Boiler operations

[sbradt]

We have a low pressure steam boiler that we use for wort boiling and CIP. We have a separate boiler for hot liquor. Over the past couple of years I've had several HVAC guys tell me that we are causing problems with the boiler, increasing maintenance costs, decreasing boiler life and using more treatment chemicals than necessary because of our practice of shutting down the boiler when it is not needed. They all suggest that we'd be better off in the long run keeping it up all the time. They also recognize the inherent costs associated with this practice. I just ran a test and it looks like it costs us about $5/day to idle the boiler.

I'm curious what most people's standard practice is? Right now we probably run the boiler for somewhere between 3 and 12 hours a day about 5 days a week and that quantity is growing. I'm wondering when we reach the point that it makes sense to keep it up 24/7.

[GlacierBrewing]

We have a low pressure steam boiler that we use for wort boiling and CIP. We have a separate boiler for hot liquor. Over the past couple of years I've had several HVAC guys tell me that we are causing problems with the boiler, increasing maintenance costs, decreasing boiler life and using more treatment chemicals than necessary because of our practice of shutting down the boiler when it is not needed. They all suggest that we'd be better off in the long run keeping it up all the time. They also recognize the inherent costs associated with this practice. I just ran a test and it looks like it costs us about $5/day to idle the boiler.

I'm curious what most people's standard practice is? Right now we probably run the boiler for somewhere between 3 and 12 hours a day about 5 days a week and that quantity is growing. I'm wondering when we reach the point that it makes sense to keep it up 24/7.

Hi Steve,
We also use a low-pressure steam boiler running on propane. I do shut it down if I am not needing steam or hot liquor for a day or two. I have not seen any adverse effects. Given the rising cost of propane, it is cheaper for us to shut it down when it is not needed.

Prost!
Dave

[liammckenna]

We run a high efficiency oil fired boiler for our steam. Currently running at 87% efficiency (boiler tech just left yesterday after service).

We leave it on all the time. Shut it down the evening before maintenance. It is also used to heat the facility and the HLT.

I think it depends on a lot of things economically. Facility design, piping insulation and integrity (no leaks) and use.

Remember though that everytime you fire up a cold boiler, you've got to sink a lot of heat into it to get it up to steam. The boiler, the pipes, the condensate etc. You lose that invested energy into the system everytime you let it cool down.

You should ensure to factor this huge suck on the energy tank into your thinking.

Pax.

Liam

[gitchegumee]

Not to disagree with Liam; he's right. You do lose energy heating a cold boiler just to bring it to temperature before use. However, that energy use is smaller than the energy that is wasted in keeping hot lines hot. Heat loss is directly proportional to temperature difference. Hot pipes lose energy faster than warm pipes. You will save energy by shutting the system down between brews. This is what I normally do when I don't use the boiler for more than two days. However, you do cause stress bringing the boiler up to temperature from a cold start. And it may impact the boiler life. But I don't see how it would use any more chemical feed. Chemical feed is proportional to water use. Shutting down a boiler doesn't use any more water than not shutting it down. That said, if you're using your boiler 5 days a week, then I would follow the recommendation of keeping it on 24/7. If you have long steam lines, you could valve off the steam to the brewhouse. That would keep the energy use lower while still maintaining a hot boiler. Good luck!

[sbradt]

Thanks guys, all good insights. I was already planning to run a quick test to see how much gas it takes to bring the boiler up from a cold start. Our system has extremely short runs, it's well insulated and, at this point, everything is really tight so that would seem to be in our favor. The reason that I was given that turning it on and off raises our chemical use is that every time the boiler is shut down, you end up pulling in some air/oxygen. That requires more treatment to maintain the water in an oxygen free state in order to limit corrosion. I'll be curious to see if we see out water quality change once we do this, perhaps allowing us to turn down the feed pump a little further.

The way our chem dosing is set up is to dose when the condensate pump kicks on. Even with regular blow downs, our water use is pretty minimal (closed system) so we were told that this would be a better way to go. The other option would be to route our water feed into the condensate return pump. If anyone thinks that's a crazy way to do it, I'm all ears. This system has been my first steam experience and it has definitely been a learning experience.