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Thread: Changing Boiler from High Pressure to Low Pressure Question

  1. #1
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    Changing Boiler from High Pressure to Low Pressure Question

    I bought a used 10hp Bryan boiler, it's 150psi.

    I'm going to convert it to low pressure. I called the manufacturer and they do allow it as the unit supports both HP and LP. Bryan is saying the controls will need to be swapped out and a bigger nossle welded. Then it will need to be stamped LP. All seems reasonable. I'm just wondering if there is anything else I should consider related to brewery steam specifically in the conversion or anything else to keep in mind or feedback.

    Thanks.

  2. #2
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    HP to LP

    Don't change the pressure on the boiler, just use a steam pressure reduction valve, the steam quality will be better, and you can use smaller pipe to go to your use points. It will be cheaper than retrofitting your boiler.

    Mike George

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    Quote Originally Posted by hydromike View Post
    Don't change the pressure on the boiler, just use a steam pressure reduction valve, the steam quality will be better, and you can use smaller pipe to go to your use points. It will be cheaper than retrofitting your boiler.

    Mike George
    I know each state/province there are different rules but the general consensus is I need specific levels of boiler operator licenses and/or certified engineer to operate it if its left at high pressure which is the primary reason I have to change it.

  4. #4
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    Ahhh boiler Operator

    I am lucky where I am at I can run@150PSI without a boiler operator, I would sell the used unit and get a low pressure unit. The changeout of controls can be just as expensive as getting anther used boiler.

  5. #5
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    Quote Originally Posted by Jedi View Post
    I know each state/province there are different rules but the general consensus is I need specific levels of boiler operator licenses and/or certified engineer to operate it if its left at high pressure which is the primary reason I have to change it.
    I read your other post regarding pipe size and this post complicates the other significantly. First your boiler is rated at 10hp which is a BTU output number. Think of it as energy per hour that the boiler can transfer to your kettle/MT. That number is predicated on several factors like efficiency of the transfer due to temperature drop, length of run, etc. but a big one is how much water it can turn to steam in a given period of time and how much "reserve" of energy it can hold in the system. The energy it is storing is heat in the way of pounds of steam. A given volume of steam at 160 psi has a lot more energy stored than the same volume at 15 psi. In order to have the same energy at 15psi as at 160 the part of the equation that you need to change is the volume, i.e. bigger header pipe to "store" more steam or bigger boiler (a 10hp low pressure boiler is physically much larger than a 10hp high pressure boiler to store more volume of steam, therefore deliver the same energy as a physically smaller high pressure boiler). running a high pressure boiler at a lower pressure just reduces the amount of energy it can deliver over a period of time. Basically it will no longer be a 10hp boiler from an energy delivery per hour standpoint. Unless your headers are pretty big it will likely be undersized for your application. Did your engineer take into account for this? There are other factors involved than just turning down the pressure. Lower pressure steam moves it moves faster than higher pressure, the boiler manufacturer knows this so when they design high pressure boilers they design/build with that in mind, a big factor here is the size of the "hole" coming out of the boiler, a high pressure boiler has a pretty small hole as compared to a low pressure, and fast steam moving through small pipes/holes causes big problems like water hammer that will DESTROY the entire system. Part of converting to a low pressure boiler is increasing the size of the hole in the boiler and increasing the size of the pipe needed. On our 25hp high pressure boiler I have 2.5 inch header coming out of the boiler, on my 5hp low pressure boiler I have 4 inch pipe, just an example but you get the picture. All this to say that there are a lot of variables and I would make damn sure that your engineer is aware of all of these factors so they the system can be designed in a way that will work as you need it to. All that said your installer is not an engineer and likely is only basing their opinion on field experience, which may be great but maybe not. At least if the engineer designs the system a certain way and puts their stamp on it and you install it the way its designed and it doesn't work or has problems you have some legal recourse, with the installer perhaps not so much.
    Last edited by Luch15; 08-17-2017 at 08:52 AM.
    Luch Scremin
    Engine 15 Brewing Co.
    luch at engine15 dot com

  6. #6
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    Quote Originally Posted by Luch15 View Post
    I read your other post regarding pipe size and this post complicates the other significantly. First your boiler is rated at 10hp which is a BTU output number. Think of it as energy per hour that the boiler can transfer to your kettle/MT. That number is predicated on several factors like efficiency of the transfer due to temperature drop, length of run, etc. but a big one is how much water it can turn to steam in a given period of time and how much "reserve" of energy it can hold in the system. The energy it is storing is heat in the way of pounds of steam. A given volume of steam at 160 psi has a lot more energy stored than the same volume at 15 psi. In order to have the same energy at 15psi as at 160 the part of the equation that you need to change is the volume, i.e. bigger header pipe to "store" more steam or bigger boiler (a 10hp low pressure boiler is physically much larger than a 10hp high pressure boiler to store more volume of steam, therefore deliver the same energy as a physically smaller high pressure boiler). running a high pressure boiler at a lower pressure just reduces the amount of energy it can deliver over a period of time. Basically it will no longer be a 10hp boiler from an energy delivery per hour standpoint. Unless your headers are pretty big it will likely be undersized for your application. Did your engineer take into account for this?
    Those are good comments. Thanks for helping. Actually in this case this boiler is the same product for both high pressure and low pressure. It comes default with a 3" feed outlet and 2" return regardless of 15 or 150 psi. That seems to tell me it's more of a low pressure boiler that can be converted to high pressure. It also has been upgraded with a high efficiency burner.

    The concerns of it being undersized is why the one engineer is asking for 3" feed. He did factor the losses you mentioned. He figures it will end up at 9hp between the run and my altitude. Also the steam pipe will have 3" of insulation over majority of the pipe.

    In my case my steam needs are less than a typical 10bbl system though as I don't have and hlt as I have water on demand for any mash ton needs, dough in, infusion, sparge, etc. Im also not planning to double batch as I am a brewpub with 10bbl fermentators. 450 BTU would be the typical spec for a 3 vessel 10bbl system, I'm at 386 BTU steam with this boiler with 2 vessels and 400k water BTU for on demand water.

    If the 3" makes a difference even when bottlenecked to 3/4" I have no problems following that spec. I'm just trying to find a concensus vs the 3 different opinions.

  7. #7
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    Quote Originally Posted by Jedi View Post
    Those are good comments. Thanks for helping. Actually in this case this boiler is the same product for both high pressure and low pressure. It comes default with a 3" feed outlet and 2" return regardless of 15 or 150 psi. That seems to tell me it's more of a low pressure boiler that can be converted to high pressure. It also has been upgraded with a high efficiency burner.

    The concerns of it being undersized is why the one engineer is asking for 3" feed. He did factor the losses you mentioned. He figures it will end up at 9hp between the run and my altitude. Also the steam pipe will have 3" of insulation over majority of the pipe.

    In my case my steam needs are less than a typical 10bbl system though as I don't have and hlt as I have water on demand for any mash ton needs, dough in, infusion, sparge, etc. Im also not planning to double batch as I am a brewpub with 10bbl fermentators. 450 BTU would be the typical spec for a 3 vessel 10bbl system, I'm at 386 BTU steam with this boiler with 2 vessels and 400k water BTU for on demand water.

    If the 3" makes a difference even when bottlenecked to 3/4" I have no problems following that spec. I'm just trying to find a concensus vs the 3 different opinions.
    Gotcha, that all makes sense now, our 5bbl system on the 5hp low pressure has 3/4 inch inlets and outlets the steam lines after the headers are 2 inch inlet and 3/4 outlet but we have a condensate return pump so we dont use steam to push the condensate back to the boiler. On the high pressure boiler it's a 20 bbl brewhouse and HLT. We use a 2.5 inch header to a pressure reducing valve that lowers the pressure to about 20psi and then back to a 2.5 inch pipe with 3/4 inch drops into the kettle, MT, HLT, I like this set up much more than the straight low pressure. As mentioned by another post it's a much soother system without all the peaks and valleys in steam pressure at the jackets, keeps a steady 15psi at the jacket inlet. The outlets are also 3/4 inch and go to a 1.5 inch condensate return, pushed with steam back to the condensate tank. This system works great, I have no issues whatsoever. If you want to error on the safe side, basically if it was me on a straight low pressure system I would go with a larger pile size overall. Bottom line as before if you want to totally CYA go with what the engineer designs, at least you know on that first brew day it will actually work! As far as the size of header pipe think of it as an extension of the boiler "storing" more volume of steam for when your kettle calls for it, not really an issue of bottlenecking at the 3/4 inch drop. With a low pressure system, up to a certain point a larger header is a good thing as I understand it.
    Luch Scremin
    Engine 15 Brewing Co.
    luch at engine15 dot com

  8. #8
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    Quote Originally Posted by hydromike View Post
    I am lucky where I am at I can run@150PSI without a boiler operator, I would sell the used unit and get a low pressure unit. The changeout of controls can be just as expensive as getting anther used boiler.
    I'm not sure what you mean expensive. The controls are super cheap. 120 bucks each and can be installed in minutes.

    https://www.ebay.com/p/Honeywell-L40...PSI/1300627264

  9. #9
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    Quote Originally Posted by Luch15 View Post
    Gotcha, that all makes sense now, our 5bbl system on the 5hp low pressure has 3/4 inch inlets and outlets the steam lines after the headers are 2 inch inlet and 3/4 outlet but we have a condensate return pump so we dont use steam to push the condensate back to the boiler. On the high pressure boiler it's a 20 bbl brewhouse and HLT. We use a 2.5 inch header to a pressure reducing valve that lowers the pressure to about 20psi and then back to a 2.5 inch pipe with 3/4 inch drops into the kettle, MT, HLT, I like this set up much more than the straight low pressure. As mentioned by another post it's a much soother system without all the peaks and valleys in steam pressure at the jackets, keeps a steady 15psi at the jacket inlet. The outlets are also 3/4 inch and go to a 1.5 inch condensate return, pushed with steam back to the condensate tank. This system works great, I have no issues whatsoever. If you want to error on the safe side, basically if it was me on a straight low pressure system I would go with a larger pile size overall. Bottom line as before if you want to totally CYA go with what the engineer designs, at least you know on that first brew day it will actually work! As far as the size of header pipe think of it as an extension of the boiler "storing" more volume of steam for when your kettle calls for it, not really an issue of bottlenecking at the 3/4 inch drop. With a low pressure system, up to a certain point a larger header is a good thing as I understand it.
    Ok thanks, good info. I will ask the boiler authorities if I can keep it High pressure and reduce it. I have a feeling they will say no as technically the boiler itself is still high pressure and I have zero boiler operator certifications.

  10. #10
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    Boiler Operator

    In Colorado, except for Denver county allows for a high pressure boiler with a lock out at 50 psi, they tag it and check yearly to ensure that it has not been tampered with, also since it is below 1,000,000BTU they do allow much more. Also it took me 1 week to get my boiler operators lic. Well worth what I learned about steam and operating a boiler. But i do have a 40 HP boiler, at our new production facility at our first location we have two 3HP boilers.

    Mike George
    Blue Spruce Brewing Company
    720-982-4303

  11. #11
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    Quote Originally Posted by hydromike View Post
    In Colorado, except for Denver county allows for a high pressure boiler with a lock out at 50 psi, they tag it and check yearly to ensure that it has not been tampered with, also since it is below 1,000,000BTU they do allow much more. Also it took me 1 week to get my boiler operators lic. Well worth what I learned about steam and operating a boiler. But i do have a 40 HP boiler, at our new production facility at our first location we have two 3HP boilers.

    Mike George
    Blue Spruce Brewing Company
    720-982-4303
    Ya I'm thinking the knowledge is worth learning too, but I'm so busy on the brewery build its another item for the list.

    I spoke to the local boiler authorities, I can run it at high pressure if I complete the; Special Boiler Operators exam, 50 questions multiple choice, 65% passing mark. It is a site-specific certificate of competency that certifies the operator to supervise a power plants with lower HEATING SURFACES like mine. Talking with them I can run high pressure to the vessels and put restrictor valves before the jackets inlets to reduce the diameter of the feed pipe dramatically or I can put a restrictor at the boiler and run low pressure steam pipe as discussed in this thread. I'm double checking with my brewery manufacture if the jackets are rated for high pressure steam as I have feeling they are designed for low pressure.

  12. #12
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    HP to LP

    Just use a pressure reduction valve at the point of use, Special Boiler Operators exam is one step below what I took, it should be open book test, maybe one night of study. My 1 week of study for 250 multiple choice test with three show your math design questions I got a 98%. I had to do the harder test because of the size of my boiler 2,130,786 btu's. It would be well worth it, because you can use smaller piping for the steam. You could then use 2" for the steam and 1.5 for the condensate return. The steam quality ie dry steam would be much better with the high pressure. The cost savings of the install should easily cover the cost of the test and your time. Also a lot of what is on the exam is extremely helpful on trouble shooting problems on a steam brewhouse. Most jackets on tanks are rated for 14.9 psi or 1 Bar, with the reduction of pressure you still will keep the extra temperature from the high pressure side. 15 psi steam temp 249˚ F vs 150 psi steam temp of 365˚ F This helps reduce time to boil and boil times to 60 min boils on every beer style. If you are at high elevation the higher pressure is more helpful as well.

    Mike George
    Blue Spruce Brewing Company
    Director of Brewery Operations

  13. #13
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    Quote Originally Posted by hydromike View Post
    Just use a pressure reduction valve at the point of use, Special Boiler Operators exam is one step below what I took, it should be open book test, maybe one night of study. My 1 week of study for 250 multiple choice test with three show your math design questions I got a 98%. I had to do the harder test because of the size of my boiler 2,130,786 btu's. It would be well worth it, because you can use smaller piping for the steam. You could then use 2" for the steam and 1.5 for the condensate return. The steam quality ie dry steam would be much better with the high pressure. The cost savings of the install should easily cover the cost of the test and your time. Also a lot of what is on the exam is extremely helpful on trouble shooting problems on a steam brewhouse. Most jackets on tanks are rated for 14.9 psi or 1 Bar, with the reduction of pressure you still will keep the extra temperature from the high pressure side. 15 psi steam temp 249˚ F vs 150 psi steam temp of 365˚ F This helps reduce time to boil and boil times to 60 min boils on every beer style. If you are at high elevation the higher pressure is more helpful as well.

    Mike George
    Blue Spruce Brewing Company
    Director of Brewery Operations
    Thanks Mike! That sounds perfect. The 2" will still need to be welded but so did the 3" low pressure, I'm guessing the pipe drop size will save me 1k.

    Does the return need to be all welded for high pressure? I'm guessing it might cause its closed loop. In that case i will be more expensive with the high pressure piping overall but it will be an investment that will pay itself off quickly from saved time in production. Plus the beer quality will be a tad higher with a quicker/harder boil.

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