From what I can tell with my SLP98 is does modulate down. I can hear it back-off the fan speed during this time and I assume the heat setting is coming as well. The Icomfort also has programmable setback/ramp-up rates like the Infinity.
From what I can tell with my SLP98 is does modulate down. I can hear it back-off the fan speed during this time and I assume the heat setting is coming as well. The Icomfort also has programmable setback/ramp-up rates like the Infinity.
I did get the HVAC-Calc (as per Commerce48's recommendation), and used the basic setting for 1 big room, where I added the Condo's total square footage, wall height, length and width, and construction information, as well as the Window size, construction and glass type with the correct perspective (Nth, West, etc). I followed the easy guide and I'm pretty sure the info I fed was accurate.
For the glass I put in the info for the new windows I'm about to install in the house.
The results says the condo has a Heat gain of 13,712 and a Heat Loss of 20,449. What does this mean in terms of Furnace sizing?
If it's supposed to show me the size furnace I need in terms of output BTU, then I've done this wrong I'm thinking......
I'm glad you've enjoyed this discourse. I can't say that I've been overly enthused about the some of the nastiness and direction of some of the repartee by some of the posters. Being a long term blogger and board member (on many various boards) I try to keep my comments on topic and civil. Humor is always welcome. It's fine to disagree, but insults never help to change anothers mind.
I appreciate any advice I have received so far on this board, and would appreciate your thoughts on the topic. I see you're a very active poster, with a long history on this board. have you installed a third party thermostat on any modulating furnace? What were the results? Did the system perform well? or was some of the system intelligence lost as a result causing performance degradation?
Sorry for all of the questions, but with 2 days before installation, I still have many questions.
Thanks in advance to everyone for further advice and thoughts.
Somewhere in HVAC-Calc help and/or one of the videos there is a discussion about system selection based on heat gain and heat loss results. Check that out, it explains a bit including about margins of safety.
You added both walls and ceilings? Doors? Ducts? Fireplaces? Skylights? Miscellaneous loads for kitchen, computer & AV equipment, and anything else in your house that would significantly affect your heat gain? FWIW, I googled a bit to see what others throw in form such miscellaneous loads, and in some cases I looked up figures for computers and TVs.
What you are hearing may be at the end of a heating call. The variable speed fan is ramping down the speed to match the drop in heat exchanger temp as it cools down. I believe every well designed furnace with a variable speed blower does this, even a single stage furnace.
If it does modulate down, then that would also be the case. However, two professionals here have already stated that it does not stage down, and that was also the case for the predecessor model, the G71.
I added in the floor, ceiling (same size as floor), all 4 walls, and all windows. I defined what the windows, walls, ceiling/roof & floor were composed of, etc. Also defined that the ceiling and the roof were together with 10" joists, as well as we are above other condo's in our building.
I added 4 people to the mix.
I didn't add the kitchen factor (1200 recommended), as I did the house as 1 big room, which obviously is not good for precise measurement. Nor did I add the the Computer, A/V or other electric equipment. I'll check where that should be added.
We have a full on A/V system with a receiver/amp that called be called a heater in it's own right, it puts out so much heat (hot to the touch). A 50" Plasma that gets toasty warm, as well as 4 - 6 computers/laptops running at any given time. So I imagine the electronics would contribute quite a lot of heat.
I'll check the video's tonight, as well as triple check my other numbers.
So what numbers do I look at (or use to calculate) specifically to get the number of output BTU required for the furnace?
Even if true, I can't imagine it would be a limitation of the hardware or that it wouldn't be corrected soon. Can furnaces get firmware updates? What about communicating stats, can they get firmware updates?
Does the iComfort report CFM and other interesting info like that (may not be needed, but nice bells-n-whistles I guess). By the way, the picture of the iComfort screen in the brochure looks nice, easy to read IMO, not that you need to stand and stare at it :-)
Overall I'm still interested in how steady the Infinity 3-stage holds the temperature in a decently insulated/ducted house, and how that compares to a properly working fully modulating furnace (which I'm sure the SLP98 is or at least will be soon don't you think). Are we talking 1 to 2 degree swings for 3-stage versus 1/2 degree swings for modulating, over say an hour, with doors staying closed etc..? I still think I read a post with someone's experience with the infinity, but can't find it now.
I'm not talking about differences in temp from one room to the next. But how much the temp at one particular spot changes with time. I would think with a fully modulating furnace the temp would stay very steady, as long as over the minimum load.
2400 sf duplex needing anything larger than 60mbtu indicates envelope issues to me. Have you had an audit? Blower door test? Your heat exchanger probably cracked because your furnace is grossly oversized.
Putting a non-communicating stat on a communicating furnace is pure idiocy. I suspect most consumers that have this setup were improperly educated or sold. The rest, well, no cure for stupid.
Putting a single stage stat on a multi stage furnace is nearly as bad.
Right now if you want Internet control you would be best served going with infinity. I've sold 2 of these units, overpriced and really poor web-site but functionality is there.
You won't know the infinity is running, much less notice when it shifts between stages. Any of the manufacturers top models are going to be a big change over what you currently have.
The stat was purely my decision so I'll personally wear the results at the end of the day. As I've said before, if it doesn't work effectively, I'll ebay it and get the Icomfort. I will report back about the experience, whether positive or negative. I did call Lennox and spoke to a tech about using another stat such as the Ecobee. He said that it should work fine, with no loss of efficiency. He said the only things lost would be the error message display, as well as the display of the model and serial number. If he's wrong I'll be giving him and his company a call back.
The infinity web control is no where near as good as the Ecobee, and the Infintiy has a monthly fee for internet access, while the Ecobee is free via web page, Iphone or Android app. Far superior stat in terms of user interface design (albeit at the potential cost of ultimate HVAC performance due to it not being a matching communicating stat).
From what the guru's who inspected the furnace say, the heat exchanger crack was near the connector to the A/C unit where the diameter went from 24" to 21", likely causing a hot spot due to poorer circulation in the area as a result (their opinion).
The windows have been very drafty due to poor design and terrible rotting issues around the base of the sash. No vacuum between the glass panes as well. Having them all replaced shortly (did advise the dealers of this when they came to estimate). Doubled up all insulation in the roof and upper floor external walls, as part of a project to replace Dryvit 2 years ago, so house seems better sealed and insulated, which will improve shortly after the new windows are in (with low-e glass).
Furnace output is based on your Heat Loss estimate. The idea being that if a home can lose 30000 BTU per hour during cold conditions, the heater needs to output 30000 BTU per hour in order to offset the heat loss rate and prevent the home's temperature from falling. However, if you do a little bit of reading you will find that professionals consider both the Heat Loss estimate and some other things to arrive at what they feel is the truly appropriate equipment size. I'm really not qualified to advise anyone on how to size equipment based on Manual-J estimates, and therefore can only encourage you to check out the HVAC-Calc help and other resources. Hopefully you've done that by now and progressed your understanding.
The G71 never was able to modulate down and they've replaced it with a similar design. I don't know if it is hardware or software, but you are dreaming if you think they are going to "fix" fundamental design.
My single stage furnace digital stat never varies from the set point. That could mean a swing of close to 2 degrees, but from what I see from a digital temp that reads tenths, my rooms appear to stay within plus/minus seven tenths.Are we talking 1 to 2 degree swings for 3-stage versus 1/2 degree swings for modulating, over say an hour, with doors staying closed etc..?
Most manufacturer pages of multi-stage furnaces (including two stage furnaces) will have pretty graphs comparing temperature swings of basic and higher end models. The more stages, the lower the amplitude of the swings. Can you tell the difference between half a degree swing and a tenth of a degree swing? Probably not - I believe human resolution of temperature is about a degree. But the graphs are pretty.
Yes, more stages have theoretical advantages, but probably not noticeable. When it comes to comparing the SLP to the Infinity, I would say that the Infinity is more likely to hold an exact temp. Advantage might go to the SLP under certain circumstances. However, the SLP has several strikes against it doing so. It appears to work as a four stage under most circumstances (still better than the current model Infinity). It can only modulate up (thus no better than a single stage in some conditions) - thus cannot ramp down when it approaches the target temp (which it doesn't know anyway). It cannot tell the inside temp and ramp accordingly - it times stages instead (and possibly has a learning algorithm as well to set times).
As much as I personally want a "fully" modulating furnace, there is no way I would pick the SLP over the Infinity based on technical features. Obviously, you really want to buy it for whatever reason, and there could be other excellent reasons to get it. I suspect you are really sold on the installer, and getting a great install can be more important that the actual equipment (assuming rough equivalence in equipment). The SLP is a couple points more efficient. You could have a significantly better quote for all we know. Might have a better warranty offered.
But from what I know currently, no one will be able to convince me that the SLP is more technically capable than the Infinity based on number of stages.
Because of your posts about the Ecobee, a few days ago I read half a dozen reviews. Reviews were mixed and there were some issues that were perhaps surprising - such as how well the touch screen recognized input and some confusing interface issues. That said, it is probably on a par or better than other high end stats, including the Infinity. Lack of ability to use proprietary information and interface commands from the furnace board strikes me as the biggest drawback.
The Ecobee has wireless connectivity out of the box, far better website than the very clunky Carrier, no annual fee, and a cool iPhone app. So that is a huge win. I believe it is also lower cost than the combo of the Infinity controller and the access module.
I did mention that the Infinity access was hackable. This removes the annual fee issue for the crappy access. There are instructions for port forwarding in this forum here. I've read similar discussions elsewhere on the internet in the past, so there are more resources if you are interested. But that is far different than out of the box functionality that the Ecobee has.
Actually not true. Both installers seem fine, and I am close to pulling the trigger on the Carrier. Trying to get all of my questions out of the way now, cause once it's done there's no looking back. Getting a 3-stage furnace, when fully modulating is out there with other brands, has been one of the issues holding me back. But if the 3-stage can hold fluctuations to within a degree or two, while a fully modulating (with a communicating stat) holds to less than a degree, is kind of in the noise I'm hoping in terms of comfort. Regarding your comments about the SLP98, I do have a hard time accepting that it couldn't do as well as or better than the more mature Infinity 3-stage in terms of heating control, but that's why I'm hear asking.
When used with a communicating outdoor AC unit, what information gets communicated, and how important is it? That's one of the + for Carrier IMO, since you don't have to go to their top-of-the-line to get communicating AC (Lennox get's really pricey for communicating AC). But not clear to me communicating with the outdoor unit really matters. Or maybe it is mostly useful if the outdoor is a 2-stage? It's the more affordable communicating AC that is pulling me toward Carrier, but for all I know the comfort gains are minimal.
(ozguy, sorry for having hijacked a little, hope you don't mind)
I know exactly how you feel! Same thing holding me back, even though I know that it will not make a noticeable difference.
It is much less, and you would have to have some fancy equipment to tell if it is holding within a quarter of a degree or a tenth of a degree.But if the 3-stage can hold fluctuations to within a degree or two,
If those were my two choices, the Infinity would be the clear winner for all the reasons I have already mentioned. Now if it is between the York and the Infinity, that is a much more difficult choice.Regarding your comments about the SLP98, I do have a hard time accepting that it couldn't do as well as or better than the more mature Infinity 3-stage in terms of heating control, but that's why I'm hear asking.
Honestly, I don't know. Apparently the outdoor temperature makes a difference in how stuff is controlled. I think some units may have humidistats as well. It should be useful for the furnace to know other equipment operating parameters and measurements to make intelligent decisions about how to condition your home, but it is open what actually happens.When used with a communicating outdoor AC unit, what information gets communicated, and how important is it?
If none of the pros here answer the question, ask your installers for additional info. I'd like to know myself. I can't find any information on manufacturer's sites at all, other than Trane says their communicating ability help the tech nail the charging on initial set up. But that apparently is unique to them.
The term communicating seems to have two separate meanings in HVAC. One is just the simple act of talking to equipment remotely via a digital rather than analog connection, without having to go set physical dip switches. Simple computer type stuff.
The other is really transmission of data, as in being able to tell what the temperature delta between set point and actual. That would appear to be simple remote sensing capability, but not all so called communicating stats seem to do this easy task or act on the information.
See post 38# on this thread for comment regarding outdoor sensor so the Icomfort can sense the dew point.
Apparently each brands communicating stat has different communication abilities, so the value of the communicating stat is more apparent with some brands over others. If only there was a good list of the communicating features each brand has.
Why can't all furnaces get the actual temps themselves? Why do they need a stat for that? Seems very illogical. Save duplication of duties I guess (the stat is already connected)....
All good.
The carrier does look very good, and I wish I had more time to look at other furnace options. However with the weather here getting colder (Chicago), and I've had to rush my decision as a result. Wouldn't have been looking if our Furnace hadn't been diagnosed with a cracked heat exchanger with leaking CO2 2 weeks ago.
I've been very appreciative for all post. Thanks commerce48 for all of your valuable input. It may be that I've gone against your advise (and many others here), but that doesn't mean I haven't appreciated and thought about every comment you and the others have posted on this thread.
The new furnace goes in tomorrow. Feedback coming soon.
I saw that post, but it doesn't explain what use the outdoor dew point is. Seems like it is the indoor conditions that is important.
Seems like it would be easy enough to put a sensor on the return side. Lots easier than trying to guess with various algorithms. Got to be a good reason.Why can't all furnaces get the actual temps themselves? Why do they need a stat for that? Seems very illogical. Save duplication of duties I guess (the stat is already connected)....