| Author | Message | ||
     Two_seasons |
Looking to replace our 37 year old Lennox furnace and 24 year old Armstrong central air. Current furnace is a 82,000 btu's. Our home is 1600 sf. We are looking at natural gas for the furnace and single stage scroll compressor for the air. Cannot use heat pump in this climate. Can I ask you for your opinions regarding each system. Give me the pro's and con's from your decisions to upgrade. Thanks all. | ||
| Sifo |
Why not heat pump? My mom has had heat pump systems in three houses up in norther MI. No problems. | ||
| Sleez |
the biggest mistake is usually oversized a/c units. happens all the time, seems like if a 2ton is good, a 3 ton for a couple hundred more would be better. wrong!! if you oversize, then the system starts/stops more often and the start up loads are greater. it's better off having a properly sized system running longer cycle times. get the highest efficiency rated furnace and a/c you can afford. will pay for itself in the long run. | ||
| Two_seasons |
Heat pump not efficient in this climate unless you go into the earth to get it. Unless a semi-retired like yourself wants to start digging  More work and $ then I'm willing to give. | ||
| Sifo |
You do need a ground loop system for a heat pump. They can either be trenched if your location will allow it, or drilled in vertically. It does take a while to get the ROI though. | ||
| Wolfridgerider |
Geo has a 30% tax right off. So it costs about the same as traditional systems once its all said and done. | ||
| Kenm123t |
If your going single stage cooling find out what the the sensible heat ratio is for that unit. In so Fla we live in a swamp so we seldom sell super hi eff units the do not remove enough moisture. Have a load calculation done based on how your home is built and local weather. You will find the new hi eff unit do not dehumidify well so look in to a Thermastor dehumidifier made in Wisconsin Your existing unit had a design coil temp of 40f the hi eff are 45f at best | ||
| Fahren |
Looked at gas boiler for heat and HW, with hydronic coil for heat thru the air handler? The boiler would also give you the opportunity to add some floor heat/floor warming loops if you have access to the underside of your floor structure. You would need boiler, HW storage tank (indirect heat exchange), air handler and AC condenser. Definitely stay with gas. | ||
| Fast1075 |
(a) What Ken said. (b) The danger in oversizing an A/C unit is in the loss of humidity control. "Sick building syndrome" is invariably due to poor humidity control. I have spent a lot of summers in central Mi. when I was a kid, and it can be every bit as hot and sticky as Florida (at least near the lake). I would suggest a system with an SEER (seasonal energy efficiency ratio) NO higher than 14. (there may be local codes that specify system efficiencies) Carrier and Goodman/Amana have good conventional systems with a great "bang for the buck". Stay away from variable speed and "X-13" motors unless you buy an extended warranty. They currently cost nearly 1K to replace if one fails out of warranty (and they are prone to failure if there are any issues with the duct system, especially in the return side. Listen carefully. BUY THE EXTENDED WARRANTY. (Parts and Labor). And make damn sure it is a factory warranty, not one underwritten by the dealer. If the proposed provider cannot, or will not test the system air flow capacity and duct static pressures BEFORE giving you a quote, find a competent dealer. It is not possible to explain how important air flow is to the efficiency and life of the system. On a system as old as yours, it is quite likely there will need to be some modifications to the air side for it to work properly. (I make a large part of my living correcting fouled up jobs). If you have allergies or medical conditions that require air as clean as possible, please, please invest in an electronic air filter. Do not used washable filters, or those so called high efficiency pleated filters. They are far too restrictive to air flow. They WILL KILL your system. | ||
| Hootowl |
Wish you were in Houston Fast. It's tough finding an AC shop here that isn't out to rip you off. | ||
| Fast1075 |
It's a tough business to be in. It is expensive to operate, with expenses running 36-38% of gross. Our fuel cost alone last month was $5,200.00. Throw in all the red tape, and regs. It is tougher every day. The residential market is rife with unqualified and unlicensed "contractors". And people are duped into believing them until they face the hard reality of a crap job. If you are considering an A/C contractor, call them at 2:00 am, and see how you are handled. | ||
| Two_seasons |
Here is what we were quoted yesterday. 1) Lennox Signature furnace, variable speed fan, 70,000 btu (the 37 year old is an 82,000 btu) 2) Lennox XC17 central air, 24,000 btu 2-ton, single stage scroll compressor (old is 2-ton as well and cools real good and is 24 years old) 3) Pure Air filtration system Not going to mention price we were quoted, but talked with two neighbors who went with Carrier over the last several years and this quote is in line with theirs, adjusted for inflation. As stated in original post, current system is Lennox. I think it was Lennox several years ago that had the "Pulse System" that was, as I recall, a complete disaster. Will a 70K btu unit replace an old 82K unit without issues? And, does the Lennox brand have a stellar reputation today for both heating and air conditioning? | ||
| Fast1075 |
Post up the model numbers of the old outdoor unit and the cooling coil, if available. | ||
| Kenm123t |
The Btus are they stating the input or the output btus and % of eff? Older furnaces used more gas to get the same btus into the home. | ||
| Hughlysses |
Good advice from Fast1075 above. A more efficient unit does not necessarily pay for itself. You have to consider not only first cost and cost of fuel or electricity, but maintenance & repair costs. | ||
| Sifo |
While we are on this topic, I was wondering if the experts would care to weigh in on the ductless AC systems like Mitsubishi advertises. We have a two story house with central AC, but it's not zoned. At night it cools off enough down stairs that the thermostat won't turn on the AC at all. The heat of course rises to the upstairs bedrooms making it very hot for sleeping. Currently we are using a window AC units too cool zones as needed. It works well enough, but eliminates opening windows on nice nights. Anyone have experience with these? | ||
| Fahren |
Tom, they are great. the Mr. Slim ductless splits have been around a good, long time and have gotten better. The outdoor unit is really small and quiet. For the right application, they are winners. Or, any way you can have someone look at a Honeywell (or similar) zone control system for you, for the existing install? Crazy to only have one t-stat in a 2-story home! | ||
| Two_seasons |
Fast: Old AC unit was a Magic Chef, now known as Armstrong Air, CJK Series, Part # 36993A086. It's a 2-ton unit. Proposed new is a 17SEER, 2-ton Lennox Single Scroll Compressor unit, Model XC17-024. Ken: Your statement on old btu vs new btu output is confusing. I think what you are trying to say is that the old system @ 65%, while giving off more heat initially until the temp is stable in our house, will cost ALOT more every day to operate vs a 97% unit. I've heard that the new furnaces don't have HOT heat coming out of them like the current one does. It would appear that we'll probably, then, need to pull the system off setback sooner in the A.M. to get the temp stabilized by the time everyone is getting up. | ||
| Fast1075 |
That Armstrong unit had a capacity of 23K BTU and an SEER of 9.1 when it was new in the early 90's. Anything new and properly installed will kick it's old butt for efficiency. Zone systems with gas heat are really tricky, you need a variable speed furnace. Also the tricks used by the system tend to shorten the life of the equipment. (too much to explain here.) but they do work if set up properly. BTW, if you are thinking zone system. RUN SCREAMING away from Lennox, it is a proprietary system and they regularly obsolete their stuff. Mini splits: great idea, I have a Sanyo variable capacity system in my Studio. It is whisper quiet. But standard Mini Splits are only good for one room. They make what are called multi plex units with multiple heads and one outdoor unit. The best thing about mini splits is you lose the ductwork headache. They are pretty dern efficient, but you need a well qualified service company because the controls are fairly complex, and the manuals are written in engrish  . | ||
| Kenm123t |
What I am talking about is the difference between the amount of gas in BTUS you burn to get the out put BTUS into your home. In order to get the most BTUS out of the furnace the discharge temp will be lower than older furnaces. Input BTUS X % of eff = output BTUS. Sifo the easy way to deal with that is to close a door or some other separation between up and down stairs. And use a wire less tstat that can be master sub mastered based on time of day operation. If you like zoning look into the Daikin VRVS system you can use exposed ahus or ducted models on the same system. Typically up to 8 ahus on a system. Pm me if you want to discuss them | ||
| Two_seasons |
Fast: No zoning on existing or new. Will I have any issues regarding getting our home warm/keeping it warm with new 70K vs old 82K? Thanks for the answers guys. You are educating me! | ||
| Fast1075 |
Only a heat load calculation can tell on the capacity question. I have no real experience with climates where it is as cold as it gets where you live. (here that furnace would be huge, 50K are more common) Anything else would be a guess. If I had to guess, I would say "most likely" since in the old days overkill was common. | ||
| Fast1075 |
And on the Pure Air filter, please don't do that to your system and your pocketbook. a HEPA filter has a continuing expense. The filters still need to be replaced on a regular basis, and they are expensive, as much as 100+ dollars per change. They are also extremely restrictive to air flow if they are incorrectly sized. Get an electronic filter. More expensive initially, but maintenance is simple and easy. If you get one, buy the extended warranty. | ||
| Two_seasons |
Fast: Filtration System I'm of the same opinion. We do have alot of the issues that this system will help alleviate. We're going over to the showroom today and getting some more ideas. Thanks. We've been in this house for 23 years. Haven't had the ducts cleaned and are looking to get that done PRIOR to new install with old furnace out of the way. Looking to use company called DUCTZ. I would imagine that clean ducting helps lower restriction at the blower and will, overall, benefit the dust conditions within our home. Load Calc So far, haven't gotten any more than the salesman coming out and "sizing" up the situation. The upside is he is asking a lot of questions regarding our comfort with existing system. Frankly, we are very happy with our old system. But, it's time to replace as our electricity up here is getting very costly. Gas use will go down too with new, so it seems to be a win-win for us. And another benefit, we are stimulating our local economy! After all, I'm doing that daily with our local micro brew | ||
| Fast1075 |
We own Ductz franchise #16  They are the real deal. The good thing is when they inspect your system, they will shoot straight. If it needs attention they will tell you what and why. If it is ok, they will tell you that also. Ductz is held to a high standard, you can trust 'em. If you have any trouble with them, I know the guy that holds their franchise . | ||
| Bluzm2 |
We replaced our HVAC a couple of years ago with a Carrier system. The A/C unit is a 3 ton dual speed unit. The original was a 2.5 Ton single speed. The furnace is about 86% (still condensing) with a 3 speed blower. Smart integrated thermostat. I have NO regrets going with a larger A/C unit. It cools fast when needed then shifts to low speed so it runs longer to dehumidify. It has worked perfect. Our house calculated out for a 2.5 Ton unit however they didn't factor in the south facing walkout and all the solar gain. The 3 Ton unit works perfect. Really saves on electricity too. Oh yeah, CLEAN YOUR DUCTS! You won't believe how dirty they are. Also make sure the installer checks and seals all available duct runs. Makes a big difference. Brad | ||
| Kenm123t |
Bluz thats what capacity controls do for you adapt to the actual load.The low speed running for a longer time does a better job of dehumification. I put a American Standard dual compressor system in Dads house 11 years ago its worked well. | ||
| Rkc00 |
2 Tons seems a little low on the AC. I would do the 3 tons. The 72000 btu's sounds a little low also. | ||
| Hughlysses |
If existing unit is 2 tons and cools fine, you don't want to arbitrarily upsize the new one by 50%. One thing to consider in sizing new HVAC equipment is that people have often added more attic insulation, insulated windows, etc. in the time since the house was built, which reduces the cooling and heating loads. | ||
| Two_seasons |
Hey guys. Well, we made the decision to stay with Lennox for the heat and now will have Lennox for the cooling too. The duct cleaning company, DUCTZ, will be cleaning out the 37 years worth of crud out of the ducting. And, we went with the MERV 16 Hepa without the EV lamps. If we made a mistake here, I hope it will be a small impact on our finances. Time will tell for sure. Thanks for all the great advice. If you're at HC next year, stop on over for a brewski on us |
