repalacing a 40 year old standing pilot furnace

11 years ago

I am very soon going to be purchasing a new furnace. I own and live in a 1-bedroom condo in Denver, Colorado. it is about 700-750 square feet, all on one floor.

The condo was built in 1972 as an apartment and was "converted" to condos about 1979. It has the original 40 year old standing pilot furnace that is still in working order (I had it checked in Dec. 2011 by our local utility, Xcel Energy and it passed with no leaks or CO problems. Yes, I have a CO detector installed!)

Since these units were built as apartments there are no separate gas or water lines for individual units. I pay a monthly maintenance fee and the gas/water costs are taken out of that. Therefore whether I have the present furnace or a new 96% efficient energy saver it will make no difference in my utility costs.

I have decided to replace it with an 80% AFUE furnace.

The building I live in has two stories, four 1-bedroom units on the ground level and 4 identical units on the second floor. I am in a ground unit in the middle, so I have other units on either side of me as well as someone above. Below me there is a crawl space. I only have two walls facing the exterior, a north and a south wall.

There are a total of 203 condos in this complex so there are other buildings and 40-year old trees surrounding me.

The furnace is in a closet in the hallway. The closet interior is 22-1/2 inches wide and the doorway is 17 inches wide. I will need to go with a 14 inch wide furnace in a downflow configuration. (the present furnace is 16-1/2 inches wide.)

I have had two installers come to make a bid on a new furnace. They both said I needed a 45K model. The first installer offered either a Trane XL80 or an XV80.

(It turns out that the XV80 doesn't come in 45K, 60K is the smallest. What really puzzles me is that the product data sheet says it is 19-1/2 inches wide! How are they going to get that through a 17-inch door opening? Do they know about some law of physics I don't know?)

A second installer offered initially a basic Payne 80% model. (He also has available Goodman and Bryant models.)

No, nobody did a load calc.

I am inclined to go with the second installer. However, I don't want the basic 80% model from Payne/Bryant/Goodman, I'd like to upgrade to the best 80% model I can get that will still be 45K.

So to that end, I have been poring over furnace reviews, forum posts and product data sheets. I have learned a few things and it has been challenging and interesting, almost fun!

I realize with the furnace in the hallway right next to the living/dining area it would be a good idea to go with a furnace with a variable speed blower and a 2-stage burner.

The top of the line 80% models from Bryant (Evolution 80v-315AAV) and Payne (PG8MVA) offer these features and they would be perfect except for one fatal flaw: the smallest they come in is a 65/70K model. I know this is WAY too big for my unit and have read of the horrors that furnace oversizing brings. I know then that I cannot choose these.

The mid-line models from Payne (PG8MEA) and Bryant (Preferred 80x-313AAV) have more features than the basic models but still only 1 stage burners and multi-speed (not variable speed) motors.

Goodman only seems to offer only one 80% downflow model, the bottom of the line GDS8. I have found distributors on the Internet offering a Goodman GDH8 which is a downflow 80% model with a 2 stage burner (but still a conventional motor.) It is not listed on Goodman's site so I'm guessing it is discontinued.

When I asked the installer about the mid-line Bryant 313AAV, he said it was not stocked by his distributor and it would have to be ordered direct from the factory, there would be shipping and handling charges. The Bryant 315AAV was stocked and so he could offer it at the same price as the 313, but as I said before the 315 is not available in a 45K so it's really not an option.

I see Bryant also sells another mid-line 80%, the 312AAV (Preferred 80t). This does have 2-stage heating, but from what I read on this forum, only a PSC motor. Not good.

In short, there seems to be no model anywhere, from anybody that is an 80% AFUE, 45K, 2 stage burner with variable speed motor. I will have to compromise somewhere. And I am very inclined to go with the Bryant 313AAV.

By the way, I do have air conditioning and the evap coil needs to be replaced. (I had a repairman come in about 3 years ago to do a heating/cooling seasonal startup. He said the evap coil was totally clogged with dust and dirt. He could attempt to clean it but the metal looked so old and brittle that he could not guarantee that it would not start to break apart during the cleaning. I am sure it has probably never been cleaned in the 40 years it has been here). The A/C does work but it doesn't get quite as cool as it did when I first moved in.

As for the AC compressor, it is still the original unit. I don't have to worry about any costs replacing this, as the condo management will repair or replace the compressor at no cost to me. (in basic terms I pay for everything "inside" i.e Furnace, evap coil, etc and the management pays for the "outside" equipment-the compressor.)

The install prices will include replacing the old evap, coil with a new r22/R410 compatible unit, put a filter on the refrigerant lines and deep clean the lines down to 500 microns.

The first installer asked $3589 for the XL80 install with a new coil and $3889 for the XV80 upgrade. The second installer wanted $2200 for the Basic 80% Payne or Goodman, $2350 for the basic 80% Bryant) and $2750 for either Bryant 313AAV or 315AAV, all with a new evap coil that is R22/R410 compatible.

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Comments (11)

juliekcmo
11 years ago
last modified: 9 years ago
So what exactly is your question?

If you want recommendations, here are some thoughts. Consider a variable speed or 2 stage80percent furnace. You may need to go up in b t u levels over your load to select an in stock size. Multiple speeds /stages will allow the furnace to run at partial load

Make sure you get something using r410a outside. Basic 13 seer will be all you will want on AC.

Know that after May 2013 regional efficiency standards are changing. I am not positive, but think that in your region 80 percent furnaces won't be allowed. In a high rise it will most certainly be easier and less costly to go with an 80% now, vs a 95% and venting later on.
tigerdunes
11 years ago
last modified: 9 years ago
Kevin

I have done a little preliminary research.

You have two issues, physical size and correct BTU sizing.

If not a var speed blower with two stg heating, then a sgl stage with the X13 high eff blower motor.

You might inquire about Carrier's Performance Boost 80 model.

I will assume when dealer says your heating load is 45 KBTU, he is speaking about input, not output. I would even say that 45K is too high. The XV80 on the smallest size would give you around 31 KBTU on low stage and I doubt you would ever require the high stage. Of course you would need a true 2 stage thermostat to keep the high stage from coming on except when needed.

Will look further when time is available.

IMO
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mike_home
11 years ago
last modified: 9 years ago
I think replacing the coil is likely to cause a problem with the AC condenser. I would not be suprised if a leak developed. The coil will have to be changed again when the condenser is replaced. Do you have to pay for another coil?

The smart thing to do is to change the condenser now and have a matched system.
Kevin-p
Original Author
11 years ago
last modified: 9 years ago
Thanks guys for the comments. I just want some professional advice before I make my final decision on the furnace.

I know the best choice is a variable speed, 2-stage but nobody makes them in a 45K 80%, period. They are all 65-70K or bigger. Bryant makes a 2-stage 45K (312AAV) but it only has a bad old PSC motor.

I could ask the installer about replacing the PSC motor in the 312 with a 'green' variable speed motor (www.evergreenmotor.com)
as he gave me a brochure on it, but replacing a brand new motor doesn't sound very wise.

The Bryant 313AAV has an ECM (X-13) motor but only a 1-stage 45K burner.

I looked at the spec sheet on the Trane XV80 (somewhere on the net) and the smallest size I saw was 60K, no 45K model in the XV80. Did I miss something?

I know probably the low stage (32K) of a 45K 2-stage burner would likely be sufficient 90+% of the time. The furnace usually runs Nov-Feb and perhaps a bit in March depending how could it gets. This past March it never ran at all. During April, May, Sept and most of Oct. i rarely use any heat and not much AC in Sept.

The condo mgmt. sent out a notice last year that if our condenser units needed replacing, that we would have to replace our evap. coils at the same time (the coil would be at our expense-$400-$800, the condenser at theirs). I figured it was because the new condensers would all be R410 and the old R22 coils in current use would have to be replaced.

the installer said he would replace my coil with a R22/R410 compatible unit so I will already be taken care of when the condenser finally fails.

Yes, I thought on my own that the new coil might be too much of a strain for the old condenser. However, if I want the condenser replaced now I have to pay for it. As long as it is working they will not pay for a new one, even if I am getting a new furnace and coil.
tigerdunes
11 years ago
last modified: 9 years ago
Kevin

You are under the mistaken impression that 45k heating load calc is correct.

I don't believe that for a second for a ground floor internal condo with sharing common walls on each side of your unit.

Trane XV80 60k model 31k output low stg, 48 k output high stage

Too bad you need a down flow model
Trane's XT80 has high eff X13 blower mtr and quiet 40 K model, 32 K output only in up flow model

Carrier has Performance Boost 80 mdl also with x13 blower motor
40 K input, 32 K output. Seems that might be a worthy choice.

IMO
Kevin-p
Original Author
11 years ago
last modified: 9 years ago
Do you think I need less than 45K? I wouldn't be surprised.

The Trane XV80 spec sheet I looked at said the smallest model (60K BTU input) was 19-1/2 inches wide. The doorway to the closet is only 17 inches wide.

Yes, it's too bad it has to be a downflow model.

I don't think this installer has access to the Carrier units, just Bryant and Payne (and Goodman but we're not going to go there!)

Looks like I'll probably end up going with the Bryant 313AAV. With the physical size restriction and low BTU I'm limited.

As for the efficiency standards changing in 2013, I read it was for the 'northern states' but maybe it includes Colorado too! I don't want to be forced into a 90% choice so I am glad this furnace change is happening now.

It would be nice if the standards change forced the condo mgmt. to install a more efficient compressor. I am paying electricity costs!
bus_driver
11 years ago
last modified: 9 years ago
HVAC is not my trade. As far as I know, Bryant is made by Carrier. The 17 1/2 door rough framing opening is larger by about 3", so the entire door casings and facings might have to be removed and then reinstalled. I had a similar situation in a house built about 1968 with an Armstrong downdraft gas furnace. Removing the blower for service was extremely difficult. So in a remodel of the house, I reframed for a 24" door, the absolute largest possible for that portion of the wall. The crew that replaced the Armstrong a few years later were grateful for the larger door.
mike_home
11 years ago
last modified: 9 years ago
"The installer said he would replace my coil with a R22/R410 compatible unit so I will already be taken care of when the condenser finally fails."

I don't think it is a good idea to resue a coil which had R22 refrigerant with a condenser which used R410. Linesets can be flushed, but I am not sure about the coil. Ask your installer about this.
tigerdunes
11 years ago
last modified: 9 years ago
Kevin

My bad on the measurements.

Trane has two offerings with 14 1/2" cabinet width, the XR80 and XB80, output BTUs at 32 K

But your best best is the Carrier Performance Boost 80 and identical sister model Bryant Preferred Plus 80x both at 14 1/4 cabinet width with high eff blower mtr. Output BTUs at 36 K.

Links below.

IMO

http://www.trane.com/Residential/products/Gas-Furnaces

http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/pds313aav-04.pdf
Kevin-p
Original Author
11 years ago
last modified: 9 years ago
Thank you tigerdunes and EVERYONE who posted a comment!

It looks like I will be telling the installer to special order the Bryant Preferred Plus 80X (313AAV) in the 45K, 14 inch width.

Bryant does sell a 'sister' model, the Preferred Plus 80t. This has a 2-stage burner (35K/23K BTU output) but only a PSC motor. I think the Preferred Plus 80X (313AAV) with the single stage burner (36K BTU output) and ECM motor is probably a better choice.
alexbest27
11 years ago
last modified: 9 years ago
I'm not sure if you've made your decision yet, but I'd check out the Owens Corning page that shows you a lot of different information on products that may help you. It's a good place to gather info. Here's the page: .http://bit.ly/JLQ0ok, and I hope this helps. Good luck!

Here is a link that might be useful: Owens Corning Solutions

repalacing a 40 year old standing pilot furnace

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