Lake water supply winterization

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Old 09-29-16, 08:31 AM
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Lake water supply winterization

Question is about how to best winterize system when we are away from January to March. (we are in Ontario, Canada and lake freezes solid for at least 2 months). This will be long because I need to explain the system!

Water supply to our year round lake house, is drawn from lake. It comprises:
- 160ft 1 1/4" intake line with stand to keep end off lake bottom (in 25ft of water) (No foot valve)
- line terminates in shoreside pumphouse with line heater tee, check valve and filter/screen before pump suction
- There is an internal heating cable that runs most of length of intake pipe.
- Pump is a Burke stainless steel with Flowmac control, no pressure tank (works well)
- On discharge we have large automatic backwash sand filter, a whole house carbon filter and UV light.

Winterization when we go away:
- drain and blow lines from house down to lake
- remove cap on check valve and let intake pipe drain to lake water level.
- drain whole house filter, UV light and pump body
- sand filter cannot be drained, so we leave pumphouse heat on.

and

up until now, I would leave the intake line heater on. But this means that the first 15-20ft of the heating cable is running through an empty polyethylene pipe. No problem so far, but...

Question 1:
Should I be concerned about the submerged part of the poly line freezing. Water would freeze outside and inside pipe, but in Spring outside lake water would probably thaw before the water in the pipe. Can poly pipe take some freezing?

Question 2:
Read that Canadian Electric code now calls for a GFI on freeze protection used on plastic pipes with higher setting than GFICs we usually see. Apparently to protect the pipe (10-30A setting), not for personnel safety which is 6mA. GFIs of this type are very expensive ($500+) for 240V systems (which we have). Anyone else have same issue and any comments?
 
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  #2  
Old 10-03-16, 05:45 AM
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You have an interesting situation I can offer this advice- poly pipe can't take much freezing before it "splits". Steve
 
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Old 10-25-16, 07:12 PM
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Surprised that others don't have same question. Maybe most here are on wells rather than lake water?

We have always drained our line from pumphouse down to lake level. Ice freezes around outside of pipe, but 1-1/4" pipe does run inside a 3" poly and a 4" aluminum in the area it passes through the ice (which can be 2-3ft thick).

I think I will continue to leave the line heater on. However, it's temperature sensor is just below pumphouse floor, so once drained it isn't seeing water temperature.
 
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Old 10-26-16, 07:44 AM
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How much of that 160' of suction pipe is in the water? If just a few feet, would it be practical to install a union and remove the wet pipe each fall?
 
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Old 11-05-16, 08:34 PM
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In summer it is almost all in water. In winter as mentioned in original post, first 15-20ft runs on shoreline before becoming submerged. The line has a heating cord right down the center, so no way to partly remove it.

In past, we have let line drain to lake level and left line heater on. Have not had a problem, but there is potential to overheat the plastic line. Alternative is to not let line drain, but then if power was lost, the exposed part would no doubt freeze and burst. So looks like we just keep doing what we have in past.
 
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