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Pulse 90 fuel conversion?

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  • Pulse 90 fuel conversion?

    Hey Guys, I am looking to change over from Propane to Natural Gas here this summer with the prospect of propane hitting 4-5 bucks a gallon... Anyway, my dilema is that I was told that its going to cost quite a bit to transition my Lennox Pulse 90 over. (it was installed in the mid to late 80's.) Should I just replace it, or convert it? I'm also looking at remodeling my house, and adding ~600 sq ft to the total finished area (~3200 total finished) and am worried if I replace it now it might be a little small for the size of the house. The other issue I have is the furnace is in the middle of the basement in its own little room and the rest is finished. There is not much room in there, and hopefully I can get the old one out and a new one in there. (was framed and built around it after is was installed)

    Anyway, how hard is it to convert a Pulse furnace, and is it even worth it. Or should I stick with propane until I do my remodel (could be years out) and deal with the higher price of propane?

    Obviously, If I had the money I would install a heat pump or some other heating system, but I am just a broke carpenter!

  • #2
    Re: Pulse 90 fuel conversion?

    I would replace it. I don't deal with fuel heating systems alot as this is a heat pump area but I see you have a
    1) a unit that is 20+ years
    2) increase your heat load with the bigger space thereby needing a bigger unit.

    If you go from fuel heat to a heat pump, your duct needs to be replaced and to keep you comfortable you're going to use some big electric heat strips thereby increasing your electric bill.
    Buy cheap, buy twice.


    • #3
      Re: Pulse 90 fuel conversion?

      A Lennox dealer should be able to get the parts (or have them laying around) to convert this to natural. If it was installed in the '80s then the model # is probably G14Q3-80-2 (or -3 or -4..) This would be an 80,000 BTUH furnace. IF it's a G14Q3/4-100-2 then it's a 100,000 BTUH furnace. The company that used to install them in our area seemed to put in whatever they had in stock, and a lot of them were too big for the homes. 600 sq feet, though is a pretty big addition.
      • The parts are not very expensive, but there is some labor involved in setting it up correctly. I would probably charge $200 to $300 for the job.
      • Take off the upper cover (the one that has the "Lennox Pulse" sticker on it) Look at the blower deck. (the bottom of this area) If there's water there, or rusty evidence of water, you have a bad heat exchanger. This will be usually in the left corner, next to a little rectangular plate with about 6 screws in it. If it has a bad heat exchanger Lennox owes you $400 towards the purchase of a Lennox furnace. These furnaces had a lifetime heat exchanger warranty, but since the heat exchanger is no longer available, they give you the $400.
      • The heat exchanger may leak even though it's not leaking water; the Lennox dealer should be able to do a pressure test on it.
      • We quit selling Lennox in 199. We had a huge failure rate on heat exchangers on the Elite Series (G26 Models)


      • #4
        Re: Pulse 90 fuel conversion?

        Where you are I would think it gets pretty cold in the winter. An air to air heat pump won't work very well if at all when igood and cold outside.

        You might research one with underground coils. The idea is to pull heat from underground well below the frost line. I'm not sure if such is even mass produced or if it needs to be custom engineered and installed. What I do know is that in my area there are some commercial installations and the payback in energy savings should really pay off for them as long as everything holds up well. So far, so good.

        If you do switch over to natural gas, I would look into a full replacement. All forms of energy are going up like crazy in cost. Having high efficiency equipment in top condition should pay back the installation cost over say 10 years if not sooner. If a new furnace can save someone just 15% in fuel, I say go for it if you can afford the replacement costs. You might check with your gas company and county and state. They may offer special upgrade deals.

        Do check around as the quality of installation and future service matters far more than which brand and model. The best made with poor installation just can't work like it should. On the other hand a really good dealer with good techs can sometimes improve how a lesser model works once installed.

        What about better insulation and good thermal doors and windows too?

        When I think of what I've paid over the past 5 and 10 years for natural gas heat here and where it's headed, it's the fuel cost that's the killer. A new furnace is less than 2 years of my fuel costs.

        I just installed new capacitors in my AC unit and lowered the running current draw by 4%. That may not seem like much but the capacitors were about $20 (my cost) and only took 1/2 of time to replace. That little 4% savings will way more than pay for them over just one summer of use. The compressor starts up and runs nicer too.

        Sorry about all the PLPLPL but it's the little low cost extras that sometimes really help.


        • #5
          Re: Pulse 90 fuel conversion?

          If you were thinking about a heat pump, you could always do a dual fuel setup. I run the HP at my parents to about 32 degrees, then below that I have the gas furnace set to come on.

          Its very possible that your current furnace is sized too big for your house anyway. Get a good contractor out there to do a full load calc to see what the house actually needs. You might find that even with your future addition, the furnace size you currently have will work just fine. I run into this all the time. I have taken out 100,000btu furnaces and replaced them with 45,000btu units. I have done jobs like yours where a builder doubles the size of the house, and I end up with the same size furnace as what was in there originally. I think that should be the biggest concern on whether to convert it or replace it.


          • #6
            Re: Pulse 90 fuel conversion?

            Thanks guys.

            Say, which is more efficiant, natural gas or propane? Is Natural gas a better way to go, or is sticking with propane not a bad idea?


            • #7
              Re: Pulse 90 fuel conversion?

              "Thanks guys.

              Say, which is more efficiant, natural gas or propane? Is Natural gas a better way to go, or is sticking with propane not a bad idea?"

              Efficiency is a relative term

              Nat.Gas is sold by the Therm ( 100K BTU)
              LP has 92K BTU per gallon

              I guess it really depends on what you are paying per therm for your Natural gas, If it is less than a gallon of LP you are better off converting.


              • #8
                Re: Pulse 90 fuel conversion?

                Bill is exactly right. It depends on what you are paying per gallon and per therm. Everyone I know is paying roughly $2.10 per gallon for LP. Basically a 92,000 btu furnace is going to cost you $2.10 an hour to run. I'm paying roughly $1.25 per therm for natural gas. Using these numbers, that same 92,000 btu furnace would cost $1.15 an hour on natural.



                • #9
                  Re: Pulse 90 fuel conversion?

                  If it was mine, and the heat exchanger was in good shape yet,
                  I would do a heat loss calculations on the building and the future addition,
                  with the unit being 90+ percent efficient, (first your addition will probly be better insulated than the old, and you may even up the attic insulation and other in the remodel process,
                  many of the pulse furnaces were over sized to the buildings they were installed in as they had replaced many furnace of much less efficiencies, and if the furnace is of adequate size, I would not replace it until it was need to be.
                  yes it may need to be replaced in some years to come, as it is ageing, but if it is not broke why fix it.

                  The conversion should not be that much, (you may look in your decimation on the unit, there my be a envelope of the parts needed to convert, around here if there are change out parts they usually leave them with the customer).

                  As far as what is the most efficient they should be the same, as the furnace is what extracts the heat out of the flame, natural gas will vary more in BTUs, than propane, (it is my understanding the furnaces are actuly tested on a propane type gas for there thermal efficiency) but it would/should be the same in efficiency,

                  the cost efficiency may different as the fuels may cost per BTU may differ, and that would probly be local markets, (most locations that have access to natural gas usually go natural gas, so my assumption is natural gas has been the cheaper or at least easier of the two fuels historically),
                  Push sticks/blocks Save Fingers
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