Is my boiler just undersized???

jp741

Okay for the past couple months I have been trying to improve the heat distribution of my single pipe steam system.  With your help there has been improvements but I can't seem to get consistent heat in the last radiator and I wondering if I'm just expecting too much from my current system.  It is a 20yr old Utica boiler model SF41255 with a 145300 heating cap. Steam 453sq ft. 108,000 BTUs.  The main splits as it comes off the boiler with 2 lines running in a parallel 60ft. loop, one feeding the first floor rads and the other the second floor.  The first floor line is vented with 2 gorton #1 and the second has 4 gorton #1's on it. All the rads have vari-vents on them, all are practically closed in hopes to feed the last rads which vents are wide open.  Though it takes a while the first floor main vents heat up and all the rads get heat.  The second floor vents don't even get warm, and all but the last rad gets heat. I can feel heat in the basement of the pipe heating that last rad, but it inconsistantly raises to the second floor...even.with the boiler running for an hour.

Here are my rad dimensions:

#   W xH x D

2)  16x39x8  w/7rungs

2)  18x39x8   w/8rungs

2)  11x39x8   w/5rungs

2)  14x39x8  w/6rungs

1) 21x21x7   w/ 9rungs

1) 14x20x9  w6rungs

1)  23x39x8  w/5rungs

1)  29x21x8  w/12rungs

1) 17x25x3.5  w/10rungs

Is the boiler just too small to produce enough steam to fill (at least ) heat these rads.

Thanks for your effort.

jp741

2 more rads.

sorry I forgot to include 2 rads in my list

30X32x8   w/13rungs

and one straight pipe baseboard (this is the one that doesn't get heat all the time)

Charlie from wmass

Use this link

http://www.usboiler.burnham.com/contractors/tool-box-sizing you can figure your E.D.R. through this. To count the size the number of tubes or columns from the wall to the room size is your tube or column count. The number of vertical sections from left to right length wise is the section count. Height of radiators is the height of a section with legs.

Charlie from wmass

When was the boiler

last tuned and really cleaned?

BobC

How many columns

You have listed the size and the number of rungs. The other piece of info we need is how many columns in each rung - 2 or 3??



Are all the radiators and their piping sloped correctly?



If those are heat timer vents they have very high venting rates even when they are closed down. You may have to use Hoffman 1A adjustable vents to get the venting rates down so all the radiators can get steam.



Bob

jp741

how many colums

they are all 2 columns except

21x 21 x7 has 3 columns and 9 rungs

14 x20x 9 has 5 columns and 6 rungs

29 x 21 x8 has 3 columns and 12 rungs

17 x 25 x 3.5 has 3 columns and 10 rungs

jp741

cleaned

it was serviced yesterday

neilc

Insulated ?

Are your mains and risers insulated (where practical)?

Rod

Vent Sizing

Using Vari-Vents on all your radiators is sort of like opening all the fire hydrants in your city at once. All sorts of weird things happen. Some streets fill with water and other have none. However the same piping system will supply water to houses all over the city at the same time.  The difference?-Big orifices vs small orifices.

jp741

Insulated

yes all the exposed piping is insulated

jp741

vari vents

I'm starting to see that it might be an issue, as we have most of them closed or just cracked and they still get heat faster than the ones wide open on the end of the line

Rod

Vents

A Vari-vent's minimum setting is approximately equal to the middle setting on a Hoffman 1a. Vari-vents have their place, it's just that you have to be judicious where you use them.

- Rod

BobC

Boiler should be adequate

A quick calculation shows less than 300 sq ft of load, not counting that baseboard.



The boiler seems more than adequate so your problem is probably getting that radiator venting balanced out.



The heat timer will vent between 0.158 and 0.85 CFM while a Hoffman 1A goes between 0.026 and 0.225CFM. Try closing the heat timers as far as you can and see if that makes a difference. If not you need to go with smaller vents.



Also make sure the pipe and radiator slopes are all correct.



Bob

jp741

vents closed

Thanks for the help and calculations.  I have most of the vents closed especially those and the beginning of the line.  The last ones are open fully.  Though the first ones still fill first.

BobC

mains heating equally

Do your mains heat to the ends at about the same time? How long does it take them to heat? Steam will take the path of least resistance so delaying the arrival of steam to the early radiators on the mains may force it into the radiators that don't heat up. I've enclosed the rough calculations I did for your reference.



Again, the slope on all radiators and piping has to be proper.

jp741

Mains heating

Thanks for the calculations!  I didn't explain it very well in the first post, but the 2) in the first column refers to the fact that there are 2 rads that size, so I end up with a total of 387.80...is boiler still sufficent?  The mains don't heat at the same time the first floor heats faster in about 15-20 minutes, but we begin to get heat in the rads before the main heats throughly (which I know isn't the ideal)  The second floor main vents never heat up totally...the pipe gets warm, so i don't know if it ever fully heats, cause again the rads begin to heat.  On the second floor main there is a  vari vent on the main line about 6 ft before the gorton mains, but after the last rad header.  Though we get heat in the rads they never full heat across except for the smaller.

Again thanks for all your time and effort

BobC

Still fine

I thought the numbers referred to which floor and that's what I get for assuming.



If your boiler is rated at 453 sq ft of steam AND you are firing at the rated GPH  (for oil) or gas pressure than your revised 388 sq ft of load should be no problem - especially since you have insulated your piping. Just make sure the firing rate is what it should be.



Bob

jp741

still fine

 It was a brilliant assumption.  Is there a way to self test the firing rate for an oil burner?  It was just serviced for the season yesterday, is that something that would have been checked/adjusted?  Thanks again, got some heat in that last rad. tonight...it remains a mystery.

BobC

firing rate

The oil burner tech usually leaves you with a tag or printout that tells you what size nozzle they installed. The other fly in the ointment would be if the pump oil pressure was too low (140 seems to be the average number for modern oil guns), but that would usually screw up the combustion test. But then, anything is possible.



i am not qualified to say what settings might lower the heat output of the oil burner beyond that.



I suspect the problem lies in the venting balancing.



Bob

Charlie from wmass

OIL PRESSURE AND NOZZLE SIZE

also nozzle angle and flame retention ring. If the pressure and nozzle are wrong the tech can simply adjust the burner to get a proper clean burn just at the wrong fire rating. What is the nozzle and pressure listed on you service tag? also remove the vari vents and install less aggressive radiator venting. I can seem very against vari vents to people reading my posts, Well It is because I am. I have been trying to avoid saying rip them out and bring them to the scrappy but no, I have to say it.