Should I replace AC coil when replace gas furnace?

jhome2007April 10, 2012

I need to replace a gas furnace. At least two contractors suggest me to replace AC coil since it is cheaper to do now, they said. The central AC works fine, and it is about 18 years old (the same age as house). The two contractors are in heating and AC business. Another contractor does not mention it and he is in plumbing and heating business. My question is: is it worth to do it now?

Thanks,

-JH

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tigerdunes

Dumb idea, bad advice.

You have R-22 refrigerant now. New AC will be R-410a. You would not want to contaminate a new coil with the old R-22 refrigerant. Keep in mind AC condensers must be matched with the best matching evap coil.

IMO

    Bookmark   April 11, 2012 at 6:53AM
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jhome2007

Thanks tigerdunes. The contractor says that when I need to re-fill refrigerant, it will be cheaper to get new one and the old coil won't work with the new refrigerant. Also if the old coil goes bad and replace it then will be more expensive than doing it now since we are taking apart the furnace. Is this common practice to do both at the same time?

    Bookmark   April 11, 2012 at 9:16AM
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mike_home

The logic the contractor is giving you makes no sense. If you have to "re-fill refrigerant", then you have a leak. Your options would be to repair the leak and add R-22, or replace the condenser, coil and lineset which would be filled with R-410.

I think the contractor is concerned he may damage the coil or cause a refrigerant leak in the process of installing the new furnace and is looking for you to cover his costs.

Have you thought about changing the AC condenser? You said it works fine, but at 18 years it is getting to a point where problems begin to develop.

Does the furnace need to be changed now? You could wait until the fall and replace the furnace and AC at the same time. It will cost more up front, but you will have a more efficient and reliable system. In addition the Carrier rebate is up to $1100 for a complete Infinity furnace, AC, and thermostat installation. You may also qualify for additional rebates for a more efficient AC.

    Bookmark   April 11, 2012 at 9:52AM
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jhome2007

mike_home, thanks for the info. I have been lived in this house for 6 years and has never had problem with the AC. Not sure about the history though. We are in New England so summer is not that hot. We usually turn on AC for about 2 weeks per summer. As for furnace, it should be replaced but I can wait and I see your point to wait till fall to do both. But what if AC works fine during the summer and I will face the same situation, right?

    Bookmark   April 12, 2012 at 12:17AM
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handy-man

Since your A/C is 18 years old. most likely it's R22. Can you replace the evaporator coil with tbe furnace. Absolutely, most evap coil are R22 and 410A compatible. The only problem is that if your condensor go out, you will have to swap the evap coil again. If you are not ready for the whole A/C replacement. Just do the furnace now and do the A/C later.

    Bookmark   April 12, 2012 at 2:36AM
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mike_home

I was suggesting you get another summer season out of your AC before replacing it. It is very possible the AC will work fine this summer and you will be faced with the same decision again.

If it were my house, I would be concerned about damaging the current coil when the furnace is replaced. I had a bad experience several years ago when I had a HVAC contractor disconnect one of my AC condensers because I needed to fix the area for drainage. At the time the condenser was about 23 years old. The contractor told me it was a bad idea and suggested I replace the AC. I told him wasn't ready for a replacement. The condenser was disconnected and reconnected a few days later. The system developed a leak which I did not fix. I ended up replacing the sytem a year later.

    Bookmark   April 12, 2012 at 9:14AM
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heatseeker

Replace it it is in your best interest to exchange all of your equipment now, do not let that dude nickle and dime you call a more reputable company and changeout everything at once, you will regret it if you don't. I would question any contractor who would tell you to change only an r-22 evap coil given the changeover to new refrigerants. He is not looking at your best interest.

    Bookmark   April 12, 2012 at 10:45AM
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brickeyee

"most evap coil are R22 and 410A compatible."

The odds of finding a compatible coil for an 18 year old system are between small and zero.

    Bookmark   April 13, 2012 at 3:52PM
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heatseeker

Yes brickeye but once you commit to on or the other freons you can't change back to the other.

    Bookmark   April 16, 2012 at 8:31AM
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tigerdunes

Too much has been said on this.

Plain and simple, either upgrade with both new outside condenser with new matching evap coil or place old evap coil on new furnace and wait till you have to change both due to breakdown/failure.

IMO

    Bookmark   April 16, 2012 at 9:13AM
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brickeyee

"Yes brickeye but once you commit to on or the other freons you can't change back to the other."

Never said you could.

The bigger problem would be finding a listed coil for any system that old, period.

What freon a new coil might be suitable for will not make much difference.

The system is so old it should simply be replaced with a new matched component set.

The efficiency improvement alone will be significant in helping reduce the 'cost; of the new system.

    Bookmark   April 16, 2012 at 10:15AM
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jhome2007

Thanks all for the valuable advices. I will talk to contractors to find out what make them to think I need to replace coil now. Like I said the AC is 18 years old but I have been living in this house for 6 years and had never done any work on it. The previous owner said they did some maintenance work (between 2003 to 2006) but no details I would know.

If contractor would replace coil this time, would they be filling new freons if I keep the old unit? Will the old unit work with new freons? If yes, replacing it now might be an option. Or what if they discover the old coil has leak but the unit is working fine, so do I need to replace all of them?

-JH

    Bookmark   April 16, 2012 at 11:37AM
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heatseeker

just replace both of them and you will be better off.

    Bookmark   April 16, 2012 at 12:33PM
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jhome2007

Well, just spoke with one of the contractor now. He said -

1. Replacing the old coil today and fill with R22 freon to work with my old condenser

2. N years down the road when the outdoor unit goes bad, just replace the outdoor unit without replacing the coil. But they will do a flush to take out the R22 freon and fill with the new format. At that time, no coil work is required so the $$ will be saved.

Sounds not bad?

-JH

    Bookmark   April 16, 2012 at 1:02PM
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tigerdunes

It is amazing that homeowners come on this site for advice but can not accept it.

What a screw up in the making.

You usually get what you deserve taking a shortcut that is not a shortcut.

IMO

    Bookmark   April 16, 2012 at 1:20PM
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mike_home

You are getting bad advice from your contractor.

    Bookmark   April 16, 2012 at 3:34PM
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heatseeker

If you take that advise you are a moron and so is your contractor. Saving money usually cost you more money in the long run when it comes to hvac.

    Bookmark   April 17, 2012 at 9:41AM
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jhome2007

Ok, ok. At least one contractor (he replaced my water boiler few years back) said no need to do it now. If he does the installation, he would look at the coil (he said there is nothing to look at it) and the worst case is the do it when it goes down. He thinks I am wasting money....

Anyway thanks all for the help. One last thing, I need to select furnace - LENNOX #EL195UH070XE36B 95% and Concord (not sure specifics yet). Which brand is better?

My house is 2700sqf including basement and in northeast. The basement (900 sqf) have one vent to ease the chill and not need to be warm as upstairs.

Thanks again.

-JH

    Bookmark   April 17, 2012 at 10:03AM
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heatseeker

Tiger dunes said that in the first post.
I got some advice for you go to a psychologist and find out where your parents went wrong.

    Bookmark   April 18, 2012 at 11:43AM
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tigerdunes

Jhome

Both cheap furnaces.

If Lennox is the only choice, I would want a two stg var speed 95+% efficiency. Of course properly sized. The G61v model.

I see where dealer is quoting a 70 KBTU model. What size are you replacing?

IMO

    Bookmark   April 18, 2012 at 11:51AM
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jhome2007

Thanks tigerdunesmy. My old furnace is 72k BTU with 80% efficiency. It heated the house well. The new Lennix one 95% efficiency with 70k BTU. As for Concord, the contractor originally quoted 90k BTU and I believe it is over-sized for my house.

As for someone spits bad words in this forum, I would suggest him to turn around looking for something else to do. Not everyone here is sophisticated enough understanding everything and that's why I am here.

-JH

    Bookmark   April 18, 2012 at 11:44PM
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heatseeker

No bad words just making a legitimate point, that TIger awnsered your question on his first post and here you are asking the same stuff over and over again. It's just my opinion that some mental health issues might be rearing their heads. I am not a doctor but my unprofessional opinion is that you need to see one. And your right I don't have anything better to do.

    Bookmark   April 19, 2012 at 9:39AM
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