RIMS element keeps blowing

For some reason I can't understand, my RIMS element keeps blowing out. I make sure that liquid is flowing through the system back into the mash tun before I plug it in. I have a float valve on the RIMS tube, near the outlet end, and have tested that it successfully interrupts current when drained and passes current when full. But somehow my element keeps blowing out as if it was dry firing. Any ideas? My best idea right now is that somehow an air bubble is getting into the RIMS tube by the element and isn't getting purged. That's the only thing I can think of that would let the element be dry while liquid is flowing and the float switch is on. But I'm not sure how to verify or fix this. Any ideas?

My setup goes mash tun->pump->RIMS->tun. The tun is highest, the pump is the lowest thing in the system and the RIMS is between them. The tube from the RIMS to the tun does have a dip below the RIMS in it and the tube from the pump to the RIMS goes above the pump, in case that matters.

Alternately I'd be happy to throw money at this problem if someone sells a pre-built RIMS other than the mondo expensive ones from Blickmann - all I need is the element and housing, not controller or pump. But I haven't been able to find such a thing. Does it exist?

DaveSeattle said:

For some reason I can't understand, my RIMS element keeps blowing out. I make sure that liquid is flowing through the system back into the mash tun before I plug it in. I have a float valve on the RIMS tube, near the outlet end, and have tested that it successfully interrupts current when drained and passes current when full. But somehow my element keeps blowing out as if it was dry firing. Any ideas? My best idea right now is that somehow an air bubble is getting into the RIMS tube by the element and isn't getting purged. That's the only thing I can think of that would let the element be dry while liquid is flowing and the float switch is on. But I'm not sure how to verify or fix this. Any ideas?

My setup goes mash tun->pump->RIMS->tun. The tun is highest, the pump is the lowest thing in the system and the RIMS is between them. The tube from the RIMS to the tun does have a dip below the RIMS in it and the tube from the pump to the RIMS goes above the pump, in case that matters.

Alternately I'd be happy to throw money at this problem if someone sells a pre-built RIMS other than the mondo expensive ones from Blickmann - all I need is the element and housing, not controller or pump. But I haven't been able to find such a thing. Does it exist?

Click to expand...

how is it orientated? in a way were air could get trapped in it? how is the rims being controlled? have you tested the ssr/pid? and what wattage is the element? these are all things that my help figure out why your having issues...

It is horizontal, but not perfectly so - it is hanging on ropes because I couldn't figure out a better way to attach it. The wort enters through a tee next to the element, passes by a tee connected to the float valve, then exits at the far end.

It's a 1500w 120v standard density element controlled by a Brewtroller through an SSR. This config has worked for me in the past, but I blew the element repeatedly due to stuck mashes so I decided to add a float valve, but that didn't fix it. But I'm confident the problem is not on the power side, except to the extent that my valve isn't protecting the element.

Blew another one today despite taking many precautions. I am wondering if pump priming issues may be causing bubbles big enough to break the element. I'm getting flow back into the tun, but the pump does seem to stutter occasionally.

What do you mean by you blow or blew the element? It sounds like you're having to replace the heating element every few minutes! $$$

Can you link to the float valve you used?

Could be the horizontal orientation of the tube. You could get boiling in the tube that would leave the element at least partially dry, while still having enough flow to keep the flow switch closed. A vertical orientation with the inlet at the bottom, outlet at the top, and flow switch on the outlet would seem like the least likely to have dry fire problems.

Brew on

You may not even need to go vertical, since you're using ropes to hang it you could just tilt it a little with the with the element on the low end, air bubbles will still float up away from the element.

Note this is tilted the opposite way I'm describing:

DaveSeattle said:

Blew another one today despite taking many precautions. I am wondering if pump priming issues may be causing bubbles big enough to break the element. I'm getting flow back into the tun, but the pump does seem to stutter occasionally.

Click to expand...

I run horizontal, and with no float valve. If anything, the issues I've had when pump flow has decreased was scorching.


What about your pump orientation?

The pump is inlet down. The float switch is this one:

http://www.amazon.com/dp/B00NWF8L6U/ref=sr_ph?ie=UTF8&qid=1438375616&sr=1&keywords=steel+float+switch

Yes, I have destroyed a heating element in each of my last three brews. It is adding up. Also they only blow on wort, never when I test on water. I have more money than time though and would be happy to throw some money at this if it would be a permanent solution. Just ideally not Blichmann money...

I'll try orienting it with the float at the high side, that might work. Cool mounting idea also, I may try that.

I will also add, a bit off-topic, that adding a BIAB bag to my mash tun has seemingly eliminated any worry of stuck flow for me. I've thrown numerous brews at my setup that before the bag (with a stage 1 stand + jaybird false bottom) would have definitely dragged the drain (and thus, the flow) to a trickle, and have had no issues. Just something to possibly consider if you do have flow issues and it's not air causing it.


Outlet up should be good, any other pieces of hardware possibly causing flow restrictions?

Might also want to look at a flow switch rather than a float switch. Less affected by orientation. Something like this: http://www.amazon.com/dp/B00MJVMUCO/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=42D4FHK3AIVE&coliid=I1SSR9V9LPVYJE

Brew on

I would put the float switch after the rims tube. My flow meter is after the rims tube and never had a problem.

What about the time between water pushing the float open and before it submerges the element? Or if the water column is falling for some reason and the rims tube empties while the float is still opened? In both circumstances you would dry fire. Putting the float on the rims outflow avoids both circumstances.

Hmm, idea... There is a ball valve on the output used to restrict the flow to help keep the pump primed. This is between the pump and RIMS. I ought to move it after the RIMS. My other thought was to move the RIMS before the pump, so that pump issues can't cause it to go dry. Do you guys see any problems with that? The temperature sensor is in the tube so if the pump loses prime the tube will quickly hit the set point and turn off. I'm concerned the pump might empty it faster than gravity can fill it though.

@thekraken: The switch is on the outflow end.

Another thought is that to make the switch fit I had to put it in an oversized pipe section. Perhaps this is failing to drain and holding the switch open. This wasn't observed in testing though.

There is a ball valve on the output used to restrict the flow to help keep the pump primed. This is between the pump and RIMS. I ought to move it after the RIMS. My other thought was to move the RIMS before the pump, so that pump issues can't cause it to go dry. Do you guys see any problems with that? The temperature sensor is in the tube so if the pump loses prime the tube will quickly hit the set point and turn off. I'm concerned the pump might empty it faster than gravity can fill it though.

Click to expand...

No. That is what is meant by the "output side". After the heating element; not after the pump before the heating element.

It can't be throttled if there is nothing in it?

I'd leave the valve on the pump discharge port, and before the RIMS tube.

Brew on

doug293cz said:

I'd leave the valve on the pump discharge port, and before the RIMS tube.

Brew on

Click to expand...

Why? That leaves the possibility that the pump "head" gets stuck in the tube, doesn't it?

The element is "blowing" seems to say that there is not enough liquid flowing over it to cool it down. Am I totally misreading heat exchange?

I have a ball valve before and after the pump and a gate valve after the RIMS after the temp sensor and a motor speed control. None of this matters to me. Just asking.

Maybe it makes a difference it the RIMS tube is vertical or horizontal; mine it vertical.

donbrew said:

Why? That leaves the possibility that the pump "head" gets stuck in the tube, doesn't it?

The element is "blowing" seems to say that there is not enough liquid flowing over it to cool it down. Am I totally misreading heat exchange?

I have a ball valve before and after the pump and a gate valve after the RIMS after the temp sensor and a motor speed control. None of this matters to me. Just asking.

Maybe it makes a difference it the RIMS tube is vertical or horizontal; mine it vertical.

Click to expand...

The valve is to mitigate pump cavitation, by making sure the outflow is throttled to keep pump suction low, as well as control the flow rate thru the RIMS loop. By putting a flow switch on the discharge end of a vertically oriented RIMS tube, you get pump shut off before the RIMS starts to go dry.

Brew on

blizz81 said:

I will also add, a bit off-topic, that adding a BIAB bag to my mash tun has seemingly eliminated any worry of stuck flow for me. I've thrown numerous brews at my setup that before the bag (with a stage 1 stand + jaybird false bottom) would have definitely dragged the drain (and thus, the flow) to a trickle, and have had no issues. Just something to possibly consider if you do have flow issues and it's not air causing it.


Outlet up should be good, any other pieces of hardware possibly causing flow restrictions?

Click to expand...

using multiple stages of filtering works well too...I have over 50 brews on mine and never a stuck sparge..I just use a bazooka tube with a finer stainless mesh braided line inside it and a false bottom over the top... so three layers of filtration with each getting finer...

DaveSeattle said:

Hmm, idea... There is a ball valve on the output used to restrict the flow to help keep the pump primed. This is between the pump and RIMS. I ought to move it after the RIMS. My other thought was to move the RIMS before the pump, so that pump issues can't cause it to go dry. Do you guys see any problems with that? The temperature sensor is in the tube so if the pump loses prime the tube will quickly hit the set point and turn off. I'm concerned the pump might empty it faster than gravity can fill it though.

Click to expand...

I use a simple $10 flow switch wired to my ssr so if the flow drops to almost nothing the power stops to the rims... simple but effective and reliable... btw my rims is horizontal..

doug293cz said:

The valve is to mitigate pump cavitation, by making sure the outflow is throttled to keep pump suction low, as well as control the flow rate thru the RIMS loop. By putting a flow switch on the discharge end of a vertically oriented RIMS tube, you get pump shut off before the RIMS starts to go dry.

Brew on

Click to expand...

+1 for moving the valve to the outlet side of the RIMS tube.

By positioning the valve at the outlet of the RIMS tube, it will still function for flow/cavitation control and will also maintain full pump output to keep the RIMS tube flooded.

As a test, I would suggest adding a temporary valve at the outlet of the RIMS tube and leaving the intermediate valve full open. Then do a test brew.

The test brew should answer the question whether this is the solution or not. I am betting it will fix your issue.

I also agree that a vertical orientation for the RIMS tube will work better.

Something is whacky here... I would suggest a vertical orientation. The only way air can go is up and above the element. Do not turn the element on unless there is regular flow coming out.

I also think the valve at the exit of the pump (before the tube) is the preferred method but at the tube outlet should be fine too. Just remember then the silicone tubes connecting the two will be under pressure, which they are borderline rated for.

-BD

My setup is vertical, have not had an issue yet with the element being destroyed. I have use a 2 valve system to control pump output and on the output side of the rims to control flow to the top of the grain bed. My element is also on a switched circuit. I don't kick it on until I know I have the flow setup proper.

You might be creating a trapped air bubble in the rims tube, in that case an exposed element would most certainly burn up.

Progress has been made! I brewed a batch Sunday without blowing the element. Here is what I determined:

1. The float switch piping was not fully draining, leaving the switch on even when the rest of the tube was drained. I drained the system and took the switch piping off, and it was full of water. It was just slightly below horizontal and apparently this was enough to trap the water. I straightened it, though I haven't drained the system yet to check it.
2. The issue seems to be an air bubble in the tube, caused by a stuck mash, and fixed by orienting the tube diagonally with the element at the low end.

My pump has always had issues with losing prime, and I think it's because I was grinding too finely and sticking the mash. I loosened my mill gap this time. I also recirculated for a few minutes until it seemed to flow totally smoothly before I plugged in the heating element.

I realized also that there was no place for a trapped air bubble in the RIMS tube to go with the way the tubing runs - at best it will get stuck at the top of the tubing run, at worst it'll stay in the RIMS. I haven't remediated this yet, but I have a purge valve on the pump outlet that I'm going to move above the RIMS tube instead for this purpose. The other issue with the current placement is that purging the pump also dumps the contents of the RIMS tube, which I knew so I always unplugged the RIMS when purging, but it may have been introducing air into the RIMS(as well as being annoying).

P.S. In an epic sadness, on Thursday at 11:30 pm, after brewing a session IPA all night, I dropped the carboy just one inch onto the floor while moving it to the fermentation chamber and it shattered, losing all the beer. In revenge I rebrewed it the next day and brewed a bitter on Sunday. But I still cry for 6 gallons of spilled beer...