Philtrap
Member
Thanks for your time Dana - I have a graduation this weekend and will have to get back to you on the heat loss numbers. My neighbor sized it up and has them and he is using the same unit and has a very similar home.
It could but ain't that just throwing heat out the door?
I'm not sure how to prescribe a solution without knowing the system or the actual heat load.
The neighbor's AWOL heat load calculation but it doesn't take a huge amount of information to put an upper bound on the heat load, or the min-temp you'd likely be able to run without short-cycling at min-fire. The notion that the smaller boiler wouldn't cut it is dubious at best- it would even be adequate for most houses in Minnesota, where the design temps are into negative double-digits, even for the same 1950s vintage housing stock so ubiquitous on L.I.. Anything built since 1980 or so usually has even lower heat loads.
Faith-based sizing leaves too much to be desired though:
"He has the loss cacl's somewhere, but could find them during our 5 minute talk last night and I don't think I really need them since he already did them and determined the unit to be the correct size. I think I'll be fine with the 110."
Really? No numbers, no descriptions of construction or size, or the size of the radiation, just an abiding faith in a neighbor? He must be a nice guy and all, but something is really wrong here- most averaged sized houses in ALASKA that would never need the full output of the -110 and could manage just fine with the -60. The true heat loads of most mid-sized houses with OK windows on L.I. pencil out to something a bit shy of 15 BTU/hr per square foot of conditioned space, using reasonable design temps. Even at non-condensing temps the -60 puts out about 54,000 BTU/hr, which would cover a typical sorta-code-min house in the 3500-4000' range, or a tighter-than-average house with better windows in the 5000'+ range. Can't fault the newbie for being easily led down this path by the licensed HVAC guy who should have known better, but oversizing still seems to be the rule rather than the exception in the hydronic heating trades- practically a TRADITION.
I'm not sure why it's so difficult to convince people that their heat loads are as low as they really are. It may have something to do with the tradition of oversizing cast iron boilers by a minimum of 1.5x. Most I see are around 3x oversized for the actual loads, and 4x isn't rare. While oversizing cast-iron by 1.5x has no real down side, there's an efficiency penalty at 3x. The downsides of oversizing mod-cons by even 1.5x are more dramatic, throwing away the potential efficiency & comfort you might otherwise get out of it, and for no good reason. This forum and others are rife with examples of misbehavin' systems where the boiler is too big to heat the place efficiently, where the contractor or homeowner upsized it a bit "just to be sure". In some cases it's easier to just crank up the temp to make the problems go away, turning a 95% AFUE boiler into an 85% as-used AFUE boiler, but it's a shame when it comes to that, a situation I'm hoping philtrap can avoid with a bit of corrective steering.
Call the manufacturer and ask if the one you have can be converted and what it costs...
This is awkward, but...
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