How cold does it have to get for pipes to freeze?

[Rich Engelhardt]

We have a ..situation...
We're having a dispute with one of our tenants.
Our lawyer has advised us not to enter the property for the next ten days.

We're concerned that the tenant is going to shut off the heat.


Temperatures are supposed to be in the low 30's as a high during the next four days and lows in the upper 20's over that period.

The house is insulated - but - not as well as a newer house. It was built in the 1950's.

According to the long range forecast, the tempertures are suppossed to be 30's to low 40's in the day and upper 20's to low 30's at night - through next Thursday.

I'm thinking that it should be ok but - you never know.

[Gary Hodgin]

I don't think you have much to worry about, especially if the vents are closed.

[JohnT Fitzgerald]

I would agree. If all the windows are opened though......might be close.

If it's all from issues with a tenant, check your various insurance policies to make sure you are covered under both accidental and malicious actions by a tenant.

[ray hampton]

what bother me is your lawyer coment to stay out of the apartment, how will you handle the maintenance of the apartment ?

[Rich Engelhardt]

It's not ouside the realm of possibility that a window or windows could be left open.

Ray - long story, but, our lawyer says it's best if we stay out for the next week or so. Sorry I can't be more detailed, but, this being an open forum it's better to not get into certain things.

[Joe Pelonio]

I have seen outside faucets freeze at 28F overnight, if not wrapped, then break from the ice expansion. Maybe you could at least do that without going in?

[ray hampton]

It's not ouside the realm of possibility that a window or windows could be left open.

Ray - long story, but, our lawyer says it's best if we stay out for the next week or so. Sorry I can't be more detailed, but, this being an open forum it's better to not get into certain things.

well it is your money so keep the de-tails to yourself which I never ask for, all I say were the maintenance of the building but you must be too busy to read the whole post

[Rich Engelhardt]

Ray,
I read the whole post.

We've started an evicition process against the tenant. Under Ohio law, we as the landlords have procedures we have to adhere to. Entering the premisis during this time period is a very touchy area.

Yes - you are correct - it is my money. I don't wish to lose any by being sued or having to defend myself against criminal charges.

[Mike Cutler]

Given enough time, 32 degrees F at sea level for fresh water. I'd worry about those temps for an extended time, but at least it's not going to be -5 degrees or so.
Good luck with the eviction process, it's tough. I watched a co-worker get danced around by a very experienced, legal wise, tenant for about 8 months through the court system. Once the eviction process started, he also was not allowed in his dwelling, and they did do some significant damage.

[Myk Rian]

Sneak in, adjust the T-stat, and get out. Don't tell ANYBODY.

[ray hampton]

I hope that none of your building catch on fire above or below this apartment that you are barred from enter

[David G Baker]

I entered my rental accompanied by a police officer during the eviction process. My tenant stole several thousands of dollars worth of items from a detached garage that was not part of the rental. My dishes were in a drain basket on the sink and several other items belonging to me were in plain site but I couldn't do anything about it because I couldn't prove that the items were mine. The tenant was out in the 21 days allowed by California law. I found out how the items were hidden, the tenant rented a storage unit and moved my items into storage. Never got any of my items back but at least I got rid of the tenant. The place was a mess when I finally was able to gain access to work on it.

[Chuck Wintle]

could you enter the premises with a police escort? there must be a way to have access to prevent possible major damage to this dwelling.

[Daniel Berlin]

We have a ..situation...
We're having a dispute with one of our tenants.
Our lawyer has advised us not to enter the property for the next ten days.

We're concerned that the tenant is going to shut off the heat.


Temperatures are supposed to be in the low 30's as a high during the next four days and lows in the upper 20's over that period.

The house is insulated - but - not as well as a newer house. It was built in the 1950's.

According to the long range forecast, the tempertures are suppossed to be 30's to low 40's in the day and upper 20's to low 30's at night - through next Thursday.

I'm thinking that it should be ok but - you never know.

I'm a bit bored.
Assume they turn off the heat. Let's use math to waste some time

Heat loss in BTUs/hr is
HL = U-value * Area of wall (sq ft) * temperature difference
U-value = 1/ <sum of r values of layers>

(U-value is actually standardized to certain conditions, but it's all we've got :P)

A 2x4 stud wall with 3.5 inches of fiberglass is about R-15 (and a U value of 1/15)

IE the wall is 8x20, you would lose (1600*temp difference/15) BTUs an hour through that wall.

How many BTU it takes to raise or lower the air in your house one degree depends on the volume, but it's roughly 0.02 BTU to raise 1 cubic foot of air 1 degree.

Basically, as it gets closer to the outside temperature, the rate of cooling will slow down.
Worst case, assuming you have a 1600 sq ft home (which was average in 1950), and it was only walls (this is the worst case), and it was 35 feet tall (a lot of zoning codes in the country allow 35 feet from top to bottom), and it was square (40 * 40 ft), you have 40 * 35 feet of wall space on each of the 4 walls, or 5600 sq ft of wall space. Assuming it started out at 68, it will initially lose 14187 btu/h through the walls when the outside temp is 30 degrees (and the btu/h will decrease quickly as you lose temperature in the house).

You would have roughly 56000 cubic ft of air in this house (40*40*35), and it will take 56000*0.02 = 1120 btu to effect a 1 degree change in air temperature.
So over the first hour, it will lose 12.6 degrees.
The second hour, we start out at 68-12.6=55.4 and if it was still 30 degrees outside, it would lose 9482 btu that hour, or 9 degrees, roughly.
So the third hour, we are down to 46. If it was still 30 degrees outside, we'd lose 5973 btu that hour, or 5 degrees, roughly.
So the fourth hour, we are down to 41. If it was still 30 degrees outside, we'd lose 4100 btu that hour, or 4 degrees, roughly
So the fifth hour, we are down to 36. If it was still 30 dgrees outside, we'd lose 2240 btu that hour, or 2 degrees
So the sixth hour, we are down to 34. If it was still 30 degrees outside, we'd lose 1490 btu that hour, or 1.something degrees

etc
Again, remember these calculations are very much overestimating the temperature loss because it changes every instant as the temp difference goes down. I don't have mathematica to do this properly and am too lazy to do it by hand.

But basically, after the first day, inside your house is going to pretty closely follow the outside temperature, lagging behind by a few hours.

For the pipe containing your water, copper pipe heat loss for fluid inside 3/4 pipe with a 40 degree temp difference is 29 BTU/hr per foot. So it will take slower to follow the temperature, but there is less of it.
Water takes about 143 btu per lb to convert to ice (this is pure water).

Multiplying it all out, this theoretical house may actually have water freezing after the first day, at night, but its going to be close.
There are other things at play. If it's city water, it will tend to have a lower freezing point due to impurities. Additionally, once you hit back to the line you are sharing with your neighbors, , the heat from that water (at 40 degrees) is going to diffuse through the rest of the pipe/water over time. Same with all the other water that may get over 30 degrees.


All this said, i'd say
1. Its going to be close as to whether anything freezes. If it gets into the low 20's for more than a few hours, i'd be worried. If it stayed 30 degrees the whole time, i wouldn't be worried.
2. I have successfully used math to waste time.

[David Larsen]

I'm a bit bored.
Assume they turn off the heat. Let's use math to waste some time

Heat loss in BTUs/hr is
HL = U-value * Area of wall (sq ft) * temperature difference
U-value = 1/ <sum of r values of layers>

(U-value is actually standardized to certain conditions, but it's all we've got :P)

A 2x4 stud wall with 3.5 inches of fiberglass is about R-15 (and a U value of 1/15)

IE the wall is 8x20, you would lose (1600*temp difference/15) BTUs an hour through that wall.

How many BTU it takes to raise or lower the air in your house one degree depends on the volume, but it's roughly 0.02 BTU to raise 1 cubic foot of air 1 degree.

Basically, as it gets closer to the outside temperature, the rate of cooling will slow down.
Worst case, assuming you have a 1600 sq ft home (which was average in 1950), and it was only walls (this is the worst case), and it was 35 feet tall (a lot of zoning codes in the country allow 35 feet from top to bottom), and it was square (40 * 40 ft), you have 40 * 35 feet of wall space on each of the 4 walls, or 5600 sq ft of wall space. Assuming it started out at 68, it will initially lose 14187 btu/h through the walls when the outside temp is 30 degrees (and the btu/h will decrease quickly as you lose temperature in the house).

You would have roughly 56000 cubic ft of air in this house (40*40*35), and it will take 56000*0.02 = 1120 btu to effect a 1 degree change in air temperature.
So over the first hour, it will lose 12.6 degrees.
The second hour, we start out at 68-12.6=55.4 and if it was still 30 degrees outside, it would lose 9482 btu that hour, or 9 degrees, roughly.
So the third hour, we are down to 46. If it was still 30 degrees outside, we'd lose 5973 btu that hour, or 5 degrees, roughly.
So the fourth hour, we are down to 41. If it was still 30 degrees outside, we'd lose 4100 btu that hour, or 4 degrees, roughly
So the fifth hour, we are down to 36. If it was still 30 dgrees outside, we'd lose 2240 btu that hour, or 2 degrees
So the sixth hour, we are down to 34. If it was still 30 degrees outside, we'd lose 1490 btu that hour, or 1.something degrees

etc
Again, remember these calculations are very much overestimating the temperature loss because it changes every instant as the temp difference goes down. I don't have mathematica to do this properly and am too lazy to do it by hand.

But basically, after the first day, inside your house is going to pretty closely follow the outside temperature, lagging behind by a few hours.

For the pipe containing your water, copper pipe heat loss for fluid inside 3/4 pipe with a 40 degree temp difference is 29 BTU/hr per foot. So it will take slower to follow the temperature, but there is less of it.
Water takes about 143 btu per lb to convert to ice (this is pure water).

Multiplying it all out, this theoretical house may actually have water freezing after the first day, at night, but its going to be close.
There are other things at play. If it's city water, it will tend to have a lower freezing point due to impurities. Additionally, once you hit back to the line you are sharing with your neighbors, , the heat from that water (at 40 degrees) is going to diffuse through the rest of the pipe/water over time. Same with all the other water that may get over 30 degrees.


All this said, i'd say
1. Its going to be close as to whether anything freezes. If it gets into the low 20's for more than a few hours, i'd be worried. If it stayed 30 degrees the whole time, i wouldn't be worried.
2. I have successfully used math to waste time.

Take into consideration the thermal transfer of windows. Yes, they do lose heat, but they also gain heat during the daylight hours and create a "greenhouse" effect on the interior temperature. Also, the inside of an insulated/ unheated structure doesn't normally fall to the same temperature as the outside air.