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justin_bekker

Cooling 2nd floor

Justin Bekker
3 months ago

Hello,

We recently moved into a 20 year old house in Alberta, Canada. 1200 sq. ft. upstairs and 1400 sq. ft. on the main floor with an unfinished basement. The house is well built with good sealing everywhere and good insulation in the attic. The master bedroom is in the SW corner of the 2nd floor and gets hot in the afternoon. With the blinds closed and the ambient outside temperature around 20°C, the bedroom gets to 27°C. The upstairs is very open with vaulted ceilings in two corners of the house and an open catwalk between the other two corners of the house, so the cold air can fall out of the upstairs easily. Fresh air returns in each of the three upstairs bedrooms. The house has two furnaces (one for basement and main floor and one for upstairs).


TL:DR - hot upstairs, challenging architecture, good sealing and insulation.


We just put in new heat pumps and they are hardly putting a dent in the upstairs temperature (maybe 1 degree). The main floor is a 3.0 ton and the upstairs is a 2.0 ton unit. With the main floor turned off, but the upstairs cooling, the temperature is still getting to 26°C in the afternoon and the main floor is around 21°C. The basement is also cold with the furnace room probably around 18°C. There is some leaking from the ducting in the furnace room, but I taped everything as best I could. The ducting travels about 40 feet in the basement joists, which are all open to the basement, before heading upstairs. It is cold air blowing upstairs, but it can't keep up.


TL:DR - 2 ton upstairs heat pump can't cool the upstairs. The basement is cold with about 40 feet of galvanized steel ducting running through the basement joists before turning upstairs.


My suspicion is I am losing my cold air to conduction / convection of the ducting in the basement. Is this possible? I have tried closing all the bedroom doors to keep the cold air from falling downstairs, but it doesn't seem to make a difference.

Comments (41)

  • klem1
    3 months ago

    Along with leaky and poorly insulated ducts look at return air provisions. "CLOSING DOORS" is counter productive, it prevents air exchange which is necessary for proper heating and cooling. I don't suppose it does any good suggest you have installer return to check things out since he didn't do it before selling you replacements. Hold tight,the houzz crowd will be here soon to make wags at it.

  • Justin Bekker
    Original Author
    3 months ago

    Thanks klem1. I do have fresh air returns in each bedroom upstairs. My thought was that the fresh air returns would provide the proper air exchange.

    I also intend to have the installer come back in the spring when the outside temperature warms up, but I like figuring things out myself.

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  • mike_home
    3 months ago

    Alberta, Canada. 1200 sq. ft. upstairs and 1400 sq. ft. on the main floor with an unfinished basement.

    The house has two furnaces (one for basement and main floor and one for upstairs).

    We just put in new heat pumps ... The main floor is a 3.0 ton and the upstairs is a 2.0 ton unit.

    The upstairs is very open with vaulted ceilings in two corners of the house and an open catwalk between the other two corners of the house...

    I assembled the key pieces of information from you posted. Are the furnaces and heat pumps integrated into dual fuel systems? Is the furnace and heat pump for the second floor located in the basement? Do you plan to use the heat pump for heating this winter and if so how have they preformed so far? Did these heat pumps replace existing AC systems? What method did the installer use to size the heat pumps? Is it possible the installer intended to install the 3 ton unit for the second floor, and the 2 ton unit for the first floor? Does your contract state which unit is going on each floor?

    Given what you have stated so far, and without stepping into your house, I think the 2 ton unit is undersized for the second floor, and the 3 ton unit is oversized for the first floor. There are most likely supply issues on the second floor. Cooling spaces with high vaulted ceilings requires proper placement of supply and return vents. A ceiling fan will help but it is not a cure.

  • Justin Bekker
    Original Author
    3 months ago

    I appreciate your point Austin Air Company, but disagree a bit. Figuring out how to do something myself includes learning. I've done a fair bit of research before landing here with questions. I let a "professional" install it, and now I'm trying to figure out why their installation didn't work.


    Mike_home, the intention was definitely to put the 2 ton upstairs, which was chosen based on size and at least a mention of the more challenging architecture. I've suspected that it may have been better to swap them, but I'm not certain of that yet. They are also intended to heat, and there is also a new gas furnace for each floor, and they are integrated into the same ducting. The heat pumps are located on the ground floor and plumped into the basement furnaces. There was no previous A/C. Heating has been great. I have my heat pump to furnace switch at 2C.

    When I've tried to test out the cooling capability, I've turned the main floor off and the upstairs to cool, and let it run all afternoon only to watch the temperature climb up, although I can feel cold air blowing out of the vents. Return air is located at ground level and I realize it would be best to have separate return airs higher up for the A/C. Do they make such a thing as a vent extender that I could put on for the summer? Like a column that attached to the air return, secured to the wall and pulled air from the ceiling?

  • mike_home
    3 months ago

    There was no previous A/C.

    If there was no original AC then the HVAC contractor should have done a cooling load calculation to determine the sizes. This calculation is usually done by entering the dimensions of the rooms, windows, and insulation values of the exterior walls. The fact the smaller condenser (2 ton) was installed on the second floor leads me to believe this was not done. The contractor may have used a rule thumb based on the area (square feet) for each floor. This often leads to equipment that is either oversized or undersized. Heat pump sizing is usually set by the cooling load and not the heating load.

    The heat pumps are located on the ground floor and plumped into the basement furnaces.

    I have not seen this type of arrangement. Perhaps this may be part of the problem.

    Return air is located at ground level and I realize it would be best to have separate return airs higher up for the A/C. Do they make such a thing as a vent extender that I could put on for the summer? Like a column that attached to the air return, secured to the wall and pulled air from the ceiling?

    This is also another part of the problem. The supplies and return vents were located for heating only and not cooling. I am not aware of a vent extender. You many need to move or add additional supplies and returns in the vaulted ceiling space.

  • Justin Bekker
    Original Author
    3 months ago

    Thanks again Mike. I think the sizing was primarily based off a rule of thumb (square footage). He might have bumped up 0.5 tons as he did mention that the open space and windows would increase the cooling difficulty. I think the items you mentioned were "considered", but not calculated, or at best estimated. He didn't take any window size measurements and we have a lot of windows.


    I think our layout of pumps / furnace / ducting is typical for our geographical area. Houses are built here with heating as the primary concern, so the furnace is placed in the basement. In order to tap into the ducting of the house, there isn't any other practical option than to put the A/C heat exchanger next to the furnace.


    We do plan on painting, so I will look into the option of adding elevated fresh air returns. I assume this is a simple means of pulling off the drywall between the studs above my current return and adding a second vent at the ceiling. Then I would manually switch between the two vents, depending on if I was heating or cooling.


    I appreciate your comments and it makes me feel more confident for when I have a meeting with the installation company.


    One other question, if the heat pump is sized correctly, would it do any good to increase the size? I assume not, as it probably won't get the air any colder.

  • A Mat
    3 months ago

    Was a load calc conducted?

  • Justin Bekker
    Original Author
    3 months ago

    Thanks all, this is helpful for my conversation I'll have with the installer. If the calculations were done they were based off very rough estimates as there was no measuring done.

  • mike_home
    3 months ago

    One other question, if the heat pump is sized correctly, would it do any good to increase the size? I assume not, as it probably won't get the air any colder.

    Sized correctly usually means on the typcial hot summer day the house would be able to maintain a temperature of 75F (24C) degrees. The theory is your heat pump has not been sized correctly. Increasing the size does not make the air colder, but it increases the volume of cold air reaching the upper floor. This assumes the duct can handle to additional volue of air flow. That is something else the installer need to measure when doing the load calculation.


  • klem1
    3 months ago
    last modified: 3 months ago

    So the conclusion is houzzers wagged that installing contractor wagged? It has nothing to do with improper sizing ,the damned ac just isn't cooling. People in the deep South do fine with 24k btu in 1200 sq ft " well built with good sealing everywhere and good insulation in the attic" homes . On a 20c day you should almost be able to hang beef in 1200 sq with 24k cooling. Justin I appreciate your desire to learn how hvac works but imo it's foolish to go about it like this. Don't wait until next year,get the installing contractor back to fix the unit NOW before labor warranty expires. And read some books,sign up for classes or hang out with an ac tech in your spare time.

  • PRO
    Austin Air Companie
    3 months ago

    I appreciate your point Austin Air Company, but disagree a bit. Figuring out how to do something myself includes learning. I've done a fair bit of research before landing here with questions. I let a "professional" install it, and now I'm trying to figure out why their installation didn't work.


    Justin the people you are garnering advice from appear to be helping you more along the lines they are talking about things you want to hear as opposed to what is actually the case. Based on what you've said... is what I am going by.


    While AC sizing is important, it is not the end all be - all. Running heat loads isn't completely fool proof for an already built house. Over sizing can occur just as easy as undersizing if only looking to the calculation versus what could actually be the problem. Easy to pass the buck as much as blame something that is completely false from a Monday morning quarerback, who is only a spectator. Why do they chime in here> answer that then we'll both know.


    1. Equipment: new / old / few years old isn't infallible.

    2. HVAC installation isn't like plugging in a window unit. (skill: math + science plus know how required.)


    What did you say Justin? With the main floor turned off, but the upstairs cooling, the temperature is still getting to 26°C in the afternoon and the main floor is around 21°C.


    26C = 78.8F 21C = 69.8 Temperature drop of 11F


    AC is designed for 15 to 20F delta. Heat rises: by shutting off the main system the heat what there is all goes to the upper floor. That doesn't prove anything other than how little you know. Then discuss it with more people who don't actually do HVAC for a living. Great plan.


    What is the actual temperature drop of the system on the top floor across the evaporator coil?


    Based on what you've said I can conclude that most likely it's a problem with the equipment. Equipment just because it's new isn't infallible. That is why you paid a pro to do it. Not run to the internet to learn that then turns this into a suspicion the equipment is undersized when currently the size you have now is 600 square feet per ton for this area on the top floor?


    Total of 5 tons for 2800 sq ft... which is even worse considering the whole structure 560 sq ft per ton of AC for a house that originally didn't come with AC? For a house that was built only 20 years ago?


    Just stop it, Get some real help. Sign up at your local trade school if you want to "really learn".


    I service the Katy, Texas area.


  • PRO
    Charles Ross Homes
    3 months ago

    "26C = 78.8F 21C = 69.8 Temperature drop of 11F AC is designed for 15 to 20F delta.

    What the OP related is that the temperature on the 1st floor was 21C and the temperature on the 2nd floor was 26C. That's not the temperature difference across either evaporator coil; it's simply the temperature difference between the two floors. An undersized coil can produce a 20F temperature drop at a lower air flow rate than is required to adequately cool a space. While the temperature drop across the evaporator coil is a simple performance test that should have been performed at installation, it's not sufficient to conclude there is no issue with sizing of the system.

    Heat rises: by shutting off the main system the heat what there is all goes to the upper floor."

    Heat is transferred by any combination of conduction, convection and radiation, it's only directional to the extent it flows from an energy source (at higher temperature) to a sink (a lower temperature.) If the temperature of the 2nd floor is 26C and the temperature of the lower flow is 21C the 2nd floor is actually transferring heat to the 1st floor. Energy doesn't travel uphill, so to speak.

  • mike_home
    3 months ago
    last modified: 3 months ago

    People in the deep South do fine with 24k btu in 1200 sq ft " well built with good sealing everywhere and good insulation in the attic" homes.

    I agree this would be a true statement for a ranch style house built on a slab or crawl space. If furnace or air handler is inside the conditioned space 2 tons could even be condsidered over sized.

    I think the sizing was primarily based off a rule of thumb (square footage). He might have bumped up 0.5 tons as he did mention that the open space and windows would increase the cooling difficulty.

    So the rule of thumb came up with 1.5 tons pluse an extra 0.5 ton for the 1200 sq. foot second floor. Consquently the rule of thumb calculation resulted in 3 tons for the 1400 sq. foot first floor. I assume there was no added 0.5 ton. A basement Alberta, Canada probably never goes above 70F in the summer. The rule of thumb should predict a zero cooling load.

    So if the 2 tons is the correct size for the 1200 sq foot upper floor with vaulted the vaulted ceiling, then how is 3 ton the correct size for the 1400 ground floor?

    Don't wait until next year, get the installing contractor back to fix the unit NOW before labor warranty expires.

    I agree with this statement also. There are more problems in addition to sizing. Have the contractor verify the equipment is operating correctly. If it is then let him know you will be calling him back if the upper floor is not maintaing 75F (24C) during the middle of a hot summer day.

  • Justin Bekker
    Original Author
    3 months ago

    Thanks all. The weather is supposed to be relatively warm next week, so I'll see if I can get someone in.

  • PRO
    Austin Air Companie
    3 months ago

    What the OP related is that the temperature on the 1st floor was 21C and the temperature on the 2nd floor was 26C. That's not the temperature difference across either evaporator coil; it's simply the temperature difference between the two floors.


    I addressed that with this question in my previous post. I know from experience builders only read what they want and ignore everything else.

    What is the actual temperature drop of the system on the top floor across the evaporator coil?


    When you come to a forum board for clues, the answer is in written form. ~not reading and comprehending what you are reading is a form of laziness.

  • PRO
    Charles Ross Homes
    3 months ago

    @Austin Aire Companie,

    I have no earthly idea how you arrive at 11F as the temperature difference between the two floors. It's a simple subtraction that yields 9F. Further, I have no earthly idea why the difference is relevant, and more importantly, I don't think you do, either. The temperature on the 1st and 2nd floors are controlled by separate systems with separate thermostats. It's not like they are served by a single system maintaining different conditions on each level. The only reasons to compare the two temperatures are with respect to comfort and of course, to understand that heat would be flowing from the 2nd floor to the 1st.

    Heat doesn't rise, but hot air does. It does so because it's less dense--and more buoyant--than cooler air. What is more relevant for a multi-level home like the OP's is that humid air rises because it's less dense than dry air. That can put an additional latent (dehumidification) load on 2nd floor systems. The OP correlates the temperature on the 2nd floor with solar heat gain during the afternoon (SW exposure.) The attic and vaulted ceiling areas are getting the same exposure. That's creates a radiant heat load which I'm betting wasn't considered if the system was sized by a rule of thumb.

  • ginatay124
    3 months ago

    We have a similar scenario in our three-level home near Denver. The 1200 sqft upstairs with central loft and vaulted ceiling in the master would stay too hot in summer to sleep comfortably while the elderly parents in the basement were freezing. We just had a 2-ton heat pump installed to service the upstairs with two zones - one for the master and the other for the three smaller bedrooms which are guest rooms and office. It was originally sized to supplement our existing cooling system, but we requested them to increase the sizing a bit so that we could keep main floor and basement warmer - about 74 in day and 72 at night. The new system was installed in our attic and ducted to each bedroom ceiling with it’s main return in the central loft ceiling. The vents in the bedroom ceilings were placed so as to have maximum convection of the cool air before intake into existing returns near floor level. It is so nice to sleep under the cool air that is gently circulating from above. The system works so well we can sleep at 64 degrees or cooler at night if we like, even on the hottest days. We are very pleased with it, and the most surprising aspect of having it is that it did not increase our electricity bills one bit. Could it be that the location of your unit and the use of existing ductwork designed for heating is the bigger issue over sizing of the unit? And testing the unit should be done with downstairs system running. One more thought for you - we’ve found that setting the thermostat for a heat pump is not as dialed in as a regular a/c system. First we had to calibrate the thermostats so that they displayed room temperature correctly. Then, they might need to be set at 68 degrees to maintain 72 degrees room temperature. Or 64 degrees to maintain 68. One website suggested to think of that setting as a “comfort setting” - just a number that you need to set the thermostat to in order to achieve desired temperature.

  • PRO
    Charles Ross Homes
    3 months ago
    last modified: 3 months ago

    That makes twice that the OP has been chided for evaluating the 2nd floor system without the 1st floor system running. The 1st floor should be at design conditions when evaluating the other systems in the home, but it need not be operating. We don't know what the indoor design temperature was--indeed it's likely the systems were sized by applying a rule of thumb--but the 2018 International Residential Code which forms the core of most statewide building codes--specifies a minimum cooling temperature of 75F. The 1st floor was less than 75F during the OP's evaluation. From the temperatures noted, the 1st floor system was not contributing any cooling load to the 2nd floor system and any lack of performance of the 2nd floor system is not attributable to the 1st floor system being idle.

  • Justin Bekker
    Original Author
    3 months ago

    Thanks Charles. Indeed, my point when mentioning the first floor's temperature and that it wasn't cooling was to show that the first floor was at a temperature that was comfortable and should be acting as a heat sink and not a heat source.


    There was a comment about humidity - we are relatively dry here; around 40% in the summer.


    Ginatay,

    I do think your upstairs design would be beneficial for my situation as well, but our system does have completely separate ducting for the upstairs.


    I intend to measure the temperature across the coils and also from the coils to the upstairs vents.

  • PRO
    Austin Air Companie
    3 months ago

    @Austin Aire Companie,

    I have no earthly idea how you arrive at 11F as the temperature difference between the two floors. It's a simple subtraction that yields 9F.


    I have personally seen it over and over and over again -- it could be 10F it could be 12F it could be 9F --- what difference does it make? It isn't going to work like that.


    The reading is taken across the coil in question... even then the reading could be at fault for a number of reasons. Diagnosing a system or system(s) isn't performed from a forum board but you would rather argue form over function. Pretend you know something about refrigeration systems when you yourself said you couldn't be bothered with purchasing refrigerants?


    I asked what the temp was across the coil in question? Did I not ask that?


    You Charles want to pretend for some reason I didn't ask that? WHY?


    Yet you Charles would rather just send the thread into more hyperbole / compare things to code / blame the problems on that code and suggest that other things along the line of sizing are the reasons for the blame?





  • PRO
    Charles Ross Homes
    3 months ago
    last modified: 3 months ago

    You made a big deal of the temperature difference between floors (although you didn't calculate it correctly.) My claim is that it's irrelevant. Further, you insulted the OP for not running the 1st floor unit when evaluating the 2nd floor unit--even though the physics makes clear the 2nd floor would have been transferring heat to the 1st floor. Please help clarify the "why" behind your calculation and your comment.

    ETA: given your propensity to go off topic, please note the calculation in question is the following:

    "With the main floor turned off, but the upstairs cooling, the temperature is still getting to 26°C in the afternoon and the main floor is around 21°C.

    26C = 78.8F 21C = 69.8 Temperature drop of 11F"


    And the comment in question is the following:

    "Heat rises: by shutting off the main system the heat what there is all goes to the upper floor. That doesn't prove anything other than how little you know. Then discuss it with more people who don't actually do HVAC for a living. Great plan."

  • PRO
    Austin Air Companie
    3 months ago
    last modified: 3 months ago

    You made a big deal of the temperature difference between floors (although you didn't calculate it correctly.) My claim is that it's irrelevant.

    For someone (a builder) who doesn't buy refrigerants, doesn't understand refrigerant type of work... (how could you? you don't buy it?)

    What Mr Ross the builder considers irrelevant? It's just an argument with no solution.

    This and an argument in a forum board about schemantics you don't understand?

    I mean you've said it before Mr. Ross Hire an HVAC expert:

    click to enlarge:



    I live in a hot climate... it's only warm right now so people will claim it's not much different than anywhere's else. Except that about 10 months of the year AC is required here in Katy, Texas. Imagine how many different things I see here during the year? Now multiply that by 24, the number of years I've lived here. (I did AC work in Chicago area as well early on in my HVAC career.)

    When you have two AC systems (in a single structure that has two stories / two levels with the top level being on top of the bottom level) they tend to work in tandem with one another (in a hot climate) my experience. In a milder climate probably not as much fanfare... even still this doesn't negate the how, what, why, when and where.

    A builder constructs a home with no one living in it. It is comprised on paper. The home owner moves in uses the home for whatever and however they choose to use the house. This sequence was made even more clear during the pandemic because more and more people were working from home? uh, yeah.

    To a builder it's an opportunity to go back to the code book, claim the unit wasn't sized properly for home that was built only 20 years ago -- that didn't come with air conditioning at the time it was built?

    Doesn't that signify a low need cooling climate if the house wasn't built with that feature to sell the house?

    In 2023, we're then going to claim that 5 tons of cooling for a 2800 sq ft home is probably proper for a house in Canada -- until there is a no cool event for the upstairs and then we'll proceed to say that the size of this unit is too small?

    yeah the builder put a bet on it here: Didn't recommend to get the newly installed system checked.. no none of that.

    Click to enlarge if you missed it further up:



    Heat does rise does it not? let's not go around calling the kettle black?

    What other arguments will the builder come up with that only lead to new arguments with no solutions.

    Solutions are a mystery to a builder that goes to the next build (and argues with you over nothing every step of the way). It's only about building new, not going back. I've built my HVAC career on this one little fact.

  • PRO
    Charles Ross Homes
    3 months ago

    Ah, the usual attempt to change the topic in order to avoid accountability. Bullying the poster when you don't agree with them doesn't change the facts. The fact that I don't purchase refrigerants or own a gauge set didn't disqualify me from earning my engineering degree or my P.E. license. My occupation as a home builder shouldn't disqualify me to weigh in here on houzz.com--especially given the fact that I collaborate on the design of at least a dozen residential HVAC systems each year in a challenging mixed-humid climate zone. You don't do new construction and avoid any jobs that require permits or inspections so I'm guessing you don't do as much new system design as I do in a given year.

    I'll try to simplify the points made earlier so you understand them.

    You used the term "temperature drop." The term implies a decrease in temperature due to some process such as passing air over a cooling coil. If the difference in the 1st floor and 2nd floor is of interest, it would be reported as a temperature difference or temperature differential-- like a difference between a setpoint temperature and an indoor temperature. It's not a "temperature drop." Nor is it significant to diagnosing the OP's problem. A temperature difference which is significant is the indoor/outdoor temperature difference. The OP reported a 2nd floor temperature of 27C when the outdoor temperature was 20C. Sounds like a radiant load to me.

    While there can be some interactions between HVAC systems on different levels in a home, e.g., due to open, vaulted areas like two-story Foyers, zoned systems like the OP's should be designed to work independently--not in tandem. That's why each system gets its own thermostat.

    As previously explained, heat flow is not directional except that it travels from a heat source to a heat sink. Heat that is being transferred from the OP's hot attic to the 2nd floor ceiling and radiating into 2nd floor living spaces isn't "rising," is it? The OP's 1st floor at 21C is not contributing a heat load to a 2nd floor at 26C. Your claim "Heat rises: by shutting off the main system the heat what there is all goes to the upper floor." defies well-established physics. It's pure bunk. The fact that the 1st floor system can be "off" and the temperature maintained at 21C +/- for any length of time suggests a smaller heat load on the 1st floor than the 2nd floor which is what I would expect of a 1400 SF living area sandwiched between a basement with no cooling load and a 1200 SF level (86% of the 1st floor footprint.) But the "designer" has put a 3-ton system on the 1st floor and a 2-ton unit on the 2nd floor. It's time for the system "designer" to share the cooling load calculations. I'm betting they used a rule of thumb and wore the wrong thumb that day.

  • PRO
    Austin Air Companie
    3 months ago
    last modified: 3 months ago

    But the "designer" has put a 3-ton system on the 1st floor and a 2-ton unit on the 2nd floor.

    Even down here in the deep south... hot climate with 10 months of cooling needed this design is the most common. Having the larger system for the 1st floor of the structure smaller second system for the top floor.

    I have fixed these sorts of things 1,000s of times over the coarse of my 30 year HVAC career. None of which included putting a larger system on the top level of the structure.

    But we've found another "nexus of the universe event" because a builder who doesn't do HVAC thinks he can from a forum board because: "Hey, it's not rocket science."

    Nothing in and of itself wrong with putting a smaller system on top floor and larger system on bottom floor. Which is another reason the situation points to a problem with the equipment itself.

    To those who spend their time in a forum board arguing over things trying to "bully" there thoughts onto others with no real experience in what they are uttering? Let that sink in.

    I would be more suspicious this system is oversized than undersized. 2800 sq foot home with 5 tons of cooling is again 560 sq ft per ton for a home that was built originally with no cooling at all only 20 years ago. For a climate that isn't known to be all that hot. ( if it is known for being hot why then wasn't it built with AC from the get go?)


    Pay no attention to anything I say here because I am just merely changing the conversation again. If only...

  • PRO
    Charles Ross Homes
    3 months ago

    While rules of thumb for equipment sizing focus solely on the living area of a home, the real-world heating and cooling loads depend on a number of variables in addition to the living areas including solar orientation, foundation type, insulation, duct leakage rates, glazing, air infiltration, etc. That's why heating and cooling loads should be calculated as the basis for sizing of HVAC equipment. We don't have that information for the OP's home yet.

    Alberta, CA is a big place. The design temperatures (ASHRAE data) vary depending on the specific locale. Summer design temps in Alberta range from 80.3F to 90.4F d.b. and 60F to 64.2F w.b. For comparison purposes, the design temperatures (2018 IRC) for Houston are 94F d.b. and 79F w.b. Since your subtraction skills are questionable, let me calculate the temperature difference in the summer design temps between Houston and Alberta's warmest locale: 94F - 90.4F = 3.6F. That's not much of a difference. I'd want both heating and air conditioning systems in a home in either location.

  • klem1
    3 months ago

    Besides Chas Ross are there any among us that believe the average July high temperature in Houston TX is less than 4F higher than Alberta CA, ?

  • PRO
    Charles Ross Homes
    3 months ago

    Klem,

    You guys in Texas must think that you're the only ones who need air conditioning in North America. While it might not get as hot or humid as it does in your neck of the woods nor for the number of months it does there in the lone star state, air conditioning is still appropriate in many northern climate zones. For, well, calibration purposes, the summer design dry bulb temperature for Portland, Maine is 84F. That's the 2 1/2% design temperature listed in the 2018 International Residential Code, which forms the basis of most statewide building codes. A 2 1/2% temperature is exceeded 2 1/2% of the cooling season. It's not the average monthly high temperature in a given month. My copy of the IRC doesn't have data for Canada. The design temperatures stated for Alberta, CA were taken from ASHRAE data.

  • Justin Bekker
    Original Author
    3 months ago

    I can confirm that temperature sounds about right for how Charles describes the rating (2.5% temperature). Lots of houses here don't have air conditioning because the season is short and the nights cool off drastically, but the sun shines from 5am until 10pm, so a house with lots of windows gets plenty of radiant heating.

  • PRO
    Charles Ross Homes
    3 months ago

    If an HVAC contractor like klem1 has a problem understanding something as fundamental to HVAC design as a 2 1/2% design temperature, is there any wonder why there are so many problem HVAC systems?

  • dan1888
    3 months ago

    Your SW bedroom is closed with drawn shades during the day. If the outside temp is 20C, how about opening the windows? Maybe a small fan to assist in cross ventilation. I'm betting you find the room 20C when it comes time to use it.

  • PRO
    Charles Ross Homes
    3 months ago

    Klem,

    If you think I'm both OP and a poster on this thread, you're the one with the active imagination. Building codes matter where I live and work. I understand it's a lot looser in the wild west.

  • PRO
    Austin Air Companie
    3 months ago

    From the OP: Lots of houses here (Canada) don't have air conditioning because the season is short and the nights cool off drastically.


    So essentially it doesn't really matter how hot or close to hot the *temperature* gets if all it does is cascade and crash lower into the evening where one can merely open a window to cool off. But me as an internet gazer whose never been to Canada wouldn't realize this without being told? (Yet another reason I would call into question the size already of this AC system - 5 tons / 2800 sq ft or 560 sq ft per ton)


    Uh, yeah we had to wait for the OP to mention the logistics of the climate of Canada. LOL. No wait it's not cooling because of building codes? At this point make any excuse you want. It's not rocket science and it's clear as ever your license for rocket science has expired. ha, ha.


    I've lived in Wisconsin / Chicago area over 23 years ago-- many of those homes do not have air conditioning a good margin that do have are lowly window units. It can get hot there on occasion hotter than Katy, Texas for brief moments in time that however doesn't mean for a single second it is like the climate of Katy, Texas. (not hardly).



  • PRO
    Charles Ross Homes
    3 months ago

    Your posts, Ray, continue to suggest you are incapable of understanding the difference between weather events and climate.

    A decision whether to invest in an air conditioning system in any climate zone, and the specific type of system, is up to the individual who's considering the investment. It depends on their desired comfort and their wallet. Making that decision benefits from the insights of competent professionals.

    The OP has invested in new HVAC systems--at least one of which isn't performing properly. Suggesting they should just open a window or that they don't need such as system in their climate zone misses the point.

  • PRO
    Austin Air Companie
    3 months ago
    last modified: 3 months ago

    Suggesting they should just open a window or that they don't need such as system in their climate zone misses the point.

    The point continues to fly over the builder's head. Big surprise.

    Equipment sizing: 5 tons / 2800 sq ft = 560 sq ft per ton. (for a climate that barely needs it.) I mean if you want to put the cart before the horse you can, but I don't advise that. The cart was made to be pulled by the horse. The cart isn't confused, the horse is. LOL.

    But yet if we fly back in time to the first part of the thread the builder along with others were suggesting the top floor unit was undersized. Isn't that not so Charles? Abort, Abort... must flash code knowledge, pretend to be a weather man, but to this day don't extend a four day forecast to make myself look worthy in a forum board...

    I've repeated this over and over for Charles and even now he is making excuses over it. Go back an read my posts. How can the point be made any more clear. You tell me, then we'll both know.

    So all this talk about climate and sizing of the equipment go hand in hand?

    Uh, Yes. For one if temps drop below 55F over night, many AC manufacturers don't want you running the AC in that kind of weather (entry level AC unit). If you spent the money to allow that fine, but that costs more for a climate that only needs AC for brief moments of time (2 to 3 months season use). Entry level AC is more likely to suffer damage running it below 55F. So in that event, opening a window is your best choice. (OR spend more money to make it right.)

    For a climate or a passing weather event? we call this passing the buck for those who can't be bothered with buying refrigerants but pretending we know something by flashing code knowledge around like that is a solution too?

    Will Charles now get the point? I doubt it. The post wasn't really for him anyway.

    Context is always a good thing. Provided of course you actually read it and comprehend it. Don't pull a Charles.

  • PRO
    Charles Ross Homes
    3 months ago
    last modified: 3 months ago

    Ray,

    Well, your addition skills aren't much better than your subtraction skills. 1,400 SF + 1,200 SF = 2,600 SF not 2,800 SF as you stated. If that's as good as your math gets, it's probably a fool's errand to debate the design of any HVAC system with you. Your stream of consciousness isn't particularly compelling either. I'm going to invest the time to explain to whatever reasonably-intelligent life may visit this thread in the future.

    While we don't know what size HVAC systems are appropriate in the OP's home without calculating the cooling loads, analyzing the present condition by looking at it as 5 tons/2,600 SF is certainly not the right approach. The title of this thread "Cooling 2nd floor" is a good hint at where to start analyzing the problem. You'd need to consider the 2nd floor cooling loads on a room-by-room rather than a block basis, then add up all the individual cooling loads to determine the required system capacity since the 2nd floor has it's own dedicated system. To be clear, the question is not 5 tons/2,600 SF, but rather, is 2 tons/1,200 SF appropriate for 2nd floor living area sandwiched between a 1,400 SF 1st floor conditioned living area and an attic given all the particulars associated with the home's specific location, orientation, and construction?

    If you want to use the 1st floor system as a benchmark, let's assume that it is appropriately sized at 3 tons for a 1,400 SF living area sandwiched between a basement (which is a couple of degrees cooler than the desired 1st floor temperature and contributes nothing to the cooling load) and a 1,200 SF 2nd floor living area that is conditioned. If it is appropriately sized for those conditions, it's reasonable to expect the 2nd floor would need to be as large or larger capacity given the living areas are nearly the same and the 2nd floor also has to deal with the cooling load from the attic and the radiant loads related by the OP on the 2nd floor.

    As for running the air conditioning system at 55F, properly-designed systems cycle on/off as needed. If the system maintains indoor conditions during the portion of the day when temperatures are high enough to warrant air conditioning, it should cycle off completely at night.

  • Justin Bekker
    Original Author
    3 months ago

    Your patience is impressive Charles.


    I've talked to the installer and they assured me they would make sure everything is working correctly in the spring when the temperature warms up.


    Austin Air, you clearly are not able to understand my situation. My cooling season, for my house, is about 4 months long. I have bought heat pumps to heat for 8 months. For my 4 months of cooling I have much longer sun than Texas. When I want to go to bed at 10pm, the temperature is 80F in my room and the temperature outside might be 75F.


    I'm anticipating your next suggestion, so I'll beat you to it. "Why don't I stay up until 1am and then go to bed once my room has cooled off?"


    I'm not here for lifestyle advice. I'm here to learn how HVAC systems work, so that I can solve my HVAC issues.

    I'm

  • mike_home
    3 months ago

    I have my heat pump to furnace switch at 2C.

    If you post the rated effciency ratings of the furnaces and heat pump and the costs of electricinty per KWh and the cost of natural gas per therm or BTUs, a calcuation can be done to determine if using the heat pump in the winter saves you any money. If there is a savings, then you have to consider the costs of additional wear and tear of operating the heat pump through several winter months.

  • PRO
    Charles Ross Homes
    3 months ago

    "It matters not one bit that the sun stays up longer in your area." Actually, it does, and quite a bit, I suspect. The OP complained of the afternoon sun heating up the 2nd floor bedroom. That same sun is beating down on the roof. The longer it does, the more radiant load it contributes. Once the sun goes down, the heat gained by the exterior wall and roof will continue to be transferred into the home. This is a great example of why a rule of thumb for sizing air conditioning systems can get you into trouble. The 2nd floor is heating up at a different rate than the first floor due in large part to the radiant load.

  • PRO
    Austin Air Companie
    3 months ago

    The OP complained of the afternoon sun heating up the 2nd floor bedroom.


    To what 80F? I spot him additional 10F "for fun" to 90F?


    Meanwhile Texas spends months on end starting the day at 80F cruising to above 100F+?


    It does quite a bit (I suspect?-- you gonna start buying refrigerants?) OR You're confusing climate, sun position and weather again? ROFLMAO.



  • PRO
    Charles Ross Homes
    3 months ago

    Ray,

    Whatever heating and air conditioning may be required in Katy, TX isn't relevant to the OP's problem in a different climate zone. Nor is the purchase of refrigerants by a system designer. The OP is not trying to sweat as much as you do. They're trying to be comfortable in their home after paying for new HVAC systems installed on two levels.

    Solar heat gain can occur in any season of the year. It needs to be considered in the design phase. That's why manual J calculations consider the home's solar orientation, glazing area, type of glazing, and shading from trees and adjacent strutures.