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# How do you determine the input rate?

Member Posts: 77
and came across a chart that is used to determine the input rating. It had me counting seconds per one revolution based on the size of that gas meter dial.

I did that and I am not sure what to compare it to. The manual wasnt to clear on that, it looked chinese to me. Am I supposed to compare that too the BTU rating on my steamer?

I am not sure if my steamer is over or underfired or just right and I would like to check for myself

• Member Posts: 491

The chart should have BTU ratings depending on how many seconds it takes for one revolution of the meter dial.

S Davis
• Member Posts: 77
yes they have ratings in small numbers

like 90,110,125,etc.
• Member Posts: 491

Those numbers would be in thousands of BTU's.
Hope this helps.

S Davis
• Member Posts: 77
Ok now that I know that

I need to compare that reading to the steamers BTU input rating or or the output rating?
• Member Posts: 491

That would be input.

S Davis
• Member Posts: 77
So I guess what i come up with should be within

range of what the steamer is rated for?? Is there a + or - range compared to rating and what I am actually getting?
• Member Posts: 491

It should be pretty close within a thousand BTU's or so,as long as you are pretty accurate when clocking the meter.

S Davis
• Member Posts: 77
Ok i will try to reclock it in the morning

what if its off by a few thousand (more or less) is it a big deal? Maybe the steamer was set that way on purpose. My operators manual says you can adjust it..
• Member Posts: 491

Usally I try to get an appliace within a thousand BTU's or so but it's not that big a deal as long as your close.

S Davis
• Meters measure in cubic feet per hour

your equipment is rated in BTU's. What you clock on the meter in seconds per revolution has to be converted to BTU's from cubic feet. In order to do that you need to know the heat value of a cubic foot of gas in your area. The local utility can give that to you. As a ball park figure you can use 1,000 as a heat value. So as an example let us say that you let the 1/2 foot dial go around twice and it takes 20 seconds, you can divide 20 seconds into 3,600 (# of seconds in an hour) that would give you 180 cubic feet. You then multiply 180 times 1,000 which would give you 180,00 that would be what the equipment is burning in BTU's. It is okay to slightly undergas (underfire) a piece of equipment but you never want to overgas (overfire).
• It is a big deal when

overgassing can cause CO. But what a lot of people do not realize is that underfiring can also make CO. How close is close, as close to the rated input as you can get a 1,000 btu's either way is too much. One of the best ways to determine if you have the correct input after clocking the burner is to do a combustion test. If you do not test you do not know.
• Member Posts: 610
or...

you could look at your last gas bill, they will list on it somewhere the average number of Therms (1 Therm = 100,000 BTU's)per hundred cubic feet (CCF), for the billing period say 1.02 Therm per CCF, which would be 1020 BTU/cubic foot. It will vary slightly from month to month, so the firing rate will change month to month a bit too, though not enough to worry about. 1000 BTU/cubic foot is a good assumption though.

The gross output rating on the boiler nameplate reflects the input rating times the nominal efficiency, the I=B=R rating reflects the gross output less 33%(or less 15% for hot water) pickup factor (heat loss from and heat used to heat the piping).
• Member Posts: 491

If you are within 500 Btu's either way you are fine, and yes a combustion test and also gas pressure check is required to know for sure, as I have found clocking the meter is not always very accurate.
But for reference to see that you are not way off it is ok.
I guess I did not make my self very clear. sorry

S Davis
• Member Posts: 83
\"Clocking\"

A gas appliance is really pretty simple. Shut down all other gas apppliances, turn up the thermostat on the boiler at least 5-5 deg. higher than the room temp. to insure that it will keep burning. Count the number of revolutions on the meters 1/2 cubic foot dail for exactly 60 seconds. The 1/2 foot dial is divided into 10 (.10) segments so you just add however many segments beyond each revolution it revolved, such as 2.5 or 3.8 etc. Multiply the number of RPMs by 30. This is the actual consumption in cubic feet per hour that the boiler is is burning. 2.5 X 30 = 75, or 3.8 X 30 = 114. In most areas natural gas has a heating value of around 1000 BTUs per cubic foot. So the number you came up with is also the number of BTUs in thousands of cubic feet per hour of input.
In the above examples, 75 would be 75,000 BTUs/HR and 114 would be 114,000 BTUs/HR. Keep the math simple and you will be extremely accurate.