Frozen Condensate Lines

 
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Old 12-12-2009, 04:10 PM   #1
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Frozen Condensate Lines


What are you guys doing about frozen condensate lines that are piped via 3/8 id vinyl tubing? I was on a call in which the line was buried in the insulation, but still, there was a 3'section that was above the insulation.... First time, I wrapped the vinyl tubing in some r-8 foil wrap, but the line still froze up.

It's hard to specify the details. But this is the first winter I have had where I have seen so many lines frozen, and it is becoming more frequent to find condensing furnaces in the atic.

My bright idea is to pour table salt into the condensate resevoir of the pump.
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Old 12-12-2009, 08:31 PM   #2
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Re: Frozen Condensate Lines


Since 1985, we only install 90% condensing gas furnaces due to the high cost of propane - natural is not available here. The cost of B vent or lining an existing flue for 80+ furnace exceeds the cost of the 90% making it an all around no-brainer for us.

We have painfully learned about installation, especially the drains due to frequent freezing temps in our market. We always try for an interior drain but reality is a retrofit or new build will not always have this as code often will not allow the acidic condensate into a septic tank or public sewer. We now keep the drain as well protected from freezing as possible within inside walls untill just before the termination to outside. Our termination is 4-6 feet 3/4 PVC with heat tape & insulation. This has worked very well.

We also discourage attic & crawl installations. A power or system failure will expose the secondary heat exchanger to freezing which will result in failure of that component. We stress that most emphatically upfront so that when we have to install in those areas, the client knows & has no recoarse against us. We have found that even if no power or system failures are experienced, secondary failures are more common in the attic & crawl installations versus basement or conditioned space installs.

I'm sure that we've lost more than a few bids because we plan for freezing, but spending several hours on a late evening or holiday thawing out a furnace/drain only to find a failed secondary will not let the furnace run is no fun for us or the client.

I submit this for all of us professionals to consider, even in the southern climates. The factory installation instructions do not emphasize this aspect enough in my opinion. Then again, how many installers read thoroughly the instructions?

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Old 12-14-2009, 08:39 AM   #3
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Re: Frozen Condensate Lines


If the condensate is so acidic that they aren't to be plumbed into the sewer lines or septic system? then why are they being used at all. You can't drain it in the plumbing system legally, so you just dump it in the ground? I am not an extreme tree hugger, but, all the talk about energy efficiency and being green, meanwhile we are dumping "acid" in the soil by our homes? Sounds kinda ironic.

Condensate plumbing in often overlooked by installers. There are so many condensate lines that sag, droop, poor grade...etc. If you are going to install a furnace in the attic, I have come to the conclusion that if you can't drain through an inside wall, just install an 80% or a heat pump. It will save you and the homeowners from a lot of headaches.

As for the salt thing, so far, the line has not frozen.
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Old 12-14-2009, 10:28 PM   #4
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Re: Frozen Condensate Lines


Many brands have PH neutralizers that you can use to plumb the drain to the sewer line.

But, PVC, heat tape, and insulation are your best bet in cold climate areas.
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Old 12-15-2009, 06:50 AM   #5
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Re: Frozen Condensate Lines


I don't have a pH meter and can't find my indicator papers, but I made my own neutralizer.

Condensate is pumped to the laundry tub. Tubing is run to the bottom of a (2 - 3 quart) container filled with marble chips (from Lowes). Marble is composed practically all of calcite.

Condensate percolates upwards in container, then spills over into tub.

There is no acidic taste to the condensate.

If you try this method, wash chips thoroughly to remove dust.

delta
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Old 12-15-2009, 05:46 PM   #6
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Re: Frozen Condensate Lines


salt may deteriorate the pump prematurely, dumping the condensate outside in the winter is just asking for problems. beenthere's got it down with the insulation and heater on pvc drain. i make sure there is a good pitch outward so there is more than a trickle to the drain.
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Old 12-17-2009, 09:43 PM   #7
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Re: Frozen Condensate Lines


Flash,
I know that you don't do any new construction but code here allows the drain to be run to the washer box. If you think about the chemicals that are used in dishwashers and washing machines the acidity shouldn't be a problem. We usually try to do this on retrofit also if possible. Only thing to watch for is copper drain lines.

And by the way, everybody was fighting the frozen drain lines last week. It was cooollllddd!
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Old 12-18-2009, 08:58 AM   #8
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Re: Frozen Condensate Lines


Cooold...and how. Just what we needed. The problem wasn't that the lines were freezing at the terminations. They were freezing in the attic. In this one instance, the condensate was run to a washer box that was about 25 away (horizontal run). The line was buried in the insulation, but it still froze.

Well, I thought the salt thing was kinda clever. I am a little concerned about the possibility of the effects on the pump. I left some crystals in the resovoir, but I didn't cover the bottom like it was a fish tank.

I/we should know better about how cold it can get in attics, and the importance of getting the condensate out of there as soon as possible. It doesn't get too cold here in general, but we should plan for single digit temps. It would be nice if we got together with the plumbers and figure how we can use their vent pipe legally.
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Old 12-18-2009, 11:45 AM   #9
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Re: Frozen Condensate Lines


Insulation only slows heat transfer. Doesn't stop it. So if the furnace doesn't run for a while. The pipe still gets too cold.

Thats why you should use heat tape and then insulate.
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Old 12-18-2009, 09:34 PM   #10
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Re: Frozen Condensate Lines


Yeah,
90% in the attic does not work at all unless it is conditioned. We do have a few out there but it's our policy to never do it again. Even in a conditioned attic, you have to make sure that there is no horizontal section of drain line open to freezing temps.

Your idea with salt is pretty interesting. I wonder how much alcohol per volume of water would be needed to keep the condensate from freezing. I feel a wacky idea coming on.
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Old 12-18-2009, 09:45 PM   #11
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Re: Frozen Condensate Lines


You would need a way to keep replenishing the alcohol.

With salt, you might be able to put enough in to hold for a month. but, salt is only good down to 20F, and then the water and salt will separate, and the water will freeze.
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Old 12-20-2009, 12:50 PM   #12
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Re: Frozen Condensate Lines


I googled for the freezing point of salt water. It basicly depended on the ppm's of the salt content. I certainly don't know if adding salt is the end all of the problem we had. Obviously, the bottom line is make sure the system is plumbed so as to get the liquid out of the attic as quickly as possible. Heat tape and insulation sounds like the correct method. Unfortunately, sometimes field conditions make it necessary to use a condensate pump. According to the instuctions that I read, the tape is not to be put on vinyl tubing.

One outfit I worked prefered to simply plumb the condensate out via pvc. After performing service calls about leaking ceilings. I felt the best thing to do was to pump out the condensate to avoid any possible problems. Obviously, that has limitations as well.

It would be nice if there were some type of anti-freeze tablet kinda like a urinal cake that one could put in a pump resovoir. Does anybody tap into the plumbing vent? Perhaps, as Western said....don't install condensing furnaces in attics.
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Old 09-26-2010, 03:22 PM   #13
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Re: Frozen Condensate Lines


Ok, the best way to do this is by heat tape & insulation. But for those in plan B mode, I think this would do the job for those cold spell days where calls are mounting. Cheap and should be effective. What do you guys think?
http://www.autopia-carcare.com/303inwiwata.html
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Old 09-26-2010, 04:12 PM   #14
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Re: Frozen Condensate Lines


Don't know if it would reach a freeze point that was several foot away from where you put the tablet in at. But well worth the try.
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Old 09-26-2010, 07:26 PM   #15
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Re: Frozen Condensate Lines


As far as the acid in condensate and tree hugging: there has always been acid in the products of combustion it just came down as acid rain.

I too feel heat tape is the only real fix. Does anyone know the watt draw on heat tape lets see AXV=W then WX 1.8?? = BTU's so we take a 90% rather than an 80% to save fuel but spend the savings on heat tape power. This is a great plane the EPA came up with. The good news is they got a $1,500 tax credit.
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Old 09-26-2010, 07:38 PM   #16
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Re: Frozen Condensate Lines


EPA had nothing to do with the efficiency of the furnace. It was the DOE.

Amp X Volts = Watts
Watts X 3.413 = BTUs

You can get, it in 3 and 6 watt per foot in 120 volt.
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Old 09-26-2010, 08:18 PM   #17
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Re: Frozen Condensate Lines


Upon further review, I dont think those tablets are the short term answer. It looks as if they effervesce. I had to up that word to see what exactly it meant. It means that they dissolve quickly when introduced to water. I was thinking of something like a urinal cake. I'll do a little research to see how urinal cakes would do and let you know.
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Old 12-31-2010, 07:03 PM   #18
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Re: Frozen Condensate Lines


Around here, it's frozen condensate time. If anybody comes upon this situation, and calls are building up, the salt thing helped out last year. It's a good time to stock the rig with some tubing. Probably recommend to the customer quit the set-back temp until the freezing ceases and/or get the problem alleviated.
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Old 01-01-2011, 09:40 AM   #19
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Re: Frozen Condensate Lines


Quote:
Originally Posted by NickTech View Post
salt may deteriorate the pump prematurely, dumping the condensate outside in the winter is just asking for problems. beenthere's got it down with the insulation and heater on pvc drain. i make sure there is a good pitch outward so there is more than a trickle to the drain.

The the agent used in the acid neutralizer kits is basically limestone. Limestone is used to reduce soil acidity. Kits need to be used unless condensate pumps can specifically handle acids.

ICP neutralizer kit info http://icpindexing.mqgroup.com/docum...4106105000.pdf
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Old 01-26-2011, 01:31 PM   #20
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Re: Frozen Condensate Lines


Dont use salt!!! That is a really bad idea... When I was in Boston I had a customer that no mater how much insulation we put around the PVC it still froze... The customer told me to solve the problem no matter what so inside the insulation touching the PVC we ran the small plastic pipe used in a floor heat water heater circulation system. We set it up off the water heater with a small pump and now no more frozen pipe! System cost me $300 and I charged the customer $700... It was a win win!

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