Can you leave a Legalett slab in winter in Canada without the heat on?
Hi, Planning a home in rural Southern Ontario (Zone 6A). We want heated slab on grade but are concerned about preventing seasonal issues esp winter. Legalett systems look very good esp their air radiant system. THE question for us is what happens in Winter when we are away for a few weeks. We'd need to keep heat on? At what level? Would pipe size in the Legalett air radiant system (2" or 4") make a difference? Would it simply be better to go hydronic or electrical instead of the air radiant? Thanks.
Each Legalett slab is engineered using regional climate data, and they can be designed to be left at various operating temperatures, so I would for sure recommend them if you plan to leave for the winter at all.
Their standard slab requires a temperature setting of 18C, but you can specify a lower operating temperature and they will design it accordingly. Buildings can also be engineered so they can freeze without any risk of frost heave, as is often the case with detached garages.
As for the heat source (air or hydronic), that has no impact on frost heave, nor is there any impact between the 2 and 4 inch pipes. You can read here to compare air heated radiant floors to hydronic, we’ve done both and much prefer air heated, you can see our time lapse air heated slab on grade install video here.
Really all you have to do is tell the company what you want and they take care of the rest. This is different than engaging an individual designer or engineer to build a one-off slab, slabs are their specialty and they’ve been at it for decades. I’d have no concern whatsoever with frost heave, that’s their job.
Important to note - if you do go for a Legalett slab on grade kit, the temperature setting is not so precariously determined that you need to worry if there is a power outage and it drops below for a bit. It’s more about where you plan to set your thermostat for the winter in general. They just don’t want you to shut off the heat and head down to Florida for the winter if your slab has been engineered to have base temperature of 18C or 15C.
But since you are a winter traveller, I would suggest maybe going for a 15C design or even freezable to be sure, that way you won't slice your ball into the woods because you're distracted worrying about frost heave.
That's a very, very helpful response, Mike - thank you.
I've looked into these Legalett slabs, and one of the things I liked was the electrically heated version that could be left on a low setting over winter. Even if the power went out for a while there's no chance of it freezing and water radiant floors can be a hassle in my experience.