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Replacing 1951 Weil-McLain Oil Burning Boiler for Gas

Ann & Ted
Ann & Ted Member Posts: 3
Thanks to all.
While oil service can be had in our area - it's been expensive in the past years. Our home is 3500 sq ft 2 story with large lower floor rooms and four rooms + two baths upper.

Our major problem has been finding ANYone who is knowledgable about boilers in general as we would like to keep the baseboard radiant heat. We are reading up on heat loss calculations - whoa - that'll take some stick to it to understand......

We thought lots of transplants would be around - but I guess they are all enjoying the beaches and ducking the hurricanes!

Heat is our primary concern at the moment - we keep the visitors away by not having AC (ha)..... It's an old 1925 colonial with 50 double hung windows and a large whole house fan - suits us fine - but you know us southerners... anything below 70 degrees is chilly and those few days in a row of really cold (30-40) has us thinking about heat.

Also got mom here with us now and its more important to keep a comfortable temp.

Thanks again to everyone - we continue to look for the right person(s).


  • Ann & Ted
    Ann & Ted Member Posts: 3
    Replacing Oil Burning Boiler

    We are having difficulty finding an experienced HVAC provider to replace an old (1951) boiler for a gas model. Should mention - we live in Florida so experience with radiant heat is not common around here. We want to replace with a gas unit and just need to know what size to consider - all other aspects of the heating system are in good condition and work great for the few days of the year we need heat. The current model burns 1.55 gal/hr of #2 fuel oil - hence, the choice to go to gas. Any service providers have leads on providers in the Tampa-St Petersburg area that you would recommend?
  • Leo
    Leo Member Posts: 767
    I am an oil guy

    Is oil service common in your area? By today's standards 1.55 gal per hour would be for a ten plus room house. If a good oil service company does a heat loss a much smaller boiler (oil) would probably serve your needs and save on fuel costs as well as burning much cleaner than 50 year old technology. If you are definately convinced on going to gas be sure that company does a heat loss also or your gas bills will be no better than your oil. I'm sorry I am not familier with any companies in your area.

    Best of luck,
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,385

    a heat loss done or do it yourself. I don't what the design temp is in Tampa but I'd guess 30 or 35? Check out the top of page for heat loss info.You're probably going to have to find a transplanted northeasterner that knows boilers. Shouldn't be too difficult,there's more New Yorkers in Florida than Floridians.

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  • Weezbo
    Weezbo Member Posts: 6,232
    your home is designed around cooling...

    and i would make the mental leap that means while you have heat for the most part cooling is where the most of your dollars go. unless you are certain that there ever was a need for that size boiler when you do find a contractor ask him for a heat loss dad lives North of you in North Carolina, it snows a bit buh never really Sticks. he has a GSHP .... perhaps you have other choices ,...might want to explore that line of thought a bit too.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    You need to compare

    the cost per BTU of gas vs. oil in that area. Oil has 140,000 BTUs per gallon so the calc is simple. For gas, you have to figure in all the little taxes and fees that the gas company lists in very small print so you won't notice them. The easiest way to do this is simply divide the therms used (a therm is 100,000 BTU) by the amount you paid. That gives the cost per therm, divide by 100,000 to get the cost per BTU.

    You may be surprised at the results!

    The fact that the oil boiler burns 1.55 GPH is no reason to switch to gas. That translates to an input rate of 217,000 BTU per hour on a gas boiler, so if anyone is telling you a gas boiler of that size will be more economical, they're just trying to take your money.

    As has been stated earlier, you need to have a full heat-loss calculation performed on the house. If you click on "Heat Loss Calcs" above, you can get a free, easy-to-use program that does the calcs in response to your input. A calc is the only way to determine the proper size boiler in a hot-water system like yours. Again, the results may surprise you! I'd bet the program comes up with a recommendation for a considerably smaller boiler.

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  • Ann & Ted
    Ann & Ted Member Posts: 3
    Reply to Steamhead

    Thanks Steamhead,
    We did get two companies to agree to come by and do the heat loss estimate for us and then we will do the comparisons. Unfortunately, the current boiler does not have any BTU output listed. The boiler shuts off at 185 degrees and kicks back in at 165 degrees. Maybe we should just get this old unit cleaned and check the actual costs this winter (we haven't used the system in a few years). One contractor indicated that the current boiler could be converted to gas burner - so I guess we wait on the estimates and do more homework.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    If you tell us

    the make and model of the boiler, we can give you some idea of its output.

    When you say "The boiler shuts off at 185 degrees and kicks back in at 165 degrees" do you mean it maintains this temperature all the time to provide hot faucet water? If so, this is extremely inefficient. It costs a bunch to keep that boiler hot all year, due to the "standby loss"- heat going up the chimney when the burner is off. With fuel costs rising, this is a big problem. This also might explain why you're burning 1.55 GPH.

    If that were my house, I'd switch to a booster tank (stores water heated by the existing tankless coil) or an indirect heater (tank with heat exchanger thru which hot boiler water is pumped). Either solution would be much more efficient than your present system, since these tanks are usually very well insulated and do not have flues running thru them. If no one is using hot water, the boiler would only have to run maybe once a day, or even less often. And these units recover pretty fast, so you could keep them shut off while you're away, yet have hot water quickly when you return.

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