TEST 850w table heater and 685w desk heater (page 6)

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nutnspecial   1.21 GW

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

Post by nutnspecial » Dec 23 2017 2:25am

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 3:45am

nutnspecial wrote:
Dec 23 2017 2:25am
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 8:42am

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 8:52am

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

Post by Matt Gruber » Feb 10 2018 12:08pm

UPDATE:
the goodman condenser coil cracked and leaked. RIP
will not try to fix as new window units are so cheap.
So now i can possibly use some of the old ducts for unit 2. Sure would be easy to hook into the old ducts. i plan to delete 1 room, about 20% of the house.
.
Hooked up unit 1 for AC, using the tips and tricks i've read about. (like 3 bends in the supply duct and rubber feet)
It is so quiet, i cant believe it! 8) :D
46.2 db,
OFF backround is 46.0

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

Post by Matt Gruber » Feb 19 2018 4:07pm

Have decided to put a 20" fan in the attic window, as with several ac's running at once, it will surely benefit with fresh air.
.
BUT, today was warm enough 80F to do a torture test to simulate summer with just unit 1.
I kept the window closed and no fan!
after 40 minutes the attic got up to 105F(was 90 ac off)
room got down to 73 and vent was steady 63. Fantastic! 8)
So, if the old goodman did not fail, it might not even need a fan in the summer, with the window open. A lot of heat can go out the ridge vent.

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

Post by Matt Gruber » Feb 22 2018 7:26am

Was even hotter, unusual for Feb., so i did another test yesterday.
This time with the condenser exhaust hooked up to a 12" flex duct, to the gable exit on the side of the house.
Still window CLOSED and no fan yet.
Attic was 95F at 3:10 PM, 5 more than last test.
Ran 40 min same as before.
Attic steady 100F (5 less)
room vent 59F(2 lower) so unit 1 likes being vented.
uses 700 watts to cool 1 room. i estimate a 50-65% duty cycle in the summer.
20" fan will add 51 watts on low, but will be on a switch in my BR, so only on as needed (not in the morning)
Unit 1 has a total cost so far of $200.

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

Post by Matt Gruber » Mar 01 2018 8:20am

IMG_20180228_130817.jpg
IMG_20180228_130817.jpg (114.69 KiB) Viewed 904 times
pic of the 1st step in converting window ac to central. cut hole in top for duct, top exit flows, like TWICE as much air!

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

Post by Matt Gruber » Mar 01 2018 8:25am

IMG_20180228_130906.jpg
IMG_20180228_130906.jpg (92.94 KiB) Viewed 904 times
Left vent supplies fresh air to attic ac room. 20" fan on low (51 watts)
Upper right vent is exhaust of hotter condenser air, for unit #1. (no extra fan)
UPDATE: 7-4-18 due to some backflow i increased the fan to medium speed, 74 watts.
Last edited by Matt Gruber on Jul 04 2018 6:25am, edited 2 times in total.

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

Post by amberwolf » Mar 01 2018 1:05pm

Matt Gruber wrote:
Mar 01 2018 8:20am
. cut hole in top for duct, top exit flows, like TWICE as much air!
That's an idea I should've tried years ago, and knowing how squirrel cage blowers work I don't know why I didn't think of that. ;)

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

Post by Matt Gruber » Mar 21 2018 11:05am

So i have wired 3 switches in my BR for the fan, unit 1, and units 2+3, simple ON/OFF.
I was never satisfied with a thermostat, so i'm using the $1.72 one just to remote measure the attic temp.
Used the $79 electric hoist to lift the small ac's into the attic. While i could lift them now, as i get older i don't want to hurt my back.
I've been using resistance heat in my BR AND SOLAR heat in the rest of the house. Have a 30" fan(40w) that blows warm attic air into the unheated rooms. This is fantastic, but no good on cloudy days or really cold days. and it doesn't work until afternoon when the attic heats up. But, it does wonders when conditions are good, and is almost free.
2 neighbors have had the ac truck in the driveway, including the 1 with the $6000 new system. I can't help smile :P as i may never call them again :D

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

Post by Matt Gruber » Apr 15 2018 5:11am

Nearing test time for units 2+3. The whole set-up is different than i imagined. Some things you just can't plan out.
Today i'll be attaching a drop cloth across the open trusses in the 5'x10' ac area. This is because the window fan creates a circulation that pulls down very hot air from the attic peak, about 4' higher. The plastic sheet should block most of it.
Will be testing it within 2 weeks, and expect a really hot day within 1 month.
Great hobby, i can't wait for the sun to come up so i can work on it for an hour or 2. (too hot up there after 11 am)

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

Post by Matt Gruber » Apr 23 2018 8:25am

1st tests of central units 2+3. very quiet, can barely hear it. 75F outside at 9:15am, so will have to wait for better torture test.
After 53 minutes it dropped humidity in the kitchen/dining to 55% from 62% Feels real cool, temp down 4, 73 was 77F
This is only 10,000 btu (old was 35,000btu)
BUT my BR has unit 1, so it is blocked off.
also blocked LR and 1 bath.
good so far! :shock:

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

Post by Matt Gruber » May 05 2018 6:30am

So i've decided to convert my living room into a Florida room 8)
I've always wanted a screened in porch, so i could sit in the fresh air and not feed mosquitoes.
Since i decided to NOT AC the LR, this is fairly easy. The bay window catches the east sea breeze that exits thru the west window. The west afternoon sun is BRUTAL, so i'll stop it by making another louvered vent like i made for the attic window, for the ac. (see previous pic). So this is my next project.
Just started using unit #1 AC yesterday. At 5:35pm it was 82 in my BR, on for 1 hour, dropped to 78F 8) works great despite attic being 112F at start up (dropped to 96, fan on)

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

Post by spinningmagnets » May 05 2018 7:44am

cut hole in top for duct, top exit flows, like TWICE as much air!
I agree with Amberwolf, I hadn't thought of that before, but...it makes sense. I used to clean swimming pools as a second job for a while (many years ago). I noticed one pool had a LOT more flow than all the others (which used common components). I immediately noticed that the PVC tubing was twice as large, and I expected that the pump was also larger. I was shocked to see that the pump was slightly smaller than normal.

There is a lot of inertia in the design of swimming pools and their components. Everyone does what everybody else is doing ("If it works, don't fix it"). The reason I found this thread interesting is that in heat-transfer systems (whether cooling or heating) increasing flow is more important than systems are usually designed for. Take this idea to the extremes. Imagine an extra-cold air-conditioner on a hot day, but...the flow is so low that the room air is only cool near the A/C unit. Compare that to a home where the A/C is a little small for the load, but the flow is high enough that the entire home (or room) has an even temp.

Altering a window-A/C unit like this is cheap and easy, and I really like the idea of setting it back a bit, and ducting the flow into the room to make it quieter.

One of my favorite tips from "builditsolar.com" is...hang shade-cloth from the eaves over the windows (in the summer), and whether your weather is hot or cold, attach clear bubble-wrap to the inside of windows to insulate them, while still allowing light to come through (plus it also adds some privacy). Hot (or cold) glass sucks the interior temps into the outside air.

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Re: $400 zoned AC instead of $5000 central system

Post by Matt Gruber » May 05 2018 10:28am

spin
thanks for your reply! interesting on the pools, and bubble wrap.
.
When my house was new, 29 yrs ago it really needed a big ac. I planted 2 sycamore trees, and they now shade the house quite a lot, except for the west wall. So the ac load is less. With half the ducts blocked off, units 2 + 3 don't have to work real hard as they cool the east side. Unit 1 is cooling the west BR, but it is plenty big, 8,000 btu for an 11x14' room.
.
So true that everyone just does what they did decades ago, without taking advantage of low cost components.

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quickie drains need upgrade!

Post by Matt Gruber » May 19 2018 3:13pm

Had to suck on the hose to get it flowing :roll:
Now working on a better drain. Needed to see this thing work for a while to learn about AC drains. Drips into an 11 qt pan, then it exits at 1.5 inches. Except the slope didn't slope, and the water didn't flow. May raise up the pan to get more slope. With the AC working great, i don't mind a complaint. :oops:
Got 2-3 gallons in 3 hours from units 2+3. Humidity dropped to 57% from 68% 76F from 81. Rain has cooled things off, so off for the rest of the day.
Got lazy when doing the drains. :lol:

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

Post by spinningmagnets » May 20 2018 8:31am

With half the ducts blocked off, units 2 + 3 don't have to work real hard as they cool the east side
I did this too, to save on AC because I had two extra bedrooms I only used for storage, and it worked. However...

when winter came, the heater would come on for a minute, and then just shut off (blow cold air). I called around, and a HVAC guy was going to cost $60 just to look at it and give me a quote. I was resigned to my fate, but I thought I'd investigate for a day first before throwing in the towel. I got the model number off of the unit (located in the attic), and did a google search. It had a blinking LED code when I started it up, and it said there was high back-pressure. Too much back-pressure isn't itself a problem, the fan still spins, but there simply isn't as much flow as it was designed to put out.

In heater mode, the burner comes on, and the constant flow of cold/not-warm air over the outside of the heat-exchanger will keep the flame from eventually eroding through the flame housing. If it managed to erode through, then the flame could be putting a little bit of CO/CO2 into the air while you are sleeping, instead of the flame exhaust going up the chimney. therefore...too much pressure in the outlet after one minute will shut down the flame, as a safety measure.

It dawned on me that the two blocked-off room vents might be causing the back-pressure to be a bit higher than normal. I opened them, and suddenly the heater worked fine, so...saved myself $60 at a minimum, and I would have gladly paid much more if a crooked HVAC guy fixed the problem and claimed to have swapped-out an expensive set of sensors, etc...

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learning how to best use my new central

Post by Matt Gruber » May 25 2018 3:25pm

Hi guys,
Finally have a full sun ac test day. Todays test in progress it to see if U2+3 can cool my BR too! this is crazy with only 10k btu, but it is doing fine, start 11:18am, continuous on, now just after 4pm. It is not real cool, about 80F, but it has taken over 3 gallons of water out of the air, so it feels nice. I'd rather run the crap out of U2+3 since it consists of a new $85 haier and my 16 year old haier. If they wear out or fail, they are the runts, and i'll replace them with a single larger unit, possibly 18k btu. Today was a typical beach breeze day, high of 85. Unit 1 is OFF.
Attic air temp (taken at the condenser entry of unit 1) is now 108F.(with 20" gable fan on low).
since 2+3 use ~1kw, it only costs a dime an hour! 6 hrs/day would be $18/month(will be more as i plan to use unit 1 after 6pm and shut off 2+3) Maybe $25-30 total?
Thanks for reading!
.
edit, clouds appeared, temp dropped to 80, Ac OFF 5:03pm
UPDATE: 1st 15 days of ac added $10 over no ac. Nearly every day an afternoon Tstorm so not a max bill. Only hit 91 once, usually 84-86

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Hottest day so far 88F

Post by Matt Gruber » Jun 18 2018 3:26pm

I've been using units 2+3 to cool both zone 1+2 for 27 days so far. (unit 1 off)
Today is the 1st day that we had all sun, 88F, and it could not keep up :lol: I have some choices:
1. turn on unit 1.
2. turn on 52" ceiling fan.
3. turn off units 2+3, turn on unit 1 and cool zone 1 only,
4. 3 plus close den door, open br door to use just unit 1 to cool br + kitchen.
Since it was 4pm and i was done in the den, i'm doing #4.
Overall, i'm impressed how much comfort can be had from 10,000 btu's. Takes out 6 gallons of water a day :mrgreen:
.
ps: attic air entering unit 1 condenser= 102F
Last edited by Matt Gruber on Jun 18 2018 4:12pm, edited 1 time in total.

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Re: Hottest day so far 88F

Post by markz » Jun 18 2018 3:56pm

Matt Gruber wrote:
Jun 18 2018 3:26pm
I've been using units 2+3 to cool both zone 1+2 for 27 days so far. (unit 1 off)
Today is the 1st day that we had all sun, 88F, and it could not keep up :lol: I have some choices:
1. turn on unit 1.
2. turn on 52" ceiling fan.
3. turn off units 2+3, turn on unit 1 and cool zone 1 only,
4. 3 plus close den door, open br door to use just unit 1 to cool br + kitchen.
Since it was 4pm and i was done in the den, i'm doing #4.
Overall, i'm impressed how much comfort can be had from 10,000 btu's. Takes out 6 gallons of water a day :mrgreen:
.
ps: attic air entering unit 1= 102F
Sounds complicated. There have been a few times where I'd come in from a very hot day, and after a few hours of house ac be freezing and wear a light hoody, I love it!

Now, if we could come up with something where we can ride our ebicycles in the blaring hot heat, and put on our "a/c T-shirt" and enjoy. Bette yet, have our bottle cages wrapped in copper to keep our carbonated lemon water ice cold.

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Re: $400 2 zone central AC system is now working.

Post by Matt Gruber » Jun 22 2018 11:00am

So i've been plugging air leaks in the house. Bathroom was cool even with window open and door closed. Put weatherstrip under door, big leak there. Still had cool air coming out of the ac vent even tho i plugged main duct. Fixed that too. now it is hot in there, no more leaks.
Had long crack in hall where wall meets ceiling. With the gable fan pressurizing the attic, hot attic air was forced into the hall :( Ceiling there is 12' high so i put it off, until now. Didn't fall off the ladder :D
BR door had HUGE gap under it 1.5", reduced that to 1/2" Going from 35,000 btu to 18,000 requires less leaks :mrgreen:
4pm update
works much better! today 86F and sunny, only used 10,000 btus all day. did NOT turn on unit 1 at all. cooled BOTH zones 8)
I'd say 90's will require full power, but, last year there were only 12 days in the 90's 8)
7-11-18 update: 91F and sunny does not require full power. Increased attic fan to medium speed, 74 watts, due to some backflow with all 3 ac on.
7-6-18 power for the month looks to be 317 kwh, 1% less than last year.
Last edited by Matt Gruber on Jul 11 2018 5:27pm, edited 1 time in total.

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Re: $400 2 zone central AC system is now working.

Post by Matt Gruber » Jul 06 2018 9:53am

here is a $355 14000 btu portable ac/heater:
https://www.ebay.com/itm/14-000-BTU-Por ... SwDFBaA60M
if someone following this topic wanted an easier to install ac, this could be it. should be much easier to hook into central ducts. And if the heater works good, that would be a bonus.
EDIT
the numbers don't check out. more like 8-10k btu. good for 1 room for sure

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Re: $400 2 zone central AC system is now working.

Post by amberwolf » Jul 06 2018 3:56pm

Just so you know, that type has a hose designed to sit in a window, and it pulls in room air thru the heat exchanger and vents it outside via that hose, while a separate air path and fan moves room air thru the other side of the heat exchanger and back into the room.

In normal use, that's not very efficient, as it pulls outside hot air back into the room (or elsehwere in the house) from all the various air leaks in the house. If there's no air leaks that allow outside air to flow back into the house, then it can't push much air thru the outside-loop exchanger, so it doesn't remove much heat from the room.


However, in your usage, if you're putting that unit in the attic, then you can just duct the room-air-loop inlet and outlet into your indoor-loop ducting, and use the ex-window-hose part of the outdoor loop to push the hot air from it to an outside vent (so it doesn't heat the attic more, making the system less efficient).

Or if you're putting the unit in the house, you can do what I did with one of those, and setup ducting to the outside-loop exchanger's air inlet, so it doesn't move room air thru it, but rather takes outside air to pass thru it. It does mean that the outside-loop starts up with hotter air, so the air inside isn't cooled as much either, but it most definitely worked better this way than it did as-designed, keeping the room cooler for the same temperature setting, runtime, and energy usage.

I didn't ever get to doing it, but I had worked out the basic idea for an evaporative pre-cooler for the outside-loop air.

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Re: $400 2 zone central AC system is now working.

Post by Matt Gruber » Jul 07 2018 5:03am

Amberwolf- good info, thanks for posting.
.
My ac works surprising well, but unit 3 is my 16 year old former spare. So now i have no spare, and i plan to get one. Another surprise was that my 29 year old ducts are clean inside. i expected them to be clogged with dust or maybe even mold. not so! So now that i see my old ducts are good, and that 18000 btu cools fine, i could just use a single 18k ac. Last sept. walmart had a sale on one for $229 free ship. Come sept if i see a sale again, i'll buy it, and this winter i'll modify it for easy connection whenever it is needed.

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