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Anonymous
10-07-2002, 05:39 AM
OK, here are some real world energy usage numbers that are based on my ADC-236 dryers. Over a period of time I had 192,478 dryer cycles of 8 minutes each. That comes out to 25,664 hours of dryer usage. I have neglected the fact that they have a 1 minutes cool down, as it is hard to figure how many last cycles there were. During that same period the total BTU usage for the store (therms converted to 100,000 BTU) was 1,509.4 million BTU. If we convert that to BTU/HR we get roughly 58,800.

Now here is the rub if you would - I have made the totally false assumption that ALL gas was used by the dryers and that no gas was used to produce hot water or heat the store in the winter months. I know this is wrong, but it helps to make my point. Even with that assumption the gas usage is much less than the 80,000 btu/hr rating on the dryer. Thus, dryer gas usage is probably less than half of what the nameplate rating for gas consumption says.

I would assume that the actual gas for the dryers was significantly less than half my total gas usage as for the bulk of this time I was running with a 40 year old water heater rated at 1mm btu/hr and have gas heat in the store.

Gary C
10-07-2002, 07:18 AM
Kirby

The reason it's much less than the 80,000 is that it's a per operating hour rating. So the only way you would use the 80,000 is if the burner was on the whole time it was running. even during the winter where I live the burners only run 70% to 80% the time needless to say summer is much better. Thats why I think the only way to run a real efficancy test on a dryer is to draw all the air from a temp. controled room. Then you would have a constant. I am assuming you know that allready but many do not know it's a per/hr burn rate at full burn.

Gary

Fred50
10-07-2002, 07:58 AM
The manufacturers that I have spoken with state a real world usage of 60% of the stated rating / hr. This takes into account cool down time and the cycling that Gary mentioned. There should only be a minor difference between 8, 9 or 10 min cycles.

The big question is, how accurate are the manufacturer's advertised ratings???

Is the same independent lab comparing all dryers using the same controlled environment? I highly doubt it, so as always caveat emptor.

Anonymous
10-07-2002, 09:22 AM
That is the point I was trying to make, that you cannot compare dryer operating costs based on stated BTU/Hr ratings. The incoming air is a big factor as is the relative humidy and the clothing load in the dryer. I know it will never run all out, I don't even think the burner is on 50% of the time. My dryers have a little light that tells when it is firing, and I see them off more often than on.

Air flow effeciency in the dryer as well as good supply of make up air have a big factor on efficiency as well.

Rondo
10-07-2002, 11:19 AM
Kirby, you hit on the head and not to mention you need plenty of oxygen for the burners to get the most BTUs out of the gas you burn. Even if it is cold air