How much insulation is too much?

[JohnRoberts]

About a year ago I replaced my hot water heater (after getting electric shocks while in the shower).

Being green (or trying)... I wrapped the new heater in thick thermal insulation and even added a bunch of foam insulation around hot water pipes in my laundry room where the heater is located. The room is attached to my house but not heated.

One morning last week, while I was in my laundry room roasting some coffee, I noticed that the thermometer was reading <20' inside the room.  I realized that cold water pipes for my outdoor hose faucet was in the same room and exposed.

I checked the outdoor water faucet and no love,,, it was frozen solid. Hoping to avoid the drama of broken pipes I ran my dryer for around 20 minutes and got water flowing again... I wrapped some bubble wrap around the outdoor faucet but may need to add some more pipe insulation inside.

This qualifies as an unintended consequence from keeping the water heater from losing too much heat.. I've lived in the house for 30 years and never experienced a frozen pipe.

JR

 

[shabtek]

Interesting. Are your pipes metal? I am about to runs some pex up the chase where me chimney used to be. Cant help but think that big chunk of masonry running through the house and up to the sky acted as a serious heatsink.

been pretty cold lately, My water comes from a well  that can freeze this time of year. I usually Put a drop cord and heatlamp down the pit. The circuit i'd plug into was repurposed last summer, so when the cold hit i was about to install an outlet off the feed to the pump,  then realized its 240...So there is a drop cord across the drive until
Spring arrives.

 

[rmburrow]

Good idea with the drop cord.  I'm on a well but typical narrow casing precluding use of a trouble light for heat.  Some pipes run under the house; the temp got down to -6 F.  Sunday morning.  Left some faucets slow drip Sat. night just in case.  I have used heat tape over 20 years.  Go to Home Depot or your local hardware place and get some heat tapes and some pipe insulation (like rubatex).  Neatly tie-wrap the heat tapes flat to the BOTTOM of the pipe (especially if PEX), avoid kinks, and tie wrap the thermostat (near the AC plug end) directly in contact with the pipe; this is important.  Plug the heat tapes into AC; they will come on automatically when the pipe temp drops below 38 deg F.  The $30 a piece for heat tapes is good insurance.  Good idea to measure pipe lengths before you buy heat tape...do not coil or leave suspended lengths of heat tape.  If need be, "eat up" small excess length by "zig zagging" the tape across the bottom half of the pipe...  Then install pipe insulation per instructions with the heat tape.

 

[PRR]

Your first reaction should be to open the faucet. If you get flow, turn it to a trickle. In any case, apply heat around the pipe. Heat-gun, heat-lamp, open the inside door to the house, whatever you can do. If the ice inside freezes solid the pipe may split. Copper can freeze once or twice and just get oversize, but brittle, and it will split if you keep this up.

If pre-warned, you can leave a faucet at a slow trickle and the 50F water will keep the pipe above freezing. Waste of water and may be an impressive icicle. (We were at a rundown resort over Xmas once and they asked us to leave the bathroom faucet trickling because the underground pipes were freezing.)

Insulating the pipes will only slow freezing. This week+ of super-cold will freeze your pipes. Insulation on pipe may slow the freeze only a few hours after you run water. I bet you have not run the garden faucet in months.

Since it worked before, you should shed some insulation on your WH. The added cost is less than new plumbing.  Put it back when temps moderate.

My outdoor faucets are "freeze-proof", IF the long end is in a cellar. My cellar will not go below 50F, the actual valve is 8" inside the cellar, the outside drips dry (if you take the hose or wYe off... ooops). Additionally (and for other reasons) I have a valve deep inside the cellar to cut-off all the outside spigots, which I do when it is clear that we won't want to water the petunias for a while.

In your situation, you could put a valve right where the pipe leaves warm space. On copper pipe, Shark-Bite and equivalent are very convenient and you can get a valve with two shove-fit ends. There is even one with a long end for when you can't slack either side of the run. Cut pipe. Mark magic distance. Shove on, you hit the O-ring. Shove HARD to get past the O-ring and hit your mark, or it will spray bad. Obviously you need an upstream valve; the work can be quick so a whole-house shut-off is OK.

$35 heaters used to be good; but the new ones are PIC-controlled and some lose their settings if power blips.

In colder climes, heat-tape is good. The new stuff has phase-change at 35F so it hardly heats until it is needed. You can insulate over some heat-tape; read the docs.

For ad-hoc heating schemes you want a thermostat. Honeywell Winter Watchman is a 150W plug with 30-60 dial. The intent is to light a lamp when you are away and your house loses heat-- neighbor sees the light and may come over to kick the furnace. Will work for small heat sources. At larger scale, you have electric baseboard so are familiar with the line-volt thermostat. The dumb mechanical ones will work with small 120V heaters.

 

[PRR]

me> ...impressive icicle....

This is growing from the smoke-pipe of my furnace.

The furnace is 94%, the exhaust is hardly warmer than the house, so the water condenses out of the flame byproducts. The exhaust is designed for this- there is a condensate pump which runs as needed. The pipes are plastic and I was told to glue the joints. Inside, I did. Outside I opted to leave them loose in case I needed modifications. The condensate is supposed to run-back to the furnace and pump, but some leaks in the unglued joints. The right pipe has about a 2 foot icicle.

The pipe runs up and out. The brown blob on the snow lower-right is where the end drips. I think it is brown because I have a steel squirrel-screen on the end and it's rusting.

 

[JohnRoberts]

Your first reaction should be to open the faucet. If you get flow, turn it to a trickle. In any case, apply heat around the pipe. Heat-gun, heat-lamp, open the inside door to the house, whatever you can do. If the ice inside freezes solid the pipe may split. Copper can freeze once or twice and just get oversize, but brittle, and it will split if you keep this up.

I couldn't even turn the faucet at first, frozen solid...  After a few minutes with the dryer running I could open the faucet but still no water flow, so I left it open, and went inside to check the pipes some more.  After a few minutes of dryer heat, I heard the sound of rushing water and then went back outside to close the faucet, and cover it with bubble wrap..

If pre-warned, you can leave a faucet at a slow trickle and the 50F water will keep the pipe above freezing. Waste of water and may be an impressive icicle. (We were at a rundown resort over Xmas once and they asked us to leave the bathroom faucet trickling because the underground pipes were freezing.)

Insulating the pipes will only slow freezing. This week+ of super-cold will freeze your pipes. Insulation on pipe may slow the freeze only a few hours after you run water. I bet you have not run the garden faucet in months.

The front water faucet was not frozen, but i bubble wrapped it too.

Since it worked before, you should shed some insulation on your WH. The added cost is less than new plumbing.  Put it back when temps moderate.

My outdoor faucets are "freeze-proof", IF the long end is in a cellar. My cellar will not go below 50F, the actual valve is 8" inside the cellar, the outside drips dry (if you take the hose or wYe off... ooops). Additionally (and for other reasons) I have a valve deep inside the cellar to cut-off all the outside spigots, which I do when it is clear that we won't want to water the petunias for a while.

In your situation, you could put a valve right where the pipe leaves warm space. On copper pipe, Shark-Bite and equivalent are very convenient and you can get a valve with two shove-fit ends. There is even one with a long end for when you can't slack either side of the run. Cut pipe. Mark magic distance. Shove on, you hit the O-ring. Shove HARD to get past the O-ring and hit your mark, or it will spray bad. Obviously you need an upstream valve; the work can be quick so a whole-house shut-off is OK.

$35 heaters used to be good; but the new ones are PIC-controlled and some lose their settings if power blips.

In colder climes, heat-tape is good. The new stuff has phase-change at 35F so it hardly heats until it is needed. You can insulate over some heat-tape; read the docs.

For ad-hoc heating schemes you want a thermostat. Honeywell Winter Watchman is a 150W plug with 30-60 dial. The intent is to light a lamp when you are away and your house loses heat-- neighbor sees the light and may come over to kick the furnace. Will work for small heat sources. At larger scale, you have electric baseboard so are familiar with the line-volt thermostat. The dumb mechanical ones will work with small 120V heaters.

I don't expect many more cold spells like this one, but I will be more alert in the future .

I could screw an incandescent lamp into the overhead light fixture and pump 100W into the room when needed. This efficiency thing is overrated.

JR 

 

[PRR]

There are (here) foam boots to put over faucets.

Still, this only works if you have heat just inside the wall, and the pipe conductivity exceeds the foam conductivity for the temperature difference needed. Probably do about nothing on plastic pipe.

I'm not so worried about you. You are, if belatedly, aware of unintended consequences, sharp enough to do a right thing, and can walk to a store with water (or beg at the PO).

But this cold-spell is impacting people who never had a problem before, never had the experience. Even in DC the utilities and subway are having problems that seem silly to Mainers, because DC doesn't "ever" have a deep freeze. So I'm just spewing frozen thoughts.

 

[JohnRoberts]

There are (here) foam boots to put over faucets.

Yes I've seen the styrofoam boots but I had bubble wrap and cable ties handy.  May look at buying some boots for next cold snap

Still, this only works if you have heat just inside the wall, and the pipe conductivity exceeds the foam conductivity for the temperature difference needed. Probably do about nothing on plastic pipe.

House plumbing is pretty much all copper. When the galvanized water main from the street sprung a leak a few years ago we replaced it with PVC.

The front faucet with copper pipe in the crawl space under my house did not freeze, which tells me I could use more insulation under my floor, but nah... for another time.

I'm not so worried about you. You are, if belatedly, aware of unintended consequences, sharp enough to do a right thing, and can walk to a store with water (or beg at the PO).

But this cold-spell is impacting people who never had a problem before, never had the experience. Even in DC the utilities and subway are having problems that seem silly to Mainers, because DC doesn't "ever" have a deep freeze. So I'm just spewing frozen thoughts.

Even NYC had freezing/water drama, and I know it has gotten cold there before too. Of course not as cold as several miles inland away from the water (heat sink).

I vaguely recall some single digit weather just before I moved here (mid 1980s), but that was just for a day or two at most. Hard sub freezing  weather for multiple days like this time probably causes more mischief. 

So far, knock on wood, no freezing pipes problem here in 30 years.  ;D

JR

 

[dmp]

"how much insulation is too much?"

It doesn't matter how much insulation you have if there is no source of heat inside and the environment is cold.
Insulation is simply a resistance. You can use your electronics knowledge to understand heat transfer.
Heat flow (Q_dot: energy in Joules) is analogous to current.
Temperature differential is analogous to voltage difference.
The insulation R value = L/k where L is the insulation thickness and k is the thermal conductivity.
Q_dot = Delta_Temp/R
So "R" for insulation is analogous to R for electronics.
No matter how much insulation you put between a battery and ground, the battery will lose charge until it is at the same potential as the ground. Same for your water pipe.

 

[JohnRoberts]

"how much insulation is too much?"

It doesn't matter how much insulation you have if there is no source of heat inside and the environment is cold.
Insulation is simply a resistance. You can use your electronics knowledge to understand heat transfer.
Heat flow (Q_dot: energy in Joules) is analogous to current.
Temperature differential is analogous to voltage difference.
The insulation R value = L/k where L is the insulation thickness and k is the thermal conductivity.
Q_dot = Delta_Temp/R
So "R" for insulation is analogous to R for electronics.
No matter how much insulation you put between a battery and ground, the battery will lose charge until it is at the same potential as the ground. Same for your water pipe.

I have one patent (co-inventor)  for a heat sink design so I grok heat transfer....  :  (6,515,859 Roberts ,  et al. February 4, 2003).

BTW the equation related to "thermal resistance" you shared is mainly about conducted heat transfer, while I did mention "insulation".  Freezing pipes have several factors to consider.

A common redneck trick is to leave a faucet slowly dripping, so warmer water (ground water from mains is generally well above freezing) keeps the pipes warm.  I have not had to go full redneck on this, and outdoor temperature has since returned to normal (humidity returned too), so all bullets dodged.

JR

 

[dmp]

BTW the equation related to "thermal resistance" you shared is mainly about conducted heat transfer, while I did mention "insulation".  Freezing pipes have several factors to consider.

Yes, the R value of insulation only pertains to conduction. I have never seen much data on the differences in reducing convection losses through different types of insulation. With a continuous vapor barrier (like plastic sheeting), any convection losses are stopped - i.e. like with attic insulation. Often the vapor barrier for a ceiling is just the painted plaster / drywall ceiling material. The third type of heat transfer, radiation, isn't a big player unless the temperature differences are large - but reflective foil as an outer layer can be added.
The conduction portion is much easier to solve than the natural convection from the outer surface to the environment. Just assume the outer temp is ambient and you can do some back of the envelope calculations. The point is you need some heat input or else it doesn't matter how much insulation you have.
If you have 120 deg water in the water heater, and some length L of water (thermal conductivity k = 0.02 W/m-K) in the pipe (R=L/k),  you can estimate the energy in - then you can use an energy balance to see if the energy supplied is enough to match the energy lost out the insulation.  If they are equal at a temp > 32F you are good.

I went through similar trouble with a bathroom addition I put on the house. Did the calculations above, decided on a R amount of rigid foam to put under the floor - pipes still froze. I ended up connecting a heating vent to the floor space. Not allowed by code, but I ran out of alternatives.
You might want to insulate the attached room and condition it to 50 deg or so, instead of insulating the water heater.  But since you live down south you probably don't have to worry as much as us northerners.

 

[JohnRoberts]

Yes, the R value of insulation only pertains to conduction. I have never seen much data on the differences in reducing convection losses through different types of insulation.

My patent was for a variant on a heat sink cooled by forced air... not much text book math covering that either...  8)

With a continuous vapor barrier (like plastic sheeting), any convection losses are stopped - i.e. like with attic insulation. Often the vapor barrier for a ceiling is just the painted plaster / drywall ceiling material. The third type of heat transfer, radiation, isn't a big player unless the temperature differences are large - but reflective foil as an outer layer can be added.
The conduction portion is much easier to solve than the natural convection from the outer surface to the environment. Just assume the outer temp is ambient and you can do some back of the envelope calculations. The point is you need some heat input or else it doesn't matter how much insulation you have.
If you have 120 deg water in the water heater, and some length L of water (thermal conductivity k = 0.02 W/m-K) in the pipe (R=L/k),  you can estimate the energy in - then you can use an energy balance to see if the energy supplied is enough to match the energy lost out the insulation.  If they are equal at a temp > 32F you are good.

I went through similar trouble with a bathroom addition I put on the house. Did the calculations above, decided on a R amount of rigid foam to put under the floor - pipes still froze. I ended up connecting a heating vent to the floor space. Not allowed by code, but I ran out of alternatives.

Thermal mass of the water in the pipe also matters. I have seen hot water systems that drain the hot water back to the heater, so pipes stay empty when not in use. Of course that does not help your cold water lines.  You gotta do what you gotta do.

You might want to insulate the attached room and condition it to 50 deg or so, instead of insulating the water heater.  But since you live down south you probably don't have to worry as much as us northerners.

Since this was the first time I even came close to freeze difficulty in 30 years I think I can continue my low key approach... I like the idea of using an incandescent light bulb for extra heat as needed.  I already blocked the dryer vent hole that was wide open and was a few square inch air leak direct to the outside world and could make a significant difference by itself.  Next is the single pane glass window, and leaky door jamb, for next time.

Kind of like the rest of my house (this is the deep south after all).

JR

 

[PRR]

> insulate the attached room and condition it to 50 deg

Why??

It's gotta be cheaper to over-insulate the water heater, heat-tape and insulate the faucet pipe, and let the lawn furniture, chainsaw, and etc just suffer the 20 degrees. A shut-off near the warm wall may be cheaper than heat-tape. (Minor drag to remember to cut-and-drain, then turn-on for summer...)

I gather JR has been working to minimize the space he heats and cools. He's not likely to add a room to his insulation investment and heat bill.

Unexpected cold-weather consequences: my old battery tools with Ni-Cads would work in cold. Poorly, but work. The new lithium batts... the charger won't even try to charge below 40F, and it isn't clear that it isn't charging, only waiting for spring. I had a snow-sagged branch over the driveway and a delivery expected, and did not have enough juice to run a saw. (It was attached 18 feet up and in my parka I am not about to try hand-saw on top of an old ladder.) So now the dining room is full of batts and chargers.

 

[benb]

The new lithium batts... the charger won't even try to charge below 40F, and it isn't clear that it isn't charging, only waiting for spring.

I'm guessing the charger and/or battery have a temperature sensor that keeps it from charging below that temperature, in order to prevent damage or reduced life or something. It seems all the new devices are "smart" like that ...

 

[Gene Pink]

...(It was attached 18 feet up and in my parka I am not about to try hand-saw on top of an old ladder.)...

Got a 12 Gauge., some 1-1/4 oz deer slugs, and good aim? ;D

Gene

 

[JohnRoberts]

> insulate the attached room and condition it to 50 deg

Why??

It's gotta be cheaper to over-insulate the water heater, heat-tape and insulate the faucet pipe, and let the lawn furniture, chainsaw, and etc just suffer the 20 degrees. A shut-off near the warm wall may be cheaper than heat-tape. (Minor drag to remember to cut-and-drain, then turn-on for summer...)

A little surprising since the cold water line to the back yard faucet is tied in near the cold water feed to the hot water heater so should have adequate heat from that to not freeze.

I expect closing off the dryer vent hole, while only a few square inches, should make a noticeable difference in temps.  Weather has since returned to MS normal (69' today). Humidity is back too  .

I gather JR has been working to minimize the space he heats and cools. He's not likely to add a room to his insulation investment and heat bill.

In fact I do not heat the large living area at night so during the cold snap I logged indoor temps down in the 50's . That will reduce the inadvertent heat leaked to the crawl space and laundry room.

Unexpected cold-weather consequences: my old battery tools with Ni-Cads would work in cold. Poorly, but work. The new lithium batts... the charger won't even try to charge below 40F, and it isn't clear that it isn't charging, only waiting for spring. I had a snow-sagged branch over the driveway and a delivery expected, and did not have enough juice to run a saw. (It was attached 18 feet up and in my parka I am not about to try hand-saw on top of an old ladder.) So now the dining room is full of batts and chargers.

My weed trimmer with smart battery charger will not charge hot (freshly drained) batteries either. Probably senses for impedance of the battery. I do not understand the chemistry but lead acid (car) batteries are higher impedance when cold...(smart car battery charger used higher charge voltage in freezing weather).

JR

 

[PRR]

Someone told me how horrible Lithium cells get when cold. The chemistry is over my head.

Clearly these cells have internal "brains" which communicate charge and hot/cold to the controller. Laptop batts can report all sorts of data.
http://cdn.windowsreport.com/wp-content/uploads/2017/06/BatteryInfo-View.gif

 

[JohnRoberts]

I just put a 60W bulb in the laundry room light fixture. I notice that there is no light switch, but a pull cord for an adapter screwed into the base, so back when the house was built, the light probably stayed on 24x7.

I am leaning toward buying a 150W bulb (for more heat), but they make as large as several hundred watt incandescent bulbs that will screw into a standard base.

JR

 

[PRR]

There's a limit, 300W? for how big a lamp can be sold on a standard base. I have 300W standard base lamps in the garage.

In the South I have heard of leaving a lamp on 24/7 in a closet to keep the mold off.

A real cheapskate avoids the cost of a switch by unscrewing the lamp.

Unintended Consequence: *after* that major snow storm, I went in the garage loft and shut the loft door. In the next wind-storm, the garage doors (held with a bar which had never failed) kept blowing open. I think the loft door was venting pressure.

 

[Gene Pink]

I just put a 60W bulb in the laundry room light fixture. I notice that there is no light switch, but a pull cord for an adapter screwed into the base, so back when the house was built, the light probably stayed on 24x7.

I am leaning toward buying a 150W bulb (for more heat), but they make as large as several hundred watt incandescent bulbs that will screw into a standard base.

JR

Light on ceiling, pipe to heat much lower, won't do anything.

100 watt incandescent in a droplight-worklight-troublelight hung from the pipe would do something. More if you paint the pipe flat black.

A clamp-on high temp fixture with an orange 250 watt "keep the french fries warm at McDonalds" heat lamp would probably work too well. Diode in series would cut the power in half.

Or find an LED heatlamp to really save energy.  ;D 8)

If it were me, I would grab 5) 100 ohm, 10W resistors, wire in series, add 120V line cord and inline fuse, tape resistors to pipe every few inches with many turns of aluminum tape to catch the heat from all sides of the resistors, and wrap with insulation.

Or substitute 5) 1 ohm, and power with a 12V transformer. You can also tape the transformer to the pipe to catch that heat, too.

Gene