down fire Burdaru G215/6

Tim_61

I have a client looking for a home energy rating on a new home. He has a Buderus 215/6 w/Reillo 40F10 and 2.1 gph nozzle.
I requested a copy of the manual J that was done to size this boiler,
He was not familiar with the term, but assured me that an Engineer told him this was the right size.
For these ratings we use a program similar to Manual J. But we require the manual J as the tool for sizing a heating system.
My software is estimating a 65k heating load. After informing him that his heating system was most likely greatly oversized and that he should consult with his engineer or heating contractor. The response he received was that he could down fire to a 1.4 nozzle. (I still think this is to big, but I leave that up to manual J)
I've looked at the manuals for the boiler and burner and don't see this listed as an option.
My question, is down firing this an option and what would the heating capacity be in this condition?

Thanks

Robert O'Brien

No

as a rule these cannot be downfired. That's only 3X oversized,about average here!

Dan_15

I dont know anything about the 215/6 but my 215/4 is downfired by 10%. I was told by Buderus that up to 10% is permissible for this boiler and my heating guy (from The Wall) confirms this.

Paul fredricks_15

well

Even a 10% reduction is a long way from what you need. Bottom line: call buderus.

Robert O'Brien

Get

a few nozzles and break out the analyzer.You'll see you won't get very far.The stack temp will be in condensing range very shortly. I'd love to be able to understand the psychology behind oversizing,it seems to irresistible to a vast majority

Mark Eatherton

The urge to oversize is stronger than the urge to have sex...

in the field of ALL components. Dan Holohan said that, a LONG time ago.

Even if the contractor had a professional heat loss done, he looks at it and upsizes it anyway. The last thing he wants to get, is a cold call from the consumer... Fear or ignorance?

He doesn't perceive over sizing as being detrimental, an in todays modulating condensing market, over sizing is not a big deal, because the appliance CAN size itself to the real time load. Bit with an ON/OFF appliance, over sizing = fuel waste, and excess wear and tear in the controls/burner arena.

Even on jobs where the appliance WAS properly sized to the load, it has been my experience that in "real time" operation, the appliance only runs for 50% of the time at design condition anyway. So in reality, a boiler that appears to be 2 times as big as it needs to be, is really FOUR time bigger than necessary, which equates to short cycling, and excess wear and tear, extra service and poor fuel utilization. At that point, you really don't have many options to consider other than replacement.

Maybe you can peddle the used boiler on Craigs List or something.

Consider replacement with the new modulating technology whenever possible for maximum fuel savings.

ME

Tim_61

Thank you all
I also called Buderus as Paul suggested and the answer is no you can not downfire these units

scrook_2

Sheesh!

And even if you could fire it at 0.75 GPH it might still be more than enough.

2.1 GPH?! Sheesh! That's 3X the load!