What factors have caused boiler manufacturers to produce the siz

Mike Reavis_2

in the sizes currently offered? I am wondering about residential hot water boilers used with radiators, and baseboard. Are these sizes currently still practical? Do you adjust the heat input on packaged boilers?
Mike

Steve Ebels

Boiler sizes

I don't know what they use to determine sizes offered but I do know this. They all need to come up with some smaller btu input units. Lots of houses need 70K or less and the only thing that will address that right now is something that modulates. Even those are too big during shoulder seasons of the year like right now. Overnight here was 25* and supposed to hit 60* this afternoon. Heat load on house with 70K at design will probably be 6-8000 btus this afternoon. The only way you can address that and keep from short cycling the boiler is to add mass/water content or modualte the burner down that low.

Bill G

wait a minute!

There are other options other than large mass! what about outdoor reset? Allowing the boiler to respond to outside changing conditions as they happen. Here at Crown, we offer boilers as small as 37,000btu input on natural draft, and 61,000btu's in direct vent. Combine these small sizes with outdoor reset and the comfort level increases, as do the fuel savings. Just a thought!

Steve Ebels

37K huh?

What's the name of the distributor in Michigan?

As far as reset goes, yes it helps by reducing the water temp but you're still faced with input being much more than a shoulder season load. Maybe I'm looking for perfection but I'd like to see a heating plant be able to exactly match the load under any and all circumstances. Some of these new modulating boiler come darn close.

Boilerpro_3

Say Steve, ever looked at the Raypacks?

Thier residential units have had simple modulating gas valves for years that, if memory serves correctly, turn down to about 20% of maximum fire. Nice little boilers. May be what you're looking for!


Boilerpro

MikeTH

Take a look at the Baxi,

Hi Guys,
The BAXI LUNA range of boilers have been using an electronic modulating gas valve for 15 years, it will give full modulation from 105000 BTU's down to 35000 BTU's from a unit that hangs on the wall, and is the size of a kitchen cabinet.

The boilers have outdoor reset capability built into the logic on the controls, with the outdoor probe availlable as a plug in accessory. The heating only LUNA 1.31 is pre-wired to allow the boiler to prioritize a call from an indirect hot water tank. In this situation the boiler will override the output set by the installer to match his heating installation (the boiler can be set up to max fire in the heat mode anywhere from 35000 to 105000 BTU's)and ramp up to maximum for fast recovery to the hot water tank.

We have distribution across most of the U.S. and Canada, have a look at the web site to see the unit

Steve Levine

boiler sizes

Slant/Fin has recognized the need for smaller boilers for quite a while. In gas fired, atmospheric bolers the SENTRY series starts at 34,000 BTU/HR input, the SENTINEL at 70,000 BTU/HR, GALAXY at 75,000 BTU/HR. Power vent VICTORY II starts at 33,000 BTU/HR. Sealed combustion (direct vent) VICTORY VSPH at 60,000 BTU/HR, PRODIGY 21 at 50,000 BTU/HR, and CONCEPT 21 lowest input is at 34,000 BTU/HR.

Lower inputs for oil are more limited with the XL-200 staring at 91,000 BTU/HR, and the LIBERTY II at 105,000 BTU/HR. Remember, all of these are inputs.

I think the availability of these smaller sizes (especially gas fired) allows for selection of propoperly sized units for most applications.

More info at www.slantfin.com