Make old gas boiler more efficient

Discussion in 'Boiler Forum' started by pbradley_1, Mar 10, 2014.

  1. pbradley_1

    pbradley_1 New Member

    Jul 12, 2008
    I have an old American standard 1B-J1 boiler using natural gas. I would like to convert the standing pilot to a spark pilot and install an automatic damper such as the GVD-6PL. I have the R8239A1052 fan center and a model 36C03 type 300 gas valve. The input BTU is 180000 and output is 144000. I had a combustion test done a couple years ago and I was told that it was burning at 80% efficiency still. I have received quotes for cast iron boilers and different high efficiency units and I just can't see it paying itself off for 12+ years. It seems like its just not worth replacing the boiler if its still working even if it is 40 years old. Thoughts?
  2. BadgerBoilerMN

    BadgerBoilerMN Hydronic Heating Designer

    Mar 4, 2011
    hydronic heating designer/contractor
    It will pay for itself if it saves you money. A proper heat load, calculated design water temperature and from that, ROI.

    Spark and damper, 5-7% in the real world. Won't pay for itself very fast for sure. I the old boiler fails in a couple of years it is money wasted for sure.
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  4. Dana

    Dana In the trades

    Jan 14, 2009
    Steady state combustion efficiency is one thing, the as-used AFUE is another. Most homes in CO will have a design heat load under 40,000BTU/hr which means this pig is probably 3-4x or more oversized for the actual load. With standby & ignition cycle losses running maybe 65-70% true as-used efficiency. A right-sized cast iron boiler would pretty much hit it's AFUE numbers (which presume no more than 1.7x oversizing), and a right-sized modulating condensing boiler could even beat it's rated AFUE if you have enough radiation and a system designer who knows what they're doing.

    If you are heating your potable hot water with an embedded tankless coil you have HUGE standby losses. Buying an indirect-fired hot water heater (or a stand-alone hot water heater) and setting the boiler up to run much cooler plus utilizing heat-purge controllers (eg Intellicon 3250HW+) would likely pay for itself in under 12 years, provided the beast lives that long. If you're burning 1500 or more therms/year a ~$150-200 DIY-installed heat purge controller will pay off in under 2 years, probably less than 1 year, depending on the oversizing multiplier.

    The better thing to do is make a replacement plan and execute on it. If you have a fuel-use history (and aren't heating half the place with a wood-stove or something) you can size the replacement boiler reasonably without running a formal Manual-J by using fuel-use against heating-degree-day data. With a zip code (to look up heating degree day data from a nearby weather station at and to come up with a 99% outside design temp) and the fuel use between exact billing dates, using the name-plate efficiency of the boiler it takes maybe 10 minutes to come up with a number close enough to use for boiler sizing. If you are planning major upgrades to the house that involve more air-sealing & insulation it's worth running the "after" picture calculations if you're not already at the smallest-of-the-line for boiler sizing, which is where MOST houses should be.
  5. charlie.f308

    charlie.f308 New Member

    Apr 10, 2014
    Are you looking for a timer? I have a digital timer connected to mine which cuts back on my energy.
  6. boilerdonganhhn

    boilerdonganhhn New Member

    Apr 14, 2014
    Ha noi
    Boiler or Boilers. How they work

    Objective: The objective of this presentation is to give you guys a fundamental understanding of how boilers can benefit our homes.
    Boilers provide warm, even heat throughout your home by circulating steam or heated water through a system of pipes and baseboard or radiator-type heat exchangers.

    How they work

    Basically, heat is created by burning gas or oil inside your furnace. Hot gases that are created pass through curved metal tubing called a heat exchanger and then out of your home through a metal or plastic vent pipe. At the same time, the air that circulates through your home passes over the outside of the heat exchanger and takes on the heat from the hot metal. The warm air is then circulated through your home
    They provide warm, even comfort without drafts because it's not a forced air system. Instead, warmth "radiates" throughout your home without causing much of the dryness associated with heat from a forced-air system, such as furnace or heat pump


    There are two types of boilers: gas and oil boilers and they can run on hot water or steam.
    The piping systems are different for each type.
    The hot water system boiler uses a pump to circulate the hot water while the steam boiler uses its own pressure to circulate the steam throughout the system. Both use a burner to heat the water to the temperature that is set on the thermostat. An aqua stat monitors the temperature of the water and turns the burner off when the temperature reaches the desired level. Steam boilers must heat the water to a higher temperature, and therefore have lower efficiencies than hot water boilers
    Combination boilers combine water heating and heat generation in one unit and can save considerable money on heating and water heating costs. The heating part of the "combi" boiler works in the same fashion as other boilers.


    The efficiency of new boilers is measured by the Annual Fuel Utilization Efficiency (AFUE). This is a measure of overall performance. The federal minimum-efficiency standards for boilers took effect in 1992, requiring that new boiler units have an AFUE of at least 80%.
    There are three key terms associated with efficiency of a boiler:
    Combustion efficiency - how efficiently the boiler burns the fuel.
    Steady-state efficiency - how efficiently the boiler uses the heat from combustion when operating under full load.
    Seasonal efficiency - how efficiently the boiler uses fuel over the entire heating season
    Although all three are important, it is the seasonal efficiency that is most important since it determines how much the building owner will pay for fuel over the course of the heating season
    High seasonal efficiency requires good steady-state efficiency as well as good combustion efficiency.
    There are a few things that can increase efficiency
    First, using two or three boilers can greatly increase efficiency.
    The longer a boiler operates, the higher the seasonal efficiency. Therefore, a boiler that is smaller than required will more closely match the heating load of the building for a larger part of the season because of fewer on-and-off cycles. When the first boiler can no longer keep up with the heat loss, a second boiler picks up the extra load, and then a third boiler, if necessary
    Each boiler will cycle one-half to one-third less than a single boiler, thus increasing seasonal efficiency significantly
    However, the key to maximizing efficiency with two or three commercial boilers is to be sure that each boiler is completely isolated from the others so that non-operating boilers will not be hot with system water.
    Some other ways to increase efficiency include eliminating leaks, softening or treating system water, using indoor/outdoor reset thermostats, and limiting control differentials.


    In conclusion, boilers can greatly benefit our homes by providing efficiently warm and comfortable heat evenly throughout our homes.

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