Biasi B10-4 low stack temperature


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Old 11-23-09, 09:51 AM
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Talking Biasi B10-4 low stack temperature

Hello,
I am a noob here so pardon.

My system is a newly installed (by me) biasi, riello fired with Hydrolevel Aquastat cold start 180 (30 degree diff). It runs good but my stack temperature is extremely low. I have only used contact infrared thermo and got 150F at the hottest point of the flue. I know that is wrong way to measure and I am going to try bbq thermo tonight inserted in flue. I am getting condensation dripping down my chimney. My chimney is a 15ft high brick w/rectangle clay tile 7.25" by 7.25" opening. My draft over fire is 0 positive which is on point for the biasi. My draft at the breach is .03 which is in range but should probably be higher. Besides condensation, I know such low flue temps will eventually cause the system to get dirty too fast. My question is will a stainless liner fix this as far as flue temperature and condensation? I just ordered one today. Also all my settings on my burner are by the book spec. Thanks
 
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Old 11-23-09, 10:10 AM
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What are the combustion analysis readings? Sounds like it's underfired and/or way out of adjustment.
 
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Old 11-23-09, 10:20 AM
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Underfired meaning? The run times are also in range (also stock nozzle) And out of adjustment? The adjustments on the draft and turbolator are per biasi/riello. If I should change them I will. I don't have access to a combustion analyzer unfortunately. I spoke with QHT the importer of Biasi and the tech said a liner would help I am looking for confirmation or info on why that wont help. Thankd
 
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Old 11-23-09, 02:42 PM
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For the flue gas temp to be low, the water temp must be low too. What does your boiler temp gauge indicate?

But, in any case, you don't want condensation in your fire-clay chimney. I think this boiler is rated with a high efficiency, maybe 86%+? If so, I think you will have to install a chimney liner or jack up the water temp (and reduce efficiency).
 
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Old 11-23-09, 02:55 PM
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Well my water temp is 180 as per my aquastat and boiler gauge. The boiler gauge actually reads a little higher.
 
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Old 11-23-09, 03:30 PM
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Originally Posted by frylock75
Well my water temp is 180 as per my aquastat and boiler gauge. The boiler gauge actually reads a little higher.
This seems puzzling. The water temp is higher than the flue gas.
 
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Old 11-23-09, 04:05 PM
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Talking

I know it is but I get pretty consistent heat and run times. I am being told by the Qht/Biasi techs a chimney liner, will reduce my flue size, and increase heat and draft in the flue. I will know by the weekend. Any ideas are welcome
 
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Old 11-23-09, 04:08 PM
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I have only used contact infrared thermo and got 150F
If you are talking about an infrared 'gun' thermometer, no, that will absolutely give you nothing even close to the actual flue gas temp. You will do better with the barbie thermometer, but do question the accuracy of that as well.

The liner will help... even more if it's insulated.
 
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Old 11-23-09, 04:12 PM
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Underfired meaning?
Any input that is less than the manf specs... you are using the stock nozzle, so that is OK, but was the fuel pump pressure checked? If the pump is set lower than spec, you will have less input.
 
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Old 11-23-09, 04:21 PM
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The liner will be insulated. The burner is set to manufacture spec. I didn't check the pump pressure but that is set to spec.

My boss has the riello pressure gauge kit. I will get my hands on it. I am going to use the BBQ thermo tonight. What type of thermo is correct, the BBQ is temp.
 
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Old 11-23-09, 04:39 PM
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An actual stack thermometer is best... one that's designed for the purpose. A decent one will set ya back about 50-60 bucks though, so be prepared for 'sticker shock'!

Stack thermometer
 
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Old 11-23-09, 06:01 PM
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okay bbq thermo says 330 at the breach system only ran about 10 minutes to get to temp. It is oversized. I have the liner on the way, it can't hurt. My system is running a little over a week. It is a biasi so it has a combustion chamber. There is some shine towards the front of the combustion chamber near atomization proccess, no outright oil drips or anything. Cone has a little soot but nozzle is shiny clean. Anyone familiar with Biasis? is this normal. My over fire draft is perfect and my breach draft is .03 which is on the low side of the spectrum. Thanks
 
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Old 11-23-09, 06:02 PM
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When I saw your post I checked the Biasi-10 I&O manual. To see if there were baffles that could be removed to increase the stack temperature. Nope. According to the I&O maximum gross stack temperatures of 350F are to be expected.

I can see where it will condense in the chimney. The I&O also states to keep the length of flue pipe between the boiler and chimney at a minimum. Apparently condensing in the flue can be an issue.

I don't know if a stainless liner will prevent condensing in the flue. Might be best to direct vent this unit.

Al.
 
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Old 11-25-09, 08:41 AM
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I know I will get condensation in the flue At those temps, thats why a stainless insert is recommended. Over time the condensed flue gas will destroy the clay and brick chimney (or so I am told) . I have put enough into my home and the last thing I want is the chimney falling apart in 10 years. Their seems to be a push with stainless chimney inserts these days and high effic boilers. I don't know if it's marketing or neccessary engineering. I'd rather play it safe for $375 and 2 hours worth of work. And so it goes
 
 

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