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chedemefedeme posted:Humor me this, though. Last night it got down to maybe 70 outside. My wifi thermostat's stats show it ran 30 to 40 minutes of every hour to maintain 85 degrees...is that still normal? The hot has to come from somewhere. If it's not from outside, and it's not from the sun, then where? I'd bet that your electricity bill is expensive because of the thing that's making the hot. Probably either computer equipment or electric baseboards.
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Jul 18, 2016 05:51
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| # ¿ Apr 29, 2024 02:52 |
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chedemefedeme posted:I was simply trying to ask if the system needs to be checked. 50% duty cycle to maintain 85 degrees inside when it is dark out can't be normal? My point was that if nothing is hotter than 85 degrees, you should have a 0% duty cycle.
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Jul 20, 2016 02:11
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DreadLlama posted:Have any of you thoughts or experience with absorption cycle air conditioning? Absorption cycle refrigeration is poo poo. If you're thinking you want to use solar thermal for air conditioning, forget about it. It's become far more cost effective to use PV with vapor compression refrigeration. If you've got an industrial process with a lot of waste heat, it can be worth your time. Delivery McGee posted:Propane doesn't naturally have a smell, the stink is added and is mostly skunk-ish mercaptans, because the schoolhouse in the town next door to my city just fuckin' leaped off its foundation and killed a whole lot of kids, due to a leak in a natural gas line, back when gas was tapped off the oil wells as a waste product, and tapped off of that line for heating purposes. There was a leak, the shop class' saw made a spark when turned on, BOOM. My parents worked with someone (in the oil & gas industry) who got an entire city block evacuated by forgetting about a canister of thiol in the trunk of his car 
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Jul 26, 2016 05:02
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They're better than nothing. Despite the marketing, you pay a substantial efficiency cost with it, but it will at least save you from dropping soffits all over. I've only heard bad things about slab ductwork, so I'd guess you're right that it's a total loss. The other option you should consider is mini split heat pumps. It will vary quite a bit depending on your layout, but if you can cover things with a small number of heads (using ducted heads or other powered ventilation if necessary), but it can be significantly cheaper to install (ballpark $3k-$4k per head). The really good ones will work well enough in NJ to be reasonably affordable to run with electric backup heat even in a poorly insulated home, though it will still cost more than natural gas (a point source like a natural gas fireplace can offset that). And on the upside, you'll get very efficient cooling and great zoning.
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Aug 6, 2016 05:57
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It's a standard feature with ground source heat pumps as well, since it's required for the Energy Star rating needed to qualify for the tax credit. It suffers from the same problem as all schemes to generate domestic hot water: residential hot water consumption is rarely high enough to justify the upfront cost of designing/manufacturing/installing a complex system. And on the rare occasion that it is, conservation is almost always more cost effective.
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Aug 16, 2016 19:56
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Oh! I forgot about heat pump water heaters. Same concept, except the "air conditioner" is built into the water heater, so you bypass the added engineering & installation overhead costs, so it ends up being more cost effective even though you double up on compressors & heat exchangers.
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Aug 16, 2016 20:25
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People always want to put a head in every room. It blows up your equipment cost and the install labor, and you end up way oversized in every room, so you get a ton of cycling and kill your efficiency. 6 heads for <1600sqft is ridiculous. In a completely uninsulated home, you are likely to end up with a relatively large temperature differential in rooms without a head, at least without powered ventilation, but your money & effort would be better spent air sealing and insulating to address that.
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Aug 17, 2016 02:47
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Yeah, unfortunately that's pretty typical very old house construction (they also typically make the "need to breath" thing much worse by omitting things like flashing). You can't insulate without tearing down one side of the wall, but that side can be the inside - this article covers the options well. Or if you're really desperate, you can tack a foam + drywall sandwich on top of your drywall. I understand the appeal of the quick HVAC fix, but the at the end of the HVAC -> Insulation sequencing, you end up having spent more time and money to get worse sizing compared to Insulation -> HVAC. But if you don't want to do that, you can use powered ventilation to force mixing and get one head to cover more than one room. Ducted casette mini split heads can be easily hidden in closets or small soffits and cover 2 or 3 rooms, or use can use vent fans (cheap and ugly through wall fans, or better looking ones that can be hidden in stud bays, or panasonic bath fans in the ceilings) to mix air from a room with a ductless head.
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Aug 18, 2016 02:24
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The most efficient way to set both to the highest temperature you are willing to. It doesn't really matter if one is higher than the other.
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Aug 20, 2016 01:47
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| # ¿ Apr 29, 2024 02:52 |
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Your system isn't built like a commercial setup, so there's not any simple all-in-one package that's going to get what you what you want. For fresh air intake, the best option is some sort of Heat Recovery Ventilation unit, which can reclaim heating/cooling energy from ventilation air to make it reasonably efficient year round. Some units will also support an 'economizer' option to bypass the heat exchange core when outdoor conditions are appropriate. Balancing dampers are usually an easy retrofit if you don't already have them. Per room zoning is pretty much totally unreasonable with residential central forced air. IMO, even a basic 2-zone retrofits usually don't turn out all that great; to get good quality zoning you need to design the ductwork for it from the start. If you want control down to the room, your best best is a hydronic system. For humidification/dehumidification: IMO, you should never have both. If you live somewhere humid enough that supplemental dehumidification is needed, then running a humidifier in the winter both indicates a problem with your building envelope (if it's not leaking like a sieve, it won't get super dry) and risks mold & moisture damage from condensation on/in cold building materials.
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Aug 22, 2016 03:21
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