Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: mingom on December 18, 2011, 08:36:40 AM
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Hey guys, new to the forum.
I have a woodmaster 4400, with setpoints of 175 L and 180 H. Comes into the house via pex, into a liquid to liquid heat exchanger at which the honeywell aquastat is attached to the OWB side. The piping then runs from this to tie into the home loop, which consists of 7 zone valves, a Crown propane boiler w/tankless hot water. My issue is that my propane boiler keeps having to come on for some reason, I've burned way for fuel than I thought I would have to. I think the issue could be a setpoint with the aquastat or on the propane boiler. Any ideas? Any help would be appreciated.
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Seems like someone posted on this same issue not long ago, I cant seem to find the post though.
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It was mtjag. Not sure how he resolved it.
I think dean186 helped.
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What is the aquatat connected to?
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Aquastat is clamp on style on 3/4" copper
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I think he means where on your system is the aquastat located.
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On the copper piping between the pex from the OWB and the heat exchanger
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Do you know what you have it set at? ( the aquastat)
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Currently set at 70, down from 80 yesterday at the suggestion of someone on another forum. Trying to get it from kicking on the propane. I just had the tank filled a week or two ago (120 gal tank filled to 80 percent. Woke up today and it was at 65!) Other appliances use it also so I know its not just the furnace, but its the main draw.
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It almost sounds like it doesn't even see the aquastat. yet you said there is a delay before the propane kicks off, whereas it should not even be coming on.
Is there a pump circulating water from the hx to the boiler? It sounds like your boiler cools off a lot between cycles.
Any pumps on the zones? Or just valves?
I'm probably wrong since I don't know these type of systems, but maybe the aquastat should be on the line coming from the hx to your boiler, making the circulating pump come on when ever the temp drops below xxx*? Or turning off when it reaches xxx*? (probably the latter is better).
Just thinking out loud.
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I mean what does the aquastat control?
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Aquastat comes off the incoming line from the boiler, and the wiring runs back to a taco SR501 zone controller.
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Could you wire in a relay that kills power to the tankless boiler?
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Mingom,
On your Crown propane boiler, is there a removable cover on the side or front? There should be a thermostat under the cover that is wired into your Taco Zone controller. I have a Weil McClain boiler and mine was set for 165. I set it to it's lowest setting of 140 and now mine doesn't kick on at all. The other thing you might check is the pump at the OWB to make sure it's pumping enough. In my case, I have Grundfos Alpha pumps that have software built in to provide variable speeds and pressures to optimize flow rates while reducing energy consumption. I did discover that I had to set my pump to a higher level to ensure adequate return to the OWB as it would optimize and only flow at 2 GPM.
Anyway, hope this helps.
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It looks to me that the boiler is set low one side is at 120 and the other is at 140, with a differential of 20 set. I was really hoping that was going to be it. I need to put temp gauges in line, but will have to wait till the summer. It could be the pump, but feeling all the pipes they are too hot to touch. Guess its back to problem solving.
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Can the boiler just be turned off? Can you just have your aquastat cut power to it so it can't fire?
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This may be a question that has already been asked , but is the pipe from your OWB going into your heat exchange really hot? Like too hot to hold.
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Yes it is, so to me, I'm getting good, hot flow from the boiler.
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When I first fired up my new OWB, the propane boiler would fire briefly when a zone called for heat. These fine gents schooled me on how to simply turn my Weil Mclain boiler's aquastat down so this would not occur. Work just fine now. I wanted my propane boiler online as a back up system. It is all set up now, but the power remains off to the propane boiler. No need for me to keep it on now as I'm never gone from home for too long a period of time. But it is set-up. I can tell you, it will run and run, to try and keep the OWB warm!
Bill
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Talked to the boiler install guy today (not who installed this unit), his thoughts were that its either my pex lines bleeding heat into the ground, or my pump is not working correctly at the boiler. I'm hoping its the pump. I took temp readings using a thermocouple hooked to the copper line right after the pex and got readings around 160-164 pretty constantly (with a few drops here and there to 145 ish, i think it was just how I was holding it). The boiler ETC was reading 169, so no huge loss there it seems. So hopefully its the pump, does anyone have any ideas on how to check it/ how to change it with the boiler running?
Thanks
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Is the propane boiler on it's own loop? I am kind of confused how your system is setup.
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Sorry for the confusion. I have the OWB, which comes into the basement via pex lines to a water to water heat exchanger. From there the water is plumbed back into a system tied into the crown propane boiler which provides backup heat and hot water as needed. Both systems tie into 6 zones.
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Talked to the boiler install guy today (not who installed this unit), his thoughts were that its either my pex lines bleeding heat into the ground, or my pump is not working correctly at the boiler. I'm hoping its the pump. I took temp readings using a thermocouple hooked to the copper line right after the pex and got readings around 160-164 pretty constantly (with a few drops here and there to 145 ish, i think it was just how I was holding it). The boiler ETC was reading 169, so no huge loss there it seems. So hopefully its the pump, does anyone have any ideas on how to check it/ how to change it with the boiler running?
Thanks
If you have a TACO pump, I don't know how to tell how it's pumping. I have Grundfos Alphas and they have a digital display on the face that shows the GPM and Watts. Regarding changing the pump out...I'm pretty certain you will have to turn off the systems and drain the water in the return pipe (estimate about 2 gallons), to change out the pump on your propane boiler, if that is the one your are talking about. I'm not a plumber, but I helped to change out my TACO pumps on my propane boiler a couple of years back.
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So, did you add another pump when you added the plate heat exchanger? Is there continuous flow through the gas boiler and heat exchanger?
What you have to do to change the pump depends on where you have valves. I like to put one on each side of the pumps so you can just close them and pull the pump.
If you do have a valve after the pump you can usually close it down slowly and hear sound change if the pump is working. A lot of times you will hear noise change at the pump too.
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Sorry the pump I'm talking about is the pump at the OWB. Its a Taco 0011 mounted right at the woodmaster.
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If the pipes to the house are hot then that pump is working.
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So, the pump on the OWB is good and you have hot pipes going into the heat exchanger. Sounds like something is not connected right, but I'm no plumber. If you can turn off your propane boiler that sounds like the best solution to see if you still have plenty of heat throughout the house.
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Can you make a diagram of how the heat exchanger and gas boiler are piped? Or post a picture of it?
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Here is a rough sketch. MTJAG, this was a rough measurement of temps, I just don't know what else could be set wrong. I might try unwiring the low level on the propane boiler to dummy it out, I think if I hit the kill switch to it it might kill all my circulators.
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If I am looking at the diagram correct I can see why the boiler is running.
Does the pump after the plate heat exchange only run when one of the zones is calling for heat?
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Your diagram doesnt' match my setup. My heat exchanger mounts directly before my propane boiler on the manifold return "cold" line of the existing propane boiler. Also, what is that extra pump for between the heat exchanger and your common manifold?
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Not sure. trying to figure that out. Thats what the clamp on aquastat at the heat exchanger is wired to via a taco SR 501 zone switching relay.
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after looking again at your diagram, it seems something is amiss. Did your return line from your zones originally run back into your propane unit?
My setup has my original install of the propane system and zone as a completely closed loop. My install of my OWB is also a closed loop and the two systems are "connected" by the heat exchanger.
However, on my original propane/infloor heat system, the return line from the zones came back into the propane furnace. On your diagram, it's not clear that is the case. According to my understanding of your diagram, both the propane furnace and the OWB feeds a common manifold that feeds your zones. Then, the return line from your zones flow back to the OWB. The feed loop on your propane unit comes from where? As long as your propane furnace has cool water coming back from the zones, it will fire...does that make sense?
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It looks to me like the gas boiler is off on it's own loop sort of. If I am looking at it right no water will flow through the gas boiler.
It appears that a Tee was added to the return line and a fitting was added to the supply manifold.
If that is how it was installed, I would put it back how it started and put the plate heat exchanger in series with the return line going into the gas boiler.
If you want to be able to control the heat so as much doesn't go out to the boiler if you had to run the gas burner I would put the plate heat exchanger on a secondary loop with it's own pump and feed both supply and return from the plate loop into the return line just before the gas boiler.
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The confusion is my fault. There is also a common manifold on the return side that ties into both the propane unit and runs out as the cold side to the heat exchanger
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Dosen't match my set up either. I have oil boiler. My supply from owb goes to one side of heat exchanger then out of heat xkchanger back to OWB. Other side is then piped into oil boiler. It is piped with reverse flow. Oil boiler water never mixes with owb water.Piping of oil boiler is piped with with tee in return from house going into HX then out of hx back to boiler. A valve is between tees for by pass of hx when i only use oil boiler.Return line from hx to boiler has pump which runs 27/7. A tee is in oil boiller supply going into return hw to give constant flow through oil boiler. Will try to post pics later.
My existing oil boiler system has not been changed at all. Only hx was added to heat it with OWB.
Your propane system should remain a closed loop pressurized. Owb will be open loop not presurized.
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Possibly my drawing is wrong, but they systems are completely seperate. Hot water in from OWB, transfers heat through HX, cold returns to OWB. Cold Enters HX from propane system, exits warm from HX. The fluids never mix. I think I drew it wrong, they only interface through the heat exchanger.
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do they cross flow? (like though my DHWX?)
http://outdoorwoodfurnaceinfo.com/forum/index.php?action=media;sa=media;in=159;preview (http://outdoorwoodfurnaceinfo.com/forum/index.php?action=media;sa=media;in=159;preview)
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Maybe I just looked at it wrong. will try to post pic
Do you have a pump circulating water through HX on propane boiler side all the time. All return piping from house should go through HX before going back to Prop Boiler.
[attachment deleted by admin for space issues]
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Did a little research last night, looking into the system a little more. I had made a mistake. Hot side of HX goes to cold side of manifold of system, cold side is fed from hot side of system through the circulator I've been mentioning.
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Does your pump on propane boiler side run all the time circulating water through HX. If so it should keep your boiler close to same temp as your OWB.
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It does, as long as the aquastat is satisfied. If not, it'll shut off the circulator I believe. Starting to get a better understanding of how the system works, just not why I'm still burning propane. I'm afraid it could be heat loss in the underground lines, but I'm not sure. My OWB has been pushing to get its temps up over 175 this morning, so I'm also wondering if its not transferring the heat well at the boiler. Does a creosote build up prevent the water temps from coming up at all?
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Only if your flue is clogged keeping owb from comming up to temp. I Would try letting pump run constant to keep prop boiler up to temp all the time. If your operating control on prop boiler is set to close to acutual water temp of OWB it will call for heat when a load is placed on boiler causing prop boiler to fire.
You should have a by pass from prop boiler supply going back to HX inlet to circulate water and maintain boiler temp at all times. You make need a check valve in return to HX before tee so water has to go through HX instead of flowing other direction based on your piping.
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Aquastat is set to 75 degrees so the pump never shuts off. There is a taco check valve after the circulator so that it can't feed backwards
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Aquastat is set to 75 degrees so the pump never shuts off. There is a taco check valve after the circulator so that it can't feed backwards
Not sure of your piping arrangement but check valve after pump will not stop flow from going wrong way at HX if you have by-pass from supply to hx inlet. Pump should be in hx outlet or at least that is how i piped mine. so you are pulling water through hx instead of pushing. Will work either way but mechanical engineers say to pull through equip instead of pushing through.
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You diagram doesn't show water flowing through the gas boiler. You will burn gas if it doesn't.
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I've got a woodboiler installation guy stopping by tomorrow to check out the system. He's leaning towards poor quality/poorly insulated pex lines, but says theres still time to install new ones before everything is fully frozen (groundwise). I'm still hoping there is something else going on instead.
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I hope you can get it figured out without a lot of expense, however to have the OWB burning along with your propane furnace is expensive and a waste of energy. Good luck!
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If the wood boiler is heating your house ok, i think i would just turn off propane before spending a lot of money just to get propane boiler to stay on line. I have oil boiler for back up. I have never tried to keep it on line with wood boiler. It might do the same as yours. If and when i need it, i will turn switch on and isolate owb with valves i installed to keep from heating owb with oil. Just my opinion everyone has one.
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I understand what you're saying Mikenc, but I use it as a backup HW supply too, incase its super cold and I need more hot water than i can get off the OWB plus heat at once. I also travel sometimes and don't want to have the OWB be the only form of heat for my fiancee in case she can't load the stove for some reason. Thanks for all the input guys, I'll let you know what happens today.
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Please do, you never know the time may come when i might need to operate mine together. I am sure it can be done with the right control sequence, its just getting it hooked up the right way. I may fire up mine sometime today and see what it does. I think i would want to add a 3-way valve in order to by pass HX when oil boiler is running so i am not using oil to heat water in OWB.
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Okay, so the OWB installer came and left with some suggestions. We think the issue lies within the plate to plate heat exchanger, with it being a.) seemingly plugged, and b.) undersized for the application. I have a 20 plate hx, and he recommended upsizing to either a 40 or 50 plate, and putting ball valves and tees in on all four inlets so we can run hydrocloric acid through it easily when it begins to scale up again. He's estimating about 1000-1200 dollar job to put in a new hx, all the piping, and adding 2 new aquastats to control the system. One to kill power to the propane unit at B1 until it has to come one, and one to control the blower at the OWB (if the temp gets below 130 or so, as if I left and didn't fill, it would kill power).
Just wanted to give you an update. Thanks for all the help! I appreciate any comments and help!
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Well at least you have an ides of whats needed to correct problem. Don't know if you need it but when i installed mine they recommended a 60 plate for the amout of btu needed to heat my house.
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This is the heat exchanger they want to install pricing around 430 ish their price:
http://badgerpipe.3dcartstores.com/40-Plate-Water-Braized-Plate-Heat-Exchanger-1-Ports-5x12-_p_13.html# (http://badgerpipe.3dcartstores.com/40-Plate-Water-Braized-Plate-Heat-Exchanger-1-Ports-5x12-_p_13.html#)
I found it here for less:
http://www.houseneeds.com/shop/heatexchangers/brazed-plate-heat-exchanger-1-lb3140-buy.asp (http://www.houseneeds.com/shop/heatexchangers/brazed-plate-heat-exchanger-1-lb3140-buy.asp)
and I found this one, didn't know if anyone had any experience with this brand ( or any others)
http://www.brazetek.com/products/details/20/6/4-x-12-inch-1-inch-mpt-connections-stainless-steel-copper-brazed-plate-heat-exchangers/40-plate-brazed-heat-exchanger-1 (http://www.brazetek.com/products/details/20/6/4-x-12-inch-1-inch-mpt-connections-stainless-steel-copper-brazed-plate-heat-exchangers/40-plate-brazed-heat-exchanger-1)
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This is the heat exchanger they want to install pricing around 430 ish their price:
http://badgerpipe.3dcartstores.com/40-Plate-Water-Braized-Plate-Heat-Exchanger-1-Ports-5x12-_p_13.html# (http://badgerpipe.3dcartstores.com/40-Plate-Water-Braized-Plate-Heat-Exchanger-1-Ports-5x12-_p_13.html#)
I found it here for less:
http://www.houseneeds.com/shop/heatexchangers/brazed-plate-heat-exchanger-1-lb3140-buy.asp (http://www.houseneeds.com/shop/heatexchangers/brazed-plate-heat-exchanger-1-lb3140-buy.asp)
and I found this one, didn't know if anyone had any experience with this brand ( or any others)
http://www.brazetek.com/products/details/20/6/4-x-12-inch-1-inch-mpt-connections-stainless-steel-copper-brazed-plate-heat-exchangers/40-plate-brazed-heat-exchanger-1 (http://www.brazetek.com/products/details/20/6/4-x-12-inch-1-inch-mpt-connections-stainless-steel-copper-brazed-plate-heat-exchangers/40-plate-brazed-heat-exchanger-1)
Wow, $430 for just the heat exchanger? I wish I could mark stuff up that much.
The 2nd and 3rd don't appear to be 5" x 12" so not equivalent. (3" x 7.5" at Houseneeds and Brazetek is 4-1/4" wide)
Here are some prices you can use for comparison http://www.rsiboilers.com/parts/plate.htm (http://www.rsiboilers.com/parts/plate.htm)
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On the house needs one, if you scroll down and look at the dimensions on the drawing it appears to be 5x12, however you are correct in what they state, maybe i'll give them a call. Have you ordered anything from RSI boiler before?
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On the house needs one, if you scroll down and look at the dimensions on the drawing it appears to be 5x12, however you are correct in what they state, maybe i'll give them a call. Have you ordered anything from RSI boiler before?
I guess I didn't scroll down far enough. I got those dimensions from up the page a little but thinking about that now I don't think there would be room for two 1" fittings on 3" wide area and be able to get fittings on them.
Anyway, what I was trying to say is if they are a smaller size it isn't necessarily a bad think but you need more plates to be equivalent.
I just put the link for reference prices. It is my website so, no, I have not ordered from myself ;D
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Haha sorry, didn't notice the connection.. duh. Anyways, do you have any type of warranty/damage policy. Also, any idea on ship times to Maine? Looks like those are AIC exchangers?
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That picture is old. I have been selling HEX brand lately. I don't think it could ship till next week because I don't have of that size in stock right now and that supplier is closed this week.
If you are in a hurry I could do the one in your first link instead but I like the HEX brand better.
I would have to call the supplier to get the warranty details. The warranties on any brand pretty much just cover defects. If you get one that leaks or is damaged in shipping it would obviously be replaced.
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Anything available with 1" threaded ports? I see all the ones you offer are 1-1/4
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Yes, the badger link you posted has 1". They are one of my suppliers. (That mounting bracket isn't included in the price)