Slab Heat Anti-Freeze

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Old 02-09-16, 10:36 AM
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Slab Heat Anti-Freeze

If a person has in-floor hot water heat is it normal procedure to put some sort of anti-freeze in there in case the furnace goes out in northern MN?

Sister and hubby just returned after two weeks at Disney World. Son went over that morning to turn the heat up, 50 to 70, and he found the boiler or whatever they have had quit. Luckily, it had only gone down to 17 the night before so nothing froze.

I keep asking her if there is anti-freeze and she keeps telling me she doesn't know. Yesterday she says that could have been bad, they would have to tear the house down to fix all the pipes (some sort of blue or red plastic I think) so I don't think there is any anti-freeze.

Comments and thanks!

They live in the country on a well so maybe potable water heats the house too and they can't use anti-freeze??

Hope this makes sense.
 
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Old 02-09-16, 12:15 PM
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Not an expert in the area but I thought water heating systems like this were kept separate from the potable water and antifreeze was a common additive in cold climates.
 
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Old 02-09-16, 01:20 PM
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You sure would think so but I wonder the way she talked, I'll have to call her again.

When they built the house about 25 years ago they installed a fuel oil boiler. When fuel oil got so expensive they put some sort of electric box on the wall to heat the water thus saving some money. HA...their light bill in the winter is ~$750 a month on a 2400 square foot house. I'd imagine they are back to the boiler by now.

They do like to spend money.

Thanks
 
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Old 02-09-16, 03:21 PM
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They may have a form of propylene glycol in the hydronic coils . . . . which is a non-toxic food grade anti-freeze, like that sold for Recreational Vehicles. Now it's also used as the e-liquid in e-cigarettes.

After 25 years, it may have begun to acidify and a pH test can be run to test that periodically. I don't think that would alter the level of freeze protection; but that can be measured too.
 
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Old 02-09-16, 03:33 PM
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In our area in-floor heat generally uses anti-freeze but it is inhibited Polypropylene Glycol which is made for boilers and is non-toxic .
RV antifreeze is generally not used here because it is alcohol based and does not have inhibitors to reduce corrosion in a boiler.

A hot water boiler normally has domestic water piped to it through a pressure regulator to control the boiler water pressure.
When this type of system uses glycol the connection to the domestic water is removed and reconnected to an open poly tank with about about 80 litres/25 gallons of glycol.
A pump with a pressure switch then draws glycol from the tank to pressurize the system to normal boiler pressure.

They can tell which system they have by whether the connection to the boiler comes from the house water line or a tank of glycol.
 
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Old 02-09-16, 04:18 PM
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When this type of system uses glycol the connection to the domestic water is removed and reconnected to an open poly tank with about about 80 litres/25 gallons of glycol.
A pump with a pressure switch then draws glycol from the tank to pressurize the system to normal boiler pressure.

They can tell which system they have by whether the connection to the boiler comes from the house water line or a tank of glycol.
Just an FYI thats not always the case in the states.. But may be near the border IDK..

Often antifreeze is added and the main water valve kept closed...

The boiler is normally checked monthly for proper water pressure and regular water added if need.. ( Should not need to add any on a normally operating boiler). Additionally antifreeze levels get checked every year at the beginning of the heating system..

Usually its a 50/50 mix antifreeze and water...

Last a backflow preventer should be installed between potable water and the boiler connection just befor the fill valve for the boiler...

IMO if you dont need antifreeze dont put it in... Its very corrosive from what I seen and often does more harm then good.. Dont get me wrong there is a place for it in some applications..

You'd be best off to install a internet t stat so you can get alerts if the temp in the home drops significantly... Then get someone over there to help fix the issue...

There are many out there... This is an Honeywell example...

Smart Thermostat, Learning Thermostat | Honeywell Lyric

( Im not a fan of the nest t stats but thats just me...)
 
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Old 02-09-16, 05:24 PM
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Thanks very much guys, I'll send her a link to this and they can read up on it. I'm sure they'll have a plan B in place before next winter.

You'd be best off to install a internet t stat so you can get alerts if the temp in the home drops significantly... Then get someone over there to help fix the issue...
I was thinking the same thing, I'm sure they will look into it.

Thanks!!
 
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Old 02-15-16, 11:11 PM
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IMO if you don't need antifreeze don't put it in..
Turns out they have straight water in their system, her husband says it is not as efficient with anti-freeze, something about heat transfer and other issues.


You'd be best off to install a internet t stat so you can get alerts...
I mentioned to my brother I was searching for these and he says they already have those machines in all their greenhouses, if the temp drops it calls her husband's cell phone. Oh really?

Today I ask my sister about this and she says they never had trouble with the house heat before so never thought about it.

Go figure.
 
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