Hot Water Tank in Uninsulated Shed?

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Molo

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Hello Everyone,

I have a shed/storage area attached to the end of a ranch house with no basement in cold New York State. I would like to install an electric hot-water tank in there. It is an uninsulated space, yet I have access to the insulated attic from the area.

Proposed install is this:
1. Place Tank in uninsulated storage room at end of home
2. Run water lines in attic and insulate over them
3. Use heat tape to on the water lines between the tank and the insulated attic.

I have three questions;
1. What is the best brand of PEX to use for this project?
2. What is the best brand of Heat Tape to use?
3. Is there a better way to do this?

Any advice on this project will be greatly appreciated,
Thanks, Molo
 
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Cass

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Personaly, I would find another way of doing this. The whole idea does not sound good. NY can get mighty cold and I wouldn want to take a chance with a freeze break or fire from heat tape. Just my NSHO.
 

Jadnashua

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While it would take awhile, what would you do if you had an extended power outage? Pex is pretty good (much better than copper or cpvc) about freezing, but the tank could not handle it at all.
 

Cass

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Not suer if PEX can be heat taped and insulated without causing a problem.
 

Molo

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Response and Possible Solutions

Hello Everyone,
I am really trying to solve this hot water tank installation problem. I plan on taking it on as soon as i have a sensible solution. I appreciate any input/help on this project.

To Jadnashua; If the power goes out I'm in trouble even if the tank is inside the building. I figure i would have to go and drain the lines.


To Hj; I only plan on having a 10 foot section of water line wrapped in the heat tape. (the section going from the tank to the attic.) So.. I'm wondering if I could make this short section copper and then convert to pex for the long run through the attic.

Any suggestions for how to best solve this problem would be much appreciated.

Thanks, Molo
 

Jimbo

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Not knowing anything about your house, I would ask these questions: why does the water heater have to go outside? is there a way to insulate and heat the shed?
 

Molo

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Hi Jimbo

The house is a one story ranch style duplex. I have to supply water to both apts, and am therefore installing two of these tanks! Currently there are gas hot-water tanks in the bathrooms, and I want them out for safety reasons and so that i can make more room in the bathrooms for new tub units. There isn't any room in either apt for the new tanks. The end of the house has a 250 sq. ft. uninsulated storage area that is attached to the building (seperated by an insulated wall with 2 bedrooms on the other side) There is access to the attic from this space and thats how I planned on running the water lines.

Thanks in Advance for any help on this project.

Molo
 

Molo

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Hi Cass

I want to install electric tanks. The electric panel is in this storage area as well.

Thanks again,
Molo
 

viennamicro

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I had a water heater in an uninsulated area a few years back - BAD idea.

The water froze, creating real problems since it was also the same water pumped through the floor for heat. The weather broke 10 days later; only 4 more days for the ice to clear and the water to start flowing. Too bad I could only find 1 kerosene heater in town. Two or three m:rolleyes:re might have been able to raise the temp inside above 40.

My advice - find a way to insulate and heat the area or keep looking for another idea.
 

Alternety

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Why not just put the electric heater where the gas one is and run a power line the same way you are thinking about for the hot water pipe. The plumbing will basically be where is needs to be with much less to run, and the wire won't freeze:).

Sorry did not grasp the "no room" point.
 
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Geniescience

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it'll work. You can do this !!

I have done a lot of work with heat transfer problems and i know about insulating spaces and buildings. I live in a similar climate to Molo, north of the St. Lawrence.

You can do this, Molo. Yes you can.

First, let us all have a common understanding of concepts and terminology.
See
http://en.wikipedia.org/wiki/Thermal_energy paragraph #1 linking to
http://en.wikipedia.org/wiki/Heat
http://en.wikipedia.org/wiki/Heat_transfer including
- http://en.wikipedia.org/wiki/Heat_transfer#Radiation
http://en.wikipedia.org/wiki/Insulation which links to both
- http://en.wikipedia.org/wiki/Thermal_insulation and to
- http://en.wikipedia.org/wiki/Building_insulation including
-- http://en.wikipedia.org/wiki/Building_insulation#Airtight_envelope

Molo, please explain what you mean by "heat tape". A few words.

David
 

Molo

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Hello David

Heat Tape: Something I can plug into an outlet and wrap around water pipe that will warm the pip enough to prevent it from freezing.

I appreciate any help,

Thanks again,

Molo
 

Geniescience

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airtight, this is the first big concept

ok, assuming you have read up on heat, or are about to, here we go:

1. Everything works, to some extent, and all products and systems work, to some extent.

2. Combining several "ways" or "systems" is the only robust and reliable way to build up thermal resistance so you are not losing (as much) heat to the outside and you are not risking a pipe freeze when the power goes out, as it will from time to time.

3. Therefore, no relying on any one single product to do anything crucial or critical. No comparing one heat tape to another. No getting fussy with labels and manufactured products. Your key concerns here are
- 3 a.) the big picture, not missing out on significant concepts, and then
- 3 b.) the little detail, not missing or omitting to seal little air leaks.

3. I repeat, it is important to understand what needs to be done, in the overall sense, and then to execute the plan properly. Right down to ensuring airtightness as perfectly as possible.

4. to 7.
I'll skip a few steps here so I don't come across as unbearably pedantic and domineering. :)

8. So, in summary, you can make the storage room itself airtight, and the enclosure around the two HW tanks airtight, and this alone will be 90% of the solution that most people miss. Add to that, the radiative insulation that you placed in all the right places with no air gaps, and the layering (of several layers) around the pipes, of conductive and radiative insulation, and you have 99% of the ideal solution.

Quiz question: is it possible to say that, for all intents and purposes, you can stop heat transfer from occuring ?

David
 

Molo

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Hello Again David!

Hi David,

I apprecitate your attention to detail and you r cold-climate experience!
No, you are not pedantic and domineering, I am always interested in discussing details and specifics, and doing a job right.
To answer your question: No, you cannot prevent heat transfer.
 

Geniescience

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conductive, radiative barrier

ok, thanks for the encouraging words. :)

Airtightness is the big thing to prevent permanent ongoing and major heat losses from forced convection (from wind and air pressure differences) and natural convection (from warmed air rising above cooler air).

Without going back over the missing steps, or not yet, I'll say that you can plan to have
- a 99.5% airtight shed, and
- a true 100% airtight and vapor-tight enclosure around your HW heaters (above and underneath them too), which uses the same impeccably executed structure for the walls of a "chase" going up surrounding the pipes for as long as you can manage, and this structure includes a radiative barrier in its walls. The simpler the better, so think "foam and foil on top" and very little of anything else to hold it up. Foam is strong enough to be its own structure, and it is vapor-proof too (check out XPS and closed-cell as key words). Any aluminum foil on top turns it into a radiative barrier, that has air on both sides (since foam is 95% air, it is the closest thing to air that you will get unless you hang the radiative barrier from hooks in the ceiling), and radiant barriers work only when surrounded by air (otherwise the supposed radiant barrier turns into a heat conductor, not only killing its effect but actively performing the opposite function).

Foam with foil can be bought as rigid panels all in one, or can be built with any (preferably XPS) foam board or can be built from spray cans. Aluminum is aluminum, and any will work fine. Copper too.

Whether or not to make the shed building let moisture migrate out (see http://en.wikipedia.org/wiki/Weatherization#Building_wrap for ideas about airtight wraps that are not also vapor barriers), is not something I feel comfortable discussing now, except to say that humidity can destroy the effect you are building, i.e. it can make insulation fail, and do worse things like make it rot and the wood too.

Only one radiant barrier, as thick as possible, but not two barriers separated by any space, and a fair distance from the heat source, not just a quarter inch away. Only one vapor barrier, wherever you choose to build it, but not two in any exterior walls, separated by any space (moisture would get stuck in between and start an uncontrolled rot in any material). If you do seal the shed also with a vapor barrier, it is not serious that the HW tanks are also vaporsealed, since you have working space between the two and not enclosed wall cavity space.

The floor of the HW enclosure has to have aluminum trapped between foam, and that sandwich is the base, upon which the two HW tanks are placed. Whether to support this foam-aluminum-foam sandwich by legs or to place it flat on the floor, I cannot comment on now. Inside, a layer of strong flat material can cover the top of the sandwich to spread the pressure of the six legs of the two tanks.

The top of the tanks has pipes coming in and going out. Something you trust has to be wrapped / stuffed around them, that you can remove easily for maintenance, to prevent warmed up air from rising up into the "tube" (or chase) you built for the pipes, otherwise you will be building a wind tunnel that will suck air into the shed from the outside. I mean you have to block air from moving, all air, and not just wrap one or two things around the pipes themselves. Your mission, should you choose to accept it, is to block air movement.

The whole enclosure might look like a primitive baking oven. That'll be just right.

To ensure the pipes themselves remain unfrozen when the weather is 40 below zero and the power goes out for 30 days, is going to rely on two factors. One is the residual heat in the HW tanks, which keeps on spreading for days, when power is cut. The other is how you plan to manage heat just for the pipes alone, and this is best done if we analyze the pipes as a separate system all on its own for a little while, and then come back and connect this separate system to the one outlined above.

Stay tuned to this channel for more. Bye for now.

Quix question: under what temperature-spread conditions is a radiative (radiant) barrier (as opposed to conductive and convective barriers) most necessary?

David
 
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Molo

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Thanks again David

Hello David,
I'm really enjoying your posts.... They are very informative and relevant. Insulation/vapor barrier issues, especially as they relate to moisture problems, are materials and methods I have been pondering for the past year or so. I think there are alot of products out there, and most of them are used incorrectly, to the point that they may be damaging the structures they are supposed to be helping. Especially insulation and vapor barrier products. And here in the North-East we have the conditions of humid summers and then we close our houses up so tightly in the winter that indoor humidity becomes a serious problem in the winter, despite barometric drops.

To answer your question;
A radiant barrier is important when trying to prevent heat transfer.

Note: I will post photos of this space by Friday evening.

Thanks for the help!
Molo
 

Geniescience

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wow, glad to hear.

Thank you !

I enjoy your thoughts on the state of current insulating practices, Molo. The world is better off now than we were 30 or 40 years ago, in terms of insulating buildings, but we have not yet got it right, in my opinion, which seems to concur with yours too.

Today I don't have time to spell out much about the pipe "heat containment system" that I think will work well.

Here's an overview.

First, about the cold water going in.
1.) It is going to be heated.

Second, about the hot water coming out.
2.) It is very hot, and moving fast to its destination.

:)

Here is how I might insulate all four pipes together:
x x
x x

1. All four pipes crammed together. No loss since the cold is going to get heated anyway, and the hot water is not going to lose much heat on its way to the tap. Besides, it is plenty hot when it is fresh out of the tank.

2. put only 1/8th inch insulation between the two pairs of hot/cold, just to help identify which pairs belong together in the same tank.

3. include the corresponding electrical wires in each separate cluster, with minimal insulation again.

4. put 1/2 to 1 inch of insulation around the entire bunch. If foam from a can, there are no air spaces left. If any other system, some air spaces left over, good to fill in with foam too.

5. This oval-shaped riser is now about 3 to 4 inches in diameter. It then gets "glued" to the outside wall bricks with more airtight foam (3 more inches), and a radiant barriar (e.g. foil faced bubble wrap, or just a house wrap with radiant barrier in it) goes on top, on the three exposed sides but not underneath where the bricks are, but it does follow the pipes right up and over into the attic and until the pipes penetrate the building envelope. You need just as much insulation and care in execution in the attic as ouside ni the shed. See http://en.wikipedia.org/wiki/Building_envelope

Since pipe cost is low, I would use a large diameter pipe (3/4" or more), so that when the power goes out and the temperature goes down, you have more thermal mass working with you in the pipes; it takes more energy loss to freeze it at any one weak spot.

The first pipe to freeze is the cold water pipe. What is the coldest temperature water you get in winter? Is it Lake Ontario water or ground water? Do you pay for water consumption? When power goes out, does water still run?

If power is out for many days, the residual heat energy stored in the tanks will be lost and the tanks' water will get so cold you will wonder if (or when) it will freeze. But did you know that moving water doesn't freeze as "easily"? And did you know that your water source temperature is many degrees above 32 Fahrenheit? Of course! You can pull water through the tanks and keep the pipes flowing and keep the temperature of the entire system well above 32 degrees Fahrenheit! Pipes and tanks. The flow could be much less than full throttle. When to start running water? When you are really really sure that the residual heat coming through the building is not enough to keep the pipes' temperature above freezing. By this time the minimal heat left in the tanks will have long since disappeared.

If you want to wrap something with a heat tape, I think I would recommend you wrap only the cold water line, in which case it needs a little more insulation all by itself just to isolate it from the electrical wire. If power comes on for an hour or two from time to time during a month-long power outage, you will have warmed up the pipe most vulnerable to freezing.

If you don't pay for water consumption, consider using only one cold water supply pipe, extra big.



Quiz Q answer: radiant barriers are most necessary when the temperature difference you want to maintain is highest. And your case is a big one. Since the outside temperature will penetrate into your shed, the (tank and pipe) insulation will have to reduce heat loss across a higher gradient than is ever seen indoors. So you need a radiant barrier more than anyone else.

Second answer: when every last degree counts, you need a radiant barrier too. And that is the situation when you want to ensure the pipes don't freeze.

David
 
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Molo

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Hello again Genie

I apologize for not having the photos up yet, Hope to get them on disk and on this computer ASAP. Did you know that some modular homes come with warnings on them for a sickness called Sick House Syndrome (someting like that), apparantly it is caused by a lack of fresh air entering the home! But anyway...... A couple of questions before i get the pictures up;
1. The floor.. wouldn't I want to put a radiant barrier on the floor as well?

2. Is it bad to double up on the foam insulation board?

3. How do you recommend connecting the interior corners of this box? ( I am right now envisioning a box only a couple of feet wider on each side and a couple of feet taller than the tanks. I have to incorporate some access to the tanks.)

Working on the photos, Thanks again,
Molo
 
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