Extreme temperature heating

Submitted by OnePsychological6076 t3_10pxq3r in Maine

With the cold snap at the end of the week I wanted to pass along some heating tips.

Set your thermostat to your desired temperature and push the hold button, I’d recommend 68-70F.

In most cases your house may drop a few degrees below that temperature and your heating system will run continuously. This is a good thing, to circulate hot water through your piping to avoid a freezing situation.

Keep in mind that your heating system is not sized for these extreme temperatures. In the Portland area the design low temperature is -4F. Some contractors will upsize to -10 to -15F.

What this means is on a day at -4F or -10 to -15F your heating system will be able to heat your house to 70F. If the outside temperatures drop below the design temperature your home’s temperature will drop below 70F with your heating system running continuously.

If you have a boiler and heat pumps, make sure to run your boiler to circulate hot water throughout your home to avoid frozen pipes.

Best of luck to everyone!

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Comments

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Sphragis t1_j6mvlgo wrote

We have an older (1940) house with crap insulation.

Our rule-of-thumb has been to keep it no lower than 55 in order to avoid pipes freezing. But even over the past couple of weeks we turn it down 52 or so at night.

Is the prevailing wisdom that, in the case of exceptional cold like that predicted, we need to crank it so much higher? Heating oil is less expensive than fixing burst pipes, so no argument from a cost standpoint.

But... we really do prefer the house on the cooler side and the idea of setting the thermometer to 70 seems crazy and annoying from a comfort perspective. I feel like I'd have to crack a window in order to make the bedroom cool enough to sleep if our furnace is trying to heat up to 70!

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OnePsychological6076 OP t1_j6mwo0k wrote

Set to your comfort level and leave that temperature on hold. Most people turn the temperature up during, if home, and down at night for sleeping. The down side to this during extreme weather is the boiler won’t circulate hot water while the inside temperature drops. This could lead to pipes freezing during that off cycle.

Second, if you keep your home at 55, I’d recommend going to 60 and keep it at that temperature until the cold snap is over, all day and night.

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Samuel7899 t1_j6p4bkg wrote

There are a few different considerations to keep in mind.

One, is that the temperature setting is only measured at the thermostat. This temperature tapers off between the thermostat and the exterior. In well-insulated homes, the temperature only drops a little between the thermostat and exterior wall, with a big drop-off through the wall insulation.

In a poorly insulated home, this drop-off is more noticeable between the thermostat and the exterior wall. So keep in mind where any pipes may be. If you have any that are close to a poorly insulated exterior wall, they can be a few degrees cooler at that location, even though the thermostat stays the same.

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joftheinternet t1_j6mnkib wrote

Just so I'm clear, I should set my thermostat higher than I would otherwise?

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OnePsychological6076 OP t1_j6mnqi8 wrote

Yes, it’s to circulate the water in your system to avoid freezing.

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20thMaine t1_j6p0o40 wrote

If it’s that cold, I’d think a heating system is gonna be running all the time anyways to maintain whatever temp is in your house. It’s gonna be close to a 100F temp diff inside/outside anyways this weekend lol

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eljefino t1_j6pgube wrote

If your thermostat is pre-programmed for a ten-degree drop that pause in the action is when your pipes will freeze. OP suggests to use the "HOLD" feature to prevent this.

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transmorgrifier t1_j6n9zmq wrote

Those of use in older apartments have no way to adjust the heat. Thank god for space heaters and blankets and hot tea.

But if I could adjust my heat, I would not set it that high. We grew up closing off rooms, opening taps and wearing socks and sweaters.

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ecco-domenica t1_j6nqmsb wrote

Even setting 5 or 10 degrees higher than normal is a good idea. You don't have to crank it way up. Grew up the same. Live the same now.

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transmorgrifier t1_j6nsu6b wrote

I literally have no control over the heat in my apartment. It's an old building and we all share the same heat, set by the property manager :(

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Majestic-Feedback541 t1_j6p012a wrote

Wow, that's a super shitty set up. Im so sorry

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transmorgrifier t1_j6p0xs1 wrote

thx, but it's pretty typical for really old buildings in town. I'm just glad to have an apt.

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Majestic-Feedback541 t1_j6p17f0 wrote

I understand and completely agree. My building was built in 1900, old windows, no insulation, but each unit does have their own heat. As crappy as it can be, I am right there with you, very glad to have a place to call home

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KenDurf t1_j6n1xoy wrote

I have an unheated basement where my oil tank and boiler are. Do I need to keep an electric heater on to avoid the oil in the unheated basement from freezing? I guess heating oil just gels, and that happens at 16 degrees, so my assumption is that the system will be fine but you know what they say about assumptions!

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OnePsychological6076 OP t1_j6n57kv wrote

If you have a thermometer put it in the basement and monitor that the temperature doesn’t fall below 45F. Most likely this will not happen as your boiler and the heat piping in the basement will maintain above 45. We generally are not concerned with inside oil tanks gelling because of this. If you had an outside oil tank I’d recommend having a 25-30% kerosene to 70-75% heating oil mixture in your tank to reduce the gelling at extreme low temperatures.

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KenDurf t1_j6n660m wrote

You’re a gentleman and a scholar. Thanks for getting back to me and will do.

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eljefino t1_j6ph7zw wrote

Yup. Some people will put that foam stuff on all the heat piping in the basement to "save energy" but I would only do that near walls or drafts. That piping leaks a little heat to keep the basement somewhat tepid, which is good in the upcoming scenario.

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BonelessSugar t1_j6n4wu6 wrote

Oil won't freeze like water in pipes will.

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KenDurf t1_j6n6z3z wrote

I’m no HVAC guy but I do have a decent amount of chemistry - anything will freeze under the right conditions. We’re getting to some laboratory levels of cold and I prefer to be cautious over having an issue with the thing keeping the water in my pipes from freezing. I like OP’s thermometer suggestion.

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eljefino t1_j6phdg7 wrote

The oil should have thermal mass to keep on keeping on. It's only going to be super-cold for a day. If you want you can buy diesel anti-gel at an auto parts store and pour it down your fill pipe. I'm not sure how well it would mix, though, unless you maybe pour five gallons of diesel or kerosene after it.

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ouchibitmytongue t1_j6nwi9t wrote

For those in apartments or rentals without control over the heating, consider leaving the hot and cold water taps dripping. If your pipes freeze, unscrupulous landlords may blame you for burst pipes.

My landlord put my bathroom pipes just inside an exterior, uninsulated wall and was upset that they froze, burst and damaged the two floors below me. Fortunately, he ended up being pretty cool about it. He replaced those pipes with expandable pipes, but put them back on the exterior wall.......without insulation. They have frozen since, about three times, but fortunately, no permanent damage.

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indyaj t1_j6orlcb wrote

My plan is to cook my living space with the wood stove and set the thermostat in the basement to 55 so the furnace will kick on if it gets below that.

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eljefino t1_j6phkeu wrote

If you have a hot air furnace, ok. If you have a hydronic (baseboard hot water) system, no bueno.

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