Outdoor Wood Furnace Info
All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: tinfoilhat2020 on November 03, 2015, 05:01:43 AM
-
I am losing 4° from my OWB to my house on a 75 ft run....so thats 8° total loss as the water is circulating. The old lines are a cheap 3 wrap in a 4 inch tile....lines are also buried 4ft according to the old owner....I am a dumbass and should have replaced the lines BEFORE i installed my new Heatmor in August...but, i didnt. SO, now i am faced with running new lines (which will be LOGSTOR). My concern is trying to dig under the pad and run new lines up without cracking the cement....what would you guys do??? any tips???? suggestions??? how many BTUs am i losing with that kind of temp drop in water??? should i just cut extra wood???? I feel like crap after spending all that money and time on a beautiful stove and install just to have something stupid like this kill my efficiency..... :bash: :bash: :bash: :bash: :bash:
-
I don't think that's to bad,maybe wait to spring and then change the lines!
-
First I would check the temp gauges for accuracy, if you are truly losing that much and your flow rate is at an assumed 10 GPM then you are dumping about 80,000 BTU's into the groundwater, if this is the case then I would certainly be changing out the pipe! Perhaps your pad can be cut to allow for the pipe changeout at the boiler and if you are concerned about coming into a slab, I would come up on the outside of the building next to the wall and penetrate the building just above the sill plate with a set of long radius copper 90's, where there is a will, there is a way!
-
Slim....you know how the heatmor layouts are....I have a square cut out of the concrete where the two lines comes in......the boiler is set over that.....I would have to dig down, put out the old lines and try and push a new line of Logstor up through the existing hole....my concern is the concrete breaking when i start digging underneath of it......im not worried about running the lines back into the house at all....just at the boiler....and 80,000 BTU??? goood lord!!!! i have a 80,000 BTU water boiler in the house....so that heat loss could be heating my house??? wow!!! not good!!!!
:bash: :bash: :bash: :bash: :bash: :bash: :bash:
-
Is your pad built like this? If it is then cut the concrete at the dotted lines and pin it with rebar, then pour new concrete after trench is refilled.
-
Yes Slim, that is how mine is set up....thats not a bad idea.....i was thinking about putting some supports under the concrete as i dig....god knows i cant move the boiler.....that thing isnt moving...MAN, WHY DIDNT I DO THIS EARLIER
:bash: :bash: :bash: :bash: :bash: I cant stop banging my head against the wall...literally!!
-
Use caution, last time I tried that, I got a concussion!
-
Hahahahah
-
First thing to do it make sure your readings are correct. It not easy to get exact reading with different type thermometers especially if it is measuring through the pipe. If you are comparing the pipe temperature to the gauge in the boiler it could be a lot different.
Do you have any way to bypass the piping and heat exchangers in the house? If so, get the boiler up to temperature and turn it off so it doesn't run. Better yet if you could remove the remaining fuel.
Then watch how fast the temperature in the boiler drops.
Going a step further, you could bypass the underground lines and just pump from the supply to the return. Compare how fast the temperature drops to see how much went into the ground. If you do this, I would run the pump on low and maybe partially restrict the return valve since it will have a higher flow rate with the pipe removed.
-
Sorry RSI, I'm not getting it, could you Please explain your thoughts a bit more?
-
What part? You mean about bypassing and watching how fast the boiler cools down?
If you have 400 gallons (guessing by model number) of 400 degree water and you think you are losing 80K btu into the ground, bypassing the house would mean that the boiler temp would drop around 20-25 degrees in an hour. Going by the temperature drop you could calculate actual heat loss and would not matter about flow rate.
Bypassing the pipe and just getting the temperature drop of the boiler itself you could subtract that from the first number and know how much went into the ground and how much was lost out of the actual boiler.
-
I guess I'm still not understanding? I'm thinking if the water temp is measured at the point that it enters the pipe and again just before going back into the boiler and there is no call for heat, the flow rate is assumed at around 10 gallons per minute? And the temp drop is 8 degrees? I'm not seeing where heat loss in the boiler makes much difference or can be easily changed
-
If there is heat loss in the lines and no other load it will drop the temperature at a set rate. The rate it drops with and without the lines connected could be calculated into btu loss into the ground.
Here is a graph of a 275 gallon boiler. It is circulating through two plate heat exchanger and two large copper manifolds (all uninsulated inside the house)
As you can see, there is about 1 degree being radiated off the plates and copper. With it taking almost 4 hours to drop about 12 degrees we can calculate btu loss. If we figure an estimate of 2400 Lbs of water in the system and 3 degrees drop per hour, that is 7200 BTU per hour. This won't be exact though since there is some heat being generated by the smoldering fire but that probably is less that heat loss from the boiler itself.
-
But we are not talking about heat generated by a smoldering fire or heat loss from stack temps, we are talking about heat loss into possible ground water with no heat call, yes some will be lost from piping inside the home but with no heat call, it should certainly not be 8 degrees.
-
If you test both with house bypassed and then pipes completely bypassed the difference will be heatloss in the ground.
-
Anyway, if it is really losing 8 degrees round trip (which would mean the boiler would cycle about 2-3 times per hour with no load in the house) I would disconnect both ends and see if it is loose enough to pull the pipe and insulation out. If it moves easy enough, pull it out and if dry, get some good replacement and pull through. Good wrap pipe will only drop about 1/2 degree at 10gpm.
-
I guess so but it sure seems easier AND more accurate to test the lines themselves by installing accurate gauges on the supply and return at the boiler.
-
I picked these up from WWGrainger, was pretty close to where I’m doing physical therapy anyway so no shipping. I believe you can get something very similar from Pexsupply but in a 1/2” NPT. I needed the 1/4” for something else temporarily.
https://www.grainger.com/product/MILJOCO-Bimetal-Thermom-5RND7 (https://www.grainger.com/product/MILJOCO-Bimetal-Thermom-5RND7)
-
I have just seen way too many people over the years trying to test the pipe with some being over 40 degrees off from actual temperature.
If you are off by 1 degree or 1 gpm the results are not that great and if you are off by 3 or 4 on either they are completely worthless.
I built a tester for measuring BTU loss that is very accurate but requires disconnecting both ends of the pipe and it is too heavy to ship. I may try building a small version some day. It
-
if i put a temp gauge on the pipes coming out of the boiler.....it is within 1 degree....my boiler is set to shut down at 182.....the temp gauge coming out of the boiler will read 181-182 most of the time( even as high as 185 about 2 min after boiler shuts down...the water temp always seems to increase a few degrees...which is normal). Now, i have taken the same temp gauge and put it on the pipe as soon as it comes into the house (b4 it hits any exchangers, and it wil read 177-178 maxx...once in a while it will hit 180 a few minutes after the boiler shuts down and the boiler is reading 184-185. Pump size is right and i have my delta at 12° when a full load is on the house (water coming in will be 178 and water going out will be 162-164 when everything on the house loop is calling for heat).
When i installed the used boiler i got last year (a timberwolf 500) there was a small drip at the pump flange that i didnt notice (must have started after i did my checks). The water was dripping right into the drain tile of the underground pex....i noticed water coming through the drain tile into my house one day and i freaked out....i thought my lines were leaking underground....upon further inspection i found it to be a drip at the pump flange. I re sealed and re threaded everything and i only have to add a few gallons back into the boiler (say those gallons i lost went right down into the drain tile). I watched it for the next few days and the problem fixed itself,, but needless to say all that insualted (wrapped) pex got drenched with a few gallons of water at the start of last year. I spoke with an HVACC friend and he assured me that the heat off the lines should dry up any water/moisture that was still in the pipes over the upcoming heating season (this was at the begininng of last season). Well, all winter i noticed the same temp drops in the lines....they were exactly the same temp losses with a different boiler last year and i am experiencing this year. I guess i was just hoping that running all last year would have dried the underground lines out enough and was hoping upoon a prayer that i wasnt going to have those temp losses this year with the new set-up...WELL, I WAS WRONG!!! and now i feel like such a dumb ass.....it would have only cost me about $900 to run all new logstor this summer before i layed the pad and the new heatmor....what a moronic move not too!!!!!! :bash: :bash: :bash:
-
sorry i hope that made some sense....
-
thanks guys for all your help....i know i NEED to replace the lines....thats the correct fix, but man i dont want too....having to bend and burry logstor when its chilly and the piping is stiff is just no damn fun at all....im also concerned about running up through the concrete....i really dont want to crack the new pad i just put down
-
thanks guys for all your help....i know i NEED to replace the lines....thats the correct fix, but man i dont want too....having to bend and burry logstor when its chilly and the piping is stiff is just no damn fun at all....im also concerned about running up through the concrete....i really dont want to crack the new pad i just put down
I’ll agree with that, I did my Logstor last fall, waited till the warmest day of the week was forecasted and got everything ready to go. Using a cheap 1” ratchet strap to make the radius coming out of the ground made life a lot easier, that and paying a younger brawny kid with a good back was well worth it.
I see Zsupply has a new double walled underground line out, I’d make sure a person used the endcap at least at the stove just for that reason, a leak or what not will always have water going where it can cause the most damage whether it be at the back of your stove or in a house.
-
yeah i inquried about that new z supply pipe...its looks nice and seems more flexible....I also only have about 12-18 inches to burry the lines this time.....i just ran electrical about 24inch down in the same path that i have to run the boiler lines
My old lines were 4ft
-
what depth is recommended for Logstor???
-
18 inches if you are driving over it
-
what depth is recommended for Logstor???
I will post pictures when im done . But you don't need put new pipes under stove just run them into the side of the stove . take a bit of dissemble but I have to do this my 3rd zone came from wrong direction. What Im going to do is disassemble the whole back corner
to get stove set right and cut hole in the side . I have insul seal coming in the side of the stove . logstor would be a smaller hole . This is if you need to replace lines . theres a line between function and beauty gets blurred :) function always rules :) Will post pictures when Im done . :thumbup: Im a insul seal underground line believer. Harder to install yes . but It takes a tractor to straighten out the logstor also . That stuff is something else . insul seal installed right you can change out the lines if theirs any issues and dont need to dig anything up. also in the future and another option bigger lines upgrade is easyer also . I always default to most options. :) just my 2 cents .
heat550
-
thanks guys!! heat i would love to see pics!
-
Hi when I put in my boiler I put the lines down no deeper then about 20'' to keep it out of any ground water.I am not sure though of my heat loss.I used that same cheap 3 wrap pipe did not think it was so cheap at the time. I don't think it would be that hard to dig close to your pad, finishing the digging by hand. You may have chance to see what he used for the underground line my of used plain old romex??
-
thanks guys for all your help....i know i NEED to replace the lines....thats the correct fix, but man i dont want too....having to bend and burry logstor when its chilly and the piping is stiff is just no damn fun at all....im also concerned about running up through the concrete....i really dont want to crack the new pad i just put down
Why not trench around your pad a couple feet and snake the new piping right up to the back of it? :-\
When you are ready to backfill, use plywood to create forms under any edges of the concrete and just fill in with a couple bags of Quickcrete. You could even dowel small pieces of rebar into the existing pad in order to secure into the new concrete you pour in your makeshift forms. This would eliminate the pad from cracking from uncompacted backfill and settling. ;)
-
How much heat loss is contributed to uninsulated lines running through the basement and from natural convection from the heat exchanger in the furnace when the blower is not running? I measure my temp at the pump inlet and at the point where it first enters my basement to determine heat lost from the underground pipe.
-
Best way to tell would be to get some shark bite fittings with the gauges in them and place em both right at the wall. Of course no two gauges are going to read identical.