Boilers - Steam and Hot Water Systems - Poor Circulation of Steam?

Hello all. My classmates and I were given an assignment for our freshman engineering design class that involves increasing the energy efficiency of a boiler system in a community housing project. There are two main questions the community representative wants us to address:
(1) Residents on upper floors are getting too little heat. Apparently the steam is not traveling quickly enough (?), so it is losing too much energy. He wants to know if and how we can address this, since energy is being wasted. He had initially suggested using a turbocharger, but we realized that this cannot work with boiler systems, so we're a bit lost.
(2) Can we integrate the boiler and the hot water storage tank into one unit that will heat an entire building and at the same time lower utility costs? I've done research on combination boilers online, but those seem too small for our purposes.

Neither my teammates nor I know anything about boiler systems. We are eager to work and are not trying to take any easy ways out, but we would feel better about the project if we had a bit of guidance. We just want a general idea as to how we can accomplish the above tasks. If you need specific info about the boiler to answer the above questions, ask and I'll post whatever I copied down during the tour of the building. Thank you in advance.

- Ben M.

Steam travels quite rapidly when it doesent have things hindering it. Like all heating systems, they need tending to. Check the system type, one pipe two pipe, gravity return, vacuum return, proper trap operation, both thermostatic, and or float traps, if there in a vacuum pump is it running, and pulling a vacuum. You did not say how many stories. Usually 3 or 4 lbs is sufficient for several floors. Check for hot returns, return temps should not be above 180 deg. You did not mention the age of the buildings, if they are old they probably worked fine until reciently, and if they are new and under warranty thats a different animal.
Sid

This is not a real question..and thank you Ben for being honest. This is not the point of this site..and I would discourage any members from replying.

If you wish to continue the discourse..communicate your Email adresses via PM and move the discussion there.

The more senior Mods may close this thread, I'm not sure of the policy on this.

Yeah, I'm not real sure about it either... not like we want to do their homework for them... but, I'm inclined to let it play out and see how it develops for a bit... I'm all for education!

So, that said, folks please keep in mind that this is not a DIY problem, but rather an educational session. Maybe some of us can benefit from thinking about these issues.

Ben, if you have specific questions about heating systems, I don't see any harm in folks here answering them. I don't want to see anyone doing your assignment for you though!

If it gets way past the 'limits', I may choose to close though, so keep that in mind.

I don't see how this would be "doing the assignment" for them. They have very little knowledge of steam boilers and have come here to research the topic. I can't see much difference between this and opening a book in a library.

I think answering with concepts of how a steam system should work would be better suited than look at pictures of the system and telling them to add this or replace that.

I found the information on comfort-calc very informative about steam systems. Check it out. I think you will learn a lot. Technical Menu (http://www.comfort-calc.net/tech_area_index.htm#SteamBoiler)

Right, rather than draw the conclusions, and suggest a course of action, which is the goal of the excercise, instead, impart the knowledge that they would need to draw their OWN conclusions about what needs to be done. That would not be doing the work for them, rather it would be educating them and letting them use their own brainiacs to 'fix' the problem.

Ben, and classmates: You should know that there is no 'magic bullet' to be found, so don't look for one. That would be wasting your time. Unless you all fully understand the concepts of heating with steam, don't even entertain silly ideas like using a turbocharger. IMHO, the best thing you can do is learn how steam heat is SUPPOSED to work, analyze why this particular system is NOT working, and suggest changes to improve the operation. Trust me, you won't discover any miracle cures!

Thank you to all who replied. As stated earlier, we're willing to put in the work. I just want to pose questions based on things I've researched. I'm not looking for any "answers". I just trust that you all have a good amount of experience with boilers and steam circulation systems, and would be able to redirect me if I've made a stupid assumption or false conclusion. I know this isn't a DIY question per se, but I'm genuinely interested in this project and the knowledge needed to "do it yourself." I won't be offended if you lock the thread though.

Their building is old, built in the 1920, and I believe it has a one-pipe system with gravity return of condensate. The building is six stories high. The clients issues are (1) getting enough heat to upper floor residents and (2) seeing whether combining the boiler and hot water storage tank into one unit makes sense (currently they are able to shut off the steam heating system while leaving the hot water unit running during summers, thus saving $).

Based on research, the radiators seem worth targeting. I found information on thermostatic radiator valves, which can regulate the flow of heat through radiators in "zones" throughout the building according to their needs. A comment on another site suggested that in a case similar to mine, the system may not be balanced. If radiator valves were put on lower floors, they could shut off the radiators when the room became hot enough, and let the heat circulate to the upper floors where it is needed most. This idea makes perfect sense to me.

I also read a PDF on something called a "single entry injection valve", which can convert a one pipe steam system into a two pipe forced hot water system. I can't find any other info on it besides this PDF and a few patents, which leads me to believe that the idea isn't worth exploring further. If you all know anything else about such a device, I'm all ears.

As for the second issue, I did research on combi boilers, which combine the hot water systems and boiler into one unit straight away. However from the pictures I've seen they're quite compact, and I feel like they're designed more for smaller houses than for full apartment buildings. Is this true?

Thank you all in advance. If you feel I'm asking for too much, be honest about it and I'll do more research. I took a risk posting an educational question to begin with, so I'm grateful for any feedback you guys have.

- Ben M.

P.S., thank you drooplug for the Comfort Calc site. It looks informative, and I'll read it tomorrow.

Ben, while the thermostatic valves may be an option, take a look at the way that the standard non-thermostatic ones work. Also known as 'radiator vents'. Hint: they are available in different venting rates.

I would also suggest that before you look for 'band-aids', such as TRV's and such, investigate why it's not working now... it's probably been installed for many many years, and I'm willing to bet that at one time, it DID work properly.

Think about what may have happened to the system over those many years. All the DIFFERENT techs that may have worked on it... little pieces at a time... never envisioning the entire system as a WHOLE SYSTEM... how many small 'wrong' things might have been done that need to be undone so that all the equipment works in harmony... ommmmmmmm....

I really think that a basic understanding of the concepts of steam heat are the first order... take a look for a book by Dan Holohan called "We've got Steam Heat!..." even though it doesn't apply as much to larger buildings such as the one you are looking at, the basics and concepts are there, and it is quite well written, and fun to read. Dan has a unique writing style. I think if you google it up, you will find the site that has sample pages. You might find it at a library even...

I think I saw this information on comfort-calc. On my hot water system, I have an indirect hot water tank for my domestic hot water (DHW). The way they work is that they are set up as a seperate zone in the system and when the tank needs to be heated, it circulates boiler water through a coil inside the tank to make the heat exchange. This setup is considered to be very efficient for DHW. There is a way for this to be done on steam systems using the water that has yet to be turned into steam. You will also need controls to be able to stop the boiler from heating the water to steam in the summer months.

After reading comfort calc and some other websites, I definitely have a greater understanding about how one-pipe steam systems work than I did before. I also learned about how radiators work, and that they should be vented according to their relative areas. I definitely need to visit the building again to make sure that the radiators are vented properly before I add anything to the system (like a TRV). Comfort calc has formulas for relating the square footage of the radiator to the radiation output, so that should prove useful.

However, for this project our task is to design something for the client that will take care of things. The class is called Engineering Design for that reason. I feel like this overcomplicates things, but it's what we're being asked to do. We need to model the room to which our product is being applied, using 3D modeling software, and show how the design interfaces with the current system. We need to write up a Product Design Specification with the dimensions, expected cost, etc. of our new design. I'm not asking for a solution, I'm just stating that our end-result should be a product rather than a series of fixes that try to undo the errors made by others (even though this would probably be a better option).

In addition, the project makes more sense now upon looking at pictures we took of the site. There are three units: the main boiler we saw (Weil McLain LGB-9), the hot water storage tank (AO Smith TJV-120M), and a hot water heater (Mighty Therm by Teledyne Laars). I hadn't noticed the last one until recently, so I was confused as to how the water tank got its heat without there already being an indirect system in play. Now if we wanted to make the system indirect, we would need to pump hot water from the boiler to the tank in a coil that would transfer heat to the water stored (as drooplug explained). During the summer, we'd go back to the hot water heater and shut off the boiler.

So if we installed controls to turn off the boiler during the summer, we would also need controls to turn ON the water heater during those months. I'm guessing we could install thermostatic controls, one with a minimum temperature to operate for the water heater, and the other with a maximum temp. for the boiler. If these temperatures were equal, one would switch on and the other would switch off at the same time (given that both thermostats were accurate). Does this make sense? I'm going purely on common sense for this. Also, what if one unit breaks down? How could we install a control on the water heater that says "Oops, the boiler's down, I guess I need to get hot water to the residents!". Or can this only be done manually?

I know this post is wordy, but I'm just looking for clarification on some things I've observed/researched. Thanks a bunch in advance.

- Ben

Now if we wanted to make the system indirect, we would need to pump hot water from the boiler to the tank in a coil that would transfer heat to the water stored (as drooplug explained). During the summer, we'd go back to the hot water heater and shut off the boiler.


- Ben

You don't need to shut the boiler off during the summer. You need to adjust the high limit on the aquastat to 180 degrees. That will prevent the boiler from making steam.

However, for this project our task is to design something for the client that will take care of things. The class is called Engineering Design for that reason.

That's all well and good... but what's to "design"? Steam heating systems have been in existence for billions of years... ok, exagerating a little... but millions anyway! :confused: and pretty much anything that is going to be 'designed' has been done already. It sounds more to me like you are being asked to INVENT something, and that isn't going to be an easy task.

Not only that... how will you know if you aren't reinventing the wheel?

Either way, a full and complete knowledge of the subject is a prerequisite for EITHER 'design' OR 'invention'. You can't ask someone without a knowledge of say, electronics, to 'design' an audio amplifier, or a cell phone... ditto, steam heating systems.

Also, how can one be expected to 'design' something that is to be applied to a system that is probably BROKEN? By BROKEN, I mean a system that isn't operating to the ORIGINAL design specification? IMHO, the system MUST be repaired to a fully functional state FIRST... you need to be in a KNOWN STATE of functionality. I mean, how can you be expected to design something if for example all the steam vents are either not working, or the wrong size?

Personally, I think your prof is nutz. He's assigning a task that I am more than willing to bet he couldn't complete his own self.

Is the building owner his brother-in-law or something, and he's looking to get some free engineering advice?

Perhaps though, I am totally misunderstanding the objective... maybe prof isn't concerned whether or not the design actually works... maybe he just wants this done as an excercise in using the 3D modeling software, and preparing proposals, etc?

Are you actually supposed to BUILD AND APPLY your design?

If so, how can it be guaranteed that your design won't put people's LIVES in danger? Live STEAM isn't something to be taken lightly... just ask my wife about the incident with the Capuccino maker! :eek:

drooplug - That's an awesome suggestion for summer usage, given that the boiler doesn't fail. However, if the boiler's ever down and we need to supply hot water, I think we need the water heater for backup. And as I said, a control that would allow the water heater to know that the boiler is down seems unfeasible, considering that the two would not even be connected.

NJ Trooper - Yes, it is a ridiculous request. My professor is a part of the Industrial Engineering department, so while he has a good deal of experience from the business side of design, he lacks knowledge on the true "engineering" side. Upperclassmen have told me that the whole class is a test of how well one can BS, but I just can't accept that. I've already learned a great deal (compared to what I knew before) and want to come out of this truly proud of the work we've done.

In the end the model should work in theory, but the client probably won't take the idea into consideration anyway (it's a freshman project for crying out loud). So I don't think the consequences of implementing it are really an issue. As long as we address whatever they tell us to address, it should be fine. It would be cool to actually have a "eureka" moment and come up with a useful product, but that's highly doubtful, so we'll just have to rely on existing technologies to get the job done.

Oh another question. I mentioned earlier that the group has three units. A boiler, a hot water storage tank, and a water heater. I'm assuming the heater takes the water from the main and then transfers it to the tank, which is insulated and stores the hot water until a shower or a faucet calls for it. Aren't there storage tanks that have the dual purpose of heating the water and storing it? I'm wondering why they didn't just get one of those. Is there any practical reason for this? Also, I'm also curious as to how the 120 gallons stored in the tank is able to serve the 23 residential units in the building. If everyone took a shower at once, would there be enough water? In this case is there a constant flow from the main to restore the water that is being used?

Once again, rambling just to make sure all the thoughts currently in my head are in this post. Thanks a bunch. - Ben

Hi Ben, you will learn something, no doubt about that! Heck, look at what you already have! A huge part of engineering is the investigative process anyway.

I do hope that in the end, the building owner will take your advice to have someone in and at least restore the whole thing to the way it SHOULD be... in case there have been numerous attempts over the decades to repair piece by piece...

I would not think that a 120 Gallon WH would be enough to serve 23 units. Problem with a 'self contained' water heater of that size... $$$$$$ .... and what happens if say for example, the tank develops a leak? Now you have to replace the whole thing. If it were just the tank, less $$$ ... ditto the heat source. Also, by having the heat source separate, the physics of have a large enough BTU output to 'recover' the heat in the tank is simplified. Imagine if you will those two units in one package, and I think that answer will be clear.

Yeah, it makes sense to stick with just a tank. I'm just thinking, the current tank holds 120 gallons, and there are 23 units, so how are all the units currently getting hot water? It would constantly need to be getting heat from the main, which I guess would first go through the water heater and then to the tank, which makes sure that the water retains its heat. Does this make sense? If so, then it shouldn't be hard to install an indirect system between the boiler and the tank.

For our 3D modeling, we can model the pipe setup necessary to implement an indirect system. Then I think we'd be in the clear, because there's only one aspect to the project that requires detailed 3D modeling. The rest can be labeled as "low hanging fruit" and solved by fixing what's already there. For the radiators, we can just manually adjust the valves, check if the radiators are pitched, get any sludge out of the pipes, etc.

And yeah, I'm definitely learning. It's cool to be able to look at my own boiler and partially understand what's going on (although mine is oil-fired and I haven't studied that type of system). Even though I haven't actually "done" anything yet, I feel more like a Do-It-Yourselfer than I did a few weeks ago, which is a good feeling. This site is great, and you guys know what you're talking about, so I'm definitely glad I came here. - Ben