Oversizing energy waste....

kcopp

I went Friday night to look at some gas piping for a job...
2100 sq ft house, Tri-level, split level ranch. had a Weil Mclain GV-5 (140k input) running baseboard to a 50 gallon indirect and about 50' of hot water baseboard... criminally oversized boiler.
Anyone have some thoughts or a study as to how to figure the waste associated w oversizing a boiler?

nicholas bonham-carter

Maybe they use a lot of hot water?
If you can wait until the design day, when the perfect size boiler would run constantly, then a timer on the boiler would provide the percentage of actual run time to the ideal.
Do they have outdoor reset, and combustion air?--NBC

Aaron_in_Maine

Everyone that posts on here has seen this. I serviced a 1000sqft ranch that had a 7 section HB Smith boiler running 1 zone of heat and hot water off of a coil.

RJMCTAFO

Yep. The worst I have seen is an 1100 sq. foot ranch with a 3 year old Biasi B10-6. The plumber said they don't have to worry about it being big enough to put heat in the basement.
I said they could heat their house and the neighbor on either side.

kcopp

So great... is there either a rule of thumb or a formula to determine how much efficiency they lose by having a boiler so oversized....?
ty,kcopp

KC_Jones

Is it only the wasted fuel, or potentially wasted fuel? What about equipment longevity? If it is cycling incessantly doesn't that shorten equipment life? That would be almost impossible to figure out, but in my opinion it matters. Tell someone they will save a couple dollars a month on fuel they don't care, tell them they will need to replace the whole thing more often and they might care. Wait no they won't they want it cheap no matter what. Didn't mean to hijack this just thought that was another aspect of waste with respect to over sizing.