Freezing Pipes

 
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CoalHeat
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Post by CoalHeat » Wed. Jul. 16, 2008 8:59 pm

With on open system, as most are, definitely don't do it. I'm not familiar with the newer systems, but the hot water system at my parent's house was connected directly to the cold water line, through a pressure regulator. I assume newer systems have a backflow prevention device, but it's not worth the risk. If you're worried about the pipes freezing then I guess you are not using the system on the coldest days. Drain it. Won't take that long to refill it and bleed it off if you need it.

 
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Uglysquirrel
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Post by Uglysquirrel » Wed. Jul. 16, 2008 9:10 pm

why oh great sir? Your experience welcome.

 
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Post by ken » Wed. Jul. 16, 2008 9:29 pm

you lose like 10 % to 20 % of the BTU's with anti-freeze in the system. I like the idea of putting a timer on the Taco pump I can turn on from the first floor when it's nasty out. i'll have my buddy look into it.

 
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Post by CoalHeat » Wed. Jul. 16, 2008 9:30 pm

You don't want to add any antifreeze or similar chemicals to the heating system if it is connected to the water supply. There is the risk of backflow where contaminated water can enter the water supply.

I found this page on a quick Google search that explains it:

**Broken Link(s) Removed**


 
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Post by Yanche » Wed. Jul. 16, 2008 9:39 pm

Don't put antifreeze in a hydronic system. It's a last ditch effort. If you do it you will need a backflow preventer on the boiler infeed water line. Do not cheap out an use a check valve. A backflow valve is a double check valve that catches the small amount of backflow when the first valve closes. Antifreeze changes the fluid flow properties of the water. Specific heat of the mix is lowered, reducing heat transfer. Some expansion tank internals are not compatible with antifreeze. Getting the antifreeze in is a pain and it the becomes a annual testing and topping off issue. Only use inhibited propylene glycol, not automotive antifreeze. Bottom line don't do it.

 
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Post by CoalHeat » Wed. Jul. 16, 2008 9:46 pm

Thanks Yanche for the better explanation. :D

 
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Post by coaledsweat » Wed. Jul. 16, 2008 9:54 pm

This is much more important with a well, a power outage will guarantee a lack of domestic water pressure in your system in a short time creating the perfect setting for backflow from the heating system. City water is more reliable as far as the pressure goes. Unless you have a unique system, like Lsfarm's where the boiler is off site and runs the heat through an exchanger I would recommend avoiding it at all costs.

The worst case is a heating tape for the pipe will cost $10-15, and the cost to operate it for say 40 hours in all the -10* weather you'll have maybe another $4-8. There is 35-50 gallons of water in the average heating system, that's about 20 gallons of very expensive gook your going to need. Then you will have to pump it into your system (have fun with that). Like I said before, -10 or -20* degrees is a long way off, the only thing you need is a thermometer right now. If your pipes only see 45*-50* worst case, you don't have a problem.

 
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Post by Uglysquirrel » Thu. Jul. 17, 2008 7:14 am

A lot of thanks for the practical info here, the risk of freezing in my home config is pretty low, would appreciate the timer follow up for future use. We get down to -3 * min in Central CT and with the upstairs doors open at night, the air is exposed to the 6-7' long finned radiators that conduct heat to the pipe circuit, guess I did not think about that enuf. Tapes are a bit hard since most of not all of the pipe is in the ceiling behind drywall, though there is a 3' boxed in north wall pipe area I could open up and put in a tape if needed. The heat would migrate thru the copper pipe big time. That reserve plan makes me happy, now I can sleep at night.

Nepadigital, the solution to insomnia.

:>


 
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Post by Lumberjack » Thu. Jul. 17, 2008 10:20 am

Not to mention that permanently connecting a system using antifreeze to any potable water system is pretty much illegal even with backflow preventers. Even a tiny amount of antifreeze in your drinking water can cause severe health issuses. In many areas a double wall heat exchanger is as close as you can get.

If your pocket book is large enough the best way to put an end to the issue is to circulate the water through a heater set to about 50 degrees or so. A tankless or tiny waterheater might do it with the right thermostat and a tiny taco pump....

 
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Post by Sting » Thu. Jul. 17, 2008 11:04 am

You don't even have to heat it

just circulate the loop 24/7 when you think it might freeze

 
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Post by coalmeister » Thu. Jul. 17, 2008 11:56 am

Uglysquirrel wrote:Re: Freezing hydronic heat pipes in outer walls, you can fill the boiler and a water/glycol solution with lubricant, they will never freeze. Any positive/negative experience in doing this ? My Mark II is in the basement and with this baby cranking on nut on a 0 deg night, I'm concerned about the north facing 2nd floor pipes that overhang the 1st floor by 1 ft. House is build 1985, hot water heat pipes are insulated with foam in the overhang, on the plus side heat in these pipes does conduct from warm areas to cold, so this helps, though still concerned. Any comments about using tne glycol antifreeze in the boiler system?
We use a water/glycol solution in an outdoor chiller for an electric induction heater at work, but we lose about 40% on thermal transfer rate versus water so we pump it out every Spring

 
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Post by ScottD » Tue. Jul. 22, 2008 5:20 pm

My house is set up with 5 zones on my oil fired boiler, one being domestic hot water. When I put my coal stove in use this year for the first time I was wondering about freezing pipes as well. Most of my house is over my basement and I'm not too worried about that seeing I have a finished basement and I was going to leave that thermostat on 50 degrees in case it did get too cold down there. The bedroom loop is over the garage and I planned on just draining that one loop. Problem solved. I get my hot water and basement backup plan. Only thing I will have to see about is 2 of my bathrooms are over that garage space. That might be tricky but we will see this winter! So for those with multiple zones, just drain the ones you don't need and keep the ones you do. Just make sure your thermostats for that zones you drain never get turned up or you will burn the circulators out.

 
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Post by Freddy » Tue. Jul. 22, 2008 6:16 pm

ken wrote:you lose like 10 % to 20 % of the BTU's with anti-freeze in the system.
You do not lose any BTUs to speak of. What you lose is the ability of the solution to transfer the heat. When we plumbed a house that we knew was going to be anti-freezed, we'd add 20% to the length of the baseboards.
Lumberjack wrote:permanently connecting a system using antifreeze to any potable water system is pretty much illegal even with backflow preventers.
Only partially true. The key being the type of anti freeze. It is absolutly illegal to add auto antifreeze to a heating system. Proper, legal, boiler antifreeze is non toxic. Always a backflow/pressure reducer device is part of any boiler system. The law in this state, antifreeze or not.

As mentioned, unless you need it, skip it. If you freeze every year, it may be a concideration, but if you freeze once every 5 yrs, forget it.

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