SmithG8 VS. Slantfin Intredip

vaporvac

Oops!  I posted to the main wall instead of here.  Oh well.  Maybe I'll get more responses!

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

Dave in QCA

Water Volume

It appears as you say that the efficiencies of the boilers are quite similar, almost exact.  Boilerpro speaks quite highly of the Slantfin.  Also, JPF installed on in his home about a year ago and wrote extensively on his results.  Some of the other pros, especially those along the east coast are quite fond of the Smith G8.



So, I would have to say that I have heard no negative comments on either boiler.  When I look at the specifications of the two boilers and compare them, I notice that the Smith boiler water content is about double the same sized Slantfin model.  Smith also states that its sections are wider and thicker, containing more iron mass.  I cannot find the weight on the Smith spec sheets, but their claim regarding water content certainly is accurate and I suspect that their claim of having more iron mass is true too.  These are all good things in a steam boiler.

Rod

Boiler Choice

I'll go along with Dave. From what I've heard I don't think you can go wrong with either one.

The Smith has metal mass on its side and the Slant Fin is known for producing very dry steam. It also has a really neat skimming arrangement. Since you are considering going with multiple boilers, I would contact both company's support depts. and see what info they can give you on multiple boiler setups. Mention you're a "Wallie" as that seems to get you taken more seriously I have noticed.

- Rod

The Steam Whisperer (Formerly Boilerpro)

Water Content et el...

I am not  so sure that overall water content is so important as is steamable water content.....The amount of water available from the waterline to the LWCO level.   This number is very hard to get from manufacturers...so you usually have to measure it by filling and draining the boiler.

IIRC, your type of system has supply orifices (check with Steamhead), so you would be a prime candidate for a staged heating plant or a modulating heating plant, since the orifices will allow the steam to distribute evenly at varied system pressures.

vaporvac

Thermal Mass vs.Steamable water content

This is precisely the sort of conversation I was hoping to encourage.  I was getting a bit worried that this choice was a non-issue for installers, but most homeowners are mystified by the differences. So Thanks everyone who has responded so far.



I've spoken to SF and they're very forthcoming with information; Smith...not so much.That's too bad because the SF, unlike the Smith, is already set up to be modular> In fact,the SFCaravans are under the commercial section only because they stage fire them.  They are actually residential sized boilers.They recommend staging for efficiency using either  the Intrepid or their atmospherics.   When I mentioned reading "The Wall", they've jokingly asked when Steamhead iwas going to make the trip down here!.

I haven't actually asked SF to compare the TR with the G8...didn't know if that would be in good taste, but I'm sure they've been asked that before.



Anyway...I understand that an increased thermal mass and highr water content would keep the water hotter for longer.  However,  this would discourage setbacks as it would take a lot of energy to reheat that water. SF is completely insulated for a supposedly very low standby loss so perhaps this is their solution to the same problem of standby losses with less water?  In this case, the water would heat up quicker from a cold start since there's less water to boil.  Does this sound correct?



As importantly,is there more thermal mass in the Smith due to the amount of iron required to hold more water or is the thickness of the iron greater? SF said the TRs  have very thick iron since it has  to withstand the rigors of an oil fire which burns hotter, but does anyone know how that compares to the Smith, which is also designed for oil.  I just feel if the iron is thicker it will take longer to rust out, which seems to be inevitable. Plus, it naturally retains the heat.



I wonder why the SF is known for dryer heat?



Boilerpro, how exactly does the "steamable water content" work.  I've never heard that mentioned before, but it makes sense Does anyone else have a thought on this?

I am reading the posts by Steve and JPF to see their comments.

 I hope I'm not .wearing out my welcome on this site; It just appeared through reading many posts, that these two boiler are favorites and I've always wondered what differentiates them. They both seem to have their proponents, so I was hoping for a very lively discussion of their merits.

 Everyone has been so helpful and I've learned so much.  It's become such a topic that my Dad, whose an old salt and an expert in steam generated gas Turbines with Marine applications and the like, is now fond of saying that at least one of his kids turned out OK!

CTD

Rod

Casting Thickness

 While I'm not an expert on boilers, I've been involved a lot in metal casting and I don't think it is a good idea to assume just because one boiler weighs more than another that it would be slower to rust out. That might be true if the weight differential was distributed evenly throughout the casting or was distributed in the portions of the casting where corrosion was more likely to occur. However I would very much doubt if this is the case. Extra thickness in castings is usually done to help the casting process by easing the flow of the liquid metal through difficult casting areas and / or to help overcome uneven shrinkage. Both the Smith and the Slant Fin seem to be equally popular among the pros so that if either one of them had chronic corrosion problems, I'm sure we would have heard about it on the Wall.

- Rod

Dave in QCA

Good Point

Dave, you make a very good point, that total volume of water is not necessarily the same as steamable water content. The thought had not occured to me until you pointed it out.  I thought there would be a direct correlation.  However, when looking at the Slantfin boiler and the minimum water content at the bottom most portion of the boiler, it looks like it would not have as much water in that portion.  And, as you said, additional water in the bottom corners of the boiler does not equal more steamable water.

The Steam Whisperer (Formerly Boilerpro)

Steamable water volume

When you first start up a steam boiler, the boiler is filled with water to the water line (usually about 2/3 up the gage glass).   When the boiler fires up and starts making steam, the water level steadily drops.  Eventually it will get down near the bottom of the gage glass and the  low water cut off will shut off the flame.  The amount of water that you boiled off is the steamable water volume. 

If you have a system that takes a long time for water to start returning to the boiler, you will need more steamable water volume in order for the boiler to keep running while it is waiting for the water to return.   Also, if you "undersize" the boiler (install a boiler with a lot less capacity than there is radiation, which is something I often do), then having extra water volume is handy because the condensate is relatively slow to return.

I have never used the Smith G-8 boilers, so I have no experience, but I have found Slantfin to be the most upstanding company I have ever dealt with, in the heating field or elsewhere.   Also, they use cast iron push nipples to assemble the boiler sections, a proven design that can take alot of abuse.  I prefer proven designs over the latest and greatest, all else being equal.  I am not against progress ( I've been using microprocessor controls for 20 years), but when something can be designed to work inherently well, I'll take it anytime over all the advanced technology there is.  That is why I prefer steam over other heat systems.  It can be set up to run at inherently exceptional efficiencies and provide exceptional comfort and control without lots of electronics( or any for that matter).