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can't decide modulating boiler or no?

I've been given estimates from 2 HVAC contractors. The first gave me 2 prices, one price was for a modulating boiler one for a conventional boiler. Because the modulating boiler is eligible for the $1500 tax credit it cost nearly the same as a conventional boiler. This seems like a no brainer right?

The second contractor did a heat loss calculation which the first didn't. He also asked a lot of questions about the houses insulation (blown in cellulose). This fellow tells me that due to the design of the house (it was built in the 1920's) it wouldn't make sense to install a modulating boiler because it would be running full blast most of the time and because of the increased repair/maintenance costs I would be better off installing a conventional boiler.

So what do I do? Do I spend the same amount of money to install a less efficient boiler to avoid future maintenance costs?

Thanks in advance for any advice/thoughts/wisdom, Mick


  • Tim McElwain
    Tim McElwain Member Posts: 4,628
    edited September 2010
    First of all any boiler

    requires maintenance at least once a year. Most boilers today are Electric Ignition so parts can be expensive and many times it is tough to find someone who can troubleshoot them correctly. Many of the Mod/Con's however do require a little more service in that they have to be taken apart and cleaned.

    What kind of emitters do you have in the house radiators cast iron baseboard convectors or finned tube baseboard?

    The second contractor did a heat loss which is a good thing. Typically with insulation blown in the heat loss on the house has gone down so you can often run the emitters at a lower temperature helping for condensing to take place in the boiler. In the long run with ODR (Outdoor reset) and other features such as primary/secondary piping or by using a low loss header you can drastically improve the over all efficiency and give you a fairly good return on your investment.
  • harpin_mick
    harpin_mick Member Posts: 2

    Our house has finned tube baseboards.

    Thanks, Mick
  • Tim McElwain
    Tim McElwain Member Posts: 4,628
    Have your contractor determine heat loss per

    room and then measure the baseboard if it is more than you need as to BTU's per lineal foot versus the heat loss then you lower the temperature to the baseboard without losing the required BTU for each room. With the Mod/Cons you need to get return water temperature below 120 degrees. So if you can run baseboards at say 140 degrees you will have plenty of heat. If not then add more lineal feet of actual finned baseboard so you can lower the temperature to it.
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