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[RSI]

I am starting a new topic since the other is way off the original.
I have a customer that put some tubing in his sidewalk (two 1/2" loops) and wants to use it to melt ice.

I have never set any up before. I would assume you need to use tempered glycol at a lower temp to protect the concrete and not draw too much heat from the OWB. The last reply in the other thread said not to use tempered water. It seems like it would be a huge heat load running full temp water into the concrete.

This is going to be connected to a HeatMaster G100.

[schoppy]

I personally don't have any ice melt applications but I did ask about it when I did my garage (for the outside apron) and the contractor told me you needed to use an antifreeze solution as you mentioned and the water temp should not exceed much over 120 degrees to prevent cement cracking. I don't know how you would do that without tempering it.

[RSI]

That is what I would assume too. I may have misunderstood the other reply.

I am thinking about using a single manifold for basement floor heat, garage floor and snow melt. The idea was to use actuators on each loop so they can be turned on independently. It would be a much simpler and cleaner install if it would work.

[NaturallyAspirated]

I am starting a new topic since the other is way off the original.
I have a customer that put some tubing in his sidewalk (two 1/2" loops) and wants to use it to melt ice.

I have never set any up before. I would assume you need to use tempered glycol at a lower temp to protect the concrete and not draw too much heat from the OWB. The last reply in the other thread said not to use tempered water. It seems like it would be a huge heat load running full temp water into the concrete.

This is going to be connected to a HeatMaster G100.

Andifreeze for sure, however you want to keep the slab idled say 40*, and use high GPM and highest temperature possible (of your temper) when ramping up for quick melt.  1/2" tubing isn't the best choice for snow/ice melt as you want to have massive GPM movement though the system with minimal delta T.

[mlappin]

Use 5/8” tubing instead of 1/2”.

I have a separate loop for the sidewalk with glycol. Using a 20 FPHX and a tempering valve. Using a Taco pump controller and when the timer is turned it kicks in both the pump for the secondary loop to the 20FPHX and the pump for the glycol. If a large enough line is used and spaced properly 80 degrees is plenty to keep the sidewalk clear.

The snow melt is an open system and I took a  one gallon air tank and welded the extra fittings in then mounted it high on the basement wall so its the same level as the sidewalk.

[E Yoder]

We just did a G100 where the customer had some 1/2" loops stubbed out of his carport slab for snow melt. He wants to hook up later. Right now we just did the house with infloor and forced air.
What lengths are max on 1/2 Pex on snow melt to avoid too large of a deltaT? I'm assuming the problem is uneven snow melt.? I'm not concerned about low return water temps to the furnace as it has separate stirring pump on the rest of the unit to keep things a reasonably even temp in the tank.
I can see where larger lines would allow longer loops in a snowmelt system but I would think 1/2" would be OK for small areas?
We run into snow melt pretty rarely down here so I like these threads.
I like mlappin's using a small open tank for expansion. Would basically act just like a furnace water jacket if you pump away from that point.

[mlappin]

Yep, snow melt returns to the tank then a 1” pipe nipple in the bottom to draw off of. 

A 1/2” line will give a uneven melt when first started, eventually once the cement warms up a little and the return temp of the glycol starts to rise those uneven spots melt pretty quick after that.

[E Yoder]

Makes sense. I just was thinking short loops could minimize that.

[mlappin]

Makes sense. I just was thinking short loops could minimize that.

Mine are 5/8” but took almost 250 ft a run. Still get a few streaks when first turning it on especially with a wet heavy snow. Once it’s running and all of its melted off 60 degrees is almost enough to keep it snow free.

[NaturallyAspirated]

We just did a G100 where the customer had some 1/2" loops stubbed out of his carport slab for snow melt. He wants to hook up later. Right now we just did the house with infloor and forced air.
What lengths are max on 1/2 Pex on snow melt to avoid too large of a deltaT? I'm assuming the problem is uneven snow melt.? I'm not concerned about low return water temps to the furnace as it has separate stirring pump on the rest of the unit to keep things a reasonably even temp in the tank.
I can see where larger lines would allow longer loops in a snowmelt system but I would think 1/2" would be OK for small areas?
We run into snow melt pretty rarely down here so I like these threads.
I like mlappin's using a small open tank for expansion. Would basically act just like a furnace water jacket if you pump away from that point.

You could ramp up on the flow rate a little more than recommended if you are stuck with 1/2".  Could calculate out to 4.5 f/s or so and see what pump you would need for that flow rate, and what head loss you end up with in the loop.  If you are short enough you my be ok.

[E Yoder]

I don't know what length they were, just getting ideas on how much I can stretch it. My guess is they're between 100-200'.

[mlappin]

And I agree with Schoppy, I’ve seen it more than a few places, 120F is the recommended highest temp to run in concrete.

[RSI]

The line was already put in by the home owner before I was ever there and it obviously can not be changed.

If the temperature of the glycol should be similar for the sidewalk as the in floor heat, why can't they be on the same manifold? Am I missing something else here?

[mlappin]

No not really, but the sidewalk will produce a HUGE temp drop when first turned on, as long as the floor has priority with the sidewalk secondary no reason they both couldn’t be run as the same sub system.

[E Yoder]

I was under the impression snowmelt should run with water under 100℉ to minimize heat loss into the ground, but I imagine warmer would be fine for occasional ice melting. I don't see why you're idea wouldn't work too, RSI.
Didn't mean to derail your thread.