DOE efficiency testing

The Steam Whisperer (Formerly Boilerpro)

Here's a little bit of interesting reading, circa 1993.



<a href="http://www1.eere.energy.gov/buildings/appliance_standards/residential/pdfs/furnrbod.pdf">http://www1.eere.energy.gov/buildings/appliance_standards/residential/pdfs/furnrbod.pdf</a>



It is interesting to see the politics revealed here.  Also, the sandbagging of the Energy Factor idea to provide more realistic efficiency numbers versus AFUE.  It is interesting to see how the forced air industry is so opposed to the improved standards and has blocked changes for nearly 20 years. By my calculations, they efficeincy Ratings of hot air furnaces would drop about 6%  with the Energy Factor standard, while hot water boilers would drop slightly and steam boilers almost not at all. 

Henry

Changes

Things have changed since then and more scientific findings have been introduced. There is no way steam can compete with hot air units for energy efficiency! The return duct temperatures versus output temperatures insure condensation. It is just so easy to do it with hot air furnaces. One gets at least 92% and with a modulating blower and combustion over 96%. I am half of my neighbour's conventional units consumption and that includes stove and BBQ!

The Steam Whisperer (Formerly Boilerpro)

I am guessing you didn't read the info.....

the more scientific findings are the very thing the forced air industry fought, and is still fighting.  Some of the top research facilties in the country have supported some of the changes requested here and there are recent articles in energy efficiency publications discussing the problem.  You have pointed out only combustion efficiencies, not overall unit efficiency that includes electrical consumption or, to expand further, system efficiency.   The 6% reduction in efficiency of forced air furnaces would only account for the electrical consumption loss, not the additional system losses.  This parasitic elecrical consumption is virtually nonexistant in steam for most home gas fired boilers.

There's a whole lot more to true efficiency than the current AFUE, or combusiton efficiency.  

ChrisJ

electrical consumption

Ah yes, something steam boilers do very little of.



I'm curious, what is the typical consumption of the blower on a forced air furnace? Maybe in the 80-100K output range?

Jean-David Beyer

what is the typical consumption of the blower on a forced air furnace?

I have two Rheem 125,000 BTU/hour forced air gas burning furnaces. They have the fire and stuff on top, and a blower and the electrics on the bottom. They each have a Honeywell high voltage electrozapper air filter; I doubt the air filter uses much electricity.



We heat one zone to a minimum of 55F about 6 days a week, and 65F on the seventh day. We heat the other zone to a minimum of 45F 6 days a week and 65F the other day.



We also use electricity for a small hot water that is allowed to run only one day a week. It is also used for lighting, and electric stove that is used about once a month, and a microwave also used about once a month.



We use gas only for heating with those furnaces. I will put the therms for the corresponding month is in the first column. The months do not coincide exactly. You should be able to guess approximately the electrical cost of the heating system from this. I am not sure why the electrical bill was so low in Jan-Feb.



239 Our electricity bill for December 10 to January 11, 2012 was 567 KWH.

233.Our electricity bill for January 12 to February 09, 2012 was 65 KWH.

120 Our electricity bill for February 10 to March 12, 2012 was 292 KWH.

 64 Our electricity bill for March 13 to April 12, 2012 was 159 KWH.

 23 Our electricity bill for April 13 to May 11, 2012 was 138 KWH.

Steamhead

I've posted these links before

but here they are again, showing the problems of duct leakage and pressurization/depressurization of rooms. These are two factors that greatly reduce the efficiency of forced-air distribution:



http://oikos.com/esb/28/duct_losses.html



http://oikos.com/esb/44/forcedair.html



A steam system does not have these losses.

ChrisJ

consumption

Mr Beyer,



i was hoping for a wattage rating on the blower or a typical draw.

The Steam Whisperer (Formerly Boilerpro)

And here is another 166 Page report on ductwork leakage....

comparing non-ducted and ducted systems.



[u][size=12][color=#0000ff]http://www.ornl.gov/info/reports/1991/3445606042546.pdf[/size][/color][/u]

The Steam Whisperer (Formerly Boilerpro)

and another (fall 2010) addressing the same problems as in the 1993 AFUE standards..

http://www.nxtbook.com/nxtbooks/naylor/PGAQ0310/#/22



I spoke to one of the authurs for quite some time ( she is a researcher at the Gas Techonology Institute...an international research center for the natural gas industry).  It appears that a new standard may be on the horizon.   Energy professionals have been trying for a couple decades now to get the AFUE standard changed to a more realistic picture of energy use.

I also spoke to engineers at AHRI and they also acknowledge this problem.

Steamhead

Depends on the motor size

but as an example, I looked up a 1/3 HP, 3-speed, direct-drive PSC replacement blower motor, and it was rated 4.2 amps at 120 volts.

Jean-David Beyer

hoping for a wattage rating on the blower or a typical draw.

I thought actual consumption might be more useful because you get hours of blower use as a function of therms burned. With the wattage rating, you do not know how often and how long the blower(s) operate. If I had a 10 KW blower that operates only 2 minutes a month, that might not be much, but if I had a 500 watt blower that ran all the time, that would be more electrical energy used.



I would have to go in and open up one of the furnaces to look at the name plate of a blower motor. And I am not sure if that would be enough, since the motors can run at three different, manually set, speeds, and I do not know what speed they are set to (I think the highest). Done by wiring, not a convenient switch. I do not know if I can even see the name plate, since the motor is inside the squirrel cage, if I remember correctly.



Is it not possible for a heating professional to figure out the power of the blower? If the blower must move 125,000 BTU/hour and the medium is air, you might be able to calculate the minimum blower size required. Of course it would be more due to the resistance of the supply ductwork and return ductwork.

The Steam Whisperer (Formerly Boilerpro)

These meters are very useful..

http://www.p3international.com/products/special/p4400/p4400-ce.html



Start testing all sorts of things and you'll usually discover some real power hogs.

Jean-David Beyer

meters are very useful

They sure are. But not for my boiler at home (hard wired in) or the furnaces at my Quaker Meeting (also hard wired in). Other techniques are needed for things like that.

BobC

I own one of those

and they are very handy for measuring the power use over time. If you leave it hooked up for a full day then you will know how many watts were used over that day for whatever it is hooked up to. They can't be used on 3 phase circuits because they are only rated for 120v.



If it were rated for 240v you could use two of them to get the true power draw of a 3 phase motor - http://www.scribd.com/doc/7252617/2-Watt-Meter-Method  I used this method all the time to measure the actual power consumption of 3 phase equipment.



Bob

ChrisJ

watt meter

I have one of those kill-a-watt meters.  I originally bought it for testing my 1930s monitor top refrigerators.  Crummy PF of 50, but wattage draw of only 120-140W.  Not bad for an 80+ year old refrigerator

The Steam Whisperer (Formerly Boilerpro)

Yep...

I temporarily unhardwired my boiler to check power usage.  If you have an electrician around, he/she could do the same for you.