Is IBR effected by derating

Mike T., Swampeast MO

With a calculated heat loss of 48,000 you won't find any condensing/modulating boiler that "cuts it close"--they'll all be quite oversized.

DHW won't be a problem unless you have a large peak demand like a big tub or a multi-outlet shower. In the case of high peak demand, use a larger storage capacity indirect...

Bob Sweet

derating

Heat loss is 48,000, want to use Ultra 80 (IBR 62,000) with indirect.

Domestic load is not an issue, concerned about deration(5,000 ft) I really want to cut this close, it's my house, not a customers, am I to close?

Thanks.

Tony_23

You'll be fine

Remember, IBR allows for pickup of the boiler and piping. The boiler pickup is damn near instant, and the piping is too if you use ODR and insulate the runs.

Radiant or Bbd ?

Bob Sweet

BB

Tony, BB

Tony_23

Existing ?

Or do you have the luxury of sizing it for low temp operation ?

Bob Sweet

Well I could but,

am sinking some funds into tightening the envelope as well, BB is at design temp, so hoping modulation along with envelope will reap some benefits.

Mike T., Swampeast MO

Sorry--missed altitude for some reason...

From Ultra literature:

"For altitudes from sea level to 5,500 feet above sea level, the Ultra boiler requires no modifications and automatically derates itself by approximately 4% per 1,000 feet above sea level."

Even simply from I=B=R of 62,000 at sea level with 20% de-ration you still have 49,600 with a computed loss of 48,000.