Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: sdrockhauler on January 01, 2014, 10:23:52 AM
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What should my return temps be? I hav 170s coming into the house and 135 going out. Seems as though the blower fan is runnin a lot longer than it did last year . System is only on its second season. Could pump be getting weak? It has about 150 feet uphill push then when it gets in the house 50 ft to the waterheater then 50 ft to the furnace then back to the stove. With wathing the temp guage when the blower quits it takes a long time for heat to come back up on return. It has been Really cold here in sd
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From what I have read, the goal is a 20-degree difference in those temps. Can you turn up your pump speed to deliver more BTUs in the same amount of time? Did you turn up your fan speed? that would pull more BTUs out quicker as well.
If only my furnace or my hot water HX is in use, I am close to that 20-deg delta, but if both are running at the same time, I am over 20-deg but have not seen any major problems when that occurs (both pulling BTUs at the same time).
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Pumps don't get tired, they work or they don't. If you know the system is clean and no debris has fouled something like a flow check. It sounds like you need more flow. See this can change from the weather alone, on a colder day you will always pull more BTU out of the water. Even tho nothing has changed or gone wrong with the boiler. Windy days are notorious for this. This is where a delta T pump will adjust and cover this automatically. The Taco bumblebee can run 4 different fixed speeds, temp differential 5-50 degrees, or a set point delivery temp or return temp modes.
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Turn your water temp up to 185 with a diff of 10.
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I agree with Coolidge hotter is better
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I will try it tomorrow. I think i have it at 175 as I have been burning coal and it seems even after it shuts down you still get some heat for awile and will stop heating around 178 to 180. Maybe i'll play with the numbers a little maybe set at 182 0r 183. The high temp here in se sd is supposed to be -10 f for monday. that should burn up some coal
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I agree with sprinter that pumps don't get "tired", but I change out a lot of small Bell and Gossets in my job and have seen several pump impellers that are worn down to the point that there is nothing left to push the water, but still running. Might be something to look at.
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that sound to me as though you are saying electric motor is running but pump is getting weak. Think I need to look at new pump or larger one. The one i have is a pl 36. Anyone know of one that will give me more flow?
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Holy crap a pl-36. That is a huge pump, do you have 1/2" or 3/4" pex? I just yanked one of those out recently. Some bright guy put it on the secondary circuit of a little Weil McClain boiler and it blew a hole in the boiler tee. You could hear it singing water thru the pipes.
If your getting 175 at the house I assume it's leaving the boiler at 175 too. Note that on that bell and grossest label it says booster pump not circulator. The Weil would read 67 psi when running.
I don't know what you have for a loop or pex size, but your not gonna find much bigger short of going commercial. Which that pump already is.
Temp measurements at the boiler and at each exchanger and post them to give us an idea of what's going on.
Good luck in SD
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running 1 in pex 150 ft up hill into house then anothe 50 ft to the water heater then 50 ft back to the furnace then 160 ft back to boiler. I will have to find my heat gun and get more temp readings.
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Well 410' of 1" pex @ 8gpm =49.2' of head not including the sidearm (I assume your using) nor the air handler in the furnace. So yes that is a crap ton of head if you need 80,000 btu/hour. Which means you must have a 5,000 sqft house.
But if you only need 40,000btu or 4 GPM then it's only 12.3' of head or less. Still not calculating the WH or AH. And that circ would be about 10 times the circ you need, plus its a hog on electricity.
This is where a lot of systems waste half or more of the btu and consume a lot of unnecessary wood. Does the WH flow always on a call for heat? Is it on a sidearm or flat plate?
Monitoring the heat load, putting each exchanger on its own zone and controlling the flow of BTU(water) by means of delta T circulator, will or can save a lot of fuel. Look up the taco bumblebee pump
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I think house is around 2800 sq ft. water flows continually through a side arm then through air exchancer in forced air furnace. I guess i don't know what you mean by putting each on its own zone. What size of bumblebee pump would be best? Wher can I get a good buy on one?