New boiler sizing

Steve_111

I have a 1964 vintage Bryant boiler (128K btu in/100k btu out) w/baseboard & seperate 50 gal. hot water tank. Both have been reliable but low in efficiency. The house on Long Island NY, built in 1964, is a 2300sf 3 level house, poorly insulated (R11? walls/attic) w/newer double glazed vinyl widows and newer insulated outer doors and light foam insulated vinyl siding. I was looking to replace both with a much more efficient system possibly a Munchkin combi. I originally thought that a 140m (up to 140k) with a 60 gal hw tank would be needed. I have been told that that is oversized and an 80m/45gal would be more than sufficient. I have heard good things about Munchkins.

Are any of these other systems (Rinnai, Trinity, Buderus, Argo, Baxi, Viessmann, etc.) as good or better?

Thanks

Tim_24

Sizing the boiler..

without a sufficiently detailed load caluation is simply guess work. If you are going to hire a professional to do the work, see what the calculate (i.e. ask to see the calculation).

However, if your present boiler is already oversized at 128MBH, why would you consider installing a boiler that even more oversized 140MBH? On what was the 80 MBH size based?

Many opinions to follow on the brands.

Constantin

Here is what I would do...

First, try and locate the best installer for the job. Ask around, get references, check references. One place to start here is by clicking on Find a Pro. Next, have said professional do a room-by-room heat loss calculation for your home. Armed with that information, he/she can then evaluate your home heating and insulation options.

For example, there may be areas that could use supplemental emitters to allow a condensing boiler such as the one you suggested to operate optimally year-round. If you're so inclined, you can also download a free heat loss calculator from Slant-Fin or buy a two month license of HVAC-Calc for $50 to enjoy the trials and tribulations of calculating heat loss on your own as well.

The heat loss calculation is a crucial step because it will allow you to optimize the heating system and the home, not just the boiler. For example, you might discover that adding insulation in certain areas will allow you to reduce the boiler size and/or the energy consumption significantly. Some heating contractors go as far as bringing their own blower doors to determine infilatration rates, leaks, etc. Once you optimize the shell you're living in, you can set about optimizing the ways to heat it.

Lastly, go over your boiler choices. There are many brands out there to choose from, and you're usually best off going with a brand that your installer is very familiar with, for which parts are locally available, etc. Within the brands that your installer of choice is familiar with, I would choose the one that has the most features you want and are willing to pay for.