Considering multiple proposals for AC &backup heat for our 95yo home
A Fox
2 years ago
last modified: 2 years ago
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2 years agoCharles Ross Homes
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New house heat pump in Texas?
Comments (25)Ok, I now have load calculations and actual model numbers, so I'm hoping you all can take a look at this longwinded reply and tell me where to go from here. Also, while I have multiple pages of load calcs based on a Manual J8, I don't know if I am reading them correctly, so let me know if I get that wrong (there's a page for each system, then a page called "load and AVF summary" so I took the info from the summary page). Same equipment for each system. 3 ton Carrier 15 SEER/12.5 EER Base series single stage air conditioning and Carrier Performance Boost Series 96.3% AFUE two-stage condensing natural gas furnace. Condenser Model: CA16NA036; Evaporator coil: CNPVP4221A; Furnace: 59TP5A060E17-14. Honeywell Focus Pro 6000 t-stats, one honeywell two-zone damper system, aprilaire fresh air ventilation system (required for foam insulated home), aprilaire 4" media filters. Etc. System 1 - Main level, main living areas 1350 sq ft; 19933 btuh htg load; 19700 btuh clg load System 2 - Split between main level master and study, and "basement" level (this is where the controlled damper will go, and two t-stats) 1588 sq ft; 22087 btuh htg load; 18444 btuh clg load System 3 - Upstairs bedrooms 1228 sq ft; 14266 btuh htg load; 17085 clg load Does that give enough information? Should I be concerned about the "Base" model AC equipment, and try to upgrade? Would that cost a lot more? I also have some humidity concerns; originally I asked about a whole-house dehumidifier, but was told that it is not necessary for this house. Thanks for any thoughts!...See MoreZoned heat and AC in new home
Comments (5)Your situation is rather unique and presents many challenges. The biggest being simultaneous heating and cooling where any one zone may have to switch back and forth quite rapidly. There are also the challenges of cost, utility, esthetics and efficiency. There are in fact several, if not many choices available. You may want to consult with a professional HVAC designer (PE), as this is more of a commercial than residential design project albeit on a small scale. Some of the choices could be mini-splits, however this would also mean 1-condenser per head due to the simultaneous need to heat or cool over different zones. Another choice could be electric resistance heating for each room with zoned central air-conditioning. The Mitsubishi City Multi system is more suited to commercial applications with the smallest capacity being 6-tons. However, being inverter controlled, it may be able to slow down sufficiently to meet your demand. Another possibility would be a geothermal liquid-to-water heat pump with 4-pipe water supplied fan coil units. This configuration could allow true heating or cooling in all zones simultaneously with the ability to switch modes in all zones quite quickly. It also requires no ducts and no visible outdoor equipment such as multiple condenser units. Other possibilities with geothermal could include in-floor radiant with either thin slab (concrete) or tubing set closer to the surface of a thicker slab for a faster thermal response time and accompanied by forced air ducted, zoned cooling. In-floor geothermal cooling is also possible but requires careful management of humidity and airflow so as to avoid floors that sweat. All these solutions run from the very expensive to extremely expensive but can achieve your heating, cooling and comfort objectives. I canâÂÂt stress strongly enough the need to hire the experienced, accredited professional to design and oversee the installation of your system. This is not the job for an HVAC contractor whose office is a cell phone and the front seat of his truck! IMO SR...See MoreBest heating and AC options for raised 4 season porch addition
Comments (57)What I wrote never said a heat pump won't work in a cold climate like Wisconsin. Houzz actually covered up my first post. Here's what I said...... (truth is stranger than fiction) Here's the rebuttal link to going with Fujitsu mini split option or any mini split for that matter. Don't forget to read the comments at the end of all of it... My opinion is it will be short lived if you go that route. There are furnace manufacturer's that provide life time replacement if the heat exchanger of the furnace ever fails. Typically minimum heat exchanger warranty is 20 years. Do what you want builders provide me with future work so take that for what it's worth. After a year or two... you won't get a builder to come back for servicing or repairs....See MoreAC vs heat pump in Portland, OR
Comments (8)Heat pump efficiency in terms of monetary performance (what it costs to operate) is best compared to electrical strip heat. Because without really doing or needing to do math to any large extent the typical $monetary$ efficiency gain is roughly 75% better than electric strip heat. So for every $1.00 you spend on electric heat strip you could have only spent $0.25 for heat pump heat. BUT: in a cold climate that heat pump will have to defrost. The colder it gets in your climate, you will need back up heat... which is usually electric strip heat. The heat pump will have to go into defrost mode. This is why HP's are best for warmer *winter* climates. The con in using a HP in a warmer winter climate is spending that additional cost up front for using heat for a few weeks to a month of the year? So even in a warmer winter climate in an all electric house a HP can be a hard sell. ---------- HP's are draftier. Yes and no. When the HP is cranking out the heat, It's hot. Only when the temps breach about 35 degrees or so and stay that low for long periods. BUT: we're in a warm climate with lows typically in the 40's and sometimes only the 50's. --- Yeah, that's why they can be a hard sell. (The technology has greatly improved since the early 2000's. Anything can break though so it is what it is. Even AC's can break prematurely.) Some HP's perform better: Inverter HP's. Not only in heating mode, but also AC mode. I made a video embedded below, but I strictly go over AC mode only.... because most here are on gas heat and so... well it's a complicated subject. I provide the video here mainly so if this interests you, you will better understand what an *Inverter* is. (How it works, why you would want one.) Just realize that inverters are not created equally. Some manufacturer's limit them to merely 5 stages of functionality. These inverters cost even more, but they typically will cut your electric bill in half, just on the AC mode side of operation. Even more when compared to electric strip only heating mode, with much better performance of heat produced clear down to 5F in heating mode. ----------- Life span. It's complicated. Of the heat pumps that I've come across in the field... which is rare by the way in my climate... they were all older than 15 years. The other not thought of con is that there is no limitation to gas or electric heat for that matter when operating in cold weather. Cold meaning typically in the 20's and lower. The heat pump gradually loses it's ability to put out more and more heat as the temperature falls. Also in snow producing climates if snow drifts bury the heat pump, it's not going to operate well in those conditions either. ---------------- Couple related questions: 1. One of the above respondents said the ductwork in our house was optimized for heating and not cooling. How would the ductwork be any different if AC was installed when the house was built? I believe this is mostly related to cold air falls vs. hot air rises debate. Returns are placed low to the floor. In high ceiling areas and summer time conditions, heat gets trapped at ceiling level with no where to go... unless there's ceiling fans circulating things. If ceiling height is more moderate 9-10 ft. It may go unnoticed except for extreme heat wave conditions. 2. Another poster said duct cleaning isn't needed. The boss of the house really wants it. why do you say it isn't needed? thanks all! If you have unfiltered returns leading to equipment with filter(s) just before equipment. Those unfiltered returns are typically what is used in duct cleaning ads. Many on this board recommend placing these 4-5 inch filters before equipment... thus leaving the returns unfiltered. Beyond the filter. In the equipment and further down stream (supply air plenum and duct work) The dirt if any... is very fine and so miniscule that it would take some really high dollar equipment to get that dirt out. Unless they video every section of duct work they touch you won't know it's clean and it *may be* as clean as it's going to get. If duct work is so old that it's believe to be that dirty, you should probably replace it. There is nothing cleaner or more efficient than properly designed and insulated new duct work. BUT that's expensive. Well, duct cleaning is a lucrative field. They get in your door with a cheap advertised cleaning cost of $99 a system. But the end result is no where near $99. The oldest con game in the book. "High pressure sales." These people know what buttons to push to get that price up. Especially in a fear driven pandemic era of cleaning things. (no one makes enough money at $99 a system to stay in business, do not kid yourself. ) I service the Katy, Texas area....See MoreA Fox
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