Seeking help on HVAC/insulation investment choices

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trihiker
Posts: 2
Joined: Sat May 18, 2013 4:12 pm

Seeking help on HVAC/insulation investment choices

Post by trihiker »

Hi all, I wanted to request advice on making a decision on our home HVAC system and insulation needs. Sorry in advance for the very long post.

Situation:
We (me, wife, 2 kids 2 3/4 and 4 months) live in a ~3300 sq ft 2 story home (pull-down attic and no basement) in central VA, built 1994. We bought the home 2 years ago. We have a 2-zone system, with a 10 SEER Aquatherm gas furnace located in the garage, providing heat and cooling for downstairs (Goodman unit outside the house), installed ~2007. For upstairs, we have a Payne heat pump (2004, 10 SEER) also outside, with a 2 ton air handler located in the attic. Our thermostats are non-programmable. The ducts are ductboard for the main line, with flex going to the vents. There are two returns downstairs, and one upstairs. The insulation in the attic is blown-in cellulose, and ~4-7" deep depending on the location, so I guess ~R20 or so. Our total utility bills are ~$3000-3500 for the year (gas and electric), though I don't know how much is due to heating and cooling. Since I'm a stickler for costs, I prefer not to turn the thermostat too high in the winter (max 71) or too low in the summer (min 74-76), but the result is that it's never quite comfortable, and there is wide variance in comfort levels in some rooms. I am now on a mission to improve the insulation and comfort in our house, and hope to do it in a cost-effective manner.

Actions: I've done some small things (self-caulked some holes in the upstairs ceiling, weather-strip the windows, bought electric auto-off space heaters for the colder rooms), but the reality is those are somewhat marginal relative to the bigger issues. I had an HVAC expect come in an do a blower door test (infiltrometer), and the software found ~35% duct leakage upstairs, and ~20% duct leakage downstairs. He also did a Manual J calculation and found that upstairs needed a 3 ton system (he recommended SEER from 13 to 15.8, depending on what I was willing to spend), 2 new returns (located in the guest room and the master bedroom, both of which are cold in winter and hot in summer when the rest of the house is comfy), some additional vents and some enlarged vents. He said we didn't have to replace the ductboard main lines in the attic, but he did add that it's an inferior product and they've never installed it in 46 years in business. My commercial architect father-in-law recently visited, and said that the upstairs duct design was garbage and should probably be replaced.

We are definitely going to seal the downstairs ducts. For upstairs, I'm wondering whether to just seal the ducts and wait for the heat pump to die, or whether to seal them and get a new heat pump, or to replace the ductwork and get a new heat pump. We can afford all situations, but I'd like to do it smartly.

I did have some others come in to check out the situation, but none did the blower test or Manual J calcs, or even offered it. Plus this guy's price happened to be better as well than competing quotes.

Option 1: Seal the downstairs ducts and the upstairs ducts. Nothing else. Cost ~$2000 (I'd also separately get programmable thermostats for upstairs and downstairs)
Option 2: Seal the downstairs ducts, seal the upstairs ducts, add the recommended returns and vents, replace heat pump with new 15.8 SEER, 3 ton heat pump which includes variable speed motor and programmable thermostat. Costs: $10,200
Option 3: Seal the downstairs ducts, completely replace the upstairs ductboard with metal ducts and insulation, adopt new ductwork design including new returns and vents, replace heat pump with new 15.8 SEER, 3 ton heat pump which includes variable speed motor and programmable thermostat. Costs: $11,600 (basically $1400 more than option 2).

We've been in the house 2 years, and while I can't predict the future, we have no plans or energy to leave the house. I'd say we'd be here at minimum 5-7 years barring unforeseen circumstances, likely more.

Any recommendations would be greatly appreciated

Thanks!
Luke Duke
Posts: 1333
Joined: Tue Jun 18, 2013 11:44 am
Location: Texas

Re: Seeking help on HVAC/insulation investment choices

Post by Luke Duke »

IMHO, Option 2 shouldn't be an option. If you make the decision to spend $10.2K, what's another $1400 to have everything done properly?

I'm curious what your HVAC guys said about the amount of insulation that you have in the attic.
rogermexico
Posts: 161
Joined: Tue Jan 08, 2008 4:58 pm

Re: Seeking help on HVAC/insulation investment choices

Post by rogermexico »

Ductwork in the attic is generally a bad idea.. it gets tremendously hot up there. Is there any way to do it with soffits and maybe suspend air handler/furnace overhead somewhere? If you were going with #3 I'd try to get them out of the attic.
bungalow10
Posts: 2311
Joined: Sat Apr 09, 2011 6:28 am
Location: Chicago North Shore

Re: Seeking help on HVAC/insulation investment choices

Post by bungalow10 »

trihiker wrote:Our total utility bills are ~$3000-3500 for the year (gas and electric), though I don't know how much is due to heating and cooling. Since I'm a stickler for costs, I prefer not to turn the thermostat too high in the winter (max 71) or too low in the summer (min 74-76), but the result is that it's never quite comfortable, and there is wide variance in comfort levels in some rooms.

The insulation in the attic is blown-in cellulose, and ~4-7" deep depending on the location, so I guess ~R20 or so.
71 in the winter should be more than comfortable (ours is 66 - which is perfect for our household, 68 seems to be the norm among friends and family), and I think your summer temp is good too. Can you get a breakdown of the costs (heating/cooling versus non-heating/cooling)?

I do think you could use some more insulation in the attic and caulking your duct work seems like ti would be prudent. Other than that, it doesn't look to me like there really is a problem?
An elephant for a dime is only a good deal if you need an elephant and have a dime.
nordlead
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Joined: Thu Sep 12, 2013 9:09 am

Re: Seeking help on HVAC/insulation investment choices

Post by nordlead »

I would get a cheap programmable thermostat to start. You can get one for $20-30 with a 5/2 split. I'd love a Wifi one, but since my wife is home all day with the kids it doesn't make a lot of sense since the heat has to be on anyways.

We keep our house at 68 in the winter (58 at night) and 78 (off at night or if the high doesn't break ~85) in the summer. If you get cold in the winter, get off your butt and do something. My kids run around in diapers in this weather and when I pick them up they are baking hot. For the summer, get lots of fans, and install ceiling fans in the bedrooms. We installed a ceiling fan in the master bedroom and use floor fans in the kids rooms (i'll probably put up ceiling fans in a few years) and around the house. I only run the AC at night if the night is also going to be +80 (extremely rare in our area).

Costs $30(thermostat) + 200*4(ceiling fans for rooms) + 50*3 (a good number of extra fans) = $980.

Once you do all that, then consider the more expensive investments.

At least, that is what I do :D
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Bengineer
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Joined: Sat Dec 03, 2011 11:25 am
Location: NC

Re: Seeking help on HVAC/insulation investment choices

Post by Bengineer »

Those temps are a little more comfy than I run - 68 in winter and 79 in summer.

Some thoughts:

I wonder if you'd still need a 3-ton if you upped your house envelope sealing / insulation / solar window gain. Did you get the manual J for current or planned insulation / sealing levels?

Ductboard isn't the end of the world. I had it in a couple houses, it worked fine. That said, it isn't as durable and easy to seal/work with as sheet metal. Think celotex board - dense fibreglass with foil on one side. I would choose metal for an install.

The sealing and insulation isn't difficult, just dirty, hot work in the attic. You could insulate around the ductwork in the attic if moving it inside the envelope isn't feasible.

You could also add returns and improve the registers/ducting yourself, but you're getting into flow and temp drops, which are a bit more complicated. Part of what you get wit the HVAC guy. A well-designed duct/return layout will help with comfort. No more slamming doors or hot/cold rooms when the door is shut.

If you do need more oomph upstairs, you might consider a "bang for the buck" heat pump option that's not quite as much or as complex as the full variable speed - two-speed or single with a large coil/efficient compressor. Your guy can probably give you a couple options. Does gas/ac up make sense? Youve got gas down already. The gas line & added gas capacity might cascade $$$ though.

If you upgrade one or both units to higher efficiency / speeds, the payoff will be a looooong time, but you'll be more comfortable - more constant airflow, smaller temp swings, better humidity reduction in summer. And feel better about the lower bills.
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walkabout
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Joined: Wed May 25, 2011 8:28 am
Location: Northern Alabama

Re: Seeking help on HVAC/insulation investment choices

Post by walkabout »

Where are you located?

Your equipment is not extremely old (9-10 and 6-7 years), but we don't know what quality it is. Also, while a lot of people have equipment that has lasted a long time (ours was 22 years old when we replaced it - by choice, it was still working), 10 years is probably well into (or past) "middle age" in the expected life span of HVAC equipment. SEER is very low compared to what you can get today.

You might be able to increase your winter comfort some with the space heaters that you mention, but you are certainly not saving money. To be fair, incrementally higher electric bill vs possibly big expenditure on new equipment does leave more money in your pocket.

Did the air infiltration test find any other problems? Infiltration in the attic? Around/through windows/doors? What shape are your windows in?

Here is a good guide on attic sealing (in case you need your attic sealed):

http://www.buildingscience.com/document ... ling-guide

We can't see your attic ductwork, but your FIL, who seems to have some level of expertise, doesn't seem to like it and it leaks a lot.

Based on the information given, it seems reasonable to me to go with option 3. Seal the downstairs to the extent possible. Replace the ductwork in the attic. Use metal for the trunkline and either metal or flex for the branch lines. Ductwork should be sealed with mastic and insulated. Ideally the ductwork would be in conditioned space (i.e. not in the attic), but I suspect that is dirty, impractical, disruptive, expensive, and not as much of a payoff as one would hope. I would certainly go for the 15.8 SEER (if not higher).

An earlier poster implies that you might be able to add some ductwork and returns yourself (with caveats). Personally I would not recommend this. At best it will probably a hot (or cold), dirty job that takes you a long time since you are, presumably, not an expert. At worst, you might do it wrong, not realizing it, and end up in worse shape than you are right now.

Also, no offense to nordlead, but I'm not sure your wife would think that adding a bunch of portable fans would be much of a "solution". I know my wife wouldn't. :happy Also, regarding nordlead's extreme setbacks... One actually loses some of the efficiency gains of new HVAC equipment by having large setbacks. When the system does come back on, it ultimately has to bring the temps back up (in the case of heat) or back down (in the case of cooling) to overcome the deficit. Your system will work best, and probably most efficiently, if you try to maintain a more constant temperature. That is not to say you cannot have any setback at all (whether for energy savings for for comfort), but just be aware that you are asking your system to do a lot of work, possibly at peak times (in the case of a large setback during the day during cooling season, set to cool back to desired temps around quitting time). You might end up griping about why your unit can't recover (say from 80 to 75) when you get home from work in the middle of summer.

I'm glad your HVAC expert did a Manual J as that is the only right way to size a system, but it is a little surprising that the size goes from 2 ton (existing) to 3 ton (new). Generally, an HVAC system is more likely to be oversized (due to "rule of thumb" calculations or trying to head off customers' "it's not cold enough" complaints) than undersized. I think that more often, when a person has a Manual J done as part of replacing an existing unit, that it turns out that the old unit was oversized and the new unit comes in smaller. I'm not saying that your existing unit is not undersized, it may very well be. Also, since you are getting a "heat pump which includes variable speed motor" (I assume that is a two stage heat pump (or true variable speed if inverter based system like Carrier Greenspeed or Maytag iQ) with variable speed air handler), the sizing is slightly different (in some cases). For Carrier Infinity, the systems come only in whole ton sizes. So, if your Manual J called for 2.5 tons, you would get a 3 ton system.

Prefer a "media filter" (4-5" filter in cabinet near air handler or fitted into return) over 1" filters. The bigger filter provides less air resistance, meaning that your equipment doesn't have work as hard to pull air through it. Also, the bigger filter needs to be replaced less frequently, as long as once a year, vs a 1" filter. Good filtration helps the air that you breathe but, possibly even more importantly, it protects your equipment from dust/dirt/grit getting in.

We had a Carrier Infinity heat pump installed in the spring and I can highly recommend it. In hot weather it runs almost all of the time (on low) and keeps the temps very even. The long run times mean more humidity is removed, increasing comfort and allowing you to possibly run at a slightly higher temp than you are used to running.

I will say that a two stage heat pump/variable speed air handler combination can lead to sweating equipment (air handler) and ductwork if in a humid environment and if the equipment is not in conditioned space (e.g. attic in your case or garage in our case). Well sealed and insulated ductwork reduces/eliminates the duct sweating problem. Additional insulation can be added to the air handler (if necessary) to reduce sweating. The system can also be tuned so that it sweats less, but that is at the expense of being able to run at very low speeds.

Possible sweating aside, I would still recommend a two stage heat pump and variable speed air handler. Be sure that the heat pump, air handler, and coil are a "best match" according to AHRI:

http://www.ahridirectory.org/ahridirect ... /home.aspx

This ensures that the various components will work well (i.e. correctly) together. I think that a given combination (HP, AH, and coil) gets an identifier and is listed in the Directory of Certified Product Performance. If you are quoted a system that is not in the directory, you should question why. Mismatched equipment can reduce the SEER level of your system. So, if you are paying for a "15.8" system, but you have mismatched equipment, it might not be capable of reaching 15.8 SEER. If your equipment is "communicating" (like Carrier Infinity) be sure to get a communicating controller. Do not get a variable speed air handler without a two stage heat pump (and vice versa). Those two capabilities work together and having only one capability or the other is a waste of money as that capability won't be used.

If you time your purchase right, you can probably get a rebate from the manufacturer. They typically offer rebates at specific times of the year (like spring and fall).

I strongly recommend these forums to get more insight on your issues (and equipment choices):

http://hvac-talk.com/vbb/forumdisplay.p ... ntial-HVAC

http://ths.gardenweb.com/forums/hvac/

At gardenweb I especially recommend posters like tigerdunes, mike_home, ryanhughes, and energy_rater_la. Tigerdunes and ryanhughes can easily tell you if any quoted system is a "best match" and if, in their opinion, it is right for your application. Read their posts. I think that you will find that they provide high quality information.
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