Transition from Oil to Gas with one-pipe Steam System (Resid.)

Steamhead (in transit)

you may run into some issues with how the unit is vented. If the tankless requires that you vent thru a sidewall or foundation wall, you must follow manufacturers' instructions and local Codes with regard to clearances from windows, doors, etc. Also the vent should be a foot higher than the highest recorded snow accumulation, or a heavy snow will block the vent and the unit will either shut down or run unsafely.

This could open up a real can of worms. I'd use an indirect tank, which is heated by hot water from below the boiler's waterline. Not all indirect tanks are approved for use with steamers; the SuperStor is one I know of that is.

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Seth Craigo-Snell

Oil to Gas transition with one-pipe steam system (residential)

Hi, folks.

I have found very useful information here about how to keep our 65 year old, one-pipe steam system powered by an oil boiler working. So, first of all, thanks.

Now to my questions...

We are going to fuel switch to gas this summer and switch our old boiler and domestic hot water. I have been convinced to look very seriously at a Rinnai tankless water heater for the DHW.

My first question is:

What is a good, reliable, efficient gas boiler for steam heat? There is only one manufacturer of ENERGY STAR boilers and they look like custom jobs to me. The gas company here in Connecticut is willing to bring gas to the house for free, and is offering matching rebates of $200 for Burnham boilers and $300 for Williamson boilers, but I don't know how much to trust them, really. I mean they do sell gas. How eager could they be for me to put in an efficient boiler?

Second question...

My oil supplier tracks k-factors for my oil usage. Is there a way to derive an AFUE rating for my current boiler given the k-factor and some basic assumptions about the envelope characteristics and square footage or volume of my home? I would really like to have some idea of how much fuel I could save with a more efficient boiler (gas or oil) to have a better idea of the payback time for changing the boiler, and the only savings calculators I can get ahold of are driven by AFUE.

I would appreciate any help that you can give me. Thanks.

Regards,
seth craigo-snell

Steamhead (in transit)

Well, first of all

what type of boiler is in there now?

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Seth Craigo-Snell

Ok, here goes...

Ok, well, here goes....

I don't know much about the 65 year old boiler but what I can find is: Manuf.: H.B. Smith; says: "Five Star" on the fire box plate. It has a retrofitted Texaco oil burner that is probably younger than 65 years(maybe 20 years old?). I don't know the size (BTUs) of the unit, but it is physically quite large (3ft wide, 7 ft deep, and 5 ft tall). I don't know if that helps or not.

There is a No. 24, Ever-Hot All-Copper Tankless hot water heater of to the side of the boiler.

If it is helpful on the AFUE question, our house has about 1,600 square feet of heated space (not including the 95 degF basement during the winter season owing to the lack of efficiency of the boiler and uninsulated exposed piping), and is not at all drafty due to well installed replacement windows throughout the house (<10 years old).

That's all I know.

Again, I would appreciate any help you can give.

Thanks,
seth

Robert O'Brien

I

would avoid atmospheric steam boilers,Steamhead has more experience with this than I do but a wetbase boiler with a power gas burner would be a superior setup.In a straight oil to oil upgrade the savings run in the 30-50% range

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Peter Zelchenko_2

Insulate those steam pipes! You're wasting a ton of money by not.

Steamhead (in transit)

And the name is still Smith

for the most efficient residential gas-fired steamer currently available.

Smith offers their 8 series residential boiler with a factory-supplied Carlin power gas burner. The boiler is called the G-8 in this configuration. This boiler-burner combination offers a thermal efficiency (before AFUE is calculated) of about 6% better than the W-M or Williamson offerings, which are the less-efficient atmospheric type. It can also be switched to oil firing if the cost per BTU tilts the other way.

Currently, the largest G-8 is rated 650 square feet EDR or so. Do you know how much radiation is in your house?

Here are photos of two G-8 boilers we have installed. We will shortly begin installing two more.

Also, listen to Steve regarding pipe insulation.

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Seth Craigo-Snell

Not yet, but I will

Not yet, but I just looked at a Radiator Sizing Guide to figure out how to calculate it. I need to do some measuring and accounting, and I will get back with you on it.

Thanks for the help.

seth

p.s. Does your subject response mean that Smith = H.B. Smith? Because it would be ironic if I end up replacing my 65 year old boiler with a new generation of the same brand.

Steamhead (in transit)

Same company

under different ownership. The actual company is now called Westcast, which I believe is owned by Mestek.

"H.B. Smith" stands for Henry Bates Smith, who started the business that became one of the best known heating manufacturers ever. That's a fascinating story in itself.

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Seth Craigo-Snell

OK, got it. Total EDR = 485.18

I inventoried all of the radiators in the house. They are all Tube Type. I calculated the total EDR at 485.18 ft2.

I will be checking into boilers. Thanks for the pictures of the recent installs that you have done. Any chance that there is someone active on this board from the southern Connecticut area that you know and could recommend to do the work? I have checked the "Find a Professional" area and will call the listing in Norwalk, at least.

Thanks again for the help.

mark ransley

The old unit might be near 60% efficient since it hold alot of water and wastes energy just getting to steam. Your new unit will hold much less water and get to steam quickly. If you have or will upgrade insulation, windows etc a smaller size unit might be ok, whoever does the work needs to give you a written Load Calculation, you dont want to oversize and that is all to common in the industry.

Steamhead (in transit)

Make sure

you know which "tube-type" rads you have. If the spacing between the sections is 2-1/2", they're "large-tube". If it's 1-1/2 or 1-3/4, they're "small-tube". If 2", you have the original American Corto rads. You won't find the chart for these in "E.D.R." (the Corto chart therein is the later, 2-1/2" version), but we can help you out. The reason I mention this is that each variation has a different rating.

If the figure you gave is correct, you'll need the 5-section G-8, rated 525 square feet EDR. That's shown in the Jennings Boiler pic in my earlier post.

"Steamhead"

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nicholas bonham-carter

1-pipe steam boiler change

our 1885 1 pipe system runs better than ever with our new peerless 1,050,000 btu boiler.
i now wish that i had taken care of the following at the time of installation in stead of 2 mos. later when it was already very cold.some economies are certainly false.
changing all the main vents.
near boiler return piping was incorrect and not well sloped contributing to a time lag in condensate returning back so for brief periods the boiler was unable to fire due to low water for 15 minutes or so.
i wish i had ordered the hi-lo-hi burner right off the bat as it does seem to be a benefit for this type of system.
make sure you get a vaporstat--[dont bother with regular pressuretrol] and a good low pressure gauge 0-3 psi.
we donot have any condensate return pump and will try to avoid it as it is 1 more thing maybe to go wrong in a few years.
once you have found a competent steam man[not neccessarily the same as plumber]you can be his eyes and ears for any problem diagnosis.
hope these observations have been helpful.--nbc

Seth Craigo-Snell

How do you guys put up with us amateurs?

Ok, well the section spacing is 1-3/4 inches for all the radiators in my house regardless of the number of tubes.

The EDR calculation that I did was described at: http://www.colonialsupply.com/resources/radiator.htm. The chart of EDR/section is actually on page 3 of the manual:
http://www.colonialsupply.com/resources/radiator3.htm,
but there is no mention of the assumed width of the sections. Any help you can give me on adjusting my calcs would be great. The radiators in my house are as follows:

Room Height Tubes Sections EDR

Boys BR 20 5 18 48.06

Study 20 5 16 42.72

Upstairs Bath 23 3 12 24.00

Kitchen 22 5 24 68.04

Mudroom 32 3 8 26.00

LR2 25 4 22 58.96

LR1 26 4 20 55.00

DR 26 4 20 55.00

Office 19 6 36 104.40

Master BR (1-1/2 pipe 7' baseboard radiator) ~3.00

TOTAL 485.18


That's how I got it.
Thanks,
seth

Seth Craigo-Snell

Thanks for the advice. Will follow.

Seth Craigo-Snell

Thanks....

for all the advice. I will keep track of all the suggestions. Certainly hoping I will be getting by with a much less than 1,050,000 BTU Boiler, though!

Thanks,
seth

Steamhead (in transit)

Aha!

looks like they only have the large-tube type on their site.

Here's what I came up with:

Room Height Tubes Sections EDR

Boys BR 20 5 18 32.4

Study 20 5 16 28.8

Upstairs Bath 23 3 12 15.6

Kitchen 22 5 24 50.4

Mudroom 32 3 8 19.2

LR2 25 4 22 39.6

LR1 26 4 20 36

DR 26 4 20 36

Office 19 6 36 79.2

Master BR (1-1/2 pipe 7' baseboard radiator) ~40.9

TOTAL 378.1

Well, that was worth the effort- you can use a 4-section G-8, rated 413 square feet. This would leave enough headroom that you could put a real radiator in the master bedroom.

We have avoided another oversized boiler.

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Seth Craigo-Snell

OMY!

Wow. Thank you so much. I can't believe how dedicated you guys are. I really, really appreciate your time.

I'm going to start calling contractors today and set up some appointments to get the ball really rolling on this.

Again, Thanks so much for the help.

regards,
seth

Seth Craigo-Snell

Quick Follow-up question

Sorry, I must be missing something here, but I am looking kind of closely at the numbers now and I am confused by the approximate value for that basboard radiator in the Master BR. Isn't it's surface area simply:

circumference (pi*diameter) * length? For a 1.5 inch pipe that would be (3.1415*(1.5/12)*7)=2.75 This is, obviously much different than the value of ~40.9 that you estimated. It will very probably not matter that much since we will put in a real radiator if at all possible, but having come this far, and thinking that I am understanding the process, it is bothering me.

Hoping my geometry hasn't also left me.

Thanks,
seth

Steamhead (in transit)

I got that one

from the Hydronic Rating Handbook. We're not sure what brand of fin-tube you have, so I took an average value. They give a per-foot BTU per hour rating and I multiplied that by the length you gave of 7 feet.

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Seth Craigo-Snell

Thanks...

Of course it is never as simple as one thinks it might be.
Thanks a ton for the help!
seth

p.s. I'll post some before and after pictures of the project later.

BTW, did you have an opinion about the efficiency of using an independent tankless water heater as opposed to taking the DHW from the new boiler (if that is even an option)?