Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: pintopaul on March 11, 2012, 04:45:42 PM
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now that its getting warmer out should i turn the furnace down so the blower doesnt kick on at 170? :-\
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i set mine 150 on 160 off
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i set mine 150 on 160 off
leave mine there all year
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I leave mine and 170-180 until I shut it down..The boiler isn't gonna work any harder If i was to set it at a lower temp..During the warmer temps I don't burn anything for wood at 180F..It would be a same burn if I was to set it at 150F or whatever desired temp..Last yr ran mine until May 29th
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Forecasted temperatures are in the upper 60's - low 70's for at least the next week. I have a baby home and like to keep the house warm for him but don't see the house needing heat this week. Should I just keep throwing a little wood in each day to keep the water temp up or just let the fire go out and restart once the weather gets back to normal?
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keep it going, still going to get some cold nights
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I thought I read on this website on a different forum that it wasn't good to have the water temp dip below 153 with the pump on because it introduces oxygen in the water? Can anybody comment on this? Is it different on a pressurized system?
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Yes its different on a pressurized/ sealed system..I have a pressurized/sealed OWB.. There is no oxygen in the system.. I can run it at 100F if I wanted to and no worries of oxygen.. Yes lower water temp holds more oxygen than higher temps...
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So a shaver 165 is a pressurized owb?
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So a shaver 165 is a pressurized owb?
Nope...
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I have been keeping ours at 155 for a the past few weeks am I hurtung anything by doing this?
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No Ky you are not hurting anything
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So, Bull, If ky has his set at 155, then his will drop below 153 to recover sometimes. Oxygen occurs, attacking the metal. Or does it not matter because of corrosion inhibitor or that rod?
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Corrosion inhibitor helps a a lot but I thought 140 was the magic number to stay above.
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That makes me feel better if 140 is the number.
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What hapens when you shut down for the summer the? :o
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mg/l of oxygen solubility...
20 degrees C 9 mg/l
40 degrees C 6mg/l
60 degrees C 5mg/l
80 degrees C 3 mg/l
100 degrees C 0mg/l
20= 68 degrees
40 =104
60 =140
80 =176
100=212
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This is such a touchy topic and not one I am really confident in. I will however share my current thoughts.
I beleive we should keep our water as close to 180 as we can, even thought I'm 155 on 165 off. I still think it would be better for the stove to be hotter, next winter with a gasser I'm going to 180-185 or so..
As far as 140 the magic number..... I say you don't want your return coming back at under 140, if your pulling a lot of heat and the return water is coming back to a roaring firebox at 130, the stove will sweet inside the firebox and cause condensation that will put your furnace to an early grave regardless of brand.
As far as the o2 in the water itself, the hotter the water up to 180 the less o2 you'll have present.
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Okay, now I'm getting confused. I have the Shaver 250 and it has the corrosion inhibitor in. Do I need to keep that thing heated up now or can I shut it down? Granted we are going to get "some" cool nights, like last night it dipped down to the 40s. If I top the tank off and the inhibitor is in the water, it should be fine correct?
Lugnut
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My guess would be as long as your not moving the water you will not accumulate DO2.
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A good corrosion inhibitors purpose is to protect the water jacket. Does not matter if the water is 33 degrees or 210 degrees.
The problem with sending colder water back to the OWF below 150 degrees is that it shocks the furnace, causing condensation in the firebox, which is what can create wet acidic ash.
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Is that why they put the thermostatic valve in the supply and return??? So you don't shock it
Yes that's the theory behind it, it causes the firebox to sweat if return water is to cold.
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A good corrosion inhibitors purpose is to protect the water jacket. Does not matter if the water is 33 degrees or 210 degrees.
The problem with sending colder water back to the OWF below 150 degrees is that it shocks the furnace, causing condensation in the firebox, which is what can create wet acidic ash.
I don't see how sending colder water back to the OWB "shocks" it and then causes condensation in the fire box.. After all you have a live fire in the box.. If anything burning wet green wood would cause the condensation
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Matty, what happens when you first fire the stove? Water runs down the inside walls from condensation because it's surrounded by cold water, every Customer I have met freaks out on there first fire, I have to stand there and calm each one down and explain why it's sweating
The same thing happens in operation if your return water is to cold, empyre had a customer with a pro400 who had a huge pool exchanger which was sending his water back at like 100, the stove sweated internally until it failed, the customer was taken care of and empyre started installing a feature that shuts the pump off if the return gets to cold. This guy had likes 500kbtu pool exchanger on his, so it wasn't a normal application
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Scott, I can see that at the very start of OWB for the season..Everything is cold..The water, the unit itself, pipes etc....I don't see it happening when the OWB has been running for a season/ got a nice fire in the box..Then you decided to turn the temp a bit. Shouldn't have any problem with water in the fire box unless you burn wet/green wood..a low temps.... Far as the Pool exchanger sounds like the unit wasn't even big enough..So ya not a normal application
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No.... I don't see how u think it makes a difference.. I mean the stove don't know if it's the first fire or the 400th! If there is cold water being introduced to the stove it's going to sweat, I domt care if it's October 1st or january first, cold water is cold water.
The unit was not the problem as it heated the pool fine, if anything was to big it was the pool exchanger, pulling to much heat off.... Another way of having that problem if the pool exchanger and stove are sized right is a pump not flowing fast enough. If it is in the pool exchanger to long it pulls off to much heat...
Return water temp is very important, the first fire example is as goodas I can get, if you think cold water being introduced at a different time would make that different I'm not sure what you mean
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there is evaporation and condensating going on all the time..the heat in the fire boils the water from teh wood and the air that is feeding the fire... this moisture hits teh walls of the water jacket and instantly starts to turn back to liquid. i thin this happens no matter what the temp unless the steel jacket is boiling
one of the reasons there is so much on first start up is everything is cold and until everything is warmed up(including the chimney where there will be a lot of condensate) there will be more condensing than at normal operating temps.
im not so sure on this shocking thing but i can't disprove it either so i am neutral
the only reason to turn down your temps i can see (there will be some small savings in wood consumption but i dont think any thing much) would be if your underground lines were bad (if you used lower water temp your loss to the earth would be slower due to the temp. spread) or if your boiler leaked air and because the heat draw would be less in warmer weather it may boil over if left at the higher setting (lets say your shut off was 180 adn air leaked in it may (if the hosue was not drawing for an extended peiod of time) slowly crawl up to boiling. by setting the shut off temp lower you would by your self some more time between 'calls for heat" and you would use some heat before boile over occured
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Well.... I don't know what to say... All I know is what I've saw and that companies like empyre and central now require folks to run a system that shuts the pump off or something similar if return water is to cold.. Central does it different... Empyre has a system that goes right on the back of the stove. There doin this because of problems they've had and trying to prevent it from happening again.
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im not doubting you scott i am jsut saying that condensation and evaporation go on all the time..heck if there is a pool of water outside in the winter (as long as it is not freezing) that water gets evaporated into the air.
and i also know that some boilers have a thermostat that measures the outside air temp and adjusts the water temp inside the boiler to accomodate for lower temps to save on fuel as they say less btu's are required per hour on warm days. how much this saves i have no idea but it is done..and how low these settings are i have no info but i have heard that return temps can be as low as 145?
the guys building these stoves that you and i use, (hopefully) know a lot more than you and i about all this thermodynamic stuff..we are paying them big bucks to get it right but some times i wonder if some of these things they add on are just sales gimmics.
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Scott, So your saying when my house dumps the cold water back into my boiler theres water dripping in my fire box?..Im assuming you know Hydronic's...
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Well... I agree.
In regards to whether it's a sales gimmick, I know empyre would rather not do it because it adds cost and there not making anything off it, we can do a secondary loop like central does or install the factory package on the back.
But in today's world i to am so skeptical of new things because it seems everyone is out to get ya. Sometimes it's never proven whether we needed the latest gadget or not
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Scott, So your saying when my house dumps the cold water back into my boiler theres water dripping in my fire box?..Im assuming you know Hydronic's...
It depends on a lot of variables..... But when return temps are below 140, you are entering the range at which water can condensate on the walls of your firebox. I am sure in some cases it may occur at different temps, but generally speaking, when it's returning below 140, your entering the range at which it can potentially occur.
This is kinda new stuff, as only in the last couple years has companies started talking about it. Once again I will remind you that it's not an idea to make them money, because the installer can do it themselves and not use one factory part.
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for what it is worth here is a quote form "Canadian Plan Service"
quote " Non condensing boilers are the most common. they are called this because the water vapour of combustion is totally exausted with the flue gas. These boilers should not be operated with water jacket temps below 135 F"
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Yea, that's just a temp range there, it's likely slightly below 140 but companies like some wiggle room
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so now with reading the quote from the government source i inserted earlier... scot is right that return temps should not likley fall below 140..so i guess we can feel relitively safe turning our temps down some in warmer weather if we are so inclined to do so...keeping in mind that maybe the fellow who posted the magic number of 140 knew all along and just wanted to stir the nest of bees a little :-\
now the real experts will come in straighten us out :bash:
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yes i believe everything our goverment's tell us. ;)
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Well I just shut off complete power to my unit. I have a dual temp gauge in the basement attached to the in coming pex from the furnace and it's reading 88*. there hasn't been a fire in the box since Monday night. I see no sense in burning wood just because I can. There's only two of us in this house and the only thing that would be heated would be the DHW, and I just feel that's a waste of good wood. So we'll keep it shut down until the cold weather returns again in "maybe" two weeks...I dunno, but I do know what happened up here last April 1...we got cold and we got lots of snow!
Lugnut
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I shut mine down too Lug, 9:00 pm here and it is 68*
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Shut mine down too. Don't know for how long though. My mom said in '64 when my brother was born they had a snow storm and got stuck on the way to the hospital. My little brother very nearly came into this world in the front seat of a '59 Chevy! That was in MAY!! Winter will show up again.
It was still 69* when I came in @ 9:00
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Still running mine..Yeah it gets warm during the day unlike today..Man It was raw out..At night though the temps still plunge into the 30's..For me its too early to shut it down..Still can get a cold spell with a Nor'Easter off the coast with a dumping of snow..
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Shut mine down too I hope that it doesnt get cold again because I gave mine a real good cleaning Im still skinny enough I could climb inside and clean the front of the firebox without having to lean over from the outside. I wish I had the 2400 just for the extra room in the firebox I think the cresote comes off alot easier actually when it's cold it comes off in chips rather than like syrup.