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Manual J load calculation. Measuring the house, walls, windows, doors, ceiling height, wall thickness (insulation), house construction (vinyl siding, brick, stucco), floor (crawlspace, basement, concrete), attic insulation, etc.... everything gets entered into a computer program and it will compute the size needed for a specific temperature difference. Reputable HVAC companies normally do them when they get the job. | |||
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| Member |
If you have this kind of inbalance issue and the upstairs never gets cool. You're going to want to mention that to whoever is quoting the system, I would pay attention to how much time they spend looking at your setup after you mention that, and you're going to want to get a really good tech or company to figure out how to fix the inbalances in the system/your house. It may be as easy as moving a return or installing a damper or some ducts, or a lot more complicated than that. When it's hot out, the majority of heat in a home usually comes from the ceiling/roof heat. | |||
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| Team Apathy |
Hmmm, so if they don’t do the load evaluation how do they bid accurately? You mention that my current unit is a 2.5 ton but earlier I read somewhere (of unknown pedigree) that a house my size (1920 sq ft) should be in the 5 ton ballpark. So if company A comes in and says a direct replacement will cost X but company B shows up and says my unit is undersized and I need bigger that will cost 2X, how do I know which one is more accurate in their assessment? | |||
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His Royal Hiney |
And what you said is all that I was agreeing to. I glossed over the brand difference as the difference between 8 and 12 is small compared to stuff build just after WW2 and still working. The difference in the robustness between systems manufactured back then versus recent times is the determining factor with the longevity. Yes, installation workmanship is a factor but that was an issue back then also. The previous robustness was able to absorb to a greater degree any shortfall in workmanship.
"It did not really matter what we expected from life, but rather what life expected from us. We needed to stop asking about the meaning of life, and instead to think of ourselves as those who were being questioned by life – daily and hourly. Our answer must consist not in talk and meditation, but in right action and in right conduct. Life ultimately means taking the responsibility to find the right answer to its problems and to fulfill the tasks which it constantly sets for each individual." Viktor Frankl, Man's Search for Meaning, 1946. | |||
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First, by asking how well the existing system performed. Did it have any problems maintaining temperature? Companies local to the area will have a general idea on size by looking the house over. There's not a huge difference between a half ton of equipment. So if it gets bid for a 2 ton and then requires 2 1/2, no big deal... same price to the client. | |||
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| Peace through superior firepower  |
Show of hands- who in this thread works in HVAC for a living? | |||
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I do! | |||
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| Member |
I do. | |||
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| Team Apathy |
As the poor dolt looking at spending gobs of money I obviously am not.  | |||
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| Peace through superior firepower |
Stlhead and Excam_Man are HVAC professionals. Anyone else in this thread? | |||
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| Team Apathy |
Ok... I figure a professional would have some sort of idea after seeing the house and knowing our area. I’ve scheduled 3 so far to come do a consult plus Home Depot. Not sure who they contract with but no harm in getting a quote. You mention discussing the current system performance and I’ve mentioned the difference in temp between upstairs and down... what type of differential is considered normal? Let’s talk scenarios... it is late July here and the afternoon high will be 105 (common) and it’s 85 now at 8:00am. If I close up and kick the air on set at 74 (thermostat is downstairs in a main living area) it’ll probably run continuously all day and hold s comfortable temp downstairs but the unit will likely not cycle off much if at all. Meanwhile, upstairs will likely never dip below 85 at best. Upstairs is warmer in the winter too. I understand that hot air rises and the second floor is essentially directly below the roof (no crawl spaces or attic over 90% of the 2nd floor living area) but is the difference I’m seeing unreasonable? And just as added info that is somewhat relevant: the roof is wood shake that is original to the house, like the HVAC. It will be replaced before summer sets in. We are also likely updating all windows and the two patio sliding doors as well. In the summer you can feel the heat radiating from the doors as well as the cold in the winter. I figure these changes will impact our HVAC system significantly as well. | |||
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My business is an authorized Dometic reseller and installer for all of their air conditioning brands for: chilled water, direct expansion, and package units. I employ an HVAC tech with a ME degree from FSU that does the installs and repairs. Many times I diagnose the issues, pick up the parts or systems and then send him to the jobs with parts in hand. | |||
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| Team Apathy |
Do we like Rheem HVAC systems? Got a couple bids today, the better one was a Rheem AC with forced air gas furnace and I really like the proposal. It gets me away from our heat pump, which is a silly choice in our area, the price was reasonable compared to the other 3 quotes I’ve had so far, and the representative really took time to inspect my current set up, listened to my concerns, and proposed some solutions to fix them beyond “a bigger unit”. He agreed that my return system needs adjustment and said they’d fix it plus add some supply lines in the large upstairs living area. He quotes a 3.5 ton unit (current is 2.5) but said that would be confirmed in a load calculation should we proceed. Feeling good about this one. We have 2 more companies scheduled to come out, one tomorrow and one Monday. Had another company come out today who wanted to quote all3 projects we are doing, roof, windows, and HVAC. He blindly quoted 12k for the HVAC without even looking at anything of asking anything. Then he asked what my max financing approval was. I asked what possible difference it made to him quoting what I needed for my goals and he didn’t have much of an answer. I then politely ended the proposal and saw him out. I wasn’t with it quick enough to catch the first guy who did that a couple days ago but I learned a lot from that process. I saw this one coming. I’ve learned these companies who want to do it all are shady as all get out. Go prey on someone else. | |||
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| Member |
I have had nothing but issues with Rheems. The unit installed in 2010 so far has been through 2 air handler blower motors, 2 condenser fan motor and something else that I can't remember. It's had the more trouble than all other units I own combined. My preference is American Standard or Trane. But there are others that are good. Heat pumps are actually very good for your climate and efficient. Getting back to your scenario, since nobody else chimed in, in a few days. It's difficult to give advice without seeing your house/setup. But, A 2-3F differential at most is what I'd look for between rooms or rooms and floors. The vast majority of heat load comes from the roof heat. When you say that 90% of your second floor has no attic or crawl space. Is your ceiling the exposed wood 2x6"s and beams (sort of an A-frame house)without any insulation or is there a finished ceiling of some sort (dry wall screwed to the rafters) with or without insulation under it? You mention your wood shake roof is in poor condition, I'm not too familiar with them, but I do know that with the new metal roofs they reflect a lot of the roof heat and they now have insulating underlayments that go between the metal roof and the roof deck that do a pretty good job if you cannot insulate your ceiling. It sounds like the tech you mentioned has come up with a plan to fix your issues. The new houses I deal with, they have gone to a supply duct in the rear of every room, and a return duct in the front of every room (in the ceiling) near the entrance door. The returns in the ceiling in every room do a better job at sucking the rising heat out and having balanced rooms whether a bedroom or hall door is open or not. This likely isn't feasible to retrofit in your house, but getting more return(s) somewhere up on the second floor to the unit and more supply vents and a large enough unit should correct your issue. | |||
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| Team Apathy |
The upstairs predominantmy have a sloped ceiling that follows the slope of the roof itself. Drywall fastened to the joists. I assume there is some sort of insulation in there. Several roofers offered to blow in additional insulation for various rates but I don’t know that it would even be able to take anymore given the lack of airspace. While the heat pump isn’t a terrible fit for this climate it is much more expensive to run a heat pump when compared to natural gas. The running cost of NG is less than half that of electricity. Would you ask about brands other than Rheem? He quoted a Trane but it was significantly more expensive and he didn’t think it was worth the price difference. | |||
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| Member |
American Standard is owned by Trane and quite a bit cheaper. It's a good balance of cost versus quality. Are there any light fixtures or anything attached to the ceiling that you could take off and peek into there with a bore scope camera or mirror? Generally given the age of the home, they would've used rolled insulation with a vapor barrier paper and stapled it to the wood underlayment, if it was insulated. If it's not insulated and someone can blow it in, it should save you in electric, in what it costs to do in 4-6 months generally. Call your utility company (electric) and see if they do free home energy evaluations. If so, they'll generally send someone out to check everything, give you a survey on what adding things like insulation would cost and how much you'd save. I would think that in CA they would, and they usually give fairly good rebates for things like insulation, windows and doors etc. | |||
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| Member |
Thumper, Good advice here. Once last suggestion is a quote from the Costco-endorsed HVAC vendor. Costco has a reputation to protect and tends to endorse/support middle to higher-end contractors at competitive prices. Good luck. I'd say go for the windows and HVAC and have them throw in a whole house fan and smart T-stat for kicks and giggles. P229 | |||
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I don't normally talk about brands, as it is more important to find a reputable installer. But Rheem isn't on the best liked list of manufactures. Why do you feel a HP is a silly choice for your area? According to the weather data for your area, a HP would be the preferred equipment. Unless, your electrical rates are crazy compared to natural gas. Which wouldn't be normal. If you know the cost of each, post them and I can see which would be more beneficial. I would be skeptical of any company which blows away the competition. As quality work takes time and materials, neither of which are cheap. So the question you have to ask yourself, is why can this company be so cheap compared to the others?
This would be highly unusual. Do you have a cost per KW (electric) and cost per Therm (NG)? | |||
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| Team Apathy |
As I understand it 1 therm is approximately the same as 30 kWh, correct? According to my last bills each KWH cost me $0.16 and each therm of NG cost me $1.24. $0.16x30 = $4.80 for an equivalent amount of energy. The electric rate will go up in the summer too, though won’t be using the heater then. Unless I screwed that up somewhere. | |||
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| Member |
Your math is pretty close if you are using resistance heat. You are missing the 8% - 10% efficiency loss of the gas furnace, and the efficiency gain of the heat pump. You get about 2.5 times the heat from a heat pump as you put in in electricity. With those energy rates I would estimate that the actual numbers for heat pump vs gas furnace are $1.35 for gas and $1.85 for a heat pump. Note that your climate and your equipment selection can change these figures, along with energy cost changes. You guys get robbed for energy in your beck of the woods. | |||
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