underground piping
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i used fred setons method with corigated pipe , pex inside then insulate over the top. worked last year , but this year im having a problem with ground water and it melts snow. at its worst id loose 15 degrees in 240'. i saw some new stuff on ebay , its similar to maxx but it comes in a roll not in 8' pieces.didnt know if any has tried this. i need to change my pipe asap . im burning oil now because its using to much wood, seems like a waste to heat the earth.
heaterman
Minister of Fire
2.beans, We use bare pex and hire an insulating contractor to spray foam it in the trench. Cost is usually about $6-10 / ft depending on the tube size, how much product they use, travel time etc. It works great for us. I don't use anything else now but I have had good results with InsulSeal in the past. Don't get sucked in by the corrugated stuff with the pex inside wrapped in a couple layers of bubble foil. My nephew is growing green grass above his as we speak. He loses about 9* from his OWB to his house in only 80'.
the stuff on ebay wasnt the bubble wrap. the pex is inside 1/2" rubber tube with foam oxygen barrier. is the spray foam dense enough to not absorb water? can break/crack and allow water in?
trehugr
Member
Heaterman, with there being so many kinds of PEX, what specific brand would you use for the system your using ?
trailhound68
New Member
I have 1" pex about 75' underground each way. The tube is in insulation, that is in 4" electrical conduit, glue joint.
Supply and return are seperate. Each in its own insul and conduit.
I thought this was a darn good installation, yet I have a 10 deg loss if all stats are accurate. it will also melt the snow if its a thin layer.
Most of my tubing is 24" plus below grade with no water issues.
I'm wondering if my pump speed is too slow?
Supply and return are seperate. Each in its own insul and conduit.
I thought this was a darn good installation, yet I have a 10 deg loss if all stats are accurate. it will also melt the snow if its a thin layer.
Most of my tubing is 24" plus below grade with no water issues.
I'm wondering if my pump speed is too slow?
Yikes
If you're pumping 5 gallons per minute with a 10 degree F. delta T that works out to ~ 25,000 BTUs per hour loss. Pumping faster will actually increase the loss a bit due to greater delta T that will occur. The loss will be proportionally more or less if you're pumping a a higher or lower gallonage/minute.
I would double check the temps.
Hugh
If you're pumping 5 gallons per minute with a 10 degree F. delta T that works out to ~ 25,000 BTUs per hour loss. Pumping faster will actually increase the loss a bit due to greater delta T that will occur. The loss will be proportionally more or less if you're pumping a a higher or lower gallonage/minute.
I would double check the temps.
Hugh
henfruit
Minister of Fire
2 beans what are you useing for a heating unit? also what part of nh are you in. i am in effingham.
heaterman
Minister of Fire
trehugr said:
I use Viega and Rehau pex just about exclusively. I've had excellent results with both and to me it's not worth risking an installation on something I can save a dime a foot on. I know a lot of contractors have good luck with Wirsbo/Uponor but I've heard issues with customer service since they changed names and got rid of a bunch of the folks that grew the company to where it is today.
henfruit, i have a seton w130 or w200, whatever one you want to call it. the boiler is in my shop which is 240' away.i live in hillsboro
heaterman when you spray foam the ditch is the pex in pipe or do spray a layer down lay the pipe then spray over it? on the insulseal how rugged is the outside insulation? thanks
henfruit
Minister of Fire
EForest
Member
trailhound68 said:
two problems here. Every person I have spoken to on this subject will agree.
1.should have been below frost line at minimum 42" in CT
2.Glue joints are too risky. every one has a chance of failure.
Are you certain that water hasn't filled the pipe?
What size/brand splitter you selling and how much $?
henfruit
Minister of Fire
heaterman
Minister of Fire
2.beans said:
We have the Pex in the trench when the guys come to spray it. As the guy with the gun moves down the length of the trench, he'll lift the pex with his foot and spray 3-4" underneath it. The product they use blows and hardens in a matter of seconds, at which point he'll drop the tube on the foam and proceed to spray the sides and top. The only disadvantage of this that I can see is if for some unknown reason you would ever want to pull the tube like you could in the InsulSeal type system. We typically go one size bigger on our tube just in case an additional load pops up in the future. Going to 1 1/4" vs 1" tube greatly reduces the flow resistance (head) on any run over 75 or so feet or that requires more than 6-8 gallons per minute. It makes the difference between having to run an 0011 vs a 007 Taco for example. Substantial savings in long term electrical costs between those two circs.
The foam on the outside of the InsulSeal is pretty rugged. Nothing that you would want to cover with rocks mind you but it will certainly hold up under normal backfilling.
heaterman i asked a local spray foam guy for a price and he told 2600.00. thought that was enough. i can buy pipe for that but not 1 1/4, which id like. thanks for the help
heaterman
Minister of Fire
Don L said:heaterman said:
Don, Both of the tubing brands I use have their own fittings for large bore tube as you already know. Viega uses a pretty much standard type fitting which is interchangeable with anyone else's but the connection is made using a pressed on stainless steel sleeve not a ring. There are hand operated press tools for 1" and down but you have to use an electric tool similar to The Ridgid ProPress system for 1 1/4" and up. They are not cheap, about $2K for the tool and the jaws for different sizes.
The Rehau you obviously know about and have already checked the price of their hydraulic press tool. OUCH
Tools like that are just something a pro has to add into the cost of doing business.
I don't know of any manufacturer that makes larger bore fittings that use a basic clamp type attachment method. You just need a little more oomph when your fooling around with that size pex. It gets pretty nasty to handle........My boys call it "wrestling the anaconda". Glad they are both the strapping young lads that they are when it comes to the 2" jobs.
I'm having problems getting a large slab to heat up using a Seton 300...his biggest I believe?
Running 3/4" line Pex 150' in a 4" flex line that's uninsulated except for 2-4" of rigid over the top...all above groundwater.
At the manifold in the warehouse (uninsulated), I'm tapping into 7/500' 1/2" lines and seem to only be getting 2 to 2-1/2 gallons of flow total.
Temp is around 170 degrees leaving the heat exchanger near the stove and 130 at the end of the 150' run...the return is down around 100 degrees.
2 questions on the 3/4" supply/return lines...
Should I upsize to 1" or 1-1/4"?
Should I use insulated PEX (if I upsize), or spray foam (If I retrench)...(has anyone tried those small cans or containers of spray foam?...Is there a special density or ? when purchasing it?
Fred Seton has suggested I install a mixing valve between the heat exchanger and the pump going to the warehouse to keep the return temp up. Does this sound correct?
Regards, Scotty
PS...I'll be posting about my "MAJOR" creosote problems along with some pics that will have you smiling.
Running 3/4" line Pex 150' in a 4" flex line that's uninsulated except for 2-4" of rigid over the top...all above groundwater.
At the manifold in the warehouse (uninsulated), I'm tapping into 7/500' 1/2" lines and seem to only be getting 2 to 2-1/2 gallons of flow total.
Temp is around 170 degrees leaving the heat exchanger near the stove and 130 at the end of the 150' run...the return is down around 100 degrees.
2 questions on the 3/4" supply/return lines...
Should I upsize to 1" or 1-1/4"?
Should I use insulated PEX (if I upsize), or spray foam (If I retrench)...(has anyone tried those small cans or containers of spray foam?...Is there a special density or ? when purchasing it?
Fred Seton has suggested I install a mixing valve between the heat exchanger and the pump going to the warehouse to keep the return temp up. Does this sound correct?
Regards, Scotty
PS...I'll be posting about my "MAJOR" creosote problems along with some pics that will have you smiling.
heaterman
Minister of Fire
Seton stove said:
Let's start at the beginning. The first question you have to ask in any situation is what is the heat loss of the structure. From there you can determine flow rates required which will tell you tubing size, loop length, and circulator selection. From there you have to look at the type of equipment and heat emitter being used to select the right control set up.
Here's some rules of thumb: rough but generally accepted as safe
The following flow rates will all develop about 6' of head per 100' of the corresponding tubing size.
Using a 20* drop you can figure that each gpm is good for 10,000 BTU of heat transfer.
1/2" = 2 gpm
3/4" = 4 gpm
1" = 8 gpm
1-1/4"= 15 gpm
1-1/2" = 22gpm
2" = 45gpm
Note that the 6' of head is PER 100' of tubing length. Taco or Grundfos' website will have specs detailing the performance curve of the circ you're using.
Loop lengths recommended for good performance without resorting to ultra high head circs in a slab heating application (IE) 009/0011/26-99
1/2" 300'
5/8" 400'
3/4" 550'
Each of those will give you about 1-1.3gpm per loop or using the 20* drop, 10,000 - 13,000 btu per loop.
A well insulated cement slab in a building with normal heat loss will require no more than 120* water and usually it will be closer to 100-110*.
Now back to your system............
I'm assuming that your building is about 3,500 sq ft based on the 7-500' loops. 30 btu's / sq ft. (WAG) would equal about 105,000 btu heatloss. This translates to roughly 10-11 gpm flow required.
From that you can see your main loop out to the building should be 1-1/4". A 007 Taco or a 15-58 Grundfos will provide all the push you need to get the water there and back.
In the shop you have loops that are overly long so the temp drop is going to be higher than you would like due to reduced flow rates. In a warehouse application the excessive temp variation in the loop probably isn't a big deal other than you'll probably have to use a high head circ. (009)
Seeing as you have no storage you'll have to limit flow or temp drop in order to keep water temps up in the boiler above the creosote threshold. Then in the warehouse you could use a straight thermostatic mix vavle to limit the temp going out to the slab .
A cement slab can drain enormous amounts of heat whil coming up to heating temps. Far more than the actual heating load per hour would normally be. Picking up a load like that with no storage or backup means you have to rely totally on the output of the boiler. If the pickup load is greater than the boiler output you'll find that the boiler temp will just plummet and stay there. Hence the need for a mixing device in order to protect the boiler from condensing temps.
Tell us how you're system is piped exactly. What model circ do you have on the 3/4" lines and what model is running the warehouse floor?
Are you using a thermostatic mix valve to drop the temp going to the slab?
What a great amount of information...let me start off by expressing my thanks for your (and every other posters), time helping with this.
Building is 4500 sf, uninsulated Quonset style warehouse. uninsulated slab is 6" on pig wire over compacted sand (I think there was a vapor barrier in there somewhere), with 1/2" lines attached to the pig wire. I recall the lines being approx. 18" apart.
When setting up the loop lengths, diameters, spacing, pumps etc., I relied on the same person who sold me the Stove...thus I didn't insulate under the loops (water table is pretty low), used 1/2" (why pay for 3/4" when you don't need it), 500' loops (experience has shown the old 'limits' to lengths are incorrect), and a Taco 0011 to push the water to the warehouse (again, it's all you need for your circumstances...comments are those of the stove seller).
You mention a Taco 007 and 009. I'm using one Taco 0011 about 3' from the heat exchanger that pumps to the warehouse AND pumps the 3500' of 1/2" in the slab (I was told 1 pump does it all)(I do have a spare Grunsfos 15-58 F4 on the shelf).
So...with some items indelibly fixed, here's what I can change...
I can insulated the walls of the warehouse...probably take a season or two to get it done however.
I can upsize the supply lines to 1-1/4 (Ouch)...at least I can use the existing 3/4" stuff for future expansion to a greenhouse, kiln, or mobile home.
I can upsize the pump.
I can put in a storage device...with propane backup?
You mention using a straight thermostatic mix valve (in the warehouse), to limit the temp going out to the slab...I was recently told to install a mixing valve between the exchanger and the 007, not out at the warehouse...do these provide the same result e.g. keeping the water temp at the stove up?
When it comes to storage/backup heat...Easiest around here would probably be a propane fired - water heater. Any thoughts on this? (I can possibly do this quicker than insulating the warehouse as it's full of stuff and will be hard to access other that a bit at a time).
Next, I'll get to working on the pics of the creosote problems.
Regards, Scotty
Building is 4500 sf, uninsulated Quonset style warehouse. uninsulated slab is 6" on pig wire over compacted sand (I think there was a vapor barrier in there somewhere), with 1/2" lines attached to the pig wire. I recall the lines being approx. 18" apart.
When setting up the loop lengths, diameters, spacing, pumps etc., I relied on the same person who sold me the Stove...thus I didn't insulate under the loops (water table is pretty low), used 1/2" (why pay for 3/4" when you don't need it), 500' loops (experience has shown the old 'limits' to lengths are incorrect), and a Taco 0011 to push the water to the warehouse (again, it's all you need for your circumstances...comments are those of the stove seller).
You mention a Taco 007 and 009. I'm using one Taco 0011 about 3' from the heat exchanger that pumps to the warehouse AND pumps the 3500' of 1/2" in the slab (I was told 1 pump does it all)(I do have a spare Grunsfos 15-58 F4 on the shelf).
So...with some items indelibly fixed, here's what I can change...
I can insulated the walls of the warehouse...probably take a season or two to get it done however.
I can upsize the supply lines to 1-1/4 (Ouch)...at least I can use the existing 3/4" stuff for future expansion to a greenhouse, kiln, or mobile home.
I can upsize the pump.
I can put in a storage device...with propane backup?
You mention using a straight thermostatic mix valve (in the warehouse), to limit the temp going out to the slab...I was recently told to install a mixing valve between the exchanger and the 007, not out at the warehouse...do these provide the same result e.g. keeping the water temp at the stove up?
When it comes to storage/backup heat...Easiest around here would probably be a propane fired - water heater. Any thoughts on this? (I can possibly do this quicker than insulating the warehouse as it's full of stuff and will be hard to access other that a bit at a time).
Next, I'll get to working on the pics of the creosote problems.
Regards, Scotty
Ouch is right. 4500 square feet of un-insuated space will be a tough go. It's more like a snowmelt system with a metal roof over it 
With 1/2 tube, 500 foot lengths and 18" on center you have the deck heavily stacked against you.
Building insulation would be the first place to start. Spray foam works well in that type of building. You could add additional lines from the stove. Maybe another set of 1" lines, manifold them together to get your flow up. Then you can move all the heat the boiler is capable of producing.
Without under slab insulation start up may take days. edge insulation would be a huge help.
Run a load calc as the building stands, and one with an R-19 insulation. 50 BTUs per square foot, for example would require 225,000 BTU per hour. Divide that by the amount of loops you have to distribute it. doubtful that 1/2" tube will ever move that much load, even with a 5 HP pump
Run the load calcs, maybe we can tune around what you have.
hr
With 1/2 tube, 500 foot lengths and 18" on center you have the deck heavily stacked against you.
Building insulation would be the first place to start. Spray foam works well in that type of building. You could add additional lines from the stove. Maybe another set of 1" lines, manifold them together to get your flow up. Then you can move all the heat the boiler is capable of producing.
Without under slab insulation start up may take days. edge insulation would be a huge help.
Run a load calc as the building stands, and one with an R-19 insulation. 50 BTUs per square foot, for example would require 225,000 BTU per hour. Divide that by the amount of loops you have to distribute it. doubtful that 1/2" tube will ever move that much load, even with a 5 HP pump
Run the load calcs, maybe we can tune around what you have.
hr
Your analogy of a 'snow melt' under a metal roof made me laugh...that's about what I have at best of times.
As to spray foam...I did a bit of checking on this, and it appears I've got to be careful about the fire hazard (and I'd probably have to empty it out for a couple of days),...so I'm thinking of firring it out with horizontal 2x4 2' o/c then attach 1-2" rigid with a face of some sort (looks like plastic or vinyl-blue in color)...been told I should fasten 2x from the outside and rigid from the inside.
Load calcs...can you point me to a formula, work sheet, indepth explanation?
Regards, Scotty
As to spray foam...I did a bit of checking on this, and it appears I've got to be careful about the fire hazard (and I'd probably have to empty it out for a couple of days),...so I'm thinking of firring it out with horizontal 2x4 2' o/c then attach 1-2" rigid with a face of some sort (looks like plastic or vinyl-blue in color)...been told I should fasten 2x from the outside and rigid from the inside.
Load calcs...can you point me to a formula, work sheet, indepth explanation?
Regards, Scotty
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