Help with condensing boiler

[Deleted User]

IF you want to reduce your energy bill by 30 to 50 %...

Otherwise, stick with the 80 percenter.

ME

Mattr1

Help with condensing boiler

I am in the process of getting quotes to replace a 30+ year old oil boiler with a new nat. gas unit in upstate NY. One contractor has giving me quotes for a cast iron 81.6% Dunkirk Plymouth and another for a Dunkirk Quantum 90. My home has three zones - the largest being cast iron baseboard and the other two copper fintube. I've been trying to educate myself on this board about the high-eff. boiler but seem to get more confused the more I read...corrosion in the system between aluminum block and cast iron baseboard, loss of efficiency because the baseboard needs higher temps and boiler needs low water return temps. to condense, etc.

Could someone help explain if a high-eff. condensing boiler should even be considered with my existing system? I'm sure it's not a straight forward answer but any additional information is helpful. Thanks

Matt

Dave Yates (GrandPAH)_1

it depends

The first most important step (IMHO) to help make an accurate assessment and determination for which one is best, is an accurate heat loss. Baseboard (CFT) can be operated at lower temperatures without any problems - if there's enough of it installed (lineal feet).

We've been installing the high eff condensing modulating boilers for several years in homes with CFT baseboard and haven't yet had any problems. The heat loss calculations allow us to determine how low we can go (temp wise).

New slant fin low temp output numbers were posted here a few weeks ago, which will now allow us to take our outdoor reset to new lows. Chances are you'll be able to stay within condensing temperature ranges for 80% to 90% of the heating season.

But - it all depends on the heat loss calculation. That's the foundation from which to build. Our customers are seeing the savings ME posted above.

Unknown

Energy savings

I am curious on the type of systems which were replaced to gain the 30% to 50% energy savings. Were these cold start systems, or boilers which maintained temperature at all times. I can understand the savings if the boiler is at constant temperature and therefore suffers from substantial standby losses. I am less clear on the amount of savings if the boiler sits cold most of the time consuming no energy.