Using a boiler to stay warm when the power is out with heated floors

tbrooks

Is this even possible? I'm in the process of choosing a boiler now. I have a stick framed floor. I'm going to have pipes above subfloor with plates and plywood sleepers, heating load of 26k BTUs. I wanted wood, but don't have the money for initial install and long term I just can't justify it. Then I was thinking propane, but I have been recently thinking electric may work better with my low load. No matter what, we are in a rural area, and do get power outages. We had one this year lasting 72 hours. I have a portable generator that I use for necessities in these situations, mainly just for the fridge and freezer, our current house has 2 lp heaters, so we stay warm. It was pointed out to me that the power would not have a clean sine wave for running newer tech with computer boards. What are my options here? I could get a couple lp wall heaters for backup, but then I'll also need make-up air for combustion. We don't usually have long outages in the winter, but I like to be ready when we do. I'd hate to install lp heaters to use once a year.

Jamie Hall

If you can find a suitable boiler for that small a heating load, I'd go with an LP boiler. If not, I'd use a couple of LP vented fan forced heaters -- sidewall type.

You could go with electric heat, but that would take a pretty good sized generator -- and a lot more LP (the efficiency of the generator isn't even close to an LP heater).

As to the clean power problem, there are a number of newer invertor type generators which are quite efficient and are alleged to produce reasonably clean power and may be big enough.

STEVEusaPA

Get a bigger, better generator. At least big enough to include the heating circuit. I have a permanent whole house.
But before that I had a 6500 watt portable. I was able to run a boiler with all it's controls-Tekmar, 6 circs, etc., 2 refrigerators, and minimal lighting, small tv.
I held off the boiler until the refrigerators cycled.
You could check to see how clean your electric is with the gen.
In the summer, was able to run refrigerators, and 2nd floor AC
You say you can't justify spending the money. It's alot cheaper than frozen pipes, especially radiant, ripping out, fixing re-doing, throwing out all your food, and overall worrying about it.

Dave H_2

I ran into the same thing when Sandy hit Long Island. My boiler's electronics did not like the portable generator. However, with radiant in my house, it took 5 days for it to start getting cold in the house where heat was needed. At that point, we stayed in the family room most of the time with the fireplace.
My biggest concern was that I had no hot water (indirect tank) where a seperate water heater does have its advantage.

Dave H.

hot_rod

It depends on how long you wish to run the system. some of the wood boiler users have a few deep cycle batteries and a quality inverter. If you use all ECM circulators and look for way to avoid other power stealing components like transformers, digital controls, etc.

An LP standing pilot cast boiler with and ECM circ would be a simple low power system, but not the most efficient boiler to run.

Those small Honda 2 and 3K generators provide real clean power, Extremely quieted run about 6 hours. Find them used around the RV crowd.

NY_Rob

You can get a small 2,000 watt generator that outputs through a built in inverter, so it's a clean sine wave.

Here's a youtube review where a guy charges his Tesla from a Honda and Generac 2kW generator. FWIW- Electric Vehicles are extremely fussy when it comes to their electrical supply... it needs to be locked in at 60 Hz, and a clean sine wave. If one of these portables can recharge the $80K Tesla safely... it will work fine for modern computer based boilers (mod-cons) and ECM pumps.

https://www.youtube.com/watch?time_continue=3&v=Nf6WgQfL7DY

tbrooks

So it sounds like lp boiler would be the way to go, I just need to find the smallest possible. I had actually thought about getting one of those ups boxes, I had one before that I could watch satellite TV and run the blower on the wood stove for a couple hours. But that probably wouldn't last long for a long outage which is my concern.

I know those Honda's are nice and quiet, at a cost though. I have a Coleman powermate 6250, how would I know how clean it is without an oscilloscope? It's probably not since it's a cheaper gen.

I know my house won't stay warm for long in the winter. Since it's all stick frame, there is no thermal mass, other than whatever I end up with for a buffer tank. I'm not really concerned with having hot water, because unless I get a larger gen, I won't have the well running anyway.

Leonard

Generators are ~17% efficient at best (full load) so don't heat with electric heaters run off gen power.

Get an old Onan gen, like NH model ( 6.5kw) bullet proof and reliable sinewaves.

Total1

I have a 10,000 W Generator that runs off natural gas , It automatically starts and runs everything in the house and garage . and the AC in the summer .. Just about everything is on natural gas now ..

NY_Rob

tbrooks said:

...I have a Coleman powermate 6250, how would I know how clean it is without an oscilloscope? It's probably not since it's a cheaper gen.

Got $25?

https://www.ebay.com/itm/Fully-Welded-Assembled-DSO138-2-4-TFT-Digital-Oscilloscope-1Msps-Probe-Kit/142642969949?epid=20012346666&hash=item21362efd5d:g:ossAAOSwEOpaSyIO

That's where I took the snapshot below from (waveform of a cheap UPS), I confirmed the readings with my $$$ technician grade Tektronix scope... same waveform.
Of course the Tektronix scope is much more versatile, but for measuring 60Hz waveforms the $25 scope works great and I store it in a desk draw vs. dragging out the 30lb Tektronix.

Gordy

Everyone knocking the efficiency of a generator, remember it’s temporary emergency power.............The best of PV panels are only 21% efficient, and lose efficiency over time.

Zman

Gordy said:

Everyone knocking the efficiency of a generator, remember it’s temporary emergency power.............The best of PV panels are only 21% efficient, and lose efficiency over time.

Don't forget that the electricity at your meter is only ~30% efficient when you consider plant inefficiencies and line loss....

I have been meaning to log my systems usage and see if a UPS would work. It would help clean up the generator power if needed.

Gordy

True.

Leonard

Just saying at 17% efficiency (at best) you don't want to burn fuel in your gen to make electricity , just to turn around and make heat out of it again.

Other issue is gens require a certain fuel consumption even at no-load, and that amount scales up as increase gen kw rating. So don't want more gen kw rating then you absolutely need, if you want low fuel bill on long runs ( a week without power)

7kw Onan NHM on gasoline 0.4 GPH @ no-load, 1.3 at full load
15kw Onan JC 1 GPH @ no load , 2.4 full load (~ 250k BTU/hr on nat gas)
Calculate how much fuel you'll use in a week 24/7 and the cost .... WOW!!!!!!! It will amaze you.

There are cheap kits to convert gen to propane or nat gas fuel.

Utility power plants with regenerative staged tubines are ~ 40% efficient at full load, % drops off quickly as throttle down.

Gordy

Who cares in an emergency, so Long as you have fuel. That’s my point. I’d sacrifice the efficiency to maintain freezer,fridge,heat,and hot water.....usually not long term unless major event.

Leonard

Emergency is an emergency , but don't want to plan on oversizing a gen or extra fuel costs will quickly put you in the poor house

Maybe I'm just cheap. But the 15kw gen just running near no-load will consume at least 168 gallons of gasoline $420 in one week of continuous running. Few years ago after ice storm some people in Maine were out for 2 weeks others for months.

168 gallons is a lot of heavy gasoline to haul and store, that's over three HEAVY 55 gal barrels of fuel. But if you only needed a 7kw gen your fuel cost would be cut in1/2.

Just saying plan ahead and save. In another website some guy picked up a 60kw gen free, and plans to use it for his house, but he'll only use 10-15kw of it . It would be cheaper for him give gen away for free and buy a used gen of proper kw size than pay for all the extra fuel the 60kw beast would drink in a week.

flat_twin

I like the idea of having central heat as part of a back up power plan. Last fall we sold an old 5500 watt generator and bought a 2000 watt Honda inverter generator specifically for the clean power.
I measured .9 amps on my boiler circuit. I have one 80w circulator for heating and another for dhw. My kitchen circuit with the refrigerator is 7 amps. These two circuits and a couple led lights are all I need for emergency power. I just got a two circuit transfer switch to make it safe and easy. Should have that installed soon.

Gordy

If one was really having outage issues either by way of weather, or poor grid infrastructure an NG genset is the way to go if NG is available. NG is cheap, no worries about fuel unless someone disables the NG grid.

hot_rod

Gordy said:

If one was really having outage issues either by way of weather, or poor grid infrastructure an NG genset is the way to go if NG is available. NG is cheap, no worries about fuel unless someone disables the NG grid.

And with NG or LP gensets the fuel never goes bad. You will need to keep "souping up" the gas if it sits more than a month. The bio blends are tough on rubber components in the fuel system.

LP and NG engines fire right up.

Leonard

Nat gas really is the way to go ,it's cheaper than gasoline/propane. For small couple hundred watt loads bat bank and RV inverter is a cheap way to go. If your only going to be out of power for a day. For mulitday /week outages really want consider a gen ,at least to recharge the bats. On the other hand your car has a 12V charger, it's called the alternator.

I have a trifuel 7.5 kw Onan 7.5JB gen to run house lights fridge and most importantly the oil furnace, it gets down to -5 deg here and we NEED heat. Starting on propane is wonderfully easier than starting on freash gasoline. Problem is a large tank is not super cheap like 6 gal gas cans are. On the other hand with ethanol in gasoline these days need to use stabilizer and run the gen once a month to keep carb from ethanol gumming up. Although I put gas stabilizer in gen and let it sit a year only starting it ~ every 3 months and carb is fine. It's all about tradeoffs and what you decide to do.

tbrooks

Good points guys. I think we all know generators are inefficient, but in a pinch they get the job done. I never run mine continuos, or without much load. I fire it up for an hour or so to get the fridge/freezer cold and shut it down for 4 or 5 hours. Honestly I don't mind being without power for a day or so, and it's prob good for the kids to go without for awhile.

I live in the NC mtns, lots of trees and curvy roads and all the lines are above ground. So bad weather plus bad drivers, and we lose power. Usually it's not off for too awful long, but occasionally it is. Luckily we are surrounded by country clubs, and seems they like to keep those rich people happy lol.

I wish I could get ng here, but it's just not possible yet.

Leonard

If no NG then propane stores well, never goes bad, but then there's the tank cost. BBQ tanks aren't going to cut it for 1 week run time. Need ~ min of 100+ gal tank for 7.5 kw gen at close to no-load.

Here in February when it's 0 degs and wind howling for day or so. Furnace had to run almost constantly to keep up with heat loss. That's why we got a gen.

Once was a calm day no wind and relatively warm 30 degs. Power was out for18 hours and dad was freezing , room temp dropped ~ 8 degs in 18 hours. Dad (98) kept saying crank up the heat and I couldn't. Made feel bad that all I could do for him was pile on the blankets.

We almost never loose power but ~ 8 years ago major ice storm hit all of New England. We had power but neighborhood behind us was out for a week. That was an eyeopener, decided to get a gen to gaurentee we could make heat using existing heating equipment. Researched it and found Hondas were good but $$$$$$$, cheaper to get an old Onan. They were very reliable and made clean power. Much better than the china junk in big box stores.
Info on Onan gens (bunch of old Onan gen techs) ----> https://www.smokstak.com/forum/forumdisplay.php?f=1

Jamie Hall

It's really a matter of figuring out -- accurately -- what one needs for backup power, and for how long, and then figuring out what one can use to produce that. One size is not going to fit all! In a few situations, batteries and true sine wave invertors may be the best bet. In others, one may need a really good size generator. Other situations will be in between. Then if it is a generator, there is the question of fuel. If one has natural gas -- and there is adequate gas pressure at all times (not always the case) -- then that is a good bet. Diesel is also a good bet, if one is also using #2 for heating anyway, or if you have diesel machinery and thus fuel available. Diesel is not cheap, however. LP is fine -- if you have a big enough LP tank as mentioned, usually also for heating or domestic use. Gasoline isn't bad -- and is actually a good choice if, again, you have gasoline for other reasons and keep it properly treated.

Zman

It sounds like the plan is a propane boiler. Propane boiler, propane generator all good...

Leonard

Make gen rated kw small unless you need the power for other house loads, fridge,tv lights,etc. Gen can consume more BTU than heating.

7.5 kw gen draws ~ 125 k BTU/hr nat gas at fullload. Typical house furnace here might be 100 k BTU/hr input. Means big gen needs a bigger propane tank. Also tank freeze up sizing issues.

Gordy

If one uses the generator wisely, it need not run 24/7.

Cycle generator as needed to maintain a reasonable CH set point, keep perishables from spoiling, and DHW. Lights are an option at night in my opinion. Remember emergency living not leisure living.

Total1

All my electronics everywhere in my house is fed from a 3.1 KVA UPS that will run for 2.0 Hrs before that battery dies . The generator takes 14 sec to fire up when the power goes out , and that ups takes care of that time . Perfect power all the time ...

tbrooks

And I will go lp with the gen, when I get to that point. I already have 250 gallon tank that came with the house. Down the road, may look into some batteries and inverter.

That's what I do Gordy, cycle as needed. We used to go stay often in a cabin up here of grid. Had gen and batt storage. We ran the gen a few hours first night, went on batt rest of the weekend. We're country lol, we get along without power pretty well, but gotta stay warm.

Leonard

I figure on cycling gen if it's not hurricane 0 deg winds and I need furnace to run 24/7. Which sometimes happens in February and March here.

Some people with medical issues down south need house A/C to be available 24/7 , so larger gen, 3-4 ton A/C.

For couple hundred watt load for 1/2 day , likely cheaper to go with battery bank and inverter. Batteries do have to be replaced periodically. Some here have gone with old golf cart bats, but that runs TV , fridge, couple lights for the night.

mxfrank

I live in a semi-rural area that's hard hit in emergency situations. I have a Reliance Controls manual transfer panel which supplies the boiler, fridge, sump, well, and a couple of rooms. The generator connection is an outdoor receptacle. I roll out a portable 6.5kw generator and plug it in when I need it. Yes, it consumes a lot of fuel even running just eight hours a day. We were out for three weeks after Sandy, and the fuel bill was only the half of it: most of the gas stations were powered down, so just finding gas was a chore. Still, it was worth all the effort to have a dry basement, heat, water and light. My next generator will run off diesel, so that I can fuel it from the heating oil tank.

As for waveform, the generator waveform is cleaner than most UPS's. I have a Buderus boiler and control system, and no problems when running on generator power. The generator also supplies power for my computers, TV, satellite dish, and other electronics. Really, it's fine.

JUGHNE

Some years ago there was a unit discussed that was a liquid cooled outdoor NG/LP gas powered engine with the waste heat piped inside for heating and/or DHW.
Now with the advance in inverter and battery technology it seems that this engine could be on call as needed for waste heat and also top off your batteries. You would have to strike a balance between battery bank size and hot water tank (battery) size. This would be to keep engine from running at no load to simply supply heat.
Solar panels could supplement battery charging, especially in the summer when heating not needed.

Or did this go the way of the future "flying cars" promised to me in the early sixties by Popular Science/Mechanics printings.

Sal Santamaura

NY_Rob said:

...Got $25?

https://www.ebay.com/itm/Fully-Welded-Assembled-DSO138-2-4-TFT-Digital-Oscilloscope-1Msps-Probe-Kit/142642969949?epid=20012346666&hash=item21362efd5d:g:ossAAOSwEOpaSyIO
...

Interesting. That eBay listing makes no mention of what powers the thing. Looking closely at one of the circuit board pictures, it seems like 9VDC is required. Was a 9VC wall wart included or did you have one / source one elsewhere? Thanks in advance.

hot_rod

JUGHNE said:

Some years ago there was a unit discussed that was a liquid cooled outdoor NG/LP gas powered engine with the waste heat piped inside for heating and/or DHW.
Now with the advance in inverter and battery technology it seems that this engine could be on call as needed for waste heat and also top off your batteries. You would have to strike a balance between battery bank size and hot water tank (battery) size. This would be to keep engine from running at no load to simply supply heat.
Solar panels could supplement battery charging, especially in the summer when heating not needed.

Or did this go the way of the future "flying cars" promised to me in the early sixties by Popular Science/Mechanics printings.

The ECR FreeWatt was another packaged system

Gordy

I still think solar HW offers the best bang for the buck, especially when coupled with hydronic.

steamedchicago

Gordy said:

I still think solar HW offers the best bang for the buck, especially when coupled with hydronic.

In most cases, it's now cheaper to use PV solar to run a conventional hot water heater than to install solar thermal. Using a heat pump HW heater makes it even more lopsided.

Leonard

Here in NH I wouldn't be too eager for solar inverter power. Here outages come from ice storms or wet snow sticking to trees and the falling branches/trees taking out power lines. So thick layer of ice/snow over solar panels and short gloomy dim day for little solar power production (not reliable power). Plus it's usually very cold after a storm here (MUST have heat).

I was interested in the $25 scope till I saw display was ~2 inchs, I got old tired eyes, maybe a magnifying glass would help. There are some real scopes on ebay used with standard 5-6+ inch display. Prices are not $25 but reasonable for a scope.

SIZING THE BAT PACK.....
With inverter and bat , need to get a handle on how large a battery pack you'll need, not going to be small. Rough estimate: suppose you need 200 watts at 50 % duty cycle for 8 hours. ASSUME 85% efficient 12V inverter.

So at 12V input to inverter need rough average of (200 *0.5)/.85 = 118 watts. that's 118/12 = ~ 10 amps at 12V.

10 amps * 8 hours = 80 amp-hr, however good bat practice says shouldn't discharge bat to more than ~50% so need 160 amp-hr bat.

Typical larger good grade car bat is 50 amp-hr,so would need about 3 car bats to do the job when bats are new. However bats lose capcity as they age, so need more bats to compensate for this .So maybe double that??? I'm not sure. But at this point your up to at least $600+ in bats, plus extra for inverter for ONLY 8 hours MAX of backup. Also have to replace bats at least every 10 years. Fossil fuels store vastly more energy than bats can. Starts making a gen look cheap.

Although for only 200 watts you could power inverter from a RUNNING car. I'm guessing fuel consumption will be 2-3 GPH VS ~ 1/4 --1/2 GPH or less with a generator but if you don't have many long outages it could make sense $$$ wise.

Be warned most car alternators can only continuously make ~ 50% of their max rated amps. They undersize the rectifier diodes, they assume a dead bat will quickly charge and load on alternator amps will quickly drop. 100 amp alternator uses six 25 amp diodes arranged in 3 phase configuration, that's 25* (square root of 3) = ~ 43 DC amps continuous rating. So shutoff heater fans, back window heater, headlights,and other high loads. Also don't have a junk bat in the car, old junk bats continuously draw 40 amps and that together with other car loads fry the alternator diodes. They overheat and leads crack off, seen it.

NY_Rob

Sal Santamaura said:

NY_Rob said:

...Got $25?

https://www.ebay.com/itm/Fully-Welded-Assembled-DSO138-2-4-TFT-Digital-Oscilloscope-1Msps-Probe-Kit/142642969949?epid=20012346666&hash=item21362efd5d:g:ossAAOSwEOpaSyIO
...

Interesting. That eBay listing makes no mention of what powers the thing. Looking closely at one of the circuit board pictures, it seems like 9VDC is required. Was a 9VC wall wart included or did you have one / source one elsewhere? Thanks in advance.

Mine came with a 9v walwart, you can power it w/a 9v battery too. You just need to get a 9v batter battery cable plug that fits the 5.1mm jack on the scope. It's the same jack as on an Arduino so you can find them on Amazon, ebay, etc..
https://www.amazon.com/5pack-Battery-2-1mm-Arduino-Corpco/dp/B01AXIEDX8/ref=sr_1_3?ie=UTF8&qid=1517771064&sr=8-3&keywords=9v+battery+arduino

If it doesn't come w/a wallwart, just get the 9v to 5.1mm adapter listed above. It runs forever with the battery.

Gordy

steamedchicago said:

Gordy said:

I still think solar HW offers the best bang for the buck, especially when coupled with hydronic.

In most cases, it's now cheaper to use PV solar to run a conventional hot water heater than to install solar thermal. Using a heat pump HW heater makes it even more lopsided.

I think it’s debatable.

psb75

steamedchicago is right: esp. with the price of pv panels (before Trump taxed Chinese pv imports) matched with heat pump DHW, beats a solar thermal system hands down.

Gordy

psb75 said:

steamedchicago is right: esp. with the price of pv panels (before Trump taxed Chinese pv imports) matched with heat pump DHW, beats a solar thermal system hands down.

Storage is a hassle with both.

Solar PV efficiency degrades over time. What works for watts when new, not so much down the road. Now couple that to an appliance that requires x amount of power to function, or it doesn’t function. Not to mention the littering of excessive panels to make up for their 16-21% efficiency compared to 70% plus for SHW.

Elon musk with the solar PV shingles lol. Looks great however the cost is that of half a new home.

Solar thermal has much more potential. Besides heating my domestic hot water. Like my whole house. I don’t mean just starting the boiler to run on grid fuel, and running pumps. I would much rather use PV to run some low watt ecm circs than a dedicated air source heat pump for heating, or domestic. hot water. Ever heard an air source dhw heat pump? Not quiet by any stretch.

However we are now getting into complete off grid discussion verses an intermittent emergency.

PV has great potential when it clears the storage, and efficiency hurdles. Years out, and don’t forget when BP solar has a hand in it there won’t be huge leaps, and bounds so long as fossil fuels eclipse alternative energy.

Total1

I had to get my old 20 mhz BK oscilloscope out of storage to check the UPS waveform . It sure looks like a sine wave to me .. Also when the generator is running the ups always keeps checking the incoming power and it thinks we are running the grid power not the generator .. .