Our boiler issue

[fa50driver]

We do have vents and vacuum breakers installed, and we also have pressure gauges at the jacket inlets. We are holding about 12.5 to 13 psi at the jacket inlet. Anything much over that and I hit the electronic cutoff from the boiler due to about 1-2 psi variation from the boiler.
Now, I am assuming that the vacuum breakers/vents are hooked up correctly but I am very suspicious because we can't get the air vents to release any pressure. The vent is hooked into one of the inlet sides of the steam traps.

Essentially, the jacket outlet hooks into the left side trap inlet, the vent is hooked into right inlet side of the steam trap and the condensate return out of the lower outlet side of the trap.

[cpelz]

Given the pressures you're seeing at the inlets and assuming the plumbing is correct, I'd suspect fouling of the heat transfer surface. I wonder what would be depositing, seems the steam should be pretty clean.

When we had our boiler physically cleaned recently our boiler water tech suggested doing an acid clean next time. Sounded like his intention was to set up a circulation loop from a brink and to hit it with a lot of citric acid.

Again that's on the boiling rather than condensing side so the chemistry might be different.

[fa50driver]

Specific Mechanical's response

My partner just hung up with a rep from Specific Mechanical. He indicated that the kettle probably won't boil unless we had steam pressure of around 13 psi, and it won't boil with just the bottom jacket, that the side jacket is needed as well. Seems strange that a kettle would be engineered to be used at close to its maximum pressure rating, and even then would need the side jacket on to get a good boil. He also indicated that the side jacket would not need to be covered entirely to be used.

He didn't make any recommendations for chemicals to be used for removing internal mineral scale, but said removal may help with energy transfer. I was thinking of using heated Acid #5. Perhaps I will give 5-Star a call and see what they would recommend.

I had envisioned a nice rolling boil from just the bottom jacket. I guess that isn't happening.

[fatheads]

frustrating ...we just got through that phase of the install..we got a 7bbl with a 400,000 btu steam boiler.boiler guy said no less than 3 inch feed our run is about 30 ft,we reduce to 1 1/2 right before kettles.Did you check that the solenoids are doing their jobs?
When the boiler cycles at 13 how low does the pressure drop off?Check the differential at the boiler.

[fa50driver]

I don't know exactly, but the differential is around 2 psi. If I push any more than 13 psi at the jacket, the high pressure cutoff engages at the boiler.

I don't like hearing that your boiler guy required 3 inch pipe, since we only have 2.5 inch.

Solenoids appear to be doing their job.

[HinduKush]

I don't know exactly, but the differential is around 2 psi. If I push any more than 13 psi at the jacket, the high pressure cutoff engages at the boiler.

I don't like hearing that your boiler guy required 3 inch pipe, since we only have 2.5 inch.

Solenoids appear to be doing their job.

The boiler cut-off knows nothing about your jacket pressure. Make sure your hi-limit on the boiler is set to 15 psi for cut-out and 13 for cut-in.

[fa50driver]

What I meant to say is that since there is a 2psi differential, trying to get anything more than 13psi at the kettle results in a 15psi at the boiler, thus hitting the overpressure limit.

On a good note, I have another possible lead... We have 1.5 inch solenoids AFTER the pressure gauges a few feet from the kettle, so we may not be actually getting the full 13 psi/ steam volume at the kettle. Manufacturer indicated that this has been a problem in the past and that the solenoids will effect the flow. A few psi loss through them may be causing the issue. We are going to remove the solenoids to see what we get. On a bad note - if it works, I wasted a ton of money on a custom built panel and steam solenoids.

[fatheads]

We cycle at 11 and with a 2psi differential it drops to 9...your 13 sounds fine after reading all the posts and just going through what we went through I tend to think as I said its could be the solenoids,maybe they are not opening all the way reducing pressure at the kettles.
We use propane,so we also had to increase our regulator size at our tanks and add a secondary regulator at the boiler...
The smaller reg was choking down the boiler so it took twice as long to cycle which in turn it could'nt get back to pressure fast enough

Good Luck

[fa50driver]

It is possible that the solenoid isn't opening all the way - it is tough to tell. The kettle manufacturer seems to think that even if open all the way, it is still blocking full flow (by way of design) and causing a pressure drop/volume reduction. Once we rid that sucker, we will know for sure.

Now learning about CV flow factors and Delta P's across solenoids. For any engineers out there - if our 1.5 inch solenoid has a CV flow factor of 22.5 and I have 13psi before the solenoid, what would be the resulting pressure drop after the solenoid? Not sure if I have provided enough info...

[gitchegumee]

Solenoid should be fine. Cv is usually specified for water flow, not steam. I would guess that your solenoid is NOT the problem. If the solenoid valve did restrict flow, gases are able to recover without much pressure loss after a restriction. And your boiler operating pressures sound good. I set boilers for 13 cut-out and 11 cut-in. You shouldn't need any more pressure. Look elsewhere for the problem.

[fa50driver]

I just spoke with an ASCO tech on the phone (manufacturer of the solenoid.) He did indicate that the solenoid valve requires a differential in pressure to actuate and remain fully open. It takes 5 psi differential to open and 3 psi differential to remain open. So... not being an engineer, I am not sure if this has a direct 3 psi reduction in operating pressure or not, but if it does, it seems to me that it would certainly effect volume of gas moving through the system. Going to remove that sucker and then test the system without it. Not much else I can do at this point to troubleshoot....

[HinduKush]

I just spoke with an ASCO tech on the phone (manufacturer of the solenoid.) He did indicate that the solenoid valve requires a differential in pressure to actuate and remain fully open. It takes 5 psi differential to open and 3 psi differential to remain open. So... not being an engineer, I am not sure if this has a direct 3 psi reduction in operating pressure or not, but if it does, it seems to me that it would certainly effect volume of gas moving through the system. Going to remove that sucker and then test the system without it. Not much else I can do at this point to troubleshoot....

Oh yeah, forgot to add: buy zero differential pressure solenoids. I prefer globe valve on kettle steam.

[fa50driver]

Finally able to boil water....

Removed solenoid on the bottom jacket and circulated some Acid through the jacket to try to remove some scale if any. I took a peek up inside the jacket and there didn't appear to be much of anything in there. I guess that the bottom jacket was never meant to boil alone. With both jackets on I can boil water with 13 to 14 psi, although it takes a while to heat up. According to a rep from Specific Mechanical, they have since added a third jacket to their 20 bbl kettles, so I guess that pretty much explains the situation. We will see what happens with wort... Thx for all of the feedback!