Atmospheric Boiler AFUE

Steamhead (in transit)

from a wet-base boiler with a power gas burner. The dry base in an atmospheric boiler just loses too much heat. Also, atmospheric burners need more excess air than powered ones to burn cleanly.

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JackR

Energy Star

I was looking at all of the manufacturer's for a atmospheric boiler that hit 85%, the threshold seems to be at 84%. Does anyone know why they can't squeak out 85% to make it energy star? I know it would certainly require a liner but is there any other engineering reason? I'm not looking for 87% just 85%

Just Curious..

JackR

Wouldn't that depend

on the manufacturer? I've seen some with little refractory, burner floor pan or insulation and some that were very beefy with a lot less loss from the underside. I think Burnham was one of the few that had a very beefy base the least loss from the underside.

Kevin__Flynn

85.5 AFUE

The Viessmann Vitogas 100 GS-1 Series has an AFUE of 85.5% and is a Category I, chimney vented appliance. It is also an atmospheric boiler.

Kevin Flynn

Uni R_2

85%?

And what's the seasonal efficiency of this 85% boiler? And what would the true efficiency ratio of a modcon be in terms of house ratios, conventional NG vs modcons? It is probably at least 4 to 3. It's almost the same as if the demand of every fourth house on every street in NG neighborhoods was completely removed from the gas line, if that became the norm for changeouts. Seems wise to me. Will they require more to service? Well that's what we'll see over the next few years. Service is steadier income so even if there are some glitches on the way to heating our homes more efficiently, so be it, we'll be moving in the right direction.

These modcons for the most part have integrated controls that allow you to maximize comfort and savings at the same time.

Do you plan on using a buffer tank? If you don't then you won't be able to heat the house nearly as comfortably or efficiently in the shoulder seasons.

You could be somewhere in the middle of a modcon and an atmosheric ng if you were to be heating a buffer tank using a wide differential allowing long enough burn times. The zones could all draw and mix using something like iSeries mixing valves. You can do 6 temps or more temps and their own curves if you want to. Each valve is maybe aorund $300... that a pump and a t-stat. It has a simple ODR curve and outdoor sensor. Then any zone takes mixed water off the buffer tank. The buffer tanks differential at the bottom being the highest temp demand zone. An indirect could be integrated into this. The heating loads in zones and houses as a whole are simply too small in the shoulder seasons for ng fired equipment. They condense at below 140 F, which isn't very hot to heat a home in April and May. You either condense or the temperature yoyos.

Using a buffer would help but if we really want to reduce consumption of natural gas this industry should really be pushing modcons as the way to go.

Steamhead (in transit)

There are three problems

with an all-mod/con strategy:

1- Some mod/con heat exchangers have been failing after only 5 years. Like it or not, the average consumer won't stand for that.

2- Exhausting a mod/con is critical, and not all buildings offer a proper and safe place to do this without extensive modification. There have already been CO deaths from improperly vented mod/cons. Granted, some of this comes from installers not reading instructions.....

3- We don't have mod/cons for steam systems.

The wet-base power-burner boiler is a more efficient alternative to the atmospheric unit, and can use a standard chimney. That's why we use them instead of the atmospheric.

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