Newbie HVAC Questions

wynswrld98March 19, 2013

I own a 2-story daylight/walkout basement home, 3676 s.f., have a very old Bryant 80% efficient 5 ton furnace (was old when bought home 8 years ago) with outside condenser also can tell very old. Live near Tacoma WA, can get down to 8 degrees on occasion and up to 90s rarely in summer. Home built in 1972.

I had a duct sealing contractor (A+ BBB) referred by my energy company come out and look at things. He thought ducting looked good from what he can tell (it's all indoors running between the two floors where a drop/acoustical tile ceiling exists) except for the immediate ductwork coming out of furnace, part of it was some kind of board material and he said should be metal ductwork. He recommends getting the blower pulled and cleaned out.

The air flow is NOT good and he suspects the old furnace is the problem. I'm trying to figure out if it is worth me paying a contractor to come out and clean blower/replace the "board" ductwork or buy a new furnace since this one is old and I believe contractor would replace that board ductwork included with new furnace install.

I'm a total newbie to HVAC and have been googling some things such as heat pumps, I read something that if temps get below mid-30s where you live heat pumps won't heat and you need secondary heating (furnace?) anyway so a heat pump doesn't make sense where i live since it can get down to 8 degrees and often gets down to high 20s/low 30s in winter?

And considering size of my home, is a multi-zone system something I should consider? The downstairs is cold year round due to daylight basement design and really doesn't need A/C in summer but upstairs DEFINITELY needs A/C in summer, gets hot up there and most of upstairs has vaulted ceilings.

I have replaced most of the windows in the home with high quality Milgard fiberglass windows.

Thanks for all advice, trying to learn and be educated when I start talking to contractors.

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Are you running natural gas or propane? At what price? What are your electric rates?

Actually, having lived around Puget Sound, I'd say a Heat Pump makes perfect sense. But it depends on the costs above. When I lived there, electricity was cheap, hence auxiliary heat with electricity did not cost much at all.

You could zone, but the installer needs to know what they are doing. The alternative would be to get two smaller systems. As you implied, you may need no AC for the basement/lower floor and only for the upper. This could be a smaller unit.

someone does need to come and look at your heating/cooling loads. They also need to look at the airflow issues it sounds like you have.

    Bookmark   March 20, 2013 at 4:00PM
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Poor air flow is usually caused by duct problems. This is usually caused by leakage and poor design. The low air flow could also be caused by an air filter which is too small or too restrictive, or a dirty coil.

If the furnace is more than 20 years old, then it would make sense to put the money into a new unit. AC unit are rated in tons, and furnaces are rated by input and output BTUs. You should be able to find the size information on the the manufacturer's name plate.

Do you have natural gas? If yes, then it doesn't make sense to get a heat pump unless your electric rates are very low. If you are using propane or fuel oil,then a heat pump can save you money. A back up heat system is used for temperatures below freezing.

Your first step is to find a good contractor. See if you can find one who will do a heating and cooling load calculation. Zoning the basement is the only way to get comfortable temperatures in the winter and summer. Not all contractors are good at zoning. This is more reason to select a contractor who will do a good installation.

    Bookmark   March 20, 2013 at 4:02PM
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I'm on natural gas. My latest gas/electric bill has the following for the latest month

Basic Charge $4.24
340 KWHS @ $.088594 per KWH
225.53 KWHS @ $.107172 per KWH
565.54 KWHS @ $.004359 Per KWH

Basic Charge: $10.34
Delivery Charge 99.11 Therms @ $.3924 Per Therm
Cost of Gas 99.11 Therms @ $.56627 Per Therm
Gas Conservation Program Charge 99.11 Therms @ $.01927 Per Therm

My gas furnace is a Bryant Plus 80 High-Efficiency Model 395CAV060155 says Input BTU 154,000 Output BTU 124,000 14 amps 3/4 HP motor. The plate says the first 4 digits of the serial # indicate week and year it was manufactured -- so it was manufactured in 1997.

As much as I can see of the blower fins they look very clean to me.

It has a Honeywell Electronic Air Cleaner attached to it.

So is the 3/4 HP motor spec an idea of how powerful the blower is? I'm trying to understand how powerful the blower is in my furnace compared to other units used for a home as large as mine at 3676 s.f.

The more I've been thinking about my big complaint with it is the A/C -- the heating is okay, takes awhile but does get house warm, the A/C is next to useless -- my theory is the air flow isn't great and since the hot part of the home is upstairs and all of the registers are upstairs on the floor and the fact heat rises but cool air falls I'm thinking it's a losing battle trying to cool the upstairs with this type of setup, made worse by the fact the upstairs has a huge great room (family room/dining room/kitchen) with vaulted ceilings. What about the idea of adding a multi-zone ductless air conditioning system to cool the upstairs only? That way the registers for it would be up high on the walls where they should be and cool air fall as it's supposed to. I'm a newbie on those as well, don't understand how big outdoor unit is, how each register of the multi-zone connects to the main unit, etc. The center part of the roof is flat (the other sides are pitched) and would probably be an excellent place to put a ductless unit. Thoughts?

    Bookmark   March 20, 2013 at 6:28PM
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    Bookmark   March 22, 2013 at 5:43PM
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Your furnace is very big is over sized for your house. You post the size of the AC but imagine it is also over sized. The problems you are having on the second floor are likely to be duct issues.

You should be able to cool the upper floor even with the registers on the floor.

My suggestions is to have get thorough evaluation of the duct system. Zoning of the second floor may not be feasible depending how the duct is connected in the basement. If you can't improve the duct work, then you may need a second system for the second floor. Perhaps you can add a mini split to the great room to help with the cooling. You should also look improving the insulation of the attic. Can you add insulation under the flat roof area?

    Bookmark   March 22, 2013 at 10:32PM
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I'm surprised to hear you say it's oversized for the house considering the house is 3676 s.f. and the top floor is mostly vaulted ceilings.

There already is insulation in the flat part of the roof.

I'm also surprised you don't seem to think there would be an issue with cooling with the registers all on the floor upstairs and most of the upstairs having vaulted ceilings.

I had mentioned I already had a duct sealing expert out to look at ducting and he says it's fine. He has a A+ BBB rating and was referred by my energy company.

    Bookmark   March 22, 2013 at 10:43PM
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I had mentioned I already had a duct sealing expert out to look at ducting and he says it's fine. He has a A+ BBB rating and was referred by my energy company.

so did the expert test the ductwork for leakage?
or just look at it.
btw..ductboard isn't a bad product, and unless there is
damage..there is no reason to replace it with sheet metal.

the expert shoud test for leakage, verify that sizes
of duct are correct and at minimum verify that static
pressure is correct.
energy company referals mean little since they have
gotten into the free & reduced audit business.

best of luck.

    Bookmark   March 22, 2013 at 11:18PM
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You mentioned the current AC condenser is very old. Perhaps it is not operating properly. Do you know what size it is?

    Bookmark   March 22, 2013 at 11:25PM
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He looked at the duct work only. So should I just call a generic HVAC company (with good BBB feedback) and ask if they know how to do a "static pressure test"? And if they don't know what a "static pressure test" is keep calling companies until I find someone who does?

What's a reasonable cost for a static pressure test so I know what is reasonable when they quote me a price to do that test?

Then when they come have them do that test and also ask that sizes of ducting are correct?

Thanks for the help!

    Bookmark   March 22, 2013 at 11:25PM
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Re: A/C condenser I believe he said 5 tons -- and very good question re: if it's operating correctly -- what type of diagnosis can an HVAC company do of an A/C to truly know if it's operating properly? Knowing this info will help me to make an educated decision about who I have checkout the A/C so I can make sure they test everything that should be tested.

I know there are a lot of flakey HVAC companies so knowing more and more of what they should be testing (specifics) I think will help me a lot make a good decision about who I use.

Thanks again!

    Bookmark   March 22, 2013 at 11:27PM
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Checking the AC condenser involves checking the refrigerant levels. If the condenser is low on refrigerant then then there is a leak in the system. You can add more refrigerant but the proper fix is to find and fix the leak. The tech should also check the air temperature differential between the return and supply air. Ideally you get a delta of 20 degrees.

What type of filter do you use in the furnace and do you change it regularly? How big is the filter. A filter which is undersized, restrictive, or dirty will reduce air flow. This may be contributing to the air flow problem.

How big are main supply and return ducts? You have a big furnace and AC. The bigger the equipment the bigger the duct work needs to be in order to supply the air. Most houses don't have duct work large enough to supply the air for a 5 ton AC unit.

There are some simple things you can try to help the air distribution problem. You can trying balancing the system by closing some of the registers on the first floor so that more air is diverted to the second floor. It is not a real solution but it would be interesting to see the effect on the air flow.

It is possible for an HVAC tech to increase the speed on the blower. I suspect the blower is on the maximum speed since you have the biggest furnace and AC available, but if it is not then this is something that would help the air flow issue.

    Bookmark   March 23, 2013 at 9:36AM
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Thanks again everyone for all of the great info, I'm going to pull info out and make a list of requests/questions for diagnostics. What does anyone think is a reasonable cost for the type of diagnostics being recommended? I have no idea but that info will help me not get ripped off.

Re: filter, it's a Honeywell Electronic AIr Cleaner and I do wash its filter in dishwasher periodically.

I already close the registers as mentioned, in summer the upstairs registers are open, downstairs closed, perhaps there is something wrong with the A/C, it's presumably same age as furnace at 16 years old.

    Bookmark   March 23, 2013 at 5:06PM
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I have read this thread several times.

It would be helpful if you would give a brief description of each zone including size of basement, main floor, and upstairs.

Is the basement at or partially below grade?

Where is existing furnace located?

I think your problems are related to ductwork system and expecting too much off one system considering size of your home.

You need a load calculation performed both cooling and heating broken out for each zone.

I would try to find out from an experienced HVAC dealer if zoning controls for a single system is practical. If not, I would be leaning toward two systems, one for the basement and main floor, one for upstairs.

And like another post suggested, I believe you are also oversized on heating.

I certainly do not believe closing registers is a good idea. Any idea if your main supply duct has manual dampers? That would be something for a dealer to check on.


    Bookmark   March 25, 2013 at 8:36AM
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The home is a two story. The lower floor is a daylight/walkout basement, house is 3676 s.f., lower floor same footprint as upper floor except lower level has a two car garage as part of it too. So yes lower level is partially below grade.

The ducting runs between the two floors and on the top of the ducting are registers for the upstairs, on the bottom of the ducting are registers for the downstairs.

The furnace is located in a utility closet in the lower level (not in the garage but part of the living space in a large closet).

I'm getting conflicting advice on whether closing registers is a good or bad idea. In the summer we've been making a habit of closing downstairs registers because it is cool year round down there and doesn't need cooling but the upstairs really needs it since heat rises plus most of the upstairs has vaulted ceilings so large amount of cubic feet to try and cool.

Any guess what's a reasonable cost for the type of diagnosis being recommended here? I'm compiling all of the diagnostics requests into a long list and will start asking HVAC companies what they'll charge for the diagnosis but would like anyone's guess what is reasonable cost for this type of diagnosis.

Thanks again!

    Bookmark   March 27, 2013 at 11:31PM
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How's this list of requests for diagnostics? What should I expect to pay to get all of this done?

-- A/C doesn't cool home even if left on for many hours
-- Low air flow out of registers

Diagnostics needed:
-- Heating and cooling load calculation (Manual J Calc)
-- Test ducting for leakages, perform static pressure test, is ducting sizing large enough?
-- Coils are clean?
-- A/C condenser diagnostics, refrigerant has leaks? if so, isolate and repair rather than just add more refrigerant
-- For A/C, what is air temperature differential between the return and supply air? Should be about 20 degrees?
-- Honeywell electronic air cleaner is working properly?
-- What is speed set to for furnace blower? Set to maximum speed?
-- Should leave all registers open all the time? or close downstairs registers in summer because only upstairs needs cooling in summer?

Bryant Plus 80 High-Efficiency Model 395CAV060155 says Input BTU 154,000 Output BTU 124,000 14 amps 3/4 HP motor. The plate says the first 4 digits of the serial # indicate week and year it was manufactured -- so it was manufactured in 1997.
? Square Footage:
3676 with most of upstairs with vaulted ceilings so large cubic feet to cool

    Bookmark   March 28, 2013 at 12:29AM
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So to be clear, the home is two levels, main floor and a lower floor with a two car garage? Garage is heated as well?

Current furnace location is close to external wall for venting a new high eff condensing furnace?

Is ductwork accessible?

Most homeowners are not aware that lower floors(basements) below or partially below grade have low heating and cooling loads.


    Bookmark   March 28, 2013 at 7:10AM
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It is difficult to say how much an HVAC company will charge to come to your house to run a full set of diagnostics on the furnace and AC. A lot of companies will advertise a low price in order to gain access to your equipment. They will quickly come to the conclusion that your equipment is old and inefficient and you should replace everything.

Call some companies and ask how much they charge for their service. You need to pick a day when it is warm enough to run the AC. My guess is it will be in the range of $200 to do a complete diagnostic.

    Bookmark   March 28, 2013 at 10:27AM
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I would expect a higher price than Mike....especially as far as ductwork and possible leaks...

    Bookmark   March 28, 2013 at 10:37AM
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you should add to you list specific info as
to comfort.
which rooms have hot/cold spots.
which areas are too hot/cold.
install manual dampers at duct take offs at plenum.
set all to fully open & mark on plenum direction to
close. then you can adjust to your heart's content
to get the air where you need it.

check air flow. have them use flow hood to measure
what air is moving through the ducts. this cubic feet
per minute (cfm) of all ducts should add up to the
capacity of your unit. 5 tons would be 2000 cfm
of air. the cfm should match the size of the duct
as each duct moves X amount of air.
this may be more than they can do. but at minimum
they can measure air thru each duct, so that you
KNOW where the ducts are not providing correct air

if you have 1800 cfm of total supply measured, then
there is 200 cfm leaking.
this would be done in cooling not heating as air flow
is higher for cooling.

testing with duct blaster measures leakage, but
flow hood measures each duct for air flow, leakage
is determined as above.

as for shutting vents on supplies.
the supply plenum holds all the air to be distributed
via ductwork. shutting the supply grill off still
lets the air leave the plenum & go into the duct..
it just keeps it from exiting the supply grill.

the correct way to adjust the air flow is to
put dampers at the plenum/duct collar.
this is usually a manual damper that you
adjust as needed.
this way the air stays in the plenum & is
distrubuted to other ducts with dampers
closing off ducts at plenum keeps
the air that would enter the duct wher it
can be distrubuted. closing @ supply grill
doesn't do this.

best of luck

    Bookmark   March 28, 2013 at 2:21PM
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The A/C is a Bryant 561CJ060 manufactured 1997 hard to find specs (model not found on Bryant's site) but the best I can tell is 5 Tons 57,000 BTUs 10 SEER. I have read a lot of postings that this model A/C is junk and has failed for people at 5 years so I would assume (but will verify with HVAC companies) that it will need to be replaced.

What price range would a new high efficiency A/C of this size cost (wild guess)? I have NO idea at all.

    Bookmark   March 29, 2013 at 11:25PM
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I was speaking to an HVAC contractor today and he highly recommends getting ducts cleaned then have them apply Aeroseal (, anyone have any experience with this system? He explained it as a fogging they put in ducting that seals gaps up to 5/8".

    Bookmark   April 3, 2013 at 11:39PM
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What is the cost?

And what has he said if anything about how this will address your issues that you have discussed in this thread?

I certainly would not do this until you have an action plan on addressing your problems and how this plan might might affect existing ductwork.


    Bookmark   April 4, 2013 at 7:40AM
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I don't have any experience with Aeroseal, so out of curiosity I looked at the corporate and Aesoseal of NY web sites. There claims are too good to be true. The process requires large holes be cut into the duct work in order to do the blow in the sealant. The claim is only 1-2 oz of sealant is left in the duct work after the process is completed. If find this hard to believe.

I would not waste time or money with Aeroseal. You can take down the ceiling tiles in the basement and seal all the exposed duct work yourself or pay someone to do it. This should be done after you address any other problems you have. Duct cleaning is usually a big waste of money. Don't fall for these gimmicks.

    Bookmark   April 4, 2013 at 8:55AM
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Re: Aeroseal, he said the reason for the duct cleaning is because if there is dirt in the crevices the Aeroseal is sealing the sealant could be dislodged when the dirt moves during normal air flow of furnace.

I asked about mastic duct sealing vs. Aeroseal since most (but not all) of my ducting is exposed and he said the problem is it can't get everything which is true, the ducting is hanging from the upstairs ceiling so you definitely can't get to the area between top of ducting and wood subfloor and also where two lines are running very close to each other I don't think you could get mastic in there. And as I said most but not all of my ducting is exposed, it has drywall over it in a couple of rooms so if there were leaks in there they would remain.

So the theory behind Aeroseal sounds good but execution, who knows? I need to do more research into it.

The next step for my situation is they're going to send a tech out to run diagnostics on the furnace and A/C.

This guy's general opinion of the ducting is the house is too big for a single system no matter how big the furnace is. He says ideally it would have been broken out to two systems but it is what it is...

    Bookmark   April 5, 2013 at 4:01PM
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    Bookmark   April 5, 2013 at 4:23PM
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He quoted $1500 for the Aeroseal for my size home (3676 s.f.) plus duct cleaning prior which they don't do, not sure what they costs. I get ads in the mail all the time for super cheap and I'm sure it's a gimmic, he said that's true but that there are places to do clean ducting legit.

I didn't ask what they'd charge to do mastic sealing of the ducting to compare costs, thought of it after they left. If Aeroseal worked as good as the THEORY it would probably be worth the $$ since it would seal areas that are inaccessible (e.g., behind drywall or between ducting and subfloor above) but I would bet the execution is different than the theory... He talked about them plugging all of the registers in the house then measuring pressure at the furnace to figure out how much airflow is being lost/escaping, they do the Aeroseal fogging then redo the test.

    Bookmark   April 5, 2013 at 4:51PM
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The company know how to seal, but they don't know how to clean? If the process doesn't work well, are they going to claim the ducts were not cleaned properly? That is a lot of money for something that may not work well. You would be better served sealing all the joints which can can access with Nashua tape.

You have a 5 ton AC and a 154,000 BTU furnace. I find it hard to believe the cause of your problems is the duct work is too big.

You need to find a reputable HVAC contractor who can do an analysis of your system.

    Bookmark   April 5, 2013 at 5:09PM
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the thing about aeroseal is if the gap to be
sealed is larger than 5/8", aeroseal can't seal
gets smaller leaks...but not large leaks.

I've never been impressed with aeroseal.
having testing duct leakage before and after
their work didn't do anything to change
my mind.
although their testing showed more
leakage reduction than my testing.
I was working for homeowner testing
their work, not testing my own work
as they did.

all the ducts are hard pipe ducting with
duct wrap? or flex ducting?
I don't think you've posted that info yet.

& btw...I question about ductwork being too
big also.

best of luck.

    Bookmark   April 5, 2013 at 7:41PM
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Ductwork is all hard tubing, not wrapped because it is all in interior of home running between the two floors.

Re; find a reputable HVAC, suggestions HOW?? I check BBB (this place is A+), chk L&I, was considering subscribing to Angie's List to checkout companies but everyone knows there are a lot of overpriced, unethical and/or uneducated companies so this is a tough proposition to find a really good one.

My biggest problem is cooling with the upstairs almost all vaulted ceilings and lots of windows (view property), the registers on the floor (heat rises, cool air falls) and the air flow not great IMO.

    Bookmark   April 5, 2013 at 7:54PM
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"I was speaking to an HVAC contractor today and he highly recommends getting ducts cleaned then have them apply Aeroseal"

How did you select this HVAC contractor? Does he think the cooling problem on the second floor will be solved after you have the Aeroseal installed?

    Bookmark   April 5, 2013 at 8:51PM
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Based on BBB feedback A+, local company and checked out on L&I. He stated if he were doing the house from scratch he would have installed two systems. Based on that he believes the air flow will improve with Aeroseal but believes in summer what we'd need to do is not let house get really hot then turn A/C on which he said won't work re: cooling, he suggests when temp predicted to be hot turn A/C on before leaving for work in the morning so house doesn't get a chance to get hot otherwise the system won't be able to recover and properly keep the house cool.

This company is sending out techs to run diagnostics on the furnace and A/C, that is the next step. Who knows what the techs will be like vs. the sales guy was here, maybe I'll get lucky and they'll do a really good job on diagnostics, I'll be giving them the list I compiled from great info from you all in this topic.

    Bookmark   April 5, 2013 at 8:59PM
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I agree with his general assessment. It is difficult to maintain an even temperature on both floor of a large two story house with a single HVAC system. I also agree you can't do a large set back during a hot day and expect the AC to recover when you come home from work.

Let's see what the tech has to say about the status of the equipment.

    Bookmark   April 5, 2013 at 9:19PM
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