How oversized and the difference?

SpeyFitter

So I'm going to retrofit radiant floors into my house with a Lochinvar WB050 more then likely. Got a 6 year old furnace I'll be ripping out. Just happened to check the rating plate recently, and no wonder it short cycles so well, it's a 66,000 BTUH input, approximately 52,800 output BTUH furnace serving a house with a 17,698 BTUH heat loss ( and today is a shoulder day too).

So this got me thinking - for those of you guys who are doing re & re's - what is the most oversized piece of equipment (i.e. Boiler) you have replaced? How much smaller could or did you go after doing an accurate heat loss? And if you had the fortune of checking, how much of a difference in gas consumption did this make?

Timco

retro jobs

I have pulled 400K units (snow-man units) that were serving a 120K degree day load, and the gas bill went from 600 to 275 mid january...and that was using a CI nat draft boiler, not a mod con.



Tim

The Steam Whisperer (Formerly Boilerpro)

I got one even better

Pulled a 3,100,000 btu/hr hot water boiler and replaced it with 2 Prestige  250's and added the Hot water load to the boilers..  Heating load was about 350,000 btu/hr input.   Not sure about the savings because this was only one of a couple of heating plants on the same meter.   Our local high school was running about 15 million btu/hr input and had a load of about 3 million.

Boilerpro

Mark Eatherton

Personal experience.

In my house, I installed my "Y2K" system in 1999. Used a stand alone tank style water heater (GASP!!!), and connected it to a gravity circ one pipe system with Buderi panel radiators. It had a circulator on it, but it was designed for forced circulation, but could provide minimal heat with gravity if needed. Y2K came and went, and nothing happened...



Switched over to a 50 K ModCon Munchkin (DOUBLE GASP!!!) and watched my fuel consumption drop a total of 60% over the 150K GFA furnace that was displaced.



Actually, my boiler is half as large as the calculated heat loss would have had me believe, and I have NEVER been uncomfortable at design condition.



Now, as a contractor, I wold NEVER consider installing an appliance that was half as large as the calc's called for, but in my house, in my own back yard, it was not a problem.



These days, with the ability of the appliance to modulate down to the load, but in your case, you load is so small that I would consider a buffer tank to avoid short cycling during shoulder season loads....



Commercially, I have displaced 1,500,000 cast iron boilers with 600K worth of modcon and watched the energy consumption drop by 40%.



ME

bill_105

Definition?

What's a shoulder day? The dictionary didn't help. I'm thinking real close to design day. Where is Weezbo?

shoudabeenaplumba

my own house

I currently have a 164k ouput boiler serving a 90k heat load.  Funny thing is the boiler was installed before a 900sqft over-garage addition and an 800sqft finished basement.  It was at least tripple what was needed.

My first house had a 250k boiler with a modified gas burner installed.  When the previous owners split up the utillities for the 3 family they installed gas space heaters, but left the downstairs baseboard / monoflow system.  I don't think the circulator was ever used, just a big warm cube in our basement.

Steamhead

A shoulder day

is one that isn't very cold- so you just need a bit of heat to take the chill off. The amount of heat needed in the dead of winter is much greater, and on a graph that period looks like someone's head with the fall and early spring on either side as the "shoulders". 

Steamhead

We just did one

where we replaced a 100 MBH input gas hot-water boiler with a Burnham ES-23, and are going back to replace the 40-gallon/40 MBH input water heater with a 40-gallon indirect. Total input will be 70 MBH for the entire load, which is half of what it was. The heat loss was 38.6 MBH. Look for pics when we get everything done, and fuel-savings figures at the end of the heating season.