Furnace replacement

I am getting absoluetely fed up with fixing one thing on my "made in America" 18 year old Carrier only to see something else bite the dust. I wish it was European. You get 30+years out of those things.

I recently replaced the three-wire pilot assembly and now the gas valve sporadically clicks. During long warming cycles the burner will slowly dim and surge again a few times. You have to sit there for half an hour to see it. I am guessing it might be a weak coil.

It will get me through the rest of this season (probably with a CO headache) but I need to get something done before next year.

Since I am also remodelling the basement (very slowly), I'm thinking this might be a good time to replace the thing.

So, I want some tips. Any tips will do. I don't have high expectations (I am on old-timer on this forum now)

How much can I expect to pay? (I know you hate that question).

Is it really worth getting a high efficiency one (extra cost, extra complexity)?

If I replace the AC later will this be a problem (it works, but it's also getting old. I just want to keep the costs down)?

And anything else you can think of.

Any good makes of mid-efficiency furnaces you can think of? My old Carrier seemed pretty good. Anything to avoid?

And is it just plug and play? Will the engineer just replace the old with the new or do you often need new ductwork?

Like I say, any tips will do.

Nothing is ever truly "plug and play" but it is not a big deal,either.

I you live in a very cold climate, the extra efficiency can save you some bucks, but as you noted, there is added complexity and maintenance. You might opt for something in between a basic single speed 80% job, and the way up top line models.

Makes sure they size the furnace blower properly to support the tonnage of A/C you have.

Thanks Jimbo. What do you mean by way-up top line models?

What more can there be than just a single speed 80%?

From what I've seen, furnaces don't have modulating burners like the best boilers, but there are various two-stage versions. The best condensing furnaces are in the mid-90% efficiency range. For comfort, one feature that I really like is a variable speed fan. Makes that cold shot when the fan comes on a thing of the past, and you rarely notice that it is running. I have a weird system, part radiant flooring, and an air handler with a hydro-air heat exchanger rather than a furnace, but my a/c and air handler are Trane. I chose the thing with a 16-speed fan. No belts, all electronic. It's going on 15+ years with no maintenance other than filters. I did add an electronic protection device during the install that monitors power for brownouts or spikes...it prevents the system from energizing until things get stable. Made by (I think) IDE. The variable speed blower also makes the a/c much more efficient in many places since it starts out slow to let the air linger over the coil which extracts MUCH more moisture that running it at the normal speed. If it needs to run longer to meet the cooling needs, it ramps the speed up, then ramps down at the end to extract cool from the coil after the compressor stops.

You will almost always need to make some changes to the ductwork, but it may not be major. Ducting exhaust and intake air may be an issue (the more efficient units use PVC for both), and you need a place to dump condensate from both the a/c and furnace once you get this efficient.

If you try to reuse your old evaporator coil and a/c unit, you will almost certainly need to change it out with a new unit - different refrigerants and design to meet the newest efficiency requirements...the old one just won't be compatible when upgraded later. Depending on how it is mounted, this may mean additional rework.

A/C units are mandated to be significantly more efficient than they were 15-years ago, so operating expenses might be significantly reduced if you upgrade that now verses later, especially when you consider the rework that will be required to put in a new coil.

Around where I live, it's often in the $8-9K for a new furnace and a/c unit. You can get less expensive units. I live in a townhouse condo complex...people have been replacing their old units with Trane stuff, and that's the local cost for a 90%+ efficient unit and a 14SEER a/c unit installed with take away of the old unit.

I have heard that it is hard to stop a Trane.

But fixing Tranes is even harder!

Any comments?

I've had the panel off my a/c and installed the air handler...panels come off and parts seem to be accessable...just never had anything break. Well, I actually had a mouse electrocute itself across the main power contactor on the a/c unit...it needed the fried carcass to be removed and some contact cleaner, but it worked afterwards - cooked guts will do that.

There are furnaces in the 92% efficiency range which use a multispeed blower, and possibly a two stage burner. There are 95+ % efficient which use variable speed blowers, multistage burners, etc.

I can't help feel though that single-speed 80s are just more rock-solid when it comes to maintenance. I can see the advantages of these high efficiency ones, but when I read the literature they look so complicated to fix.

And as a DIYer I will want to fix it....someday. But I'll talk to the people that give the quotes.

Any comments on the AC condenser? My existing 2.5 tonne unit struggles to keep the place cold. It always runs when the AC is on. It never turns off. Should I upgrade to a bigger one or is this just a sign of age? I live in a 1300 sq feet rambler, but remember I want to finish the basement some day.

How big should I go and what impact does this have on power and wiring, for example? I think the current unit is on a 30 amp breaker with 10-2 wiring. Again, not for me to fit but when I get quotes I may need to keep my (old 100 amp) electrical system in mind. Note: yes I will have this upgraded to a new 200 amp service when the basement is further along, so no lectures please.

I am getting three quotes. One from a nice cowboy who fitted my Bradford White ($800) on the cheap: $5,500.
Sears are coming next Monday.
And later in the day a sound local company.

In this climate though, it'll be all about cost and financing. Anything over $7000 and I'm going with cowboy, with my toolkit at the ready after he leaves.

He left the Bradford leaking slowly at the hot outlet.

The magic to a/c and comfort is size it to run constantly at the max load for maximum dehumidification. If a choice between slightly too big and too small, choose too small as you'll be more comfortable in warmer, but drier air than colder, clammier air. The worst choice is an oversized unit that runs in short cycles, can't dehumidify because it isn't running long enough (not enough air passes over the evaporator), and results in cold but clammy air.

The only way to decide what size to use is to run a heat load analysis...this takes into account the floor space, outside walls, windows, insulation, and orientation. Then and only then should you decide what size to get. There are some that are multi-stage, and may be a good choice for pending additions without over sizing the current house's cooling capabilities, but they cost more. What may work out is to just make that addition a separate system altogether and size what you have now with the replacment unit.

OK, I have had Sears come round to give a quote and then a local firm visited too.

It appears that my current furnace is well over-sized (100,000 BTUs) and I probably need closer to 50,000. The AC, in contrast appears to have been under-sized, and is 2.5 tonne. They are both recommending a 3 tonne.

But there is a dilemma here. Sears want $8,000 for an 80% dual stage furnace (Carrier Performance) and a 13 Seer (bottom of the range - Carrier Comfort Series) AC. They have interest free financing.

The trusted local firm want $7,500 for the top of the range 80% (Bryant Evolution variable speed and multi-stage burner) and a mid-range 13 Seer AC unit (Bryant Preferred). They'll throw in the funky Carrier T-stat/interface too. But no financing. Sears quoted above $9,000 for a similar set-up.

Sears did a load analysis but the local firm just looked and found similar conclusions.

All Carrier or Bryant. So what do I do? Or is it a no-brainer i.e. go with local and talk to my bank?

One thing is for sure. The cowboy is out of the running.

Take a look at Rheem. And if you want to save a little money chech out Goodman, its built well and has a good warranty. Any system is only as good as the installation.

I just bought my first house. It's a fixer upper and it has the original furnace about 28 years old! I know a new furnace is in my near future. I wondered if any readers could give me advice about buying a furnace. Which brands are best? How can we get the best deal? Does shopping in the off-season help?

I am buying now and although nobody is going to tell you this when they come to give you a quote, the HVAC business is down in this economic climate. If people are putting off buying new cars you can bet your bottom dollar they're patching their old furnace up too to keep it going until times get better. So ask the guy how business is when he comes to call, and smile when he says "we haven't noticed any difference really". Yeah right!

So now is probably a good time to buy to get a good deal. And you always get the best deal if you are patient so make sure you buy before your current system dies. Estimators love to visit cold houses.

I have taken three quotes and am trading them off against each other. The companies use a lot of tricks. They won't just try to bid in terms of offering the lowest price but will start to keep the price the same but offer higher levels of equipment and warranty coverage. Some might offer high prices but then throw in rebates. So know your model ranges; what SEER means; and the difference between single stage; dual stage and variable speed furnaces. Oh and high efficiency too.

It is important to compare like-with-like though. So make sure the models being offered are comparable (easiest if they are the same brand). Also make sure you get a proper assessment done by at least one of them of your home's heating and cooling needs. Your current system may be over- or under-sized. For example, my current furance is too big and my AC is too small.

I am about to blow-off Sears today. I cannot wait. They couldn't match the quote of the local firm.

Also be aware of home warranty-type individual contractors. I had some real low quotes (several thousand dollars below what firms were offering) by people that I feel just wouldn't cut the mustard and do a good installation. These are the type of guys that you call to your house to fix your furnance; don't know how to do it and blame the problem on the gas company for providing too low gas pressure. I think you know the ones....

It's a buyers market. Just don't rush.

In 2005, I replaced my 55 year old furnace. It was actually older than me.
I bought a Lennox G61V gas furnace. I am very happy with it. It runs. It doesn't shut off when it is not supposed to, and it is very quiet. Energy efficiency 94.6; duralok plus heat exchanger, 2 stage heating, sure light control ignition, and 5-year limited on covered parts, lifetime warranty on heat exhanger. It cost me, 2, 683.00 Plus they took away my old one. I could had gotten the air but, I hate air conditioning. I don't know what it was sized at, but my house is not tiny. That prices includes a new flue liner.

I have been very pleased with it.

Stop it. I am already tempted to do my own gas work but my wife won't let me.