Jimbo.Automates Posted April 23, 2019 Share Posted April 23, 2019 I have to update my AC system, and thus have to replace my current zoneing system with a more sophisticated one to handle variable speed. The installer wants to use the Nexia system, which doesn't seem to be very open to integrating with others, but looks like it is possible. Does anyone have experience with these or others that can provide any input or recommendations? My current zone system allows simple thermostats to be used, but I guess that is not possible with the new variable speed systems. Link to comment
larryllix Posted April 23, 2019 Share Posted April 23, 2019 I have a third party programmed GE DCM motor in my air handler. They come with many 24 vac inputs to give you a speed for every application needed. One input ramps the speed up over several minutes to allow ducts to pressurise without pops and banging as well keep the system quieter, unless massive heat rise is needed. My son had some variable speed motor a few years back and it locked him into special stats that didn't do much at the $250 mark and he had to replace one after a few year at his own cost. I would avoid the variable speed motor when multiple DCM motors are common now. On a side note: I got caught feeding the 24vac control signal from a mixer panel and the motor would not ramp speeds. After some support calls a tech identified my voltage was different than the supply. Turns out the 24Vac input was phase sensitive to double up their logic input count. Link to comment
Jimbo.Automates Posted April 23, 2019 Author Share Posted April 23, 2019 Thanks for the advice Larry, but it's not just the air handler that is variable speed, it's also for the 18 seer compressor. For the zone system a variable speed air handler works best to not over pressurize the ducts when only running a single zone, this way we won't need the pressure bypass duct we currently have which is a big waste of energy. At least that's what they are telling me and it make sense. Haven't had much time to digest it all yet... Link to comment
larryllix Posted April 24, 2019 Share Posted April 24, 2019 3 hours ago, Jimbo said: Thanks for the advice Larry, but it's not just the air handler that is variable speed, it's also for the 18 seer compressor. For the zone system a variable speed air handler works best to not over pressurize the ducts when only running a single zone, this way we won't need the pressure bypass duct we currently have which is a big waste of energy. At least that's what they are telling me and it make sense. Haven't had much time to digest it all yet... With synchronous motor run squirrel cage blowers the energy used is mostly proportional to the air movement. The pressure does not increase with restrictions. Restrictions in the air result in less load on the fan and less load on the electric meter. How this works with the new DCM motors, I do not know. Interesting to note on my DCM motor as the filter gets clogged it increases the fan speed in order to compensate. My air handler is the receiver of the A/C system containing the evaporator coils, also. Are you saying the variable speed control, controls the speed of both motors, the outside condensing unit fan, and the inside evaporator fan (central ventilator)? Link to comment
Jimbo.Automates Posted April 24, 2019 Author Share Posted April 24, 2019 Are you saying the variable speed control, controls the speed of both motors, the outside condensing unit fan, and the inside evaporator fan (central ventilator)? Yes, that's the way I understood it.Sent from my Pixel 3 XL with Tapatalk Link to comment
Scottmichaelj Posted April 24, 2019 Share Posted April 24, 2019 I have to update my AC system, and thus have to replace my current zoneing system with a more sophisticated one to handle variable speed. The installer wants to use the Nexia system, which doesn't seem to be very open to integrating with others, but looks like it is possible. Does anyone have experience with these or others that can provide any input or recommendations? My current zone system allows simple thermostats to be used, but I guess that is not possible with the new variable speed systems. Have you thought about a Mitsubishi split system? They have a wide range of items and you can do a in attic/crawl SEZ ducted system instead of ugly splits. Theres a nice Kumo Cloud, with local access and third party integration. Link to comment
Jimbo.Automates Posted April 24, 2019 Author Share Posted April 24, 2019 Have you thought about a Mitsubishi split system? They have a wide range of items and you can do a in attic/crawl SEZ ducted system instead of ugly splits. Theres a nice Kumo Cloud, with local access and third party integration.Haven't heard of it but will look it up. We already have the zones, just need to update controls from our 15yo system, and half the ducts are in between the first and second floor.Sent from my Pixel 3 XL with Tapatalk Link to comment
apostolakisl Posted April 24, 2019 Share Posted April 24, 2019 9 hours ago, Jimbo said: Haven't heard of it but will look it up. We already have the zones, just need to update controls from our 15yo system, and half the ducts are in between the first and second floor. Sent from my Pixel 3 XL with Tapatalk A multi-zone Mitsubishi (or other brand) is not going to be cheap. But, you might do a cost analysis on updating a 15 year-old system considering its remaining life span is probably 5 to 10 years. Hard to say for certain. The split systems like this are very efficient. With a single small outdoor condenser unit you can feed multiple indoor air handlers each with its own evaporator. The air handlers are very small and would be located close to the point of use eliminating lots of ductwork and the inefficiencies produced from said ductwork. Or you can use the air handlers that hang on the wall and have no ductwork at all. They are heat pumps and can function quite well even in very cold outdoor temps. But probably not the best solution if it regularly gets down below 20F. Link to comment
Jimbo.Automates Posted April 25, 2019 Author Share Posted April 25, 2019 Yes that sounds interesting, but sounds like more ripup, but we are already tore up good due to water repiping of the whole house. Oh, and the outside condensers are 20yo so they are a big reason we are considering doing everything now. Sent from my Pixel 3 XL with Tapatalk Link to comment
apostolakisl Posted April 26, 2019 Share Posted April 26, 2019 On 4/24/2019 at 8:59 PM, Jimbo said: Yes that sounds interesting, but sounds like more ripup, but we are already tore up good due to water repiping of the whole house. Oh, and the outside condensers are 20yo so they are a big reason we are considering doing everything now. Sent from my Pixel 3 XL with Tapatalk Yeah, this is the time to do it if the house is already being pulled open and you have 20 year old system. The beauty of the Mitsubishi and similar systems is that you only run thin copper lines to all the zones, not big fat air handling ducts. Depending on the model, they are also usually continuously variable speed from barely on to full speed, so they keep things very constant. They tend to run all the time at just the right speed vs on/off/on/off etc. Link to comment
Jimbo.Automates Posted April 26, 2019 Author Share Posted April 26, 2019 Yeah, this is the time to do it if the house is already being pulled open and you have 20 year old system. The beauty of the Mitsubishi and similar systems is that you only run thin copper lines to all the zones, not big fat air handling ducts. Depending on the model, they are also usually continuously variable speed from barely on to full speed, so they keep things very constant. They tend to run all the time at just the right speed vs on/off/on/off etc. Thanks. What about noise with air handler in each room? My wife is sensitive (annoyed) by noises, especially when sleeping.Sent from my Pixel 3 XL with Tapatalk Link to comment
apostolakisl Posted April 26, 2019 Share Posted April 26, 2019 17 minutes ago, Jimbo said: Thanks. What about noise with air handler in each room? My wife is sensitive (annoyed) by noises, especially when sleeping. Sent from my Pixel 3 XL with Tapatalk I can speak for the minisplit mitsubishi that we put in a couple rooms at our church. These are the ones that hang on the wall. The are just a whisper. I also experienced some other brand (don't remember what) in Playa del Carmen where we vacationed last year. They had one of these units (wall hanging) in every room. Again, it was just a whisper that didn't affect my sleep. I would suggest you contact a dealer and they will probably have show rooms for you. Link to comment
mwester Posted April 26, 2019 Share Posted April 26, 2019 Dead quiet, can't hear them at all. New construction, we have forced air throughout -- but I had the splits installed in both second-floor bedrooms, since we use those as home offices, and the splits allow us to keep those two rooms air-conditioned while letting the rest of the house warm run with the A/C set far higher. My desk is right under one of the units, and I'm on the phone all the time - can't hear it at all. Highly recommended. Link to comment
Recommended Posts
Archived
This topic is now archived and is closed to further replies.