Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers WITH EPA-Certified Models => WoodMaster => Topic started by: Sawdust on September 28, 2012, 01:22:02 PM
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4400 HD OK So I filled the water resivor to within 2 inches of the top of the fill pipe. While filling I made sure to remove any air in the system. Fired the unit up and at about 130 deg. FH the water started to percolate up out of the fill pipe. I kept watch while the heat built up to 168 deg and the percolating stopped even though the blower did not cut off until unit read 170 deg. Of course the temp continued to climb to 174 and then stopped climbing. I suppose the water should expand some as the temp climbed from 70 deg. To 170 deg. When the water cools back down to 70 or so deg. I will check the difference in the water levels. Should the water level be high enough to stand up into the fill pipe? Or would it be lower than that?
Also, I thought it might be the pump was not moving enough GPM . However when I installed the unit , I put a Tee with a cutoff valve in the return line at a point about 1 ft. From the return line connection elbow at the furnace. I can open the cutoff at the Tee and, close the return cutoff located just above it where the water enters the furnace, that way I could check the rate of flow. I collected 6 gallon in about 22 seconds or less. Would appreciate any info from other owners experiences , so I can compare, Thanks
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Your moving plenty of water. But yea, the water will just adjust where it wants, don't matter where it settles in at as long as it's not low. When you heat that much water from 70-170 your going to push ut several gallons.
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Scott, I am waiting on the water to cool back down and then I will check the difference in water level, also I will refill to original water level and keep record of how much water was lost. Last winter I observed the percolating one day and I immediately added water, however the same thing happened. The water level does not get low enough to show up on the monitor light. I did have the draft control ( fan cover ) break. I replaced it quickly. I just don't understand why the volume of water is percolated out. When the unit cools off , I believe the water level will be below the dipstick that is used to monitor the water level. I know the water temp is not getting too high, I stole out my wife candy therm and checked the water temp as compared with the led readout on the burner, they were reading within 10 - 15 degrees of each other. That should be close, as I was checking at a different level than where the thermistor is located. Thanks for the reply.
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Water level should be checked when at full operating temp, not when cold.
I don't remember exactly the amount it expands but I think it is in the range of 10-30 gallons depending on the size of the boiler.
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I'm not sure why you want to check it after it cools, of course it will be less water than it was originally
As water heats up it expands and has to go somewhere
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RSI is correct, water level only matters when you are using the unit. Get the furnace up to 170 and fill it full of water and you will be good to go.
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I think a 150 gallon unit would expand like 6 gallons, I don't think it's as much as 30.
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You may be right. I really can't remember right now. I had figured it out several years ago when I had a boiler that held 310 gallons.
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Yea I'll check and see what the formula is
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Scott, I want to satisfy my curiosity as to the volume of water that is expelled.
Yoder, After I have determined the loss of water volume I will refill as per Manf instructions. It will percolate out again. When it reaches 170 deg I will add water to fill, I believe it will just heat up to percolate temp and come right back out. At that time , will the water level be acceptable?
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Yea.. Once the water has found it's set point of what you want, it will stay at that point.. You can top it off if you want, if the stove can't handle it, it will simply puke it back out
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An article about thermal expansion
http://inspectapedia.com/plumbing/Hot_Water_Expansion.htm (http://inspectapedia.com/plumbing/Hot_Water_Expansion.htm)
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So.... I waited until after miday and the water temp had dropped to 90 deg. 12 - 13 degrees higher than when I started at around 77deg. I refilled the boiler, it took 3 gal. To get back to same water level I had at the beginning.
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Mine did the same thing at first startup. That is normal. If your draining your boiler every year and refilling it to the top while it is cold you will lose water while it is heating up.
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3 gals isn't much, I would have guessed you would have lost at least 5 but I have never checked it. Doesn't matter so long as it is full when you are using it.
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Thanks to all who replied, turns out every suggestion or diagnosis was either spot on or close. I did visit the suggested link To inspectapedia hot water- expansion? I used the coefficients as presented in the formulas.One of them calculated out to 2.64 gal. Expulsion if my memory is working. The range of temps , altitude, station pressure and, I think the water being circulated were all difficult to deal with, for me anyway. The link provided by Scott7m has a lot of info.
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:thumbup:
Glad you found out
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Scott is pretty sharp on this stuff but don't tell him I said that (may make his head swell ) LOL