Pex tube and a frozen floor...

[milkman636]

Well, I've seen pipe split during the thawing process. With no air space the pressure increase is not linear. The math in post#6 is flawed. And that is why I recommended "It is best to thaw pipes slowly and evenly making sure that the warming water has somewhere to expand to".

 

[Rustyiron]

The anti freeze slightly reduces the efficiency of the system, I was told by my radiant design Co. I used. I'm not sure if this is "splitting hairs" but if there is any chance of the system getting to that point, prolly a good option. Sounds like just dumb luck for the OP.
I'd get down to the rental store & snag as many concrete blankets as needed to cover the whole thing. Maybe he could get a bunch of garden hoses and rig them up to is boiler and lay them under the blankets. If really worried (I would be), he could rent a commercial ground heater. It is a trailer mounted oil boiler with LOTS of hose on a reel that you lay out just like you would your pex lines. The lines are then covered with the concrete blankets or hay. I have done this thawing out 4' of frost in the ground and the hay works better than those blankets. In my use, it snowed during the thawing time (3-4 days) and the snow was melting on the blankets but not on the hay! These units are only at the larger rental houses like United or Sunbelt.

 

[CalG]

Well, I've seen pipe split during the thawing process. With no air space the pressure increase is not linear. And that is why I recommended "It is best to thaw pipes slowly and evenly making sure that the warming water has somewhere to expand to".

There are times that the events we witness do not fully reveal their mechanisms.

Have no fear about the rate at which you thaw your floor, concrete is a great equalizer! Keep those wood fires burning!

 

[Raspy]

I am not that familiar with in floor heating but the folks that I know that use them use a closed system with antifreeze in the water to keep this from happening. I was wondering why the OP didn't do the same thing. If he had, he could have not worried about lines freezing without heat.

I can only speak for myself on this, but it's simpler, safer (from contamination) and cheaper to use water. It's hard to freeze a whole slab inside a house. I have both solar and oil heat to keep it going. But it's still a danger. In mine, I planned to use only solar this winter, but it became overcast and cold for a long enough time that the slab was getting into the high thirties and I had not yet insulated the house. I kept it circulating 24/7 to prevent a local problem somewhere in the slab. Instead of adding antifreeze, I started the oil boiler. Also, the climate here in Western Nevada isn't very severe.

 

[dstig1]

Everyone has told you the right way - get more heat in there. Get a propane heater or something else and put it close to the suspected frozen sections. Tarps/tents to get the heat to stay down low will help too. Heat doesn't rise but hot air does, and most of life's heat is hot air... Once you defrost the frozen sections, it should stay like that, as long as the heat stays up. My radiant company clearly says to NEVER fill tubing in a slab that is below 32 degrees, as it will cause all kinds of problems when it freezes up. If this slab is going to be subjected to freezing temps in the future - like if it is occasionally heated, and not all the time, then you should add antifreeze to it, and make sure it is isolated from any domestic HW.

 

[Hudsoner]

Anybody around here, who has in floor heating (me, too) has antifreeze in the system. We can rest in peace that nothing can happen to our systems.

 

[Raspy]

Anybody around here, who has in floor heating (me, too) has antifreeze in the system. We can rest in peace that nothing can happen to our systems.

This obviously the right thing to do in cold climates. What kind of antifreeze are you using, what is the maintenance schedule and how are you isolating it from the domestic water?

Thanks.

 

[Hudsoner]

I have two different systems. I use one solar system for heating my water, and one system for in floor heating. II use RV antifreeze in my water system and normal automotive antifreeze in the floor heating system. The water system has two circuits, an antifreeze filled has a heat exchanger inside a water tank, and the water from that tank is my domestic water. the antifreeze circuit is a closed system. The infloor heating system is a closed system, too. Neither system comes into direct connection with my domestic water. The anti corrosive properties of the antifreeze helps to maintain my circulation pumps to stay in great shape. The system is running for five years now without any problem.

 

[Toyboy]

I have Hydronic heat w/Pex in both my home and garage w/anti freeze in them just in case. We've been to -30 a couple times this year and it good insurance against problems if we have a system go down for any length of time.

The anti freeze is not your everyday type (as far as I know) and comes in 5 gal pails especially for hydronic heating systems. The brand in my garage is Cyro-tek-100 and the house has Noburst -100. I would guess they're the same stuff just different brands. Both are made for hydronic and solar hot water systems. I think mine is down to -10? I have the boilers services every two years and it gets checked then.

The water make up valve is a ball check type that keeps the system from back feeding your water supply.

 

[Gary Fowler]

The anti freeze slightly reduces the efficiency of the system, I was told by my radiant design Co. I used. I'm not sure if this is "splitting hairs" but if there is any chance of the system getting to that point, prolly a good option. Sounds like just dumb luck for the OP.
QUOTE]
I wonder about the truth of this. In a car radiator it increases the efficiency of cooling compared to plain water due to the wetting agents in anti-freeze. Why would it be different in a system that is basically doing the same thing, removing heat from hot water lines. I think your design company was blowing smoke up your ***** but don't know why they would do that, unless they wanted to come back to repair your lines after the froze and burst.