oil furnace setup

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Old 11-13-05, 10:10 AM
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oil furnace setup

When setting up an oil furnace you adjust the burner to specs, that ends that. Then you have vent temp and heat rise to set. Now is it more important to set vent temp for efficiency ,then let heat rise fall where it may or sacrifice some efficiency for higher temp rise. Is higher temp rise just for comfort or are there other issues involved.
 
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Old 11-13-05, 11:21 AM
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I wouldn't say adjust burner to specs, that ends that. The burner needs to be tested after set up with combustion testing equipment. Please explain what you mean by heat rise and vent temp?
Mike
 
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Old 11-13-05, 02:18 PM
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By specs I meant per manufacture specs, 0 smoke 11.5 CO2. By vent temp I mean heater exhaust, if you very fan speed it effects vent temp and heat rise, higher vent temp higher heat rise.
 
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Old 11-13-05, 02:32 PM
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Wink

You set an oil burner to specs First. Then with the blower control its more in what the people want are what you want. Set it so the air dont feel cool to you at the (vents) or "register". So its hard to say what temp for on and off of the blower as all homes and duct work are not the same. Then also a lot has to do with what speed the blower is set for.


ED
 
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Old 11-13-05, 02:42 PM
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I might not be explaining this right, the amount of heat that goes up the chimney is related to efficiency , if you very the fan speed you also change the efficiency.
 
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Old 11-13-05, 05:25 PM
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slls

The exhaust temperature does relate to efficiency but fan speed does not. Changing the fan speed will not affect the stack temperature. The biggest change in stack temperature is related to draft thru the fire side of the heat exchanger not the room air side. If the air/fuel ratio were changed to increase the CO2 to 12.5% the stack temperature would likely go down causing combustion efficiency to go up. If your furnace is approved for multiple firing rates, generally, the lower the firing rate, the higher the efficiency. Make sure you stay within the manufaturer's specs both for firing rate & temperature rise across the heat exchanger.
If you do not have combustion test equipment, don't start messing with the burner. To do so can create a hazzardous condition.
 
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Old 11-13-05, 05:34 PM
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The other part of the question you were asking is a little complicated and has to do with duct design and static pressures. It isn't really part of furnace setup except for selecting the correct fan speed for heat and cool. Too much airflow and too high of supply air temperatures cause uncomfortable living conditions. A nice easy movement of air at a low (110-120) makes for as comfortable an environment as possible with a warm air system. Adequate return air is one of the most prevalent reasons for airflow problems. Hopefully everything works in your system and the burner adjustment puts things right.

Ken
 
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Old 11-14-05, 02:55 PM
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Grady I found your comment on co2 set to 12.5 % interesting . I have Thermoflo CLB105 and the manual states set co2 to 10 - 11.5 %. Looking at the Thermo Pride manual it states 12 % would a good setting. Do you think it would be a good idea to set my to 12.5 % or stick with the manufactures settings, which is on the lean side. The firing rate for my furnace is nozzle size .65 .75 .85, I have the .65 in right now and being it will be another 5-6 weeks before we get the -10 to -20 below F its doing just fine. Being its my furnace I want to fine tune it. I don’t have a draft meter at this time, the chimney is a 40 ft masonry, If anything too much draft, I have the draft minder set in the middle. When the burner is firing it will draw a flame into the draft test port at the flame view port.
 
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Old 11-14-05, 03:31 PM
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KField the old furnace was installed in 1960, it was 112000 btu input an 95000 btu output. The duct that attached to the plenum are larger than the new Thermoflo CLB 105 that I installed. The heat side I had to down size about 1 inch on each side, and the cold much more, an inch on the sides and 4 inches on one end. The fan motor is ˝ hp, why so much I have no idea, the old furnace was 1\3 hp. The motor pulley is adjustable so I can change air flow. I have 10 heat registers and they all have flow control valves in the ducts. Compared to the old furnace the heat rise is not as much, the old furnace you could not hold your hand on the heat plenum a foot above the chamber or it would burn your hand , not very efficient. So far it is more comfortable than the old setup, got really hot then a cool down. I think the digital thermostat is helping in that regard, the temp only varies 2 deg. My concern was other than comfort the heat rise is not that important.
 
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Old 11-14-05, 06:13 PM
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slls

The fan motor is rated at high speed. On low it is more like 1/4 hp.
Unless you have a full combustion analysis kit including CO capability, I would suggest sticking with the 11.5% CO2. I have some equipment out there running at 13% or slightly higher & still have low CO readings BUT that particular equipment was designed to run with very high CO2 levels.
 
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