I had two houses with frozen pipes - one of them burst in the laundry which thankfully was semi-exterior so didn’t cause any house damage. The other one was just frozen water heater pipes which I fixed with a heat gun (two times on two different days!). Down here they installed the water heater outside and the pipes are uninsulated and on the *exterior* of the house.
Thankfully my tenant at the house where the pipes burst is a contractor and fixed it himself for free (bless him!) so no plumber bill there. But my third house texted the other day complaining of a gas smell in the house (to which I replied call the gas company!!!) Turns out when we were doing renovations my contractor cut off the chimney pipe for the water heater exhaust (water heater is in large crawlspace and exhaust is piped out to side of house). He replaced it with a shorter pipe and the exhaust was wafting up to the window (which is brand new and not sealed properly grrr) and coming in the house. So I had them turn off the water heater for the night and run both taps and then the HVAC guy came out and reinstalled the pipe correctly - all the way to the roof above the windows so that the exhaust does not come near points of entry for the house. I haven’t gotten a bill yet but I’m sure it won’t be nothing.
Now that tenant’s father wants me to “get the water heater serviced” and I’m not sure what to do. I don’t think it needs it, it’s newish and we identified the issue. But if something were to go wrong down the road I would hate to be the landlord who refused to service the water heater if that ultimately caused an issue.
So...yeah. 3 out of 4 houses with issues despite me being proactive and telling tenants to run their water at night. The houses just aren’t made for this cold!