Print

[tinfoilhat2020]

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.....

[fireboss]

I don't think that's to bad,maybe wait to spring and then change the lines!

[slimjim]

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!

[tinfoilhat2020]

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!!!!
 

[slimjim]

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.

[tinfoilhat2020]

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
  I cant stop banging my head against the wall...literally!!

[slimjim]

Use caution, last time I tried that, I got a concussion!

[tinfoilhat2020]

Hahahahah

[RSI]

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.

[slimjim]

Sorry RSI, I'm not getting it, could you Please explain your thoughts a bit more?

[RSI]

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.

[slimjim]

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

[RSI]

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.

[slimjim]

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.

[RSI]

If you test both with house bypassed and then pipes completely bypassed the difference will be heatloss in the ground.