Steam Sizing Help

Kenster63

Hi,
I have a two family house in Long Beach NY. It has an ancient Thatcher oil steam boiler that costs a fortune to run. I have gas in the house and would like to replace the boiler with a steam unit. I measured the radiation and came up with 283 square feet of steam in the living space and 308 if including a radiator in the basement that is connected to the return.

The plate on the existing boiler states 666 steam sq. ft. which seems way oversized if I did my radiator calculations properly. It also states Water BTU/H 1065 and IBR Burner Cap 2.00 GPH.

I had a plumber come over to look at it and without looking at any of the radiators and barely looking at the boiler tell me I need at least a 200,000 BTU boiler. Seemed high to me so I did the radiator calculation.

To complicate matters, the house sustained storm damage from Hurricane Sandy and may require me to elevate the house in the coming year which would require moving all the mechanicals at that time. At that point I would consider installing two separate boilers, one for each apartment.

In the short term I don't want to spend $10,000 in oil to get through another winter. Hence, my dilemma.

I have been looking for a used gas steam unit to have installed and believe that it will be cost effective to do so because it will cost significantly less than the $10,000 in oil. I need to be sure that the size of the boiler is appropriate to heat the house and efficient enough to leave in place if I never split the system into two units.

I realize that's a lot of info but would certainly appreciate any advise. Thanks in advance.

Kenny

Kenster63

Kenster63

So something like a Weil McLain EG40 is what I thinking. Does that seem right?

Fred

Is the 283 sq. ft or Radiator EDR a total for both units or just one? I'm assuming the radiator in the basement is actually a hot water loop. Is that correct? Is that radiator mounted on the floor or basement ceiling? Some pictures of that radiator and its piping would be helpful. Clearly, if your EDR calculations are correct, the current boiler is way over-sized. even if the 283 is X's two (for both units) it is still way to large.
Even if you have to raise the house, if the near boiler piping is done correctly, it should not be difficult to extend the risers from the header to the Mains to accommodate that. Also, I wouldn't buy a used boiler. That probably isn't a very good use of your money as you don't know the condition until you flood it to check for leaks and even then you don't know how much life is left in the boiler block, unless you happen to find one that was removed because it was a new install that was either over or under-sized and removed to install a properly sized one. That will be a difficult find.

Kenster63

The 283 sq. ft. is the total for both units. The radiator in the basement is mounted half way up the wall and it is piped off of the steam return to the boiler. I don't have any other pictures of the basement radiator and I don't live there so I'll have to go back there another day. In the picture of the boiler, to the right of the window you can see the left edge of that radiator but not much.

Kenster63

In some stuff I've read people talk about removed radiators. I have two missing but have adequate heat.

Kenster63

There are a total of 10 radiators in the house including the one in the basement. There was a radiator removed from the first floor bathroom when I renovated it and electric radiant was added. There was also a radiator removed from the first floor living room prior to me owning the house. It was capped.

Jamie Hall

Assuming that your arithmetic on the radiators is right -- and I would think it probably is -- your existing boiler is way oversize. And your plumber isn't helping any.

Kenster63

Fred
I have seen a few used that had either been under or oversized replacements but wasn't sure if my calculations were correct because they are so far off the existing boiler. Didn't want to make a mistake.
Jamie
I'm thinking my math is right. And plumber is definitely no help.
Are either of you able to read the tag on the old boiler? Did I correctly read that 666 sq. ft. of steam ?

Kenster63

The math is pretty straight forward right?

KC_Jones

Yes the math is straight forward. Use a sizing chart to find out the EDR per section, multiply by number of sections which gives you radiator size. Add up all the radiators in the house and you have your number. Which sizing chart did you use? You can post all the measurements and the type of radiators you have and we can double check your math if you would like. It never hurts to double check.

Kenster63

Is radiator EDR the same as Sq. Ft. of steam?

Kenster63

So if you don't mind, here are my radiator sizes.

#1 26" -5 Tube 13 sections
#2 20" Sunrad 5" X 16 sections
#3 20" Sunrad 5" X 12 sections
#4 38.5" 3 column X 5 sections
#5 26" 5 Tubes X 14 sections
#6 26" 5 tubesx 7 sections
#7 26" 3 column X 9 sections
#8 26" 5 tube X 9 sections
#9 26" 5 tube X 3 sections
#10 26" 5 tube X 7 sections

#10 is the one in the basement on the return. Not sure if it should even be counted. I used the chart and info on Comfort Calc website.

Fred

Kenster63 said:

Fred
I have seen a few used that had either been under or oversized replacements but wasn't sure if my calculations were correct because they are so far off the existing boiler. Didn't want to make a mistake.
Jamie
I'm thinking my math is right. And plumber is definitely no help.
Are either of you able to read the tag on the old boiler? Did I correctly read that 666 sq. ft. of steam ?

Yes, the old boiler says 666 sq. ft and yes, Sq. ft and EDR are terms used interchangably. Sq. Ft. of EDR = Sq. Ft of Equalivant Direct Radiation

Dave0176

If I had the replacement job I'd use a Weil McLain EG35 with 258 sq ft steam, the .333 pickup factor would heat that no problem. However if using a 2 stage CGV I'd run the EG40.

Kenster63

A 2 stage CVG?

Dave0176

Abriviation for Combination gas valve (the gas valve in laymens terms)

Fred

Kenster63 said:

A 2 stage CVG?

That's a 2 stage gas valve. It allows the boiler to run at two different input/output levels. usually High (full output until boiler reaches a preset pressure, and then switches to low to maintain that pressure (range) until the thermostat is satisfied or back to high if pressure drops below a preset pressure).

Dave0176

Honestly a used gas boiler will only save you about $800, not worth it in my opinion.

Kenster63

Dave
Is .333 the right pickup factor?

Kenster63

What are the benefits of a 2 stage CVG?

Kenster63

Can anyone offer a ballpark # for this job?

Kenster63

Is it advisable to upsize a bit to allow for future needs if finishing basement?

Fred

Kenster63 said:

So if you don't mind, here are my radiator sizes.

#1 26" -5 Tube 13 sections
#2 20" Sunrad 5" X 16 sections
#3 20" Sunrad 5" X 12 sections
#4 38.5" 3 column X 5 sections
#5 26" 5 Tubes X 14 sections
#6 26" 5 tubesx 7 sections
#7 26" 3 column X 9 sections
#8 26" 5 tube X 9 sections
#9 26" 5 tube X 3 sections
#10 26" 5 tube X 7 sections

#10 is the one in the basement on the return. Not sure if it should even be counted. I used the chart and info on Comfort Calc website.

Your calculations seem right. I wouldn't count that one in the basement if it is on the condensate return.

Kenster63

Ok thanks for checking it. I have to figure out my best option. Perhaps a new boiler is the way to go.

Kenster63

Dave & Hatterasguy
The WM boiler guide has the EG 35 at 258 EDR. So that's net? They have already deducted 21 % for piping etc.? So the gross EDR is 312? If the pipes aren't insulated and such will the EG 35 be big enough?

Dave0176

Kenster63 said:

Dave & Hatterasguy
The WM boiler guide has the EG 35 at 258 EDR. So that's net? They have already deducted 21 % for piping etc.? So the gross EDR is 312? If the pipes aren't insulated and such will the EG 35 be big enough?

Like I had said earlier the EG35 will definitly handle that load, however If the customer so decides to go with a 2 stage I'd run the bigger boiler.

Dave0176

The 2 stage only adds a few hundred more, but I feel it's worth it.

Dave0176

Who ever you have do it whatever size they choose, make sure they know how to properly pipe a steam boiler, or you will be miserable.

Steamhead

Kenster63 said:

Can anyone offer a ballpark # for this job?

We do NOT discuss pricing on this forum- like it says at the top of the page.

Dave0176

I'd do it for you, i'm not sure how far you are from me but I do have a good friend that lives in Massapequa.

Kenster63

Ok sorry. I thought that meant specifics.

Kenster63

Dave
I'm about 25 minutes closer to you than Massapequa.

Dave0176

Hmm well you got my info call me tomorrow and we'll talk

Dave0176

I just hate driving on the Belt and past JFK but....

Kenster63

Ok I'm traveling tomorrow but will try to call at some point.

Kenster63

Thanks everyone for your input. Will keep you posted.