Homemade outdoor wood boiler

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Old 02-13-16, 09:58 AM
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Homemade outdoor wood boiler

Wood burner does ok when temps are in 20's n 30's but single digits it doesn't really keep up with house and garage..... Better with house by itself .... Turn on garage heat and it drops rather quick.... Both r water to air heat exchangers n series.... 1st incoming to house furnace then to attached garage and back to boiler.... Any suggestions ? Extra storage?
 
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Old 02-13-16, 04:08 PM
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It might be a simple case of not big enough. The boiler may not be able to deliver enough btu's to heat both your house and garage when temps get that cold. It sounds like you've found the solution. Stop heating the garage when temps are that cold and your boiler is unable to keep up.
 
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Old 02-13-16, 04:39 PM
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Either the outside boiler isn't big enough or the lines aren't big enough and you can't move enough hot water.

Do you have a gauge on the outside boiler...... is it sagging ?
 
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Old 02-14-16, 07:34 AM
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I have 1" pex lines .... Which I recently found out weren't true 1" id.... Wrapped together with fiberglass insulation .... Nothing between the two so they r touchin... Could that b stealing btu's?? The firebox is 20" diameter x 54"s long.. Approximately 200 gallons of water.... Do u think that's enough? Thanks any opinions r appreciated
 
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Old 02-14-16, 07:39 AM
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The gauge on the boiler is just my digital aquastat ... What do u mean by sagging?
 
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Old 02-14-16, 08:07 AM
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You first need to measure incoming and outgoing water temperatures at the boiler.
It would be reasonable to have up to 180 degF supply water temperature.

What are you using for water temperature control at the boiler?
 
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Old 02-14-16, 09:04 AM
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What is the temperature of the water entering the house?

How far is the wood boiler from the house? Do the supply lines run outside to get to the house? Is the garage detached?

I would say having the lines together is part of the problem. You will certainly transfer heat between pipes. If the pipes are run outside, that fiberglass insulation is not going to stop air flow. So when the wind blows, its insulation value is nothing.
 
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Old 02-14-16, 05:38 PM
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If your lines are touching the cold return is stealing heat from the hot line to the house but since it's part of the same loop it's not as bad as it might sound. The root is to supply enough btu's to the house and garage. You need a boiler that can supply enough btu's and you need piping that can transport those btu's. You need to find what part of your system is the bottleneck. Checking your water/glycol temperatures exiting and entering the boiler will help a lot.

You might have a boiler that's too small. You might have undersized piping. You might have too small a circulation pump... There's a lot that can be done to fix a system but without knowing more it's just guessing. As a first pass I'd consider a more powerful circulation pump as it's the cheapest and easiest part of the system to change.
 
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Old 02-15-16, 08:34 AM
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My boiler is only 40 feet from house ... Lines r buried underground ( homemade) fiberglass wrapped around 1"pex.. ( not true 1" I come to realize) the pump is just a cheap one... Steibel Elton 16 gpm on speed 3 I believe... Good point on checkin to n from temps at boiler... Do u think the no contact laser guns r accurate for that?? And also it is a natural draft as of now ... Gonna modify n put blower fan on ... Hopefully will help with recovery times.. It just seems like it cools down rather quick... The unit has 2 layers of r30 can't c how that's not enough
 
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Old 02-15-16, 08:52 AM
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Also the controller at boiler is ranco 11000
 
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Old 02-15-16, 09:45 AM
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A no contact IR thermometer can be helpful. How accurate the readings are will depend on where you take the readings.

You mentioned that it's 40' from the house so we know you have at least 80' of tubing. How much pipe are you running the water through? It's possible that you have significant restriction and are getting nowhere near 17gpm flow.
 
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Old 02-15-16, 11:43 AM
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Take the temperature of the supply and return at the boiler and the supply and return at the inside coil.
This will give us an idea what might be going on.

Be aware that non-contact thermometers, especially inexpensive types are not that consistent in how they read temperatures.
The color, sheen and even position of the gun can give different readings but is a place to start if that is what you have.

Your solution could be as simple as raising the supply temperature.
 
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Old 02-15-16, 07:39 PM
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Gonna try n get no contact gun I guess n get supply n return temps at boiler n next day or two... I do have a temp reader with probes taped to supply and return entering house... The supply is entering sometimes reads a degree up to 5 -6 degrees lower.... Once n awhile it's the same as aquastat at boiler but not a lot.... Today it read way off entering house compared to aquastat... 9. -10 degrees for a lil while now it's withi. A few... Don't know if the second heat exchanger fan was on or not .... Every once n awhile it gets way off like that makes me wonder bout my lines touching Cooling supply down..... Gonna try to get better readings and get back here.... Appreciate all the info
 
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Old 02-15-16, 08:56 PM
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Those numbers don't make sense.
You would expect the supply at the boiler to be 140 deg F to 160 deg F.
Temperature drop at the coil in the house should not be much more than 10 deg F lower.
Can you grab the supply line to the coil in the house and hang on to it?.....if so it will be less that 140 deg F.
If you can grab and hold onto the supply at coil the temp isn't high enough......either because the boiler temp is not set high enough or you are loosing too much heat to the return or the ground.

You need to give us four temps.
Supply at boiler, return at boiler, supply at coil inside house and return at coil in house.

A thermal bulb taped tightly to the line would be more accurate than an infrared thermometer.
Just tape a piece of insulation over bulb for a more accurate reading.
 
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Old 02-17-16, 07:30 AM
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Boiler temps r for sure 140 to 160...as long as that aqua stat is right... Got it set at 175 on and 163 off .. The digital temp reader in house has 2 probes taped to line and insulated... That's y I was wondering bout poor lines to n from being sometimes the temp from the aquastat and reader in house r the same or real close than once n a while r way off... I understand what u r saying bout the four temps... Gonna try n get them for sure .. Good idea... Not to ask a stupid question but should my blower fan b running when I read return temp at coil ?im gonna try n get thermal bulb... Where would b best to look. Thanks Greg
 
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Old 02-17-16, 09:40 AM
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What does "n" mean. You use it numerous times but I don't understand it's use here "...poor lines to n from being sometimes..."?

You want the system operating normally when you are checking temperatures. The blower should be running and the circulation pump should be running. A huge drop across the heat exchanger might mean you don't have enough water flow but if the blower is off you won't have as big a temp drop which would mask the water problem.
 
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Old 02-17-16, 09:57 AM
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"n" = "and" ................. "b" = "be" ..............................................
 
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Old 02-17-16, 04:18 PM
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Having your lines buried in the ground with just fiberglass could be a major loss as well. If the fiberglass is wet, it is worthless. If water is getting to your pipes, it's going to remove even more heat from your lines.

If the return line is being heated by the supply line, that will prevent btu's from getting into your house.

How big is your house and did you calculate your heat loss?
 
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