Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Plumbing => Topic started by: Wi woodburner on March 09, 2014, 02:51:34 PM
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I am very new to heating with my new woodmaster 5500. I have the owb 150 feet from the house. I have the insulated pex running on top of the snow for now as I installed in January. I have about 75 foot run once inside to my forced air furnace. Installed at the furnace is a Ranco temperature controll. The temp probe is installed on the supply line going into the 18 x 20 hx. The temp reading at the ranco is at 120 degrees when the stove is 160. The supply line is warm but not hot to the touch. I am using the supply line to heat my hot water as well.
The air blowing out of my ducts have never been warm. The house does heat up but takes a while to raise the temp 1 degree. I increased the blower speed but that just let more cool/warm blow through ducts. I am very green when it comes to any of this and would appreciate all the help. from what I have read, could I have a pump issue?
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There are many things to check, pump size, restriction in loop, to small piping, poorly insulated lines, air in the loop, all these are problems, your water losing 40 degrees is crazy!
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What model of pump do you have?
Neal
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Yeap, major issue somewhere. You should have the same temp outside as you do inside or within a degree or two. First off most of us run our stoves at 180 +. This ensures that return water back to the boiler is not below 150 which can cause condensation to form in the fire box and early failure of your owb. Next we need to make sure that the water leaving your owb is actually 160. Do you have a IR thermometer you can use to get an idea of the line temp? I believe the Ranco in the house is reading true if you do not have warm air coming from the vents. My water goes into my HX at 180 and comes out of my vents at 135-150. Snow melt ontop of your insulated pex lines? Won't be a pump issue if between your boiler and your supply side of the hx are a 40 degree difference.
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if your aquastat at the stove is right and you have 160 at the stove and you have only 120 where it enters into the house...you have one of 2 problems...pump is too small or junk....or ...you have air in the system and the pump is not moving enough water.
if you were only moving 5gpm and the water was leaving the stove at 160...in a 75 foot run in unisulated pipe i doubt if you would lose more than 10 or 12 degrees
to be leaving the stove at 160 and losing 40 degrees in that 75 foot run....there is barely any water .
when my water lines were comprimised years ago..i was moving about 7 gpm and my underground lines were 250 feet from stove to house, i had a 3 foot wide melted (no snow or frost) for the whole 250 feet and i was still getting enough hot water to heat the house and my hot water...i can only assume you are not (for what ever reason...bad pump..wrong pump...or air lock) moving enough water
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Just checked again and owb is 170 and inside temp before hx is 150. No demand for heat in the house. The pump is a taco 011 with 1.00 lines in the house. I am going to check the temp tomorrow at various spots on the run...where it enters the house, leaves the owb, enters hx at dhw and where it leaves the hx at the furnace.
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What brand of insulated pipe?
Sounds like a air lock.
May sound a little silly, but check the obvious like that the pump is installed in the right direction.
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Outdoor lines are thermoplex at 10.00/ft. The supply line does run through the dhw first. Could this be taking the heat first before the hx at the furance? If there is air in the lines what can be done?
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Interesting, how is the DHW run before your HX? Do you have a sidearm or a tank or? Sometimes opening and closing a valve in the supply line slowly and repeatedly will move air out of a line.
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sidearm or plate type for DHW? It would take a huge DHW draw with a pretty big plate type exchanger to eat up 40 degrees.
I'm betting on a airlock. I have a auto vent installed at the highest point in the basement, also have another installed at the highest point of my sidearm.
http://www.pexsupply.com/Watts-0590716-1-4-FV-4M1-Auto-Air-Vent?gclid=CObUsdHjhr0CFbQWMgoddUEAjg (http://www.pexsupply.com/Watts-0590716-1-4-FV-4M1-Auto-Air-Vent?gclid=CObUsdHjhr0CFbQWMgoddUEAjg)
Can you crack a fitting in the basement somewhere? Is the pump at the stove or in the basement?
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It is a gea plate heat exchanger. I have an inline valve that I can use to fill up the stove from this location. This is right at the hot water heater. The pump is at the owb. With no need. For heat, I feel the temp difference is around 20 degrees. I am send a pic of the setup if that would help.
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If you have the ranco probe taped to pex pipe you are going to be off as much as 20 degrees. If that is the way its installed retape it to the copper inlet of the coil and then insulate it well. It still will not be accurate but should get within 10 degrees of actual temps.
If you are checking the supply pipe by hand always check before the dhw. If the outdoor furnace is showing 170 you shouldn't be able to hold the supply line where it comes into the house. Compare temps where it comes out of the back of the furnace and where it comes into the house.
An 011 with one inch pipe should be sufficient. When you filled the furnace did you work all the air out of the system by closing the return valve at the furnace and then reversing and closing the supply valve? This is very important, all air must be out of the system.
If the supply line in the home is showing 150 with the ranco probe taped to the outside i=of the pipe you should be getting hot heat out of the vents with a 18x20 coil. Any chance air can flow around the coil?
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Not sure what's going on for sure but all yoder said was spot on, test methods of temps on here are wrong 90% of the time
But don't worry about going to plate exchanger first, I do all of mine that way, never a problem
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From your name I am guessing you are from Wisconsin. If you are in the southern part of the state I may be able to take a look at your system if you are interested.
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My mistake I guess not thinking that a bad pump could move water so slowly that you could possibly lose 40 degrees from the stove to the house on a 75 foot run. I can't imagine how slow the water would actually have to move to lose that much?
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A pump moving the water slowly could cause the flat plate to really pull it down before it got to the coil in the duct.
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Great point Yoder.
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Just to verify your stove is 150ft outside + 75ft in home to your hx? So 225ft each way for a total of 450ft round trip? What size plate exchanger? Definitely sounds like a low flow/air lock problem.
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I taped a thermometer to the pex at several areas inside the house. All readings were basically the same as the Ranco temp display which is still 20 degrees cooler than the reading at the stove. Today I am going to do this outside by the boiler to see if the heat loss is happening from the stove to the house.
As far as air in the lines, would I be safe to open the valve and run water out the top of the vent to know it is full of water?
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If you have a valve and vent after the pump open the valve slowly with the pump running and see if it puts any air out, you should be able to hear it purge any air if it's in the line, you will most likely hear the water fill the line as well. Just curious, where about are you in WI? I'm in NW corner of the state.
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Sure sounds like an airlock to me!
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Yea if you tape it to pex you will be 20 degrees off, pex just doesn't transfer heat as well as copper. After you tape it to the copper inlet of your coil you also need to insulate it.
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Yea if you tape it to pex you will be 20 degrees off, pex just doesn't transfer heat as well as copper. After you tape it to the copper inlet of your coil you also need to insulate it.
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