Background:

- We live in Chester County, PA - about 30 miles west of Philadelphia.

- House is 38 years old. It is pretty much a standard center-hall colonial design. Approx 2500 square feet. It was good quality construction for its day (one of the reasons we love the house), but we still have original windows, there's no house wrap around the exterior sheathing and the exterior walls are only standard 2x4 construction - they are insulated with fiberglass batt insulation (R-11?). The front fascia of the house is brick (not veneer, real full bricks - if covers from just about grade to the roof line on the front face - which is also the southwest face of the house). Windows are single pane, double hung, wood frame with individual lights - 12 over 8 downstairs, 8 over 8 or 6 over 6 typical upstairs). There are glass storm windows on all the windows in the house. The wood construction is still tight and solid and there are no significant drafts. We don't intend to replace the windows as we love this era/design of windows (they are the same windows we had in the house I grew up in - which was built in the same era).

- The only major upgrade to the house envelope that has been done in the past was additional fiberglass batt insulation in the attic - I believe the total is effectively about an R-26 to R-30

Now for the HVAC system.

The system is 17 years old. It was a pretty good system that was installed by the owner back then. It is a Heil heat pump (I don't know the SEER/HSPF rating equivalent from the time it was installed) with a Heil gas furnace as the backup heat source. The furnace is a 90% AFUE condensing gas furnace that is direct-vented to the outside. With our annual pre-heating season contract cleaning of the system, the tech informed me that the furnace was putting out a lot of CO when he did a combustion test and on inspection he could see a crack in the heat exchanger. It needs a new heat exchanger and due to the age, he recommended replacement. (As info, we also need a new Honeywell smart valve if we are going to keep the furnace. We've been nursing the original smart valve along for the last couple of years and based on what I've read, it's kind of a miracle that we got 17 years out of it, but it is now shot and needs to be replaced to have reliable ignition when the system calls for gas heat).

- So to get the current system up and running, we are looking at somewhere between $2000 and $3000 worth of repairs. With a 17 year old system, I agree that we should think about replacing the whole thing.

I started by getting a homeowner copy of HVAC-Calc and putting in as accurate measurements as I can for room size, thermal properties of the walls and windows and ceiling and using the default design temperatures for our area and recommended values for infiltration, I get a heat gain of 27,482 BTUH and a heat loss of 54335 BTUH.

I then took a look at our existing equipment. The heat pump is a 3-ton model (CH9636VKA2) which seems to be the correct sizing, but the furnace looks to me to be WAY oversized - It is a HEIL NUG9100FHA1 and based on the literature we have on it and the plate on the furnace itself it is 90% efficient and rated at 100000 BTUH input/90000 BTUH output.

I hadn't thought about it closely before, but it does seem that the system short cycles in the winter when we are using the Aux heat, and this makes a lot of sense as to why. Based on the load calc that I am using it appears to be nearly 70% oversize for what we need.

I wonder if this short-cycling could have contributed to the failure/crack of the heat exchanger as it would seem to me to subject it to more fatigue that way.

So, I have two main things I would like opinions on before I start to talk to contractors:

What would be appropriate sizing for the system? 3 tons of cooling would seem to be right - leaving a little bit extra margin (33%) whereas 2.5 tons would be cutting it close (about 11% margin). But the furnace would seem to be more appropriately sized if it was in the 60-70000 BTUH output. Does that seem reasonable?

Secondly, we have to decide if we want the setup to be a similar air-source heat pump with gas backup or a more traditional air conditioner/gas furnace setup. At the time this system was installed in 1994, the differential between gas and electricity was such that it probably made sense to use the heat pump, but I just used our latest PECO energy bill (our supplier for both electricity and natural gas) to plug in the current rates and I can't find any combination of equipment where it is not cheaper to heat entirely with natural gas (note that our electric rate is a bit higher than average because we decide to pay a surcharge for wind power for a portion of our bill, something that we are not planning to change).

Given that, would it make sense to just look at a more traditional AC/Furnace than replace the existing equipment with another heat pump?

We have been pretty comfortable in the house overall since we moved in 7 years ago, but I would certainly rather put money into more feature upgrades (like variable speed compressors/blowers, better humidity control, etc) than in over purchasing the size of the system or the capabilities (like hybrid heat pump vs. traditional AC).

Thanks in advance for your help.

Ted

It should be noted that the heat exchanger may be covered by warranty. Since you are not the original owner, the warranty might be voided. Might be worth checking.

You have full confidence in your servicing dealer's diagnosis? If not a second opinion might be in order.

What is your electric rate and nat gas rate that includes all related costs for each? I will run a quick fuel comparison for you.

At the minimum , I would recommend a good two stg var speed furnace 95% efficient probably a 70-80 KBTU model. Your rates would determine whether a HP would be advisable.

I always suggest new refrigerant lineset , whole house air filter cabinet, programmable thermostat,and perhaps a humidifier depending on your
home.

IMO

Thanks for the quick response. The heat exchanger warranty was voided - I had checked on warranty on the system a couple of years ago because of the failing SmartValve. The regular maintenance had not been kept up by the homeowner in the interim between the one who installed the system and us, so even if it was transferrable, we didn't have records to keep the warranty in force.

I am fairly certain in the dealer's diagnosis. We had a problem with the fossil fuel board for the system about 3 years ago and had a different service company in to take care of that problem and service the system and that technician had informed us of a small crack, but at that time there was no apparent (or at least significant) CO problem in the combustion of the furnace. That tech's advice was to keep an eye on the issue. Also, the dealer we are working with now is very reputable, locally owned and longstanding in the community. As much as I can trust any technician when I can't diagnose a problem myself, I think this is the right diagnosis.

From my most recent utility bill, our fully laden cost for electricity is $0.175/kWh. If I've done the math correctly, natural gas is costing us $0.93 per Therm ($0.90237 per Ccf *1.031 CCF per Therm).

We've decided that we will replace the whole system, line set and all. Programmable thermostat and automatic humidity control - definitely want to add a whole house humidifier to the system.

Thanks again for your input.

Ted

Assuming your rates are correct, a HP on a BTU basis is just about doubled the cost of a nat gas BTU. Forget the HP altogether.

Obviously then spending any significant dollars on repairing the old system would be foolish and a waste of resources.

IMO

The tech did the right thing - he did not leave the gas on. He shut off the gas valve to the furnace and (I believe) programmed it out of the thermostat.

For the moment, we are operating purely as a heat pump with no backup - which is okay in this climate for probably the next 3 - 4 weeks until it starts to get really cold overnight... even then we have a few more weeks we can get by with extra blankets and the wood stove fireplace insert if we have to.

After my last message, I realized that I was looking at a summer rate schedule bill so my electricity rate for heating was overstated. However, I also found out that the Residential Heating rate for PECO Energy in Pennsylvania is being phased out - 50% of the discount is being removed this heating season and the rest is being eliminated next heating season, so effectively the 17.5 cent/kWh is still accurate.

I could cut the rate some by switching to a competitive provider, but I think instead, after discussion with my wife, we are going to switch to a provider that will be just under 17 cents/kWh but is instead 100% renewable energy instead of fossil fuels. The truly green thing to do would be to do that AND get a heat pump/gas hybrid system, but I'm not sure if I'm willing to go to that expense.

So far I have 3 contractors coming to give me quotes - one sells Trane and their own house brand, another is primarily a Bryant dealer and the third is a carrier dealer. I know about the Carrier/Bryant connection, so I think those two dealers will be providing comparable equipment.

The Trane dealer is in the running because I have my current contract with them, but I'm not sure I am interested in Trane equipment. What's the general feeling about he house branded equipment - is it usually of acceptable quality? This is a large local dealer with a good reputation and a long track record (40 years).

I also did some calculations for my heat pump and decided to pretty much turn it off for the month. I have a slightly modified spreadsheet created by Penn State using Excel if you are interested. Helps easily compare Natural gas and Electricity and has the efficiencies included in the sheets. Removed a few lines I did not need and added a few extra for heat pump use. Calculations are pretty much self explanatory.

http://energy.cas.psu.edu/costcomparator.html

Might want to keep the heat pump option on the table. If gas prices go up it might be cheaper to use electricity. Also depends on the COP of the unit. Also nice to have a backup for at least part of the year if needed.

My heat gain/loss figures are very close to yours. You'll enjoy the comfort of a smaller furnace, especially is a modulating unit.

V

Actually, I grew up in Camden County - Cherry Hill. I thought I would miss South Jersey when I moved to PA, but I've come to LOVE Chester County.

I am looking forward to a more comfortable house this winter (once I get over the big price tag)

Ted

I think the idea of keeping the HP alive is not good advice considering your electric rate.

You might want to look into several of the modulating furnaces. If you pursue, make certain the brand/ model is full modulating and both moves up and down based on the demand requirements due to your home, inside thermostat setting, and outside temperature (heat loss).

IMO

I agree that the cost of keeping HP in the system is not a winner. After talking to the first two contractors that were here this morning, I have pretty much removed that from the equation.

Are the Carrier Infinity/Bryant Evolution full modulating furnaces? I had thought not, but may have been misinformed. Of the two contractors here so far, one is a Bryant specialist and the other sells Trane and Lennox. I see mostly good things about Carrier/Bryant, and mixed things about Trane and Lennox in my research.

What is your thought on the Lennox modulating furnace?

Hopefully tonight I'll have some quotes on specific equipment to post.

Not a Lennox fan period.

Carrier/Bryant has not introduced their full modulating furnace yet.

The Infinity/Evolution furnaces are three stage and great equipment.

Right now, if I was looking at a mod furnace, it would be Trane/AmStd and York/Luxaire. You want full modulating mdls that move up and down according to demand.

IMO

Here are the details of the proposal. We'll see what comes from the other contractors, but at first glance, this looks competitive.

Furnace: Bryant Evolution 355CAV0042060 furnace 95% 60K BTUH
Bryant Evolution 187BNA036 3 ton two stave condensing unit with
CNPVPATA evaporator coil.
Evolution control SYSTXBBUID01C

Quote includes Bryant space guard air cleaner, Bryant (Aprilaire) 600 humidifier, new condensate drain and pump, new power disconnect for the condenser unit, new line set, new piping for the direct vent

Total quote $9495 less $1700 in rebates (600 Bryant, 600 from our utility co. $500 tax credit) for a total of $7795.

It seems pretty good to me (we'll see what the other quotes come in at), but I may have just been overstating the expected price in my head.

A couple of questions - in general is this a good level of equipment? The quote lists the 355CA as a modulating furnace, but Bryant's website doesn't indicate that in the product description.

Second, the include Man-J evaluation of the house is about the same as my own calc for cooling load, but is lower on the heating load. My calc showed 55K BTUH heating load. His shows 48K BTUH. I think the 60K furnace should be okay, but it's kind of cutting it close. I don't want to over buy, but want to be sure. The heating load limit only really comes in to play on those couple of days/nights per year when we are at the extreme design temperature or below, right? It shouldn't make a difference if we're at 25 or 30 degrees and just trying to keep the temperature steady?

Ted

Get the size of that evap coil.

I will look up the AHRI matching number.

That's a heck of a system. Great HVAC.

I do have a little reservation on furnace size but if he agrees that if it will not maintain your inside comfort temperature for your climate, then he will upgrade to the 80 K model on his dime. Get this in writing.

IMO

I'm not sure what info in the quote is relevant to post here. The quote does list AHRI Reference # 3747259 - does that help with the sizing of the coil?

Is the sort of guarantee on the size of the furnace a fairly standard thing to ask for? What sort of price differential would I typically be looking at to go from the 60K to 80K furnace?

This system is an AHRI matching system.

The AhRI number he provided is incorrect.

Here is the correct number below.

4795130 Active Systems EVOLUTION 16 PURON AC BRYANT HEATING AND COOLING SYSTEMS 187BNA036****B* � CNPV*3717A**+UI 355(A,C)AV042060 37400 13.10 17.00

I still like my suggestion on the furnace sizing.

It appears you are working with a very good dealer.

IMO

I did find the AHRI that he used in the proposal in the Bryant document linked below. It matches the same equipment for the AHRI number you gave, but that document is dated last year. Does the AHRI number perhaps get updated each year?

I am very please overall with the experience with this dealer so far. I think I am going to ask him to modify the quote for the 80K furnace and see what difference that makes.

I am waiting for another quote from someone who came here today, and have another appointment on Thursday (with a Carrier dealer). I will see if I can get a second Bryant dealer out to give me a comparable quote as well.

Ted

We do set back at night - most nights it doesn't ride down all the way to the set back temperature, but on the coldest days, it will I'm sure. If the upgrade is in the $200 - $300 range I will probably opt for that.

Thanks,

Ted

I asked about the cost to upgrade to an 80K furnace and he just replied that it would not cost me any additional. He said that their current software for calculating the manual J uses just a simplified exterior envelope method instead of room by room measurements and he's not comfortable that it is quite as accurate as the old software.

He said that if we go forward, he would come out and run the more detailed manual J before any equipment was ordered so we could be 100% sure.

Finally, they do not normally participate in the Bryant financing specials with GE Money, but when I asked he said he is going to investigate because he feels that they need to get good financing established.

He's saying everything right and doing everything to get my business. If it wasn't a well known, well respected, long established business I'd be afraid it was a fly-by night company and couldn't be this good, but everything seems just right.

Now I need to find another Bryant dealer close enough to home that I also feel comfortable with so I can get a true apples-to-apples comparison.

I see no red flags.

Dealer is saying all the right things and obviously he wants your business.

The idea he will perform a man J is a good indication. Before he performs this and runs the numbers, you need to agree on your inside thermostat
setting and outside temp for both cooling and heating. I always like to use a fudge factor for both. Generally you size to the average which can get you into trouble on the extremes. Ask dealer what he thinks. You know your climate though and you are the boss.

Dealer should make a thorough inspection of your duct system for size/design, leaks, insulation qualities, adequate return. If you have any hot/cold spots these need to be pointed out and suggestions made for improvement.

IMO

I'm pretty sure I know what tigerdunes will say, but here are the details for consideration.

This is private label equipment manufactured by Lennox - I'm not really sure about that, the dealer said they are the "only" dealer that Lennox has this arrangement with - I find that hard to believe, and also am wary of the fact as it seems like it might cause problems with services down the road.

Air Conditioner: Lennox XC16-036 3 ton 2 speed with matching indoor coil 16.0 SEER/ 11.7 EER - no specific model or AHRI reference number given for the coil

Furnace: Lennox G61MPV-60C-091 88K BTU (I think this is input rating on the Lennox, so it would be 83600 BTU output) 2 stage furnace

Honeywell F100 pleated air media cleaner
Honeywell Vision Pro IAQ thermostat
Aprilaire 600 humidifier

Quote includes 10 year parts and labor, 5 year maintenance agreement

All this for the Low Low price of $10039 after all rebates and tax credit - $12339 before rebates/credit

These are the guys that have the current service contract. I don't know why I would even really pursue this further.

How much is the 10 year labor warranty really worth? The maintenance plan included for 5 years is nice, but again, it just locks me in with up-front costs.

I should note that the Bryant quote also includes a 2 year maintenance agreement - I hadn't mentioned that before.

One thing I am concerned about is the clearance for the stack of equipment in the basement utility room. There is only a clearance of 63 inches to the bottom of the main supply duct. The Lennox dealer mentioned this, and the Bryant dealer took note of it as well, but here are the options the Bryant dealer has presented me with:

60K Unit
AHRI # 4891891:
Condenser: 187BNA036
Coil: CNPVP3717ATA
Furnace: 355CAV04260

80K Unit
AHRI #4891910
Condenser: 187BNA038 (same)
Coil: CNPVP4821ATA
Furnace: 355CAV060080

The coil for the 60K unit is 5 inches taller than the coil for the 80K setup.

The total height of the stack (including a 2 inch base) for the 60K unit would be over 69 inches - that doesn't seem like it would fit. The 80K setup that they have specified still has a 64 inch height, which would mean the coil sticks part way into the supply duct - is this a significant problem?

I have found the Bryant 2010-2011 product handbook so that is helping me to put together what I think is the ideal system.

If I understand it, ideally I need for my use a 3 ton condenser, a coil that can handle at least 3 tons of cooling, a furnace that can provide at least 3 tons of cooling airflow (it looks like Bryant has two options here - 3.5 tons of airflow (042 series) or 5 tons (060 series). I need the combination to be less than 61 inches tall (to allow for the 2 inch base underneath and I want it to be eligible for the cooling tax credit (which I think means minimum 16 SEER/13 EER rating).

I THINK I should be able to put that together, but I need to cross reference the overall design.

Just a quick question - the coil and cooling airflow capacity can be oversized without adversely affecting things, correct? When we talk about correct sizing we are referring to the condenser and the furnace output right?

Thanks again for any input.

Ted

He appears to be the size it based on what they had kind of operation. He must (I hope) have looked at the outside unit for the heat pump before knocking on the door - because he didn't ask me about size or location of the unit.

He took the access panel off of the current furnace, read off the size of the existing unit. Described the different options of Carrier equipment that he will quote.

He didn't ask me one question about our comfort or satisfaction with the existing system. Didn't take any measurements of the house at all from what I could see. Described the Carrier Infinity system. Said that the one main recommendation that he makes to all customers is to get a furnace with a variable speed fan, whatever they end of doing.

Talked about his 30 years in the business, blah, blah blah. And then said he'd have a quote in the mail to me for tomorrow.

That was it... 180 degrees the opposite of the Bryant dealer, and way behind the Lennox dealer as well.

I'll look at the quote when it comes, but got NO good feelings about dealing with him.

Incidentally, while I was typing this, the Bryant dealer just emailed me again asking what they can do to earn our business.

Ted

Sizing is based on the furnance and condenser capacity. The furnace blower is designed to handle a range of condenser sizes. It is very common for Carrier/Bryant systems to have a larger coil than the the condenser. You should have no worries if it is a legal AHRI match. I have this set up in my house.

Don't wait too much longer. HVAC contractors are swamped the first cold day of the season. Move quickly on this if you are ready.

So that's not an obstacle.

Now to just consider the third quote when it gets here and make a decision.

Ted

I would say you are ready to go. The remaining question is whether you require the 60 K or 80 K model.

If the load calc for heating is close on the 60 K, I would go with the 80 K. Will cost you a little more in operating costs.

IMO
Good Luck!

System is ordered. Install is scheduled for Halloween.

Got the quote from the unimpressive Carrier dealer and it was just as unimpressive as he was.

Just got off the phone with the Bryant dealer and we have decided on the 80K furnace.

I'll let you know how the install goes. This has been an exhausting week researching all of this info to make a good decision, and we still have to pay for the darned thing, but I am SO looking forward to the new system and a warm, comfortable winter.

Thanks again to everyone.

Last night we just had heat - the AC side of the install and the humidifier were completed today. Last night was another cold one, but the furnace kept things quite toasty.

First impressions are that the system is REALLY quiet compared to old technology furnaces.

The installation appears to me (an untrained eye) to be really first rate - no complaints at all.

I can't wait now for heating system to get here so we can really feel the difference.

Ted