Main Sewer Line Freezing from Boiler Condensate

[cebarker69]

I have a summer home in Colorado where the winter temp can drop to -20 degrees F. We have a propane boiler in the garage with the condensate tube draining into a floor drain to the septic tank. The flooring is heated slab both in the garage and house.

The heat in the vacant house is left on in the winter at 50 F. Last week I made a trip to the house and was surprised to find the main sewer pipe frozen for many feet outside. I was told that this could happen when a house is left vacant in the winter and the heat on because the boiler condensate flow is so small. A plumber suggested installing a small lift station to increase the boiler condensate flow rate and thus avoid the sewer pipe freezing. This sounds good, but I was wondering if there might be other options to consider besides turning the heat off in the winter and draining the water pipes.

 

[Hogger]

I had that problem last winter however this year I took a mesh bag like the ones onions and oranges come in and put salt tablets from a water softener into the collector trap so the condensate gets a bit of salt on it to prevent freezing. So far so good.


John

 

[Sureshot]

I used to heat two buildings with one large boiler. I had a hot water line failure in the middle of winter and switched to a two boiler system. Because my domestic water was paired with the boiler lines I never had any frozen lines but was leery of having issues in the future so I rigged up a system to insert into the damaged line. It may work in your case.

I took a piece of pex pipe 10' long with a plug in one end. In the other end I put a threaded T fitting with the pex adapter. The T was installed so it had the thru part straight into the pipe and leaving one side outlet(hope that explains it). In the opposite side from the pex I put an airline fitting for semi trucks with a compression fitting. The fitting needs to be drilled out to let the air line pass thru. I then slid the airline inside the pex to the bottom and pulled it back a few inches leaving a few feet or as required sticking out of the fitting.

I tied this setup into the boiler valve system with some brass valves and have one of them choked down so it barely circulates. Just enough to keep it warm. I slid the assembly inside the damaged pipe.

Since you keep the house at 50 you could also rig some other circulating system with a reservoir in there.

Upon rereading I think misunderstood your problem but left my post incase it helps.

Instead of a lift station if you drain the condensate into a 5 gallon pail with siphon tube installed. Once the water gets to a certain level it siphons out the pail all at once and waits for the pail to refill.

 

[GrahamNWT]

Happens all the time up here in the arctic. Not enough condesate flow as it probably just drips into the drain when the boiler is fireing. One solution is to build your self a small siphone tank for the condesate to drip into. When the tank gets full it starts to siphone out emptying the tank. This creats enough flow to the drain so it doesn`t freeze. Try googling it