Replies

1. Expert Member
   BILL WICHERS | Mar 21, 2023 09:22pm | #1

   Try using a "self regulating" heating cable. I like the Raychem cables, although they aren't the easiest to find. Self regulating heating cables actually vary their temperature based on the temperature of the cable itself, so the cable can run at different temperatures along it's length depending on conditions. These cables use no controller as the cable itself does the regulating. I do still recommend disconnecting the power from these cables when you don't expect freezing conditions though -- basically only turn on the cables during the season when they're needed.

   I don't use any other type of heating cable anymore. You'll pay more for self regulating cables, but they are *much* better.

   Bill

2. 
   user-5946022 | Mar 21, 2023 11:05pm | #2

   You can easily do what you are proposing using a smarthome system such as Hubitat. You can also do far more complex routines than you are proposing!

   The equipment would be:
   - Hubitat controller
   - Zigbee or Zwave temp sensors, or if you are fine with the temp in the zipcode, an internet connection to download the open weather temps in your zip code.
   - Zigbee or Zwave outlet or plugs.
   You would write your routines for the plugs to go on at x exterior temp and you can vary that by the time of day. You could even buy some lux sensors to see if there is sun outside.

   HOWEVER
   - heat tape should not cost 100's / month unless you have ALOT. If you don't have sensors on your panel, get a plug with an energy meter (see above for Hubitat, but there are many others; people seem to particularly like the Emporias, but they do require wifi/internet. That will tell you exactly how much each plugged in heat tape is using.
   - why is your piping so subject to freezing? Typically the water supply line is buried below the frost line and then enters the conditioned space, so this should not be an issue. Maybe post to explain more of the issue.

1. 
   qofmiwok | May 16, 2023 12:29pm | #7

   I live in a very snowy but sunny climate where there are a ton of ice dams. So everyone has heat tape on their gutters and downspouts. We only put gutters on half our house and it is astonishing how much our power bills were. The heat pumps cost nothing compared to the heat tape. But 90% of the time the heat tape didn't need to be one. There just has to be more sensors. The way they install these things is with 1 sensor in one location of the house, even though the S side rarely needs it and the N does. They don't detect the volume of snow melt to know if it will fill the gutters and downspouts and cause damage when they freeze. And the contractors are so risk averse that they set the temperature range so wide they run practically all the time when in fact they are only needed in a small temperature range. (Partially this is because of the lack of different sensors and smart-ness.)

   My whole house was modeled to use less than $2000 electricity per year including all heating & cooling with heat pumps, plus all the other power. As soon as they installed the heat tape the bills were $600 a month all winter! It took us a while to figure out they were the cause and start manually shutting them off.

1. Expert Member
   BILL WICHERS | May 16, 2023 01:31pm | #9

   A simple solution here might be to just get a second basic controller, then setup one controller for the north side of the house and the other rod the south side. Adjust the controller so that the heat tapes are only on when they need to be, although I recommend setting them to come on a little before you “need” them to be sure they are able to keep things from freezing. It’s easier to keep things above freezing to begin with than it is to warm them up after they’ve gotten too cold.

   Bill

1. 
   qofmiwok | May 16, 2023 02:24pm | #10

   That only solves some of the problem. There's the east and west sides also. And there's the fact that it's not just whether the temperature is freezing that determines when they are needed, but the length of time that temperature will last, whether the sun is out, and how much melt is going on. (Our climate is very dry so the air temperature is very sun driven. A cold temp with our sun will cause melt (and prevent freezing) even when the measured temp is way below freezing.) All these factors could be programed in to allow you do significantly tighten up the range that they come on, and of course also do it by zone. Because such control doesn't seem to exist, in our climate the heat tape run almost non-stop all winter.

3. 
   MartinHolladay | Mar 22, 2023 06:43am | #3

   Qofmiwok,
   There must be some kind of design error if an "almost Passive House" has plumbing subject to freezing -- especially if the electric-resistance heat tape that keeps the plumbing from freezing is using "hundreds of dollars a month" in electricity. Something is wrong -- makes no sense.

4. 
   gusfhb | Mar 22, 2023 07:02am | #4

   My last house was up on piers had about 15 feet of heat cable plugged in from October to May the entire time I owned it, for the water line. I added 35 feet to run water line to the other side of the building.
   Never used 100s of dollars of electricity, ever.
   It was no passive house, cannot imagine what you are using heat tape for

5. 
   DennisWood | Mar 22, 2023 09:35am | #5

   I did some tests on self regulating heat trace cable...it will still use a fair bit of power, depending on length. See attached pics. This cable is not cheap but it did come with connections rated for immersion etc. Pic 1 shows the cable's current and temp rating. This setup was to ensure a garage snow melt drain never freezes. In truth, it's never been used as the drain never freezes, even at -30 C outside temps.

   In my setup, I used a remote bulb line level thermostat from Honeywell similar to this one: http://tempro-products.com/product/tp504-line-voltage-thermostat/

   I am an extensive Hubitat user with automation, so I would use this, however the thermostat I linked above does not need power to work, has a remote bulb for temp sensing, and is dead reliable.

   In your situation, I'd likely look at replacing your cable with self regulating and then split up the circuits, North vs South etc. on those line level thermostats. That way you have a dead reliable system and the heat trace would use less power as well. Like Martin, I'd have to question how a builder/designer would miss this detail and require heat trace in a design ?? It may actually be cost effective to bring the pipes? into conditioned space.

   
6. Expert Member
   Michael Maines | Mar 22, 2023 09:54am | #6

   Is the heat tape for plumbing or for ice dams at the roof? Since you mention north vs. south, I'm guessing it might be the latter--in a Passive House there is next to no heat escaping the roof so if the design does not allow for easy snow shedding, ice dams can form.

1. 
   qofmiwok | May 16, 2023 12:38pm | #8

   You got it Michael. It is gutters and downspouts. Some even have on their roofs themselves to avoid ice dams but with our design we don't expect those. I explained more above in response to user-5946022.