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Insulating water line from well to house

McMike's picture

We are in the process of trying to buy a finished cabin in the wilds of Northern NH. Tha cabin sits on a slab, has a beautiful mt. view, 100 amp electric service and an artesian well. The mountain views are great as the house sits on a ledge.


My concern is the water line feeding the house from the artesian well. They had drilled down only 4 feet when they hit ledge. My question is assuming I only have 4 feet of soil to work with to protect the water feed from the cold temps of Northern NH winters, how should I best insulate this pipe to prevent freezing?


What would be some of the ways I can insulate the pipe without jackhammering through the rock? 


Would the heating tape/strips ( essentially Romex wire) be the way to go?


Would inside the pipe heat tape be a viable solution or should be dig up the line (about 75' from the well head to the house) pack the trench with insulation and wrap heat on the pipe externally and then cover it up?


Rigid insulation better than fiber glass?


Any other ideas? I could use some suggestions . Thanks in advance for all your help.


 


Michael

(post #114241, reply #1 of 29)

How deep is the frost line there?

Generally it's best to insulate only on top of the pipe, with the insulation being several feet wide. This "traps" heat from the earth to keep the pipe warm.

Rigid foam would be the insulation of choice.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #114241, reply #2 of 29)

Hi Dan


Code says about 4 feet deep for frost heaves for a foundation. I assume it's the same for water but I may be mistaken. Would you put a heat strip through the inside of the pipe or on the outside (wrapped).  


So you don't think there would be any advantage to lining the trench with FG insulation and then putting the rigid foam on top?


Thanks for the response.


Mick

(post #114241, reply #3 of 29)

Foundation frost line and water frost line aren't necessarily the same. Here in MT the foundations go down 3' but the waterlines are at 6'.

FG insulation won't do you any good at all if it gets wet. Polystyrene foam is the way to go. (Be sure to use a foam that won't water-log.) You'll have to search out what you need for width and thickness: here's an outfit i found online that you might put in a phone call to, as i coudn't find the tables they referenced. http://www.plastifab.com/coldstoragemechutility/utility.html

A friend of mine faced the same situation replacing her water line this year and used insulation as above. One of the problems in her area is gophers who eat Romex for lunch and poly pipe for dinner. She found from the locals that for whatever reason - it makes no sense to me - they wouldn't destroy PVC lines, however, so she went with that. Underground Romex has to be buried in conduit for the same reason. I don't know if this applies to your area, but you might ask the locals , before you finalize your plans, if rodents are a problem.

(post #114241, reply #4 of 29)

Putting FG insulation would do more harm than good. It would soak up water like a sponge, becoming totally non-insulative, and if it freezes, make you life miserable trying to dig it out.

Use sand at the pipe and cover it with 2" EPS or XPS foam board to at least 2' and preferably 4' either side across the top.

Remember the earth's core is continually radiating heat out. That rock ledge is a good conductor so in some places, solid rock is slightly warmer than soil is, bringing that core heat up to you. Laying the insulation OVER the pipe traps that heat under where the pipe is.

 

 


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(post #114241, reply #6 of 29)

Hi Piffin and DanH (in subsequent post),


So I understand correctly. You would dig a trench down either side of the water pipe 4 feet wide (total of 8 Ft wide) down to the ledge  (probably 3-4 ft deep). Line the hole with EPS/XPS Foam board on the sides (not underneath the pipe). Fill in around the pipe with sand. Place cap of EPS foam board on top of sand/pipe. Cover remainder with top soil to flush with slope of ground.


This trench will cut across a " gravel driveway" of sorts to my barn. Would it be safe to drive over? Should I reinforce the cap covering the pipe with anything underneath or let the volume of sane provide the support? Perhaps I can throw down a steel plate once the drive way is flush again and drive over that.


Would you also use heat tape either wrapped around outside the pipe or strung through the center of the pipe? I am curious as to how big of a circuit that would need to be hooked up to. Also, from what I have read the heat tape that is threaded thru the pipe is typically a higher voltage due to the assumption of the pipe not being insulated at all.


I am thinking that a combination of the two ideas would work. The rigid foam and the heat tape. Insulation around the pipe providing even for efficiency for the heat tape and would keep that surrounding area warmer.


If you had to drive over it would you think maybe a 2 foot wide trench on either side would work instead of a four foot wide trench? I wouldn't want to totally crush the insulation. I have no problem digging the trench and I have a small backhoe that would be happy to do the job.


I just want to do it right and do it once. As usual, thanks for all the great ideas. Comments are still appreciated.


Mick

(post #114241, reply #7 of 29)

I'm not sure what the crush resistance of the foam is, and how that would work out in terms of vehicle traffic. Of course, partly it depends on how deep things are at this point, but it sounds like you'll only have 2-3 feet of cover, so I'm guessing some sort of additonal protection may be needed, possibly in the form of concrete (reenforced?) poured over the foam.

Hopefully someone else has either some data or some real-life info in this area.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #114241, reply #8 of 29)

Foam board comes in different compressive strengths to be used for burial under a concrete slab to situations like walls. Get the stuff made for burial under a slab.

(post #114241, reply #18 of 29)

Use the blue board (Dow?), not the pink (Owens Corning?).  If my history is correct, it was invented for use under roadbeds in permafrost regions.  The pink seems a lot softer

(post #114241, reply #19 of 29)

The maker doesn't matter, only that you get extruded polystyrene instead of expanded polystyrene (Styrofoam), e.g. the white insulation board made of glued-together beads that will soak up water.

Both makers produce the board in various strengths. If you are only putting a dirt drive over it, any would likely be sufficient, but i like to do things the best i can afford, so i would at least put the denser board where it will be driven over if the cost differential is great. (I haven't priced it lately to advise you on that.) Judgment call, though, and that's mine.

(post #114241, reply #9 of 29)

now that I have a fuller picture I can say more than general principles.

I would not bother with the heat tape. I suppose you could add it in and just plug it in if it ever freezes, which I doubt.

If you go only 2' or so on either side of the pipe to save digging, use two layers of 1-1/2" instead of 2'. if you have the sand tamped under th e foam that deep, the foam will handle the traffic just fine.

 

 


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(post #114241, reply #10 of 29)

I'm thinking McMike thinks you're saying to make an inverted U out of the foam, I've only seen the foam laid on top of the pipe about 2' feet out on either side...but then, I've never had to deal with your kind of cold<G>

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(post #114241, reply #11 of 29)

I think Dan added the idea of legs to make it like an inverted U which can't hurt but sounds like a lot of extra work.

The University study on this kind of thing done up here found that 2" four feet lateral gave the best results of a lot of differing methods.

BTW, that was in a parking lot situation.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
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(post #114241, reply #13 of 29)

The inverted U lets you use a narrower trench and achieve the same effective insulation level.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #114241, reply #5 of 29)

Generally water needs to go a foot or so deeper than code for foundations -- a foundation can stand an occasional freeze, but water pipes may not.

I'm not aware of a heat strip that can be snaked inside a pipe, so I can't comment on that option.

Regular fiberglass insulation placed anywhere would compress with the soil and be essentially worthless. And in any event you don't want insulation under the pipe -- you want heat from the earth to be able to rise to the pipe.

My guess is that the most effective approach would be to trench maybe 3-4 feet wide, to a depth several inches below the pipe (or down to the rock ledge). Line the sides of the trench with foam (I'm thinking 2 inches thick) up to a point several inches above the pipe, then backfill between to cover the pipe those several inches. Compress the backfill reasonably well, then place foam (2 inches) on top, for the full width of the trench. Backfill that to grade, taking care to avoid fracturing the foam.

You can probably get away with a narrower trench, but the technique gets less effective as the trench gets narrower.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #114241, reply #12 of 29)

Tyco Thermal is a good brand for heat tracing; they sell heat tape that goes on the outside of the pipe, as well as tape that can be buried or put inside the pipe.  The advantage of the in-pipe style is that you don't have to dig the pipe up to install it - it goes through a fitting inside the building.  However, depending on the size of the pipe it may not fit...I think 1" pipe is the minimum size.


Here's a link to their website:


http://www.tycothermal.com/usa/english/heat_tracing/applications/residential/pipe_freeze_protection/default.aspx


Edited 7/2/2007 8:05 pm by Stuart

(post #114241, reply #14 of 29)

artesian well


No power needed to pump,


looked but did not see anyone in a previous post mention the obvious - just let the water run out by a trickle, better than heat tape.


1 gal/ hr equiv to about 44 watts heat tape equivalent (in head calc, need to check) or only about 2 fl oz per minute, just a drip.  4 ft deep should keep it above freezing with a  trickle.


Let it drip somewhere out over the ledge where it will make beautiful icicles.

(post #114241, reply #15 of 29)

I thought about getting into that part of it. you and I know what an artesian well is, but nine times out of eight I hear somebody mention artesian and they think it means a drilled well as opposed to a hand dug one. I try to explain that artesian has a natural flow from geological formations allowing gravity to siphon water out the well and they get a deer in the headlights look and act like they think I'm crazy.

 

 


Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!

 

 

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(post #114241, reply #17 of 29)

This confirms that there are only three of us...

(post #114241, reply #20 of 29)

No, no, no! "Artesian" means it drilled by guys wearing berets.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #114241, reply #16 of 29)

You are right, if he really has an "artesian" well, which I doubt.  If he's got "views" and shallow ledge, he's likely up on a hill and more likely to have a basic bedrock well, not a true artesian well.  The term "artesian" is way misused.  

(post #114241, reply #23 of 29)

You beat me to the "trickle flow" suggestion, Junkhound. - lol


If the house isn't a year round residence, some kind of low point drain may also work well.

(post #114241, reply #21 of 29)

dont know where in upstate NH u are, but above the White Mtn Natl Park we frequently see 30 below temps.  I have installed several in the pipe heating elements which have a temp sensor to turn them on and off when approaching freezing temps, never had a freeze up in all these years.  On the down side, it is quite expensive to purchase yet much less to operate than out side the pipe heat tape

(post #114241, reply #22 of 29)

Wow...I go away for an evening and look what happens. All these great responses. You guys are correct, it is NOT an Artesian Well. It is a drilled well. Sorry about that. The current owner (we are buying this place) contacted me last evening and told me the well company that drilled the well (over in VT) and that the pipe is down 3 feet. It is also covered with the 2" thick rigid insulation already. They had this done in 2002 and have spent a winter there with no water problems. The pipe was also packed around with sand so I feel a lot better to know it seems to have been done right. However, as Ronald Reagan was wont to say Trust but verify. I will be putting in a call to the drilling company today.


I was still thinking of running the heat tape through the pipe to be on the safe side. As the previous post said, it goes more than damn cold up there in the winter. We are just northwest of the White Mts but close enough to see 14 of them on a clear day. I have no seen any depressions in the driveway to indicate any problems either so.....


Would you folks bother with the heat tape? How expensive (ballpark) is it to string tape (I assume a Romex type wire). It is about 75 from the house to the well head. According to the owner, the pipe comes up through the slab under the house through a piece of conduit (just in case the pipe ever had to be removed for any reason no jackhammering would be involved).


I have a tendency for overkill with regards to construction projects (probably due to lack of skill) but I figured an ounce of prevention is better than a pound of cure.


So what do you think? Again thanks for all the great responses. It is hugely appreciated.


Mick


 

(post #114241, reply #24 of 29)

Since you won't be there all the time, invest $200 in a FreezeAlarm, so it'll call you when the temp inside drops below a set point.  An outage of power/heat will do damage within the house, while the line below ground will survive unscathed.


Another thought. A place we bought (also in NH) had the well installation done for shutdown during unattended/unheated winter periods. Outside the house there is a shutoff valve down around 4 feet. Line from the wellhead comes downslope to the valve, then into the house. The way I think it works is when shut off, the inside line can drain back to soil. I don't think the line from the wellhead to the valve drains. The reason I think that is because the well itself is artesian; in periods of no pumping, the well fills up and overflows through a line that tees in less than a foot below the surface. The line empties further downhill. Anyway, I would think you would have a shutoff somewhere between the wellhead and the house, so you could shut down and drain the line (maybe depending on elevations) when you are not there. If you plan to use the place regularly, as we do, you may find it easier just to turn the thermostat back all the way and let the temp settle down to 48-50 F. No problem, as long as the power stays on and the heating system runs. This is not always the case, which is why I bought the FreezeAlarm. Based on what you've told us about your installation, I don't think the well line ever will freeze; the rock is much too conductive relative to the XPS and ground above it.


Edited 7/3/2007 3:23 pm ET by DickRussell

(post #114241, reply #25 of 29)

Presumably the pipe is plastic and won't be very likely to be damaged if it freezes. Inconvenient, but not a major problem.


So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #114241, reply #26 of 29)

Maybe I'm missing the obvious, but if it's been working fine for 5 years why do you want to mess with it?

(post #114241, reply #27 of 29)

Hi,


  The current owners have spent a winter up there with no problems but I have asked these questions because I did not know what to expect. I had been told previously by the realtor that they spent time in FL during the winter (snowbirds). We are anything but snowbirds (no offense FL) and wanted to be able to spend time up there in the winter. With the pipe only being 3-4 ft down near ledge I was fearing the worst so decided to ask the Experts here.


As usual, you guys didn't let me down. Upon speaking with the drill people they verified the depth of the plastic pipe and also the existence of the 2 inch thick blue rigid insulation 4 feet wide buried above the pipe and have packed sand around the pipe and under the insulation just as Piffin and others had suggested.


At least I know a little more about it know and can sleep a little better. Many thanks to all. It is always appreciated.


Mick 

More practical experience (post #114241, reply #29 of 29)

Similar problem when I built my house on/in ledge almost 30 years ago: foundation was blasted out of solid ledge, well drilled about 50 feet away in solid ledge (after the blasting and excavation), but could only dig a trench about 30 inches deep between the well and the house. I put the (poly? PVC? Don't remember now, been too long) directly on the ledge in a shallow bed of sand, covered the pipe with another 6" of sand, and laid a 4' x 2" blueboard over top, then backfilled. 30 years later, no issues - and we've had plenty of 10-15 below nights (and even a couple of -25F!). I'm certain that the ledge is a ground heat bridge, and the insulation keeps the ground heat contained well enough to prevent freezing.  Anecdotal, but real world, data.

My house is on ledge in (post #114241, reply #28 of 29)

My house is on ledge in central Maine, I cover the area of ground above the pipe from my well to the house with straw about 12" thick 3-4' wide, and than attach a heat tape and iinsulate the verticle pipe from where the straw ends up into the house, at temps minus 30 degrees, I have never had a problem, make sure that the crawlspace is tight allowing no air to penetrate on to the pipe