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diy solar

diy solar

my furnace back up

David in nh

dreaming of 48 volts
Joined
Oct 18, 2019
Messages
162
this is my oil furnace battery back up , plus one outlet , it is a aimes hard wired 12v 1200 watt inverter with built in transfer switch
, a home built battery 200ah lifepo4 with a overkill bms , not having to add other meters to see what was going made install much cleaner , the blue tooth to my tablet works great .
battery has circuit breaker in box and is attached to inverte2 with a 175 amp anderson connector and #2 wire
this is a small system only ment to run the furnace untill i decide to start the generator , larger transfer switch on left is for that , the 12v is in line after main transfer switch , so 12v goes off gen goes on

as for charging thats a project for later , for now i use a small noco charger that does lifep4 only took me watching 100 for Will's videos to try something

below is a shot of the furnace running at 229 ways but it does go up to 497 when all zones are working , in this pic it was just heating my hot water after being off for a day , when the furnace is doing nothing it pull 23 watts

house is very well insulated and does not cool down fast , but if the power goes out over night or i am away i hoping this will get few more hours of heat i am hoping for a least 8 hrs but and will test out on a cold day at some point maybe i will ad a solar panel or two

now be kind if you see something wrong :)
20200906_180052.jpg
20200904_202946.jpg20200906_193853.jpg
 
Does this setup successfully power the burner and blower motors?
this is a oil fired forced hot water system (baseboards)so there are no blowers . and yes if you look at the screen shot screen shot of the bms
in a very well insulated 20 year olds home 1200 sq ft house
turned the heat to 80 to make it come on and heat domestic hot water i got 497 watts furnace had been of for 24 hrs surge rating on inverter is 2400 with run of 1200
 
Looks like about 4.5 hours of backup power at full blast.
yes thats what i got time wise at full tilt , but since this is a oil fired forced hot water system (baseboards) even at below zero temps Fahrenheit that are fairly rare here it never runs at full tilt more then 50 percent of the time , the one circulate pump on the heat loop takes very little power

At 30 Fahrenheit were ice storms take place and that's when i loose power furnace may only run on full 30 percent
 
this is a oil fired forced hot water system (baseboards)so there are no blowers . and yes if you look at the screen shot screen shot of the bms
in a very well insulated 20 year olds home 1200 sq ft house
turned the heat to 80 to make it come on and heat domestic hot water i got 497 watts furnace had been of for 24 hrs surge rating on inverter is 2400 with run of 1200
Ahh.
Boiler, that makes sense. Air movers are tricky to power up the loads... a boiler would be a lower demand system.
 
here are some answers to question from people i got that are not on this board

Q what did it cost ?

A about 1000 dollars for inverter bms battery wire dc breaker and wire

Q you could have done it cheaper with a ebay inverter and a deep cell battery

A yes on inverter , but then i would not have a ul approved inverter with a automatic transfer switch
A batteries for the same power i would need at least 2 sealed batteries then i would have wanted all the information the bms give me so there would have been more wiring and parts this keeps everything simple


Q seems like a waste of time and money to me

A its a hobby i enjoyed doing it , cheaper then sitting at a bar
A think of this way , power goes out at 9 pm i get up in the morning house is warm . start the generator to run the well pump , put a small added charge to battery take a shower because the furnace does the hot water it is hot already , as i get ready for work the fridge / freezer does it thing , i then shut off gen and before i leave i turn the heat down to 55. to give my battery a few hours off before they need to do anything and so the fridge warms up less
i then go to work on time , and buy the time i come home most likely the power will be on.

well at least that's my story and i am sticking to that lol
 
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Some more testing .now that I have the furnace all set I thought I would test out the fridge.
I have manually plug that in to the inverter but was surprised to see it pulling 138 wats when running , I expected more than that .
It looks like Could run the furnace and the fridge at the same time but with 200ah battery and no Solar I do not plan to do that , but if the power goes out during a non heating time , could stretch the run time on the fridge
 
Update
well we have not lost power in the last few storms , so it was time to a overnight test

#1 outside temp 20F inside 68f

#2 domestic hot water done trough furnace, still on but never used ,like if the power was out because i would have no power to well

#3 basement heat zone is has thermostat all the way down as always unless i am down there working

# 4 overkill bms reading 199.2 ah

flipped the breaker off at 6:30 pm

next morning turned power back on at 6:30 am

bms now reading 103 amp hours

one very happy camper
:)
 
Since you have plenty of high-grade thermal energy available, how about a Sterling or other heat engine running a generator? Can you come up with a safe, low maintenance generator to keep battery charged and produce 100% of the heater's electric needs?
 
I always thought if you had a wood burning stove that useing some TEG's rigged up to some PC water cooling parts with the cold side ran outside through the wall to a radiator would net you a fairly constant source of several hundred w depending on how many you used.


however I the brain threw all that section of heat transfer from college... something about 600F on one side...and how many btu can i transfer across 3800mm based on a given cold plate...20f deg liquid..what flow rates are needed..what does that result in a temp drop across the TEG
 
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Since you have plenty of high-grade thermal energy available, how about a Sterling or other heat engine running a generator? Can you come up with a safe, low maintenance generator to keep battery charged and produce 100% of the heater's electric needs?
not sure why or how i would want to do that , my electricity bill runs 35 to 40 dollars in the winter for my whole house
this is just for the few times a year i lose power during a storm

as for high grade thermal , this is the granite state so in my case i would have to have bore holes drilled , but again at the price of oil even when it was twice as high , thinking not a good choice for me

now i am adding a small solar panel at some point to keep the battery topped off
 
I always thought if you had a wood burning stove that useing some TEG's rigged up to some PC water cooling parts with the cold side ran outside through the wall to a radiator would net you a fairly constant source of several hundred w depending on how many you used.

i do not have a wood stove , not a fan of them , sure if lived out in the woods far from everything , but i live on a two acre lot in a housing development , cool idea but i think i would be better off with some solar panes
 
not sure why or how i would want to do that , my electricity bill runs 35 to 40 dollars in the winter for my whole house
this is just for the few times a year i lose power during a storm

as for high grade thermal , this is the granite state so in my case i would have to have bore holes drilled , but again at the price of oil even when it was twice as high , thinking not a good choice for me

now i am adding a small solar panel at some point to keep the battery topped off
I only meant to keep the furnace operating during power failures without sunshine.
Often it is during stormy weather when you want heat and the power is out.

By high-grade thermal energy, I meant the temperature of the furnace is sufficient to run a steam engine, not like flat-plate solar collectors.
Efficiency isn't important. Something like a sealed Sterling engine would produce mechanical power to run a generator, and the waste heat ends up in the room anyway.

Thermo-electric appears attractive at first, but cost per watt is excessive.

If you can live through power failures, bundle up if necessary, then non-PV solutions aren't practical.
 
I always thought if you had a wood burning stove that useing some TEG's rigged up to some PC water cooling parts with the cold side ran outside through the wall to a radiator would net you a fairly constant source of several hundred w depending on how many you used.


however I the brain threw all that section of heat transfer from college... something about 600F on one side...and how many btu can i transfer across 3800mm based on a given cold plate...20f deg liquid..what flow rates are needed..what does that result in a temp drop across the TEG
Since you have plenty of high-grade thermal energy available, how about a Sterling or other heat engine running a generator? Can you come up with a safe, low maintenance generator to keep battery charged and produce 100% of the heater's electric needs?

okay guys now you got me thinking , and i admit i really no idea what you were talking about , but looking at the amazon link you gave me above
i gotta ask has one any tried these out ? would they put out any power at the temp difference of my furnace and my basement say 60 degrees and 160 ? not home not sure of temp of water the runs though 180 ?
https://www.ebay.com/itm/12V-15A-He...793215?hash=item3b079ce4ff:g:-qEAAOSwbdpWYUAK

i see them as low 12 bucks

would they really produce any power when clamped on to the copper pipes coming out of the furnace ?

ais there any data for doing this like a 12v 15a Thermoelectric will produce 1v at .5 amp or if they are pruduce the volts is always 12v and the amp very s according to temp difference ? at a 100 temp difference

now if they could produce say 1 amp of power at 12 volts and use two to get 24 volt and run it though one those cheap lifepo4 chargers
that may be fun project 2 of them and 24 dollars and a 15 dollar charger . it may be a fun project to try
 
Single one, not much power.
Somebody had a listing for 30W unit with self-powered fan. But it said it works at 380 degrees C, max temperature 450 C.
Usually TEC are assembled with solder, melts at too low a temperature. For TEG application with 450 C max, there is a narrow window to avoid wrecking it.

TEG are used in some expensive industrial applications, like oil fields with gas always flaring off, for low-maintenance power.

One guy got an oil fired heater with TEG that seems to work.

 
here are some answers to question from people i got that are not on this board

Q seems like a waste of time and money to me

A its a hobby i enjoyed doing it , cheaper then sitting at a bar
A think of this way , power goes out at 9 pm i get up in the morning house is warm . start the generator to run the well pump , put a small added charge to battery take a shower because the furnace does the hot water it is hot already , as i get ready for work the fridge / freezer does it thing , i then shut off gen and before i leave i turn the heat down to 55. to give my battery a few hours off before they need to do anything and so the fridge warms up less
i then go to work on time , and buy the time i come home most likely the power will be on.

well at least that's my story and i am sticking to that lol

beautiful answer to that kind of question
people without vision/understanding it all seems useless. They are also the ones who buy $75,000 trucks and think all is well (THAT is useless to me - each of us have our choices)

a hobby shuts down most people who ask that question
 
30W to 50W hardly qualifies as an "appliance".
Good for either a small continuous load, or stored up in a battery for occasional use.
But if operating 24 hours a day, it does produce as much as a 150W to 250W PV panel.
 
Update
well it,s 55 out i thinking winter storm season is pretty much over here

i never lost power , outages came with in a few miles of me , but i never even flickered enough to have to reset the oven clock

oh well maybe we get power outages next winter i guess i will just wait :)
 
oh sure now that winter is over the power goes out , on a 50 degree sunny but very windy day

6 hrs so lets see 1000 build divided by 6 hrs so it cost me 166 dollars a hour lol :) so it looks like i used 20ah of 12v power according to my bms
 
Update
well the 2022 season for power outages is almost done1678300269206.pngver , i did loose it for about a hour yesterday maybe less then 20 hrs for the year
i did add a 440 watt solar to keep it all charged as you can see i have not built a rack yet i also have another panel
fresh pic of bms and panel my internet is also hooked into this so i can monitor it from work with a camera
1678300345245.png
 
Some more testing .now that I have the furnace all set I thought I would test out the fridge.
I have manually plug that in to the inverter but was surprised to see it pulling 138 wats when running , I expected more than that .
It looks like Could run the furnace and the fridge at the same time but with 200ah battery and no Solar I do not plan to do that , but if the power goes out during a non heating time , could stretch the run time on the fridge
The newer "Inverter" refrigerators don't require a lot of running watts, but they may consume power most of the time. Essentially they control the temperature by throttling the power up and down rather than cycling on and off. They do have a defrost cycle that will come on and run a heating element for a time to melt ice on the coils. This could suck your battery down quickly, so be aware that.
 
The newer "Inverter" refrigerators don't require a lot of running watts, but they may consume power most of the time. Essentially they control the temperature by throttling the power up and down rather than cycling on and off. They do have a defrost cycle that will come on and run a heating element for a time to melt ice on the coils. This could suck your battery down quickly, so be aware that.
yes good point , this why i do not have the refrigerator normally hooked into the backup system , if its cold out i just put the stuff some cold outside in a cooler , but it is nice to know i could run if needed for a short time , now if the power went out on a sunny day lol i would be all set

currently the only things that are on the automatic backup is the furnace , the internet . a camera to monitor the brms , and the tablet the bms is shown on

i also have 12v led set up in my basement for emergency or if i want to go down to pull out the generator ect

should the battery go dead the 12v lights can be switch over and use a ryobi 18v battery
 
David,
Thanks for the update, your system looks very nice.

In your boots, I think the next thing I'd consider is water. I'm on a well, too, and being without water during a power outage is a bummer.
If you've got room for an approx 40 gallon barrel of water in that basement, you could use a small 12VDC RV diaphragm pump to take water from that barrel and pressurize your home water system. Presto: Hot water for (short) showers, water at the kitchen sink, flushable toilets, the whole shebang.

Water barrel: 44 Gallon Brute container ($52). Approved by NSF for food contact. I'm not sure about possible PFAS contamination during fabrication, so I wouldn't drink from it without running the water through a carbon filter, but it should be fine for showers, toilets, etc. Every 6 months I'd pump out the water, add fresh water, and put in a few capfulls of fresh bleach.

Water Pump: This SeaFlo 33 series pump costs about $50, gets good reviews, puts out about 1.6 GPM at 35 PSI, turns on at 35 PSI, turns off at 45 PSI. Tech specs here. It draws about 6A at 12VDC, and you could hook it straight to your battery (so no inverter standby or conversion losses. You can flush your toilets without making a trip to the basement to turn on the inverter). A 1.3 GPM shower ain't a firehose, but it works and lots of RVers get by with less.

For a "hook it up when I need it" case, I'd just rig up 1/2" tubing from the pump to a convenient hose outlet in the basement. Your existing well pressure tank serves as a pressure reservoir. That should be okay as long as your water flow at a tap/shower doesn't exceed your pump capacity for very long. You'll hardly notice the electrical draw on your battery (you'll drain the entire water barrel in about 30 minutes of pumping = 3 AH (36WH)).

Barrel, pump, fittings, etc: It would probably cost about $130 in parts, and might get you by for a day or two of judicious water use. At any rate, when on a private well it's handy to have some water on hand. You don't need any fittings at the water barrel side, the input to the pump can just be draped over the top of the barrel and a weight on the end will keep it at the bottom. I >think< the pump will self prime.
(Pro tip: When you first turn on the shower/sink and are waiting for the warm water to arrive, catch the water in a bucket. Dump that bucket back into your barrel or use it to flush a toilet, etc)

Mark
 
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