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Gas Conversion

Sr20deMikeSr20deMike Posts: 5Member
I am interested in converting to gas heat. I already confirmed with National Grid that it would be no cost to run the line to the house.


2100 square foot house with about 200 feet of baseboard.

Newly installed (6/24/2014) 40 gallon Techtanium indirect hot water heater.

So far I received 5 different quotes. The last company recommended a high efficiency Navien NCB-240 combi. They said I would not even need to hook up my hot water heater since I only have 2 full baths. All of the other quotes used more conventional cast iron boilers like the Burnham ES25.

Is it worth going with the high efficiency Navien? How much of a savings would I get if i chose this over a Burnham ES25 hooked up to my hot water heater? Which one is more reliable, I read some mixed reviews about the Navien online.

None of the plumbers conducted a heat loss test. Based upon my calculations using the Slant Fin program, I came up with approximately 80,000 BTU loss. Do I need to include my unfinished, unheated basement and crawl space in this calculation?

Are there any plumbers near Melville NY who are willing to provide a quote? I checked the contractor section of the forum and did not find one within 10 miles.

Thanks for your help,



  • SWEISWEI Posts: 7,356Member
    Suggest finding at least one more contractor

    Most of us here would say that any contractor who did not perform a heat loss calc has in effect disqualified themselves.

    Unless the house is quite old and drafty, your heat loss calc of 38 BTUs per square foot may be a bit high.  We also don't know exactly what species of baseboard inhabits your home.  Caveats understood, 200 linear feet of Fine/Line 30 would only need ~155ºF water to heat your home on a design day.  Translation:  A modulating/condensing boiler would perform very efficiently there.

    The NCB240 is at least 2.5 times larger than you need, and would be short cycling for much of the heating season.  After checking the heat loss, a reputable contractor would quite likely recommend a mod/con boiler firing at less than 100,000 BTU/hr.
  • Sr20deMikeSr20deMike Posts: 5Member
    I agree with my heat loss estimate being high.

    I was conservative in my "exposed wall factor" and "cool partition factor" since I was not sure of the insulation thickness. I just looked again and using conservative factors I am coming in at 76,000 not 80,000.

    I am pretty sure I have slantfin baseboard. I believe one of the contractors mentioned it as 30A if that helps. Is there a way to tell what I have?

    Other than just calling different contractors, does anyone know any that will do a heat loss test on Long Island?

  • jonny88jonny88 Posts: 1,139Member
    Nat Grid installers

    You are getting ES2 quotes as you will get a rebate etc.As you have an existing indirect I personally would rule out Navien for a few reasons but dont want to derail your thread.For example when I converted my house I put in a mod/con with indirect.House is 2700 sqft and boier input is 115 btu.I cut my fuel bill by 65-70%.ES2 is fine but if you do go with it I would suggest you use the outdoor reset and pipe a bypass between supply and return to stop condensation in flue.

    Remember if you put in ES2 you have to reline your chimney.
  • Sr20deMikeSr20deMike Posts: 5Member

    I left a couple of messages today for two contractors that I saw mentioned on this website. They got some great reviews in the threads I read. I am hoping to hear back from them soon since I need to make a decision if I want to be set up before winter.

    I have been in my house for a little over a year and after spending $3,000 in oil for the year, I am ready to make the switch

    I know the ES25 is bigger than I need based on my heat loss analysis, but would the ES24 be too small for my indirect hot water heater? According to Techtanium, it requires a boiler of 120,000 BTUs.
  • jonny88jonny88 Posts: 1,139Member

    Why are you so stuck on the ES2,just curious.
  • Sr20deMikeSr20deMike Posts: 5Member

    I am not necessarily stuck on the ES2. Out of the 5 quotes I received, 3 suggested the ES2, one suggested Utica, and the last one was Navien or I can go with the ES2 that is quote "20th century technology".

    This is all new to me and I am willing and wanting to try to get the best system for my home the first time.

    I would never have thought it would be so hard to find a contractor to perform a heat loss test.
  • Tim McElwainTim McElwain Posts: 4,225Member
    edited July 2014
    An accurate heat loss is a must

    then look at a Mod/Con boiler which can match up to your heat loss and also consider domestic hot water needs.

    How old is the existing boiler?
  • Jody_SJody_S Posts: 9Member
    Right Size It

    I would size the boiler for the heating application and then figure out how much hot water the indirect will produce with that boiler. If it isn't enough hot water then look at a larger boiler.

    The 120,000 BTU/hr number is probably needed to produce the figures listed in the literature. I am not familiar with that product but based on an 80F rise the first hour rating probably is in the 150 to 180 gallon range. Are you going to use that much hot water?

    In the past I have used a 50,000 btu boiler to heat my home and support a 41 gallon indirect water heater. It was a small ranch with a single bath and we never ran out of hot water.

    On the flip side I also have designed a heating system with a 500,000 BTU/hr boiler in a home where the heat lost was only 200,000 BTU/hr. The extra horsepower was needed to support the multiple indirect water heaters for the shower in the master bath!!

    So I guess where I am going with this is discuss your hot water requirements with your contractor to see if it has an effect on the required boiler size.

    Jody S.
  • Sr20deMikeSr20deMike Posts: 5Member

    Jody_S - In your second example, is short cycling a concern because of the heat loss requirements?

    Tim - I believe the boiler is 15 years old.
  • jonny88jonny88 Posts: 1,139Member
    heat loss

    when a installer is on the Nat Grid Installer plan you can get quiet a few leads.I can't speak for all but if you are looking at a lot of potential jobs the contractor I think will not perform a heat loss every time.Sometimes they will if a contract is signed.You see they know that the customer is going to get 3-5 quotes on the job and I am not talking about you here but a lot of people go for the best price and are sold on the rebates that are offered when buying Burnham boilers.FYI you are entitled to a rebate when you convert to a high efficiency boiler of any make.Take Tims advice you wont get better here,again my IBC boiler 115k btuh heats 2700sqft and on heating mode rarely goes above 50k but it then goes into high fire for my indirect(wife,2 daughters and mother in law)so as you can imagine there is a high demand for hot water.As long as your piping is sized correctly and your circulator for indirect is sized correctly you will be fine.Good luck with your project and keep us informed.
  • Jody_SJody_S Posts: 9Member
    Oversized boiler

    The boiler that went in did have a two stage burner so that helped somewhat but as with any oversized boiler application short cycling is a concern.

    Jody S.
  • SnowmeltSnowmelt Posts: 1,061Member

    Last post was right about a heat lost, I can't possible do a heat lost in all homes,

    However the navian unit can ramp down. So let's say you needs 20,000 btu for heating it will mudulate down to 20,000.

    That being said, you have to make sure your baseboard or "heat emmiters" are sized correctly. You want them oversized so the boiler condenses.

    The other thing you want is to make sure you buy the outdoor reset, remember just because you have a HE boiler doesn't mean your getting it's full efficiency. I only say that because I just came back from a job where they had a very expensive system and it wasn't used to its fullest potential.
  • KenryKenry Posts: 2Member
    Water Filtration and gas conversion

    I currently have oil heat and water baseboards. The oil tank is leaking so we are considering a conversion to gas. Our oil supplier will do it but says that in our area Truro MA 02666, on well water, they will not warranty the equipment unless we put in a water filtration system that will cost about $3,500 dollars. He says the iron in our water is high and will deteriorate the pipes. My neighbors use another fuel company and when they converted this was never even mentioned. I have tried to do research and can't come up with anything helpful.

    Can anyone speak to this issue? Thanks!
  • SWEISWEI Posts: 7,356Member
    Fill the system wil clean water

    from a barrel if you have to.  Once it is plumbed tight and purged of air, it should hold pressure for a year or more -- no need for a permanent connection to the domestic water supply.
  • KenryKenry Posts: 2Member
    water filtration and gas conversion

    Thank you for your suggestion. I'm being told that I will not be able to get a warranty on the system unless I install the water filtration system.
  • SWEISWEI Posts: 7,356Member
    Whoever is telling you that

    probably believes that hot water heating systems need constant make-up water.  They're wrong.
  • jonny88jonny88 Posts: 1,139Member
    there is your answer

    doesnt get much clearer than that.Do yourself a favor and take some good advice from Swei,I have in the past.
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