Turning your heat off at home while in Florida

The water heater is another issue. We used to turn it off every time we went away but recently had to have the igniter cleaned due to overwork to the tune of $$$. The tech said to turn the heater down to the `on' position; not all the way off. This, however, keeps the pilot lit all the time.

For a rule of thumb, you can assume the temperature of the pipes in the exterior walls will be halfway between the interior temperature and the outside temperature. If its 0*F outside and you have the thermostat set to 60*F inside then the pipe could reach 30*F. BTW, pipe insulation does not stop freezing, it just increases the amount of time till the pipe does freeze.

DougE wrote:
For a rule of thumb, you can assume the temperature of the pipes in the exterior walls will be halfway between the interior temperature and the outside temperature. If its 0*F outside and you have the thermostat set to 60*F inside then the pipe could reach 30*F. BTW, pipe insulation does not stop freezing, it just increases the amount of time till the pipe does freeze.

Good point. That's why we don't drop our T-stat below 65F when away, and the auxiliary heating is set to fire at the same temperature, so as to not lose too much ground in the event of a power failure that takes out the HVAC system. Our security system tells us if a power outage happens, and we deal with it, as required.
So far, so good.

MDKMDK wrote:

DougE wrote:
For a rule of thumb, you can assume the temperature of the pipes in the exterior walls will be halfway between the interior temperature and the outside temperature. If its 0*F outside and you have the thermostat set to 60*F inside then the pipe could reach 30*F. BTW, pipe insulation does not stop freezing, it just increases the amount of time till the pipe does freeze.

Good point. That's why we don't drop our T-stat below 65F when away, and the auxiliary heating is set to fire at the same temperature, so as to not lose too much ground in the event of a power failure that takes out the HVAC system. Our security system tells us if a power outage happens, and we deal with it, as required.
So far, so good.

I guess I would add the phrase "it depends" to the above comments. It depends on your house design (does it have a basement, are the water pipes internal or in the walls, what sort of heating system do you have, how well is the house insulated etc.)

In our case all the water pipes are internal in the basement (except for the hose bibs outside that I drain), the heating is forced warm air, the heating ducts in the basement keep it 2C above the main floor set point and keep the pipes warm, and the house is well insulated. I don't have concerns about setting the temp at 10C. If you have the knowledge of your house and how it's built it's OK, if not, a higher temp may be mandated. The quality of the power supply network is also important.

As a FYI, we had the transformer that powers our (and our neighbours) house blow up 2 years ago during in an ice storm. It took 30 hours to bring the main floor temp down to the ambient outside temp, the electric guys installed an "extension cord" from another neighbours place to restore our power while a new transformer was installed. This experience confirmed some of the calculations that some of us did to prepare (and prevent freeze ups) for the worst Y2K situation that didn't happen at that time.

almcc wrote:

MDKMDK wrote:

DougE wrote:
For a rule of thumb, you can assume the temperature of the pipes in the exterior walls will be halfway between the interior temperature and the outside temperature. If its 0*F outside and you have the thermostat set to 60*F inside then the pipe could reach 30*F. BTW, pipe insulation does not stop freezing, it just increases the amount of time till the pipe does freeze.

Good point. That's why we don't drop our T-stat below 65F when away, and the auxiliary heating is set to fire at the same temperature, so as to not lose too much ground in the event of a power failure that takes out the HVAC system. Our security system tells us if a power outage happens, and we deal with it, as required.
So far, so good.

I guess I would add the phrase "it depends" to the above comments. It depends on your house design (does it have a basement, are the water pipes internal or in the walls, what sort of heating system do you have, how well is the house insulated etc.)

In our case all the water pipes are internal in the basement (except for the hose bibs outside that I drain), the heating is forced warm air, the heating ducts in the basement keep it 2C above the main floor set point and keep the pipes warm, and the house is well insulated. I don't have concerns about setting the temp at 10C. If you have the knowledge of your house and how it's built it's OK, if not, a higher temp may be mandated. The quality of the power supply network is also important.

As a FYI, we had the transformer that powers our (and our neighbours) house blow up 2 years ago during in an ice storm. It took 30 hours to bring the main floor temp down to the ambient outside temp, the electric guys installed an "extension cord" from another neighbours place to restore our power while a new transformer was installed. This experience confirmed some of the calculations that some of us did to prepare (and prevent freeze ups) for the worst Y2K situation that didn't happen at that time.

Our power supply is as good or as bad as any. That's the only real variable in this equation, imo. Whether the pipes are inside the exterior walls or buried in the bowels of your basement won't make much difference if your power is out for a long time, say a week or more like New Brunswick over the years, and it takes out your electrically powered HVAC, and you're not home, and even if you were, there aren't any friendly power company guys around to help you get through it, as you cite in your example. Like has happened several times in New Brunswick recently. No idea why it's always NB. Bad luck?
We set the heat sources at 65F, because it makes the drop to freezing a longer fall, in the even that both the primary and secondary heat systems fail. Our alternate heat sources function whether the HVAC is on or off, and will work for days, weeks, if necessary. At least until we can get home to address a lengthy power outage situation, if there's anything we can actually do about that.

Just a heads up for those with the high efficiency furnaces. Check your owners manual or contact the manufacturer, some have a should not set temperature below value. A lot of them are 60 deg F. If set lower than that there is increased condensation in the heat exchanger that will cause corrosion and shorten it's life.

Any structure with water pipes in the outside walls is just asking for problems. That's a NO-NO! Keep your water pipes on interior walls or wrap them with permanent self regulating heat tape like this offering from Amazon:

EasyHeat 2102 Freeze Free Heating Cable

For those of you that leave the heat on and shut off the water - a warning.

If you have hot water heat, you need to provide makeup water to the boiler. If not, the system pressure will bleed down in a few months and your circ pump will suffer. I know some weekend plumber will jump in here and say that if you don't have leaks the pressure won't drop, but the steam plant engineer in me knows better.

Most people tap into the water supply before the whole house cutoff for the boiler. If you do this, make sure the outlet of the pressure/temp valve goes to a sump with a pump. I had an expansion tank go which made the PT valve lift whenever the heat turned on (I was home and noticed the problem immediately) and it put an inch or water in the basement in a few minutes. If that ran all winter it would have been a major mess.

Last winter, the weather was so harsh without adequate snow cover that the drain for the condensate from our high-efficiency furnace froze. After a lot of furnace runs, that can add up to a lot of water in the basement.

I'm going to dig it up where it comes through the foundation and add exterior insulation.

BTW, quite a few people around here had frozen septic systems too. Ours was probably frozen but there was no one here to use it so it didn't matter.

Just a FYI. A sewer system in extreme cold climates is designed with the idea someone will be living there running hot showers and doing dishes. This water will keep the pipe from the house out (and it’s surrounding ground) from freezing.

If no one is around for a length of time do not run water into the sewer. Otherwise it will freeze an backup.

Also in extreme cold area’s if your foundation is in clay you run the risk of a lateral crack about four feet up from the floor. Not worth the expense of scrimping on heat in the basement. The heat escape will help keep the frost away.