Radiant Floor Freezing

[luvair]

Received a quote for radiant follow heating - the proposal is both for using existing boiler (creating a new zone) and a tankless water heater that would be mounted in the garage.

Question: If the radiant heat is not on in the sub freezing winter - what prevents the water in the in PEX / tubing from freezing? If they put antifreeze in the lines, doesn't fresh water flush through the tubes over time causing any antifreeze to lose it efficiency?

TIA.

 

[walrus]

Question: If the radiant heat is not on in the sub freezing winter - what prevents the water in the in PEX / tubing from freezing? If they put antifreeze in the lines, doesn't fresh water flush through the tubes over time causing any antifreeze to lose it efficiency?

TIA.

the lag time before you feel heat n a radiant floor is long as it takes a while to heat the slab up again. I think most keep it at a temp and leave it. Antifreeze has to be checked periodically for PH and freeze point. Not sure where the fresh water is coming from though?

 

[luvair]

the lag time before you feel heat n a radiant floor is long as it takes a while to heat the slab up again. I think most keep it at a temp and leave it. Antifreeze has to be checked periodically for PH and freeze point. Not sure where the fresh water is coming from though?

It is always the same water with antifreeze that circulates for the years? Like a closed car radiator system. I had thought over time fresh water pumps through the system that would dilute the antifreeze over time?

 

[walrus]

It is always the same water with antifreeze that circulates for the years? Like a closed car radiator system. I had thought over time fresh water pumps through the system that would dilute the antifreeze over time?

Its a closed loop, once full. the antifreeze needs to be checked just like a cars antifreeze.

 

[jklingel]

To answer your original question, NOTHING keeps it from freezing, except the earth, if you are lucky. Left long enough at cold enough temps, it will freeze. As stated, periodically check the "grade" of the antifreeze if you use it, and remember that the heat transfer capacity of antifreeze is not as good as water, so be careful how much you dilute it. An engineer or a boiler place should be able to give you the numbers on that.

 

[luvair]

To answer your original question, NOTHING keeps it from freezing, except the earth, if you are lucky. Left long enough at cold enough temps, it will freeze. As stated, periodically check the "grade" of the antifreeze if you use it, and remember that the heat transfer capacity of antifreeze is not as good as water, so be careful how much you dilute it. An engineer or a boiler place should be able to give you the numbers on that.

Does the antifreeze need to be changed every two or three years like a car cooling system? Thanks.

 

[jklingel]

Changing, or at least "updating" w/ refreshing additives is something I don't know. I believe you change/recharge it in vehicles because it loses its anti-corrosive and anti-scaling properties to some degree. How many people do you know who actually change their car antifreeze regularly? I imagine changing/refreshing is an event that occurs every 5 to 10 years. When you find out, please post. Thanks. j

 

[Ram]

I would not think that the anti-freeze in a floor system is not near as abused as what is in a car or truck engine. For one you don't have the heat cycles that your engine has. You don't have a bunch of dissimilar metal components, heads, block, water pipes to heater, heater and radiator cores, water hoses, water pump housing, impeller and various gaskets and gasket sealers.

It seams that a house system is pretty much all plastic except for a tiny pump and heater, some what a static heat settings compared to engine temps.

I would think that you could go several years with out having to change fluids in a floor system.

Could be wrong since I don't have one. But have wondered about them and want to install.

Interesting question, hope someone with experience installing / maintaining chimes in.

 

[jklingel]

Ram: roger that. a pretty dead system, chemically. j

 

[jayoldschool]

You don't use water in a zone that could freeze. You use glycol.

My system is two zone. The basement uses water, and the garage uses glycol that is heated through a heat exchanger. Grundfos pumps. I'm supposed to test the strength of the glycol, but haven't bothered in a couple of years. Maybe this fall

 

[jklingel]

Jay: Using glycol in radiant floor heat, or in baseboard, which will freeze up faster than tubes in a slab, is a choice. I live in Frb, and I don't know of anyone who uses glycol. You can, sure, and if you will be Outside for extended periods in the winter it may be advisable. A very well insulated house will stay above freezing, esp the floor, for days, usually (ha ha) giving people ample time to get their boiler fixed after a failure. I ran glycol the first few years, but gave up 28 yrs ago; the heat transfer thing bothered me too much, as you have to have a pretty heavy concentration to do much good. My neighbor did go Outside at 20-30 below a few years ago and forgot to plug in his warning light, so I never knew the temp in the house had dropped. Needless to say, he had a little remodeling to do when he got home. BTW: I am certain that the glycol used in heating systems is NOT THE SAME as in your car, for those that choose to run it. Either way, have a good back-up plan and insulate, insulate, insulate. later. j

 

[walrus]

No Burst is what they run in Maine, its a special propylene glycol made just for heating systems. It does hurt heat transfer and it will leak where water won't so be forewarned on that
http://www.noblecompany.com/Products/NOBURSTFreezeProtectionFluidsfromNobleCo/tabid/60/Default.aspx

 

[jklingel]

Wal: Thanks for the link. I will have to scope that out. Yes, as far as I know, any antifreeze is "thinner" than water; don't know the physics thereof, but one (or more) property of water gets tweaked and antifreeze sneaks.

 

[tcianci]

About 10 years ago me and a buddy of mine ran some insulated pex in a 4" sewer line out to his garage, maybe 20' distance about 2 feet under ground to feed the baseboard heat in his garage. We filled his boiler with a propylene glycol/water mix and it's been running fine ever since. Sorry I can't remember the concentration but I do recall the anti freeze was the typical RV winterizer stuff. It's worked fine so far and has never been freshened.

 

[Cryptic1911]

Wal: Thanks for the link. I will have to scope that out. Yes, as far as I know, any antifreeze is "thinner" than water; don't know the physics thereof, but one (or more) property of water gets tweaked and antifreeze sneaks.

it probably changes the surface tension on the water

 

[jklingel]

yes, surface tension or viscosity, and I don't know how those are linked. I can't see how they could be separated much, but I don't know hydrodynamics, fluid mechanics, or whatever it is, exactly.

 

[6768rogues]

At the school where I work, we have two glycol ice melt systems. They have a glycol tank (reservoir) and circulate a glycol mix. They really work well and the areas never have so much as a flake of snow on them.

 

[wuboring]

i see people mix methanol with the water in the loops alot

 

[MScott]

Interestingly, the outdoor wood furnace I have been researching recommends ordinary water in the cooling system....no antifreeze, glycol or alcohol. Since they have a twenty-five year guarantee on the system, and have been in business since 1984, they apparently feel that freezing is not a problem even here in Ontario.

 

[GarageHawk]

Radiant heating is great as long as you intend to maintain the same temperature at all times. The only downside is it takes a long time to warm up if you turn it down. I didn't want to keep my 4 1/2 car garage at working temperature 24X7 so I used a ceiling mounted, hot water unit heater off a zone on my existing home heating boiler (with glycol). It's basically a radiator with a blower to move air through it. Here are some examples. http://www.greenhousemegastore.com/Hot-Water-_-Steam-Unit-Heaters/products/1056/
It's controlled by a conventional wall mounted thermostat. Whenever I want to work in the garage I just turn up the thermostat, it's warm in about 15-20 minutes and you only pay for the heat when you really need it. I can also turn the fan on manually without heat to circulate air in the summer.

 

[aloysiuscarl]

Just the fact that the heater runs all the time at the highest setting bothers me. I'm designing a radiant floor heating system for a small 300 s quare feet cabin. Now, most systems call for a large boiler to heat water to 200+ F, then a mixer to mix in cool water to get it to 150 F or so, then a pump to run it through the floor. A thermostat controls the boiler and the pump.