SmithG8 VS. Slantfin Intrepid

vaporvac

Hello again,



Well, the gas valve on my last post has bit the dust and it was too expensive to replace so on to the new boiler, at last. The contenders are Smith g8 and the Slantfin Intrepid; both with conversions to a gas power burner.  I'd like to focus on the boiler only for this post and address the burner after that choice is made. I have access to the Smith locally, and the SF fairly nearby with delivery.

My EDR is 1460 so I believe I would have to twin the boilers a la The Caravan, if I want to use these boilers.  I would prefer to do this for efficiencie's sake, anyway.  I have a lot of sq. ftg. to heat so I'm looking at the long term savings. I have a 2-pipe Trane VaporVacuum system that currently works fairly well (after all the help on this site).  There are a few issues that I plan on addressing after replacing the boiler. Please view my prior posts for further info on my system if you like.

My questions are as follows:  what sizes would be best?



Assuming the installer is competent for both, what are the Pros and Cons of each and are there any particular circumstances to which either would be better suited?  For example,  is one better for smaller spaces, lower ceilings, easier to install or twin? Does one make drier steam? Is one easier to skim or flush-out, etc, etc.?  The SF seems to be made with modularity in mind, but does that mean it would be more difficult to twin the Smithg8.

I get the superiority of  wet-based boilers and it appears they have similar efficiencies, but I'm not sure what differentiates the two.  Any and all input would be appreciated.  Again, thanks for helping me get this far.

Colleen

Charlie from wmass

Weil McLain SGO

They list a gas burner for this as an option. I prefer the higher mass of the Smith between the two choices you post.

vaporvac

Narrowing it down! NOT!

Thank you, Charlie.  I'll have to research that.  Hadn't considered it so I don't know anything about it.  Just going by what I've picked up on this forum. Is this an atmospheric?  After a quick google, I couldn't tell.  It looks like I would need two sgo7 s to get my edr of 1460, but I had my btus figured at @466.000.  The sgo7 is 180,000 , but 750 sp ft of radiation.  What size would you recommend and why is this your preferred boiler?  And here I thought I'd narrowed it down!

CTD

icesailor

Answers:

You have the answers and have done the research.

I am assuming that you measured and rated your radiation and need the input you discuss and need two boilers.

I understand using two boilers on hot water systems but is that effective with steam? Have you looked at one of the many steam boilers that are designed for light commercial use? Without knowing your whole situation, I find it odd that two boilers on steam would be as cheap to install as one boiler that will do the whole load. 

Is your boiler being sized for the radiation installed and not to a heat loss of the building that someone decided was correct? You must have a very large building.

nicholas bonham-carter

Tag-team boilers

There is a problem which will need solving with 2boilers. When one is running, it's pressure will try to raise up the water in the returns, and the other boiler, because they are at atmospheric pressure. If both the boilers run at the same time, then there is equality of pressure, but then what happens if you cut the secondary out as the vaporstat senses the target pressure. Will you have a plunging waterline in the active boiler?--nbc

icesailor

Dual Steam Boilers:

Thanks Nick,

I instinctively knew that it would work on FHW boilers but that there would be a problem with steam boilers. They need to run together or you don't have enough "nuts" to make good steam.  The concept of heating to the radiation load (steam) instead of to the heat loss load (hot water) is a different concept not thought of by those of us who don't know as much about steam as we would like to.

Steamhead

With that amount of radiation

you're into a light-commercial boiler. Fortunately, there are several good candidates: Burnham V-904A, Peerless LC-04, Smith 19HE-S-5, Weil-McLain 5-80. These are all wet-base boilers that are sold with either oil or gas burners.



If available, get a burner that can do low-high-low firing.

vaporvac

More Points to Consider

Whoa!!! AlthoughI've signed up for posts on this thread, I've only received them on the Steam site. I was really surprised to see these comments.Thanks for posting here, too!



So, this thread seems to be taking another direction and raising many points I'll have to check into. My reasons for considering the modular approach are as follows:



1: Please see the attached pdf which deals with efficiency for steam and advises twinning as a great means of increasing efficiency. It also mentions using Hi-low-Hi firing to achieve something similar on its own (as mentioned by Steamhead) or together with twinning. Is this what's meant by down firing a burner because the power burners only come with one setting that I've seen?



2: this discussion by DanH on the installation of modular units for steam.

http://www.heatinghelp.com/article/323/Boilers/151/Modular-steam-boilers



3: The Caravan units by Slantfin...these use both the Intrepid and their atmospheric boilers. They are designed for commercial use, but are actually smaller units for residential use. This is what Slantfin uses itself (with atmospherics) to heat its own headquaters and manufacturing plant. It's just a series of these units adding up to over a million BTUs. They say they are installed this way all the time and it's to increase the efficiency as most of the efficiency is gained by twinning as opposed to any particular boiler, and that if I was looking to increase efficiency this is how I should go! This was both the technical department and my local rep talking to me.

http://www.slantfin.com/index.php/products/boilers-commercial/caravan-boilers



So, it looks like I will have raise the points you mention with them and see how they have addressed these issues with their install.



Any input from someone who has twinned steam boilers? This has been really helpful.



CTD

Charlie from wmass

The issue with twinning boilers

Is usually not in the idea but in the execution. Items are left out by installers and sizing is not followed on the piping. Controls are not wired as they should be.