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Calculating boiler efficiency from year to year after PM work

margaretnyc
margaretnyc Member Posts: 14
My NYC co-op 40 unit, 5-story walk up residential apartment building hired a reputable boiler and water treatment company in 2015 to begin a comprehensive "worry free" preventative maintenance contract for our 20+ year boiler. Before that time, we paid someone to do water treatment (not sure of frequency), prepare for annual inspection and do repairs as they arose. The PM contract includes: monthly PM maintenance, monthly water treatment, annual burner overhaul, annual fireside cleanings, annual comprehensive water side cleaning, preparation for annual inspection.

Our hope with investing in PM was that we would extend the life of the boiler and also save on fuel costs since the boiler would presumably be more efficient. It is time to renew our contract, and the company has raised its rates more than we expected. We are trying to determine if their service has been worth the investment as well as the expected increase in price.

I am seeking help on doing a year to year comparison with HDD to determine if our boiler has indeed become more efficient. I have the oil consumption data for the last 3 years and I can look up HDD. What other information do I need and what formula should I use?

Thank you for your time!

Best,
margaretnyc

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,169
    You have two thirds of the basic information you need -- oil consumption (hopefully broken down at least by month...) and you can get heating degree days. The third thing you need, however, is critical: what temperatures are your tenants running their spaces at, and have any other upgrades to the building windows, controls, etc.) been done? Without that information, you are really shooting in the dark, as even one apartment changing to running much warmer -- or cooler -- than before can obscure the information for which you are looking.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    edited March 2017
    Is your system steam one or two pipe, or hot water?
    The boiler is one part of the whole system, and the rest of the system should be inspected as well.
    Unless you know you have a water chemistry problem, only pure water should be in the system for greatest efficiency. Any makeup waterfeed should be monitored by a water meter, so any excessive water loss can be corrected.
    Pictures of your boiler and its piping could be posted here for an opinion as to efficiency, and maybe longevity.--NBC
  • gennady
    gennady Member Posts: 839
    edited March 2017
    We are using new electronic petrometer gage along with internet hot spot and small compressor on timer. Works great, has history of oil level and actual fuel consumption by the hour, always available on cloud.
    Hatterasguy
  • Jamie Hall
    Jamie Hall Member Posts: 23,169

    ...

    Be careful of your value for oil consumption. Most folks can only get the delivery amounts and not the actual fuel consumption for a given period. This will yield significant error if a short time period is utilized. You'll probably need to calculate on an annual basis to mitigate the error somewhat but it will still be present.

    Very true indeed, and the resulting scatter in apparent fuel use can be substantial. There are statistical methods for helping with this... but they are complex, and don't solve the problem completely! To give you an idea, the raw standard deviation for the data from Cedric (computed on a weekly basis) is about 30% of the mean consumption figure.



    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England