Boiler sizing using HDD Therms

mtnheat

SWEI: certainly throws a wrench into calculations if the manufacturers manuals can't be trusted. at the moment, my focus is on mod-con boilers and the actual de-rating per 1000'.

Paul48

In fairness to the distributors.......who could afford to stock huge dollars worth of parts? How about......Can I have it tomorrow?

mtnheat

my inherited boiler NTI T150 when i bought the place from the bank...(so no history from prior owner)
typically been good with getting a part tomorrow.
never been good with bringing the manual to a "tech" with the clock running to discern an issue... just me....(maybe you too)
definitely not slamming any techs by any means....
system pros are system pros ! mod-cons are finicky and not ubiquitous. now looking to replace the NTI, age and issues.....prefer to have, readily available solutions.. it gets cold up here...glycol can protect fin tube in the dead of winter...solutions and response are key..

NYplumber

How about a NTI TX81?

Zman

This is exactly right. Incorrect altitude derations in install manuals are pretty common.

In your area, you will find parts readily available for Lochinvar and Triangle Tube.
HTP in the past has not been as well supported. You might inquire at the local wholesaler (Ferguson) as to availability of parts.

mtnheat

NYplumber : i'll take a peek at the TX81 BUT getting the T150 properly serviced has been a struggle so inclined to look elsewhere.

mtnheat

Zman: how does one know the actual derate if the manuals are incorrect. at 8000' the difference in boiler sizing can be significant if the de-rate is 3.6% or 1.8% or zero. are you in this neck of the mountains..?

NYplumber

Mtnheat, i would stay away from the Korean heat exchangers and stick with something proven.

hot_rod

Check around the wholesalers up there to see which brands are most common. The chances of finding parts on the shelves or the various plumbers trucks around the valley will be much better if there are predominate brands sold.

The rep firms behind the boilers can make a difference, they keep common repair parts on hand, and stay current with factory training.

Counter guys are not usually shy about giving an opinion on what works and gets supported.

Zman

SWEI said:

NY_Rob said:

I just looked up the high altitude notation for the HTP UFT-80W...
"The appliance will de-rate by 4% for each 1000 feet above sea level."
So the 80k BTU boiler is actually a 54k BTU boiler at 8'000 altitude.

While it may be in the manual, that number is almost certainly incorrect. I have ASHRAE papers from 1933, 1952, and 2007 on the subject and current consensus among industry experts is something like 1.8% per 1,000 ft ASL for a natural draft appliance. The "high altitude versions" may or may not run better than the standard versions depending on burner design, gas composition, and altitude.

Fan-driven neg/reg appliances typically quote 2% per 1,000 ft but the real number is lower and really depends on the specific fan performance (it's close to zero in some.)

SWEI explains this perfectly.
When I see one that is not in this range I usually contact a rep familiar with altitude to get the correct info.
I don't work in your area but I am very familiar with your altitude and higher.
Shoot me a PM and I would be happy to discuss.