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  • Heat pump optimization

    I put in a new heat pump and ductwork in my house this year so it's my first winter using the system. I'm noticing that the upstairs is getting much hotter than the downstairs (it's a split level). Using the Ecobee Andre one sensors I canreally visualize the difference. If I key it to work off the downstairs when we aren't sleeping then the bedroom is not and at night it keys off the bedroom so the downstairs is freezing. This has been partially mitigated by modifying the schedules but I'm now wondering if the system isn't balanced right. When it kicks on there's enough pressure upstairs to close doors and when they are closed you can really feel the air coming under them.

    My hvac contractor bailed so aside from paying someone to come professionally balance the system is it safe to partially close cents upstairs? I've read about system and ductwork damage... Have also kept the baseboards it just seems counterproductive to have to use them as well...

  • #2
    Originally posted by kideon View Post
    I put in a new heat pump and ductwork in my house this year so it's my first winter using the system. I'm noticing that the upstairs is getting much hotter than the downstairs (it's a split level). Using the Ecobee Andre one sensors I canreally visualize the difference. If I key it to work off the downstairs when we aren't sleeping then the bedroom is not and at night it keys off the bedroom so the downstairs is freezing. This has been partially mitigated by modifying the schedules but I'm now wondering if the system isn't balanced right. When it kicks on there's enough pressure upstairs to close doors and when they are closed you can really feel the air coming under them.

    My hvac contractor bailed so aside from paying someone to come professionally balance the system is it safe to partially close cents upstairs? I've read about system and ductwork damage... Have also kept the baseboards it just seems counterproductive to have to use them as well...
    It is safe to partially close vents in a normally operating system however my concern with what you describe is that there may be something wrong with your system so I recommend that you have a licensed HVAC professional check the system and balance. Limiting the airflow when it will not be properly redirected can cause problems and at this point you do not know if something downstairs is blocked or if it is just an air balance issue.

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    • #3
      I would also try to get a licensed HVAC professional that has experience with system installs, some of them just provide service and they may not have the knowledge to properly resolve your issue.

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      • #4
        As an HVAC/R tech you definitely need to call in a professional, one with a lot of experience fixing ductwork issues. From your description you have a serious problem that needs attention asap.

        Sent from my SCH-I545 using Tapatalk
        RJ_Make On YouTube

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        • #5
          Oh man. The worst part is it's a simple setup the air handler is in the attic over the living room (1st floor) and it feeds right there to the living room and kitchen then a large duct to the upstairs attic that feeds the upstairs. Example the ecobee reports the master upstairs bedroom at 75 and the living room at 68..

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          • #6
            Sounds like poorly designed ductwork. You can potentially resolve much of the problem, but the fact that your installer bailed suggests he's far from being a professional. Call in someone that knows what they're doing, pay a fair (not cheap) price for their services, and next time pay a higher price, but pay only once.
            Madcodger

            This would be a lot easier if I knew what I was doing...

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            • #7
              First of all I have split level house and it is older. I had to gut the basement right down to the cinder block walls. Also, there isn't enough insulation in the attic so I've been working at that as well. Being a split level the basement is always colder that the upper level. However, as I've been slowly working on these two problems and along with air sealing the house the temperature difference is slowly minimizing. It currently sits at 68 upstairs and 63.7 in the basement with the outside temperature at 31. Hot air rises it's just a fact of life and the only way to keep it from happening is to block it with doors walls and insulation. Ideally you would want a return duct in each room and keep the doors shut which would help to minimize static air flow and trap the heat in each room. without that the air has to return under the doors so there has to be several inches of clearance for a proper air return.

              1. I don't know much about ecobee but upon a quick read on there website I fail to see how it will help do anything helpful. (what's it doing, just making it hotter upstairs so the basement is warmer?)

              2. I've never seen properly designed HVAC duct work in a residential property, it would be too expensive and all the guys who know what they are doing are doing commercial work, that's where the money is.

              3. HVAC guys will not cut doors, If you do talk them into it it will probably end up looking like it was done by a beaver that needs braces.

              In the end an HVAC system needs to "breathe" to function properly. a little common sense goes along way. for instance, My duct work and returns were full of construction debris from the original builders, clean them out. much of the duct work was not connected properly ie no tape on poorly fitting joints causing leaks etc... A couple feeds weren't even connected and blowing air above a drop ceiling. With the fan running make sure there is actually air coming out of every register. Fix the basics first.
              If it ain't broke, don't fix it!

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              • #8
                Thanks everyone so last night I went into the lower attic and checked all of the ductwork I'll get upstairs over the holiday and do the same. The duct running between the two that then branches in e upstairs attic is friggin huge. There are two cents apiece in master bedroom and the office then one watch in the small bedroom and bathroom. The living room and kitchen (one large space) have a total of four so there's ten vents in total. The debris question is a good one I saw a lot of small things like trash lying around in that lower attic. I put a mini split in the den and have started running that more often with the door open to maybe balance things out. I also put in the crawls pace vent covers and covered up the backup wall ac unit that is in the kitchen. The laundry room next to the den has a draft blocker on the door. Also put in insulation and sealed the gaps in the lower kitchen cabinetry. New windows were just put in across the board so I think the house is as sealed against the outside air as possible. The first floor and den are all brick/concrete.

                I'm seeing the system kicking in aux heat when it's in the thirties outside is that common?

                Also there are circular installed and the air seems to only blow out of one side rather than radially.

                That's all of the additional detail I have so far, it's definitely livable and more efficient than using the baseboards would like to continue to tweak it out.

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                • #9
                  I'm not an expert but..

                  So a couple things. First, HVAC systems are designed to generate a specific air flow to be efficient. The contractor should have designed the system for the appropriate airflow needed to heat each space (taking heat gain/loss from windows etc). Assuming it was designed properly you can do some pretty cool stuff with HS. For example, you could add zone dampers to open/close specific ducts based on temp sensors in those areas. I have a room right off the HVAC system that would get hot in the winter and cold in the summer. So I put in a temp sensor and a zone damper. I use an ADIO-100 to drive a small relay that opens/closes the zone damper based on the temp sensor. If you have a monitored t-stat you could put a zone damper on each run and use the temp sensors to open/close zones and turn on/off the heating/cooling. It's fun stuff. The comments about talking to a professional (which I am not) are valid. What happens is if your system relies on 2500 CFM air movement and you close half the vents and only allow 1500 CFM to flow. That will cause excessive pressure in the system which will cause the blower to work harder and possibly cause damage to the blower. What a contractor should do would be to put a duct between the supply and return side ducts with a damper in between that is usually a gravity damper. As the supply side pressurizes it pushes open the damper and blows the excess air into the return duct. As you can see, it's a simple concept but involves significant design. Definitely find someone who specializes in zone heating/cooling. You can find a lot of stuff on the web. Google "zone heat design" to get started. Here is a doc zonefirst.com/wp-content/uploads/2013/01/DesignManual.pdf I know that's a lot of info and sounds complicated but it's not. The best thing you can do is to at least read up on it so if you DO contact a contractor you don't get bamboozled.

                  Bill

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                  • #10
                    I am in a warmer climate but my Carrier heat pump kicks in the auxiliary heat when there is more than 3 degrees difference between the set point and the actual room temp (ie if the room temp is 66 and I have thermostat set to 70 then the stage 2 aux heat will kick in). Your unit may be designed differently for your climate but this is something you can test.

                    The unit cycles on and off for short periods throughout the day to maintain the temp as it drops 1-2 degrees and I have learned that it is more efficient to maintain a steady temp than to let it get very cold inside and subsequently warm up by more than a few degrees when I get home. I do set it back 3 degrees when not home so the unit only cycles every 3-4 hours instead of every 30 minutes but that is based on my Smart Meter activity, well insulated new construction and climate.

                    Comment


                    • #11
                      Originally posted by LikeAutomation View Post
                      So a couple things. First, HVAC systems are designed to generate a specific air flow to be efficient. The contractor should have designed the system for the appropriate airflow needed to heat each space (taking heat gain/loss from windows etc). Assuming it was designed properly you can do some pretty cool stuff with HS. For example, you could add zone dampers to open/close specific ducts based on temp sensors in those areas. I have a room right off the HVAC system that would get hot in the winter and cold in the summer. So I put in a temp sensor and a zone damper. I use an ADIO-100 to drive a small relay that opens/closes the zone damper based on the temp sensor. If you have a monitored t-stat you could put a zone damper on each run and use the temp sensors to open/close zones and turn on/off the heating/cooling. It's fun stuff. The comments about talking to a professional (which I am not) are valid. What happens is if your system relies on 2500 CFM air movement and you close half the vents and only allow 1500 CFM to flow. That will cause excessive pressure in the system which will cause the blower to work harder and possibly cause damage to the blower. What a contractor should do would be to put a duct between the supply and return side ducts with a damper in between that is usually a gravity damper. As the supply side pressurizes it pushes open the damper and blows the excess air into the return duct. As you can see, it's a simple concept but involves significant design. Definitely find someone who specializes in zone heating/cooling. You can find a lot of stuff on the web. Google "zone heat design" to get started. Here is a doc zonefirst.com/wp-content/uploads/2013/01/DesignManual.pdf I know that's a lot of info and sounds complicated but it's not. The best thing you can do is to at least read up on it so if you DO contact a contractor you don't get bamboozled.

                      Bill
                      Thank you. That really helps.

                      Comment


                      • #12
                        To reiterate what those of said above, in general, messing with airflow means that something is wrong with the design of the ductwork to begin with, and messing with it further can damage your HVAC equipment.

                        As an example, at one of our houses, the builder used the incorrect size duct for a long run (too small). The far rooms were always too hot in the summer, or too cold in the winter. I called an HVAC person, and he saw the problem right away. Replacing the 8" ductwork with the proper 12" ductwork resulted in perfect heating/cooling in that room.

                        Comment


                        • #13
                          Originally posted by mikedr View Post
                          To reiterate what those of said above, in general, messing with airflow means that something is wrong with the design of the ductwork to begin with, and messing with it further can damage your HVAC equipment.

                          As an example, at one of our houses, the builder used the incorrect size duct for a long run (too small). The far rooms were always too hot in the summer, or too cold in the winter. I called an HVAC person, and he saw the problem right away. Replacing the 8" ductwork with the proper 12" ductwork resulted in perfect heating/cooling in that room.
                          I agree. But even starting with a proper designed and implemented system (including duct-work), I would need to collect proper data to automate anything. I just cannot believe an "inteligent" thermostat by itself can do the work of making every area of my house comfortable, at least not effectively. No matter what the ad says.

                          I am thinking that airflow, humidity, temperature, presence, heat radiance, back-pressure, room air movement, external climate conditions and forecast, etc, need to be considered.

                          Getting that logic with the ability to adjust to what comfort means to each person in the house, summer or winter, rain or sunshine, will be a lot more challenging than figuring the duct-work or collecting this data.
                          As it was mentioned before, most home contractors will have no clue how to handle all this. But they can certainly make sure the basic work was properly done, so I can break it on my own fault

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