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Steam boiler/gas conversion

BillTex
BillTex Member Posts: 5
Hi All, noob home owner here...



Just converted steam system from oil to natural gas, a couple of questions;

* When we were running oil, a typical heat cycle would be 45min-1 hour and all the radiators would be hissing and singing.

After converting to nat gas, the heat cycle is ~ 2 hours and there is no hissing. Radiators are getting hot, but it seems the system is not building the pressure it did on oil.

All valves have been cleaned/replaced, and radiators are pitched correctly.

Work was done by licensed contractor with lots of experience with both oil and gas hot water systems...however not much experience converting a STEAM system to gas.

He has replaced air valves and cleaned the boiler.

*Contractor did mention we can still go up on size on orifice; currently at .100" can increase to .125".

Should the heat cycle be this long with natural gas?

Will increasing the orifice (fuel supply) dump more heat in the system and build more pressue so we hear that loveli hiss again?



Comments/suggestions?



Tx, Bill

Comments

  • Tim McElwain
    Tim McElwain Member Posts: 4,480
    Questions

    1. Was a heat loss done along with a determination as to square feet of radiation?



    2. What was the nozzle size and oil pressure when it was on oil?



    3. Was this a design oil boiler converted to gas or was it originally coal?



    4. What is the Make and model of the boiler?



    5. Did the installer do a combustion analysis? If so did he fire the boiler to its maximum firing rate?



    6. The point of changing the orifice size tells me that the installer did not do his homework before installation. To answer your question yes increasing the orifice size will fire at a higher BTU but there are many other things that need to be addressed on a steam system.



    7. I assume you made the change from oil to gas because of the cost of fuel. If so it seems your were satisfied with the operation on oil as far as heating, is that correct?
  • jumper
    jumper Member Posts: 1,710
    more questions

    What conversion burner was added ?

    Or did you replace the whole boiler ?

    Was an intelligent thermostat added?

    BTW lower pressure & longer cycle is beneficial.

    If you like hissing sounds play a recording.
  • BillTex
    BillTex Member Posts: 5
    A few answers

    1. Was a heat loss done along with a determination as to square feet of radiation?

    NA



    2. What was the nozzle size and oil pressure when it was on oil?

    NA



    3. Was this a design oil boiler converted to gas or was it originally coal?

    Originaly oil, it is about 8 yrs old



    4. What is the Make and model of the boiler?

    I will have to check



    5. Did the installer do a combustion analysis? If so did he fire the boiler to its maximum firing rate?

    na



    6. The point of changing the orifice size tells me that the installer did not do his homework before installation. To answer your question yes increasing the orifice size will fire at a higher BTU but there are many other things that need to be addressed on a steam system.



    7. I assume you made the change from oil to gas because of the cost of fuel. If so it seems your were satisfied with the operation on oil as far as heating, is that correct?

    Yes, love the steam heat. We are satisfied with the performance on oil...just not the expense! Would hope to achieve same performance with gas?



    I will get more info and post back here again...
  • BillTex
    BillTex Member Posts: 5
    More info

    What conversion burner was added ?

    NA

    Or did you replace the whole boiler ?

    Replace burner only

    Was an intelligent thermostat added?

    Do you mean programmable? Yes...

    BTW lower pressure & longer cycle is beneficial.

    Really? Running just under 1 psi now. Believe it was 1.5 psi on oil...



    If you like hissing sounds play a recording.

    Yes...I will look on iTunes!



    Obviously I need to get some more data and get back to you Guys...thanx...I'll be back.



    Bill
  • furnacefigher15
    furnacefigher15 Member Posts: 514
    Hissing

    The hissing was either leaking steam vents, or the sound of the air leaving the vents.



    If the vents were replaced, that solved any possible leaks. If the vents were replaced with less restrictive vents, then you may just not be hearing the air being vented due to wider air passage ways.



    If the system is heating, and is comfortable, leave it alone.



    Have the burner tuned with a combustion analyzer if the installer did not perform this task.
  • BillTex
    BillTex Member Posts: 5
    Bottom line

    I guess the bottom line is; running a heat cycle for ~ 1 hour on oil versus a heat cycle for ~ 2 hours on natural gas was not what I expected.



    I don't know the $ yet as we just switched to gas 2 weeks ago.



    I assumed the time to satisfy the thermostat would be close (I understand the difference in btu's oil vs gas) but I did not expect the furnace to run 2x.

    I also expected there would be fairly equaly pressure (hissing).



    The only thing that is different (in layman's terms) is the fuel source and the "burner".

    Is my expectation wrong?



    Tx, Bill
  • Mark N
    Mark N Member Posts: 1,090
    Cycle length

    Are you saying that when you used oil the boiler ran for 1 hour to satisfy the thermostat and now it run 2 hours using gas? I use gas and the boiler runs 20 to 25 minutes. If I were you I repost this over in Strictly Steam section.
  • BillTex
    BillTex Member Posts: 5
    Mod-please move to Steam heat

    Are you saying that when you used oil the boiler ran for 1 hour to satisfy the thermostat and now it run 2 hours using gas? I use gas and the boiler runs 20 to 25 minutes. If I were you I repost this over in Strictly Steam section.



    Yes...that is correct...



    Can a mod move this to Steam section?



    Tx, Bill
  • Rod
    Rod Posts: 2,067
    Fuel Conversion

    Hi Bill - If you want to post of the Steam forum you'll probably have to do that yourself as posts are normally moved by anyone other than the person posting.  I would also be inclined to keep this post going. Tim McElwain, who has already answered you, is a gas expert and I would follow his advice. We really need more info on your old boiler and burner, we need make and model numbers,  all of which should be available from the placard attached to the boiler.

    If it were me the first thing I would do would be to clock the gas meter and see how much gas you are using and then compare that to the BTU input of the original oil burner.

    Here's a couple of links on clocking which may be of help to you:

    http://www.cozyparts.com/calculators/natural_gas_input/gas_input.aspx



    http://hvac.amickracing.com/Formulas%20and%20Calculations/Clocking%20a%20Gas%20Meter.pdf

    - Rod
This discussion has been closed.