking at what Aleman posted above...

it really should not be getting hot, if it is, it does imply a poor/loose connection

And what Fego wrote on my AG #002 and #002b post...

Either that or faulty wiring arcing out with the heat/power demand.

In fact, looking back over one of my own threads, I noted:

There was a slightly loose spade terminal attached to the the element that looked like it could've been arcing...

Now, at the time, it didn't look as bad as the pics above... But obviously, with more use came more arcing, poorer connectivity, more resistance, more heat...

Could a loose/dirty contact really be the cause of the overheating? Enough localised heat to cause the thermal switch to trip..?



Yes.

I took the thermal switch out...


Dirty contact

...gave it a good blast and spruce up with contact cleaner...


Maplin's finest contact cleaner


Sparkly-clean contact

And, using thermal paste...


Maplin's finest thermal paste

...which only started coming out halfway down the tube...


Wot a rip-off!

...I put a blob on...


Dab of compound

...replaced the component...


Thermal switch/thermostat replaced

...cut back the charred wires & insulation, and replaced the spade terminal...


Shiny new spade terminal

...filled the sucker with water and fired it up.



Works a treat!

So, what have we learned here today..?

• Poor/dirty electrical contacts causes resistance, which equals heat
• I owe Aleman and Fego a drink
• The JBK forum is the fount of all knowledge

Thanks additionally to greenxpaddy, jmc and steve b who also contributed to this thread.

C'mon... Group hug...

Cheers,
FB.

[jmc]

Thanks for the update. Really useful.

Glad all now working OK, so get brewing

ATB John

[judasegg]

Guys - I was hoping you might be able to shed some light on my issue with the buffalo 40L boiler.

Last night, during a 90min boil, after only 20 minutes, the element cut out. When I turned the thermostat down then up to 110 again, it started up again. But then, it stopped working all together - This is only my 4th AG with it!

Now, I have a hop stopper that lies right on bottom of boiler, seems to leave wort burned at bottom of pot, i'm guessing because wort gets trapped under there. Last 3 AGs, just been cleaning it off, no problems.

This time, it died. I insulated the boiler with camping mats, to help speed up boil, which seemed slow. However, I covered up the red/green light switch, so didn't see if it was red last night during the boil.

However, I peeled back the insulation this morning, cleaned element, filled up with some water, turned it on... no lights are going on, the switch doesn't light up, seems like its just not getting power. Tried replacing the fuse, no joy.

Anyone have this problem? Not even a red light on!

Cheers,
-Lee