$680 zoned HVAC instead of $5000 central system

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Re: $680 zoned HVAC instead of $5000 central system

Post by nutnspecial » Dec 23, 2017 2:25 am

Wow, I'll just trust you about 'most' people/situations in some other areas like Seattle. But people HATE it here.

And the maths work out to 'resistive heat' being 3 or 4 times less efficient than other forms of electric heat including simple infrared type, though. Or 'expensive' 500$ minisplits etc. So even when electricity is 'cheap', 3x the usage isn't 'cheap' in comparison, imo.
Like I said, I'm curious how my fridge works out since it's almost like it's outside (maybe 70%). So far it's staying balanced at 10f/34f with barely any input energy but I wonder what will happen to the fridge side when it gets colder haha.

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Re: $680 zoned HVAC instead of $5000 central system

Post by Chalo » Dec 23, 2017 3:45 am

nutnspecial wrote:
Dec 23, 2017 2:25 am
And the maths work out to 'resistive heat' being 3 or 4 times less efficient than other forms of electric heat including simple infrared type, though.
How do you reckon? If you're using electricity to make heat, a watt can't become more than a watt. Infrared heating can sometimes be better at putting the heat where it's most appreciated, but it doesn't somehow make more heat from the same power.

Only a heat pump gives you a different equation to work with. And it has to work against its added cost.
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Re: $680 zoned HVAC instead of $5000 central system

Post by dogman dan » Dec 23, 2017 8:42 am

Havent looked at this thread in quite some time, so this is a bit of a highjack back to last summer.

FWIW, I've been on combined swamp cool, and window coolers for about 25 years now. On the very dry spring/ early summer days we have here in the high desert, swamp cool can be great. Half the summer though, the summer rains make them suck. That's when I switch to window units entirely.

They are noisy, but you know what's much noisier? The fan in nearly every central heater I've had. Last summer we got stuck in that rental house while my home got rebuilt after the fire. It had a central refrigerated AC. Noisy as hell! And in the crappy insulated house, it ran close to 24/7. The bill was double what we were used to, for a much smaller house. If you could just set the fan to a lower speed, it would be better. This particular one made the whole roof rattle. Really shitty install, should have put the compressor on the ground outside.

To be fair, when it's 90f outside at midnight, our window units run 24/7 too, but no need to run the one in the living room. I have 1300 square feet to cool, with three units. The two bedrooms have 8000 btu coolers, and the living room has a 12,000. On a particularly nasty day, it can still be a bit hard for them to keep up, but that takes a 110F day. Most days the bedroom AC's run all day, but at a low setting that just circulates air 50% of the time.

The trick to making them quiet, is don't install them in the actual window. Mount them in the wall and they get half as noisy. Use some rubber or foam, and isolate the rattle so it does not make the whole wall rattle. If I had it to do again, this time I would not mount them under the window. What I do hear comes through the glass. The fan itself is noisy on high, but I can set it on low and its much quieter than my central furnace in winter.

As for lifespan, all three of these AC's are over 15 years old now and running fine. Most of the summer, I run the swamp cooler for about an hour right at dawn, which gives my house a good air change out. Then the house stays cool enough for the window units to stay off till almost noon. By night though, hot enough to keep running most of or all night.

That swamp cooler is on the roof, and when off, it makes a nice solar chimney. The hottest air in the house vents out through the ceiling ducts, helping the house keep its cool longer in the AM. Some kind of way to vent out the hottest air in the house can do wonders. I still want to do the duct to a huge hole in the ground, deep enough to tap earth cool. But digging in my yard is like digging in rock.

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Re: $680 zoned HVAC instead of $5000 central system

Post by Matt Gruber » Dec 23, 2017 8:52 am

i can see your point, gas is so cheap.
it is worth it just to have a quiet kitchen.
I'm under the impression that a fridge is a type of heat pump, and that the waste heat is 1/3-1/2 the cost of resistance heat. Or think of it this way; a 300 watt fridge may be putting out heat, like from half a dozen 100w bulbs, into the room!
Hi dan
thanks for chiming in!

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