I rent out one of my homes to a couple that is using a space heater in the crawl space.
The heater is a small electric heater with a thermostat that is set on low. My concern is fire more than freezing pipes. Using an extension with an electric heater is not a good idea IMO and they have one heavy duty extension cord with an emergency trip on it which makes me feel a little better about it.
I advised them to just fill up the tub for flushing water and not to worry about the pipes since the pipes are pex tubing and an easy fix if they do bust.
I would think that leaving a faucet drip would be good enough right?
Would you be concerned about using an electric space heater under the house?
In my last house I had to use a small space heater underneath it to keep the pipes from freezing. Not the water in pipe from the well, (that required an in line heater because it wasn’t deep enough in the ground and froze despite the dripping tap) but the drains from the tub and washing machine would freeze if the heater wasn’t on. The heater was there when I bought the house and I left it for the new owners when I moved.
I would be VERY concerned about using a space heater. That concentrates all of the heat in one small spot which makes it more of a fire risk.
I would recommend using something like heat tape instead. It’s designed for exactly this sort of thing.
You can get heat tape at lowes, home depot, and most hardware stores. It’s not that expensive and it is usually fairly easy to install, depending on exactly how much crawl space there is in that crawlspace. You basically just wrap it around the pipes.
ETA: Also make sure that the crawlspace doesn’t have any openings. If the wind can get through there it will drastically lower the temperature.
The two winters I lived in a camper in North Dakota I used everything from space heaters to propane Mr Heaters and diesel “jet burners.” Heat tape and heated lines don’t quite cut it. With pex plumbing, freezing wasn’t a big issue, I did break a few 90s and Ts, but the pex itself never cracked or broke.
Just make sure there isn’t anything flammable around your heater and that it won’t tip over.
Space heater fires are common in these parts but probably due more to using too many or wrong type of extension cords.
So that heater tape is good to go on Pex? I have them wrapped with pipe insulation, figured that would be good enough as well.
Last year the house had copper pipes and after several breaks i put pex in. I’ve been told the pipes may freeze but not bust because the pex will expand. No sure about that either.
Heat tape is really wasted unless you also put pipe insulation on the pipes over the heat tape. Otherwise at least half the heat is wasted in the outside air instead of the piping.
When I was a kid, we lived in a house that had a bathroom that was only accessible from the outside (patio). In the winter, the pipes would freeze. My father’s solution over the short term was to put a portable 150Watt flood light near the pipes. The long term solution was the heat tape mentioned by ECG.
Be careful using any type of heater that burns a fuel.
A few years ago just outside of our city, a man went under his house to find out why the heater he had installed wasn’t working. He didn’t come out. So his wife went under the house looking for he and she didn’t come out either.
A few hours later their kids came home from school and found both of their parents dead from carbon monoxide poisoning.
If you need heat in a confined space, use something like heat tape as suggested by others here, or use an oil filled electric heater. There is no open flame in it.
Heat tape is the best solution. We had ours plugged into timers that turned them on in the evening (about 5pm) and off after sunrise (around 7AM).
They could be left on all the time. But it extends the life of the heat tape to cycle them on/off. They’ll last quite a few years. They will eventually break and need replacing. Its a good idea to check that they are heating up at the beginning of each winter.
Remembering to unplug them in the Spring is the tricky part. Dad left ours on one year till June.
I use a space heater in my garage that runs constantly, about 8 months of the year. No fire yet. It’s not a small area like a crawl space, but if your concern is the extension cord, I think it’s fine. The extension cord I use isn’t especially heavy-duty. It hasn’t melted yet.
I’ve always had good luck with pex freezing but not breaking, once it’s thawed out, it’s good as new, so to speak. Fittings, valves, etc will break however, but of the hundred or so times I’ve had my lines frozen, I’ve only broke fittings two or three times.
