Author Topic: Question about Outdoor boilers (Read 4455 times)

Snag · « **on:** January 18, 2007, 01:39:47 pm »

I installed a Heatmor outdoor boiler this past fall and had a question for othe outdoor boiler owners. I have noticed that the snow (now that we finally got some) melted at first over the pipe run from the furnace to the house. Since temps have dropped more, it is less noticable, but still, seeing that bothered me. Is that normal? I know there is going to be some heat loss and I am probably worried about nothing, but was hoping for some feedback. The lines are 1" pex with oxygen barrier, each has pipe foam around it, then the whole thing was shoved into 4" pipe and had expanding foam sprayed in........ Thanks for any feedback....

Engineer · « **Reply #1 on:** January 18, 2007, 02:04:20 pm »

How deep is your pipe? If it's only 12-18" below grade, I'd expect to see some snow melting going on. My Central Boiler manual said 18" deep for the pipe, and I decided that wasn't enough and buried it about 40" deep. There is NO evidence that the pipe is there, and the water loses only about 2 degrees temp between the boiler and house.

Snag · « **Reply #2 on:** January 18, 2007, 02:12:28 pm »

The depth varied slightly, but on average 24" deep. I thought along the same lines as yourself, but my heatmor dealer insisted over and over that anything beyond 18" was a waste. So, I went just a little deeper anyway.

How are you measuring your temp loss? What style therm.?

ronwood · « **Reply #3 on:** January 18, 2007, 02:22:54 pm »

Snag,

Mine lines to my CB is buried around 24 in and I see the same thing. Wondering if I should have went deeper.

Ron

Furby · « **Reply #4 on:** January 18, 2007, 03:48:28 pm »

In this case I don't think going deeper solves anything other then hides the truth.
You still have the same amount of thermal transfer at 18" as you do at 40".
You aren't warming the surface causing the snow to melt with your lines at a deeper depth, but you are still having heat loss in your lines.
If you want to solve the problem and not hide it, you need more insulation.

ronwood · « **Reply #5 on:** January 18, 2007, 03:54:45 pm »

Furby,

I agree with your assestment. I would think it would take quite abit of insulation to completely stop the thermal transfer. The insulation and pipe cost me nearly $6.00 uninstalled almost 2 years ago. I hear it is even higher now.

Ron

Engineer · « **Reply #6 on:** January 18, 2007, 05:49:18 pm »

Quote from: Snag on January 18, 2007, 02:12:28 pm

The depth varied slightly, but on average 24" deep. I thought along the same lines as yourself, but my heatmor dealer insisted over and over that anything beyond 18" was a waste. So, I went just a little deeper anyway. How are you measuring your temp loss? What style therm.?

I have a temperature gauge in the basement, and the digital readout on the boiler. The difference is usually about 2-3 degrees, regardless of outside temperature. Of course, they could both be wrong.

As far as my burial depth, I had an overzealous excavator who liked to dig. Plus, he had a CB himself and thought that the lines should be deeper.

Quartlow · « **Reply #7 on:** January 18, 2007, 06:15:08 pm »

I don't have CB, But I buried mine down about 40 inches. Ran them through a piece of 4 inch pvc No insulation except for where they come out of the ground and run under the trailer.
On a 60 foot run I lose 2 degrees. I feel they need to be below the frost line at the very least. but thats just my $.02 worth, that and a buck may get you a cup of cheap coffee

Snag · « **Reply #8 on:** January 19, 2007, 07:18:38 am »

When I ran the electrical out to the boiler, I ran it in 2" pvc and also ran 6 pair wire to hook up any sensors I decided to add on in the future. I would like to hook up a temp guage on the water coming directly out of the boiler and via these wires, have it display in the basement (the other end of the 6 pair). Anyone know what type sensor/guage I need to do this. I also want to hook up a temp guage on the line where it enters the house, but again, any suggestions on a type/brand/model? Thanks for all the help everybody.

Ghost River Timber CO. · « **Reply #9 on:** January 19, 2007, 07:31:30 am »

Furby's assesment is probably right but for the sake of asking, what depth is th efrost line in your part of New York?

Dana · « **Reply #10 on:** January 19, 2007, 07:41:03 am »

Furby, The thermal transfer would be less if the lines were buried below the frost line wouldn't they?

The greater the temperature difference between two objects the quicker the heat loss. I agree with you that more insulation is the best answer.

Snag · « **Reply #11 on:** January 19, 2007, 07:43:50 am »

Our frost line depth is roughly 36" to (more likely) 42".

Ghost River Timber CO. · « **Reply #12 on:** January 19, 2007, 07:52:18 am »

Quote from: Snag on January 19, 2007, 07:43:50 am

Our frost line depth is roughly 36" to (more likely) 42".

I just looked you up(well Tonawanda, NY) and found out your footings have to be poured "below the frostline of 42" deep." In Woodstock, NY it's 4 feet. IF you have the means and are that worried about the heat loss I'd re-dig it and bury below the frost line. You might also step up the insulation value aswell if you are going through that much trouble anyway. Here in NC code is R-8 on waterlines in unconditioned attics but the local big box store sells an R-3 for real cheap, so I have to turn a lot of people down for that one.

Snag · « **Reply #13 on:** January 19, 2007, 08:16:15 am »

Unfortunately going deeper at this point isnt an option. My run is around 150' and each pipe is continuous. In order to do deeper, I would have to splice it, and really dont want to. The other thing, digging it up wont be quite as easy as the initial excavating. The risk of damage with the backhoe to the lines and the insane amount of handwork. I guess I would like to dig it and add insulation to the outside, but again too much handwork , right now anyway. Guess I was hoping I wasnt the only one seeing this and that I didnt really mess something up. If 20 people responded and said things like "I buried mine 12" deep and dont see any snow melt" then I would start to get worried. I guess the truth will be told when I hook up the temp guages. Also, I misspoke about the frost line. I was thinking of my last residence. I believe when we had our footers pured here and waterlines buried they went down 4'. Dont know if that is the frost line, but that is what the foundation guy and water guy both said to do.

Ghost River Timber CO. · « **Reply #14 on:** January 19, 2007, 08:26:39 am »

Well look at it this way, fill dirt is a decent insulator. And beig it's a wood furnace You're probably only talking enough energy loss to acount for 2 extra sticks of wood a week. At the most 1 a day. I wouldn't sweat it.

Snag · « **Reply #15 on:** January 19, 2007, 08:31:01 am »

Thanks.

While I wait (hope) someone chimes in with some guage info, let me ask y'all this. I plan on paving the driveway in the next couple years (gotta save some moola first), anyone using their boiler to melt the snow? Purposely this time?

farmerdoug · « **Reply #16 on:** January 19, 2007, 04:26:11 pm »

I know of a couple of businesses that do that. One has two CB pallet burners plumbed together. They burn their waste pallets and wood from the warehouse. They heat their warehouse and the main parking lot to use up all the heat from the stoves. They do it to save on rubbish disposal fees.

Farmerdoug

thecfarm · « **Reply #17 on:** January 19, 2007, 09:16:29 pm »

I would think your driveway would have to be above ground level.Need a place for the water to run off or would there be much?I would like to do the same thing to my 500 foot driveway.Would need another pump at the bottom of the hill I would think.

maple flats · « **Reply #18 on:** January 19, 2007, 09:52:39 pm »

Until I retired in 1999 I sold and installed these for 12 years. We had the customer get a trench dug about 4' deep. We installed the heat pipes inside 3/4" foam insulation and put it all inside a 4 or 6" corrogated tile. This still showed the line of melted snow early and late in the season. In the dead of winter the snow rarely showed melting. However you were loosing heat. If your pump is moving 10 gpm and the temp drop is 2 degrees lets figure it out. 1 gal=8# and 10gal/min = 80# x 60 min/hr = 4800 #/hr a BTU is the heat required to raise or lower a # of water 1 degree F from 62 to 63 degrees or from 63 to 62 degrees. Not trying to calculate the difference of the 62 to 180 degrees and exploring how BTU's compare just take the 4800# x 2 degrees = 9600 btu heat loss or roughly 10,000 btu/hr loss. Insulating better can help but you need to balance the cost of getting enough insulation to drop the temp loss against the cost of the wood you burn. Some improvement in insulations has occurred for doing this since I was doing it but you need to have a big improvement to be worth it. 10,000 sounds big but in reality it is rather small if you are burning your own wood or scrap wood from the sawmill or logging operations. Wood IS cheap. As a side note 1 btu is the amount of heat needed to raise 1# of water 1 degree F from 62 to 63 or about the same heat as generated by burning 1 wooden kitchen match.

Snag · « **Reply #19 on:** January 20, 2007, 06:56:05 am »

Thats some good info maple flats. Thanks.

Dana · « **Reply #20 on:** January 20, 2007, 07:36:36 am »

Central Boiler recommends the shallow bury depth in case you have ground water near the surface. Water will conduct heat out of the plumbing much quicker than frozen earth.

woodmills1 · « **Reply #21 on:** January 20, 2007, 08:54:23 am »

Yes, ground water in contact with the heat pipes would be a much larger problem. My pipes are shallow, around 2 foot. They have a 1 inch black foam insulation and then a styrofoam box around that. The whole outside run was then encased in a 9 mil poly sock, one piece from cellar to stove, being careful not to perforated it during installation. I also lined the trench with sawdust and then covered the pipes with sawdust to keep from puncturing the bag. My company, Free Heat Machine, made a big deal about excluding water from contact with the pipes. Waters ability to either hold or remove heat is amazing. I can still see the look on my students faces when I boiled water in a plain dixie cup using a bunsen burner.

Furby · « **Reply #22 on:** January 20, 2007, 02:51:45 pm »

That's why dirt is such a poor insulation.

OneWithWood · « **Reply #23 on:** January 22, 2007, 03:06:45 pm »

Much to my horror I discovered that wrapping the pipes in plastic was a big mistake. It just traps condensation, saturating the styrofoam

woodmills1 · « **Reply #24 on:** January 22, 2007, 08:43:18 pm »

my plastic is a one piece bag from back of stove to inside the house.

Mtnjack · « **Reply #25 on:** January 22, 2007, 09:17:17 pm »

Remember insulation only slows heat transfer, does not stop it,just have to start mowing before every one else.I heat with a taylor 165 feet from house and lose 10 to 20 degrees,180 to 160 not a problem. Just taped bbq meter to pipe in basement.House is plenty warm. Mtn Jack

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Author Topic: Question about Outdoor boilers (Read 4455 times)