Backup Heat

[SolarAndWood]

I've been traveling a lot for work and looking to make life easier on my wife while I'm gone. We have an open floor plan and the stove does fine heating the whole house. Easy fuel choices are electric or propane. I'm thinking something like this might make sense?

(broken link removed to http://www.hvacdistribution.com/product/rinnai-38400-btu-direct-vent-gas-wall-furnace-lp?utm_source=googleshopping&utm_medium=cse&utm_campaign=product)

 

[flyingcow]

Look at mini-split heat pumps. Or the newer heat pumps in general. They do a very nice job for the Kw useage. A few more dollars.

 

[woodgeek]

Probably your cheapest option that provides full backup heat. Easy install and (prob) lower operating cost than elec baseboard. While a minisplit would be great, give some cooling and cheap BTUs, one would be unlikely to carry your whole house except in the shoulder seasons.

 

[SolarAndWood]

Any idea how much more overall system efficient the heat pumps are than the 60s era Honeywell baseboard convection system that I could probably resurrect? I have a 32 ft clear run that I could probably get up and running in a weekend at minimal cost. I just read about a pulsing thermostat for these that will probably make them perform a lot better than when I uninstalled them 5 years ago to replace an exterior wall.

 

[jebatty]

We have a 35,000 Btuh propane direct vent wall heater similar to the one you show. We heat 100% with wood from a wood stove, but also have electric baseboard which was installed when the house was built. When we we are gone for brief periods in the winter, the electric baseboard is the primary heat source to keep the house at about 50F, but in the event of a power outage, the propane heater kicks in to keep the house above freezing. After 22 years the propane heater never actually has been needed, but it has been a great insurance policy.

 

[SolarAndWood]

I suppose another advantage of going the electric route is I won't need a bigger propane tank. I currently get away with tandem grill tanks with one of the auto switching valves. The ability to buy propane from whoever you want whenever you want is big to me given past experience with a delivery company. Looks like I am off to resurrecting my 50 year old free solution. I think it will work a lot better now with the shell redone and a modern thermostat. Thanks for the input.

 

[flyingcow]

Probably your cheapest option that provides full backup heat. Easy install and (prob) lower operating cost than elec baseboard. While a minisplit would be great, give some cooling and cheap BTUs, one would be unlikely to carry your whole house except in the shoulder seasons.

I didn't look at his location. Syracuse NY. The january cold snap might be a bit much. But some of those units seem to do well from 0 and above.

 

[woodgeek]

Any idea how much more overall system efficient the heat pumps are than the 60s era Honeywell baseboard convection system that I could probably resurrect? I have a 32 ft clear run that I could probably get up and running in a weekend at minimal cost. I just read about a pulsing thermostat for these that will probably make them perform a lot better than when I uninstalled them 5 years ago to replace an exterior wall.

I would expect a minisplit to have a COP ~4 during the shoulder seasons, 3 just above freezing, and closer to 2 when it is very cold out. Take the reciprocal to convert COP to cost per BTU relative to baseboard/resistance. In the shoulder seasons, the mini costs only 25% as much as the baseboard, around freezing 33% and when its super cold, still probably only half as much.

I know there are 'pulsing' tstats for baseboard that some folks claim boost the eff, but I think that is bunkum. If you like them for some other reason, go for it.

Do you know your BTU load at typical winter temps??

 

[SolarAndWood]

Do you know your BTU load at typical winter temps??

No idea. Previous owner was going through 4000 gallons of propane a year with a 80s era forced air furnace. Propane was $4.25/gallon then so I put a stove in. Since then I have completely rebuilt the shell and the results have been pretty dramatic. I burned 12 cord the first two years and still used electric backup. The BK cut that to 8 and then the shell cut it to 6 the last two years. So, my guess is I am somewhere in the 1500 gallons per year range now whatever that converts to for BTU load.

 

[DexterDay]

It may not be the answer you want, but pellet stoves can be rather simple. I have burned just over 30 bags and have done nothing to my Quadrafire upstairs, other than fill the hopper.

Fully automated and easy as pie. Most clean on a weekly or bi-weekly basis. Only takes average of 10-15 minutes, every 2 weeks.

A stove with a large hopper can go several days and not need touched.

Just another option. Pellets are cheaper than LP, Elec, HHO, etc. The cost of the stove can be expensive, but look for used with all venting, and hearth pad and it can be pretty cheap.

Just a thought

I love my wood stove. But given a choice. Pellets win. To easy and house is ALWAYS an even temp.

 

[Don2222]

I've been traveling a lot for work and looking to make life easier on my wife while I'm gone. We have an open floor plan and the stove does fine heating the whole house. Easy fuel choices are electric or propane. I'm thinking something like this might make sense?

(broken link removed to http://www.hvacdistribution.com/product/rinnai-38400-btu-direct-vent-gas-wall-furnace-lp?utm_source=googleshopping&utm_medium=cse&utm_campaign=product)

How about a cheap Kerosene Heater? Maybe a Wood pellet stove? 1 bag will go for 24 hours.

 

[woodgeek]

Based on the 1000 gallons/yr estimate for oil, it sounds like you will often want ~40,000 BTU/h. The rating of the BKK is ~50 kBTU/h on a sustained basis....does it ever come up short?

Anyhoo....40 kBTU/h = 12 kW of baseboard...but that would run ~$40/day.

Pellets...40 kBTU/ 6 kBTU/lb = 6.5 lbs/hr....160 lbs = 4 bags/day. Get the big hopper.

 

[DexterDay]

Based on the 1000 gallons/yr estimate for oil, it sounds like you will often want ~40,000 BTU/h. The rating of the BKK is ~50 kBTU/h on a sustained basis....does it ever come up short?

Anyhoo....40 kBTU/h = 12 kW of baseboard...but that would run ~$40/day.

Pellets...40 kBTU/ 6 kBTU/lb = 6.5 lbs/hr....160 lbs = 4 bags/day. Get the big hopper.

Pellets are between 8,000 and 9,000 BTU per lb. I heat over 2,000 sq ft and have Never used more than 2 bags a day. On the coldest of days. Or 3.33 lbs an hr (26,640 BTU per hr, based on the average 8,000 BTU pellet).

Of course these are input numbers.. Not output.

 

[woodgeek]

I am thinking in terms of BTU demand by the house....and thus output. Might be 6500 or 7000 BTU/h output. S&W's fuel usage seems high, (1500 gallons oil/yr) consistent with the BKK. If 40 kBTU/h output is needed for 24 hours, that is more than 3 bags.

 

[SolarAndWood]

Based on the 1000 gallons/yr estimate for oil, it sounds like you will often want ~40,000 BTU/h. The rating of the BKK is ~50 kBTU/h on a sustained basis....does it ever come up short?
.

-10 and blowin 20+ I am on 12 hour burn cycles and the house drops to the high 60s. But, those are 125 pound loads every 12 hours.

 

[SolarAndWood]

IS&W's fuel usage seems high, (1500 gallons oil/yr) .

600 ft above the valley on an exposed ridge with 2 floors of glass facing the predominant wind (and the predominant view).

 

[SolarAndWood]

Pellets are between 8,000 and 9,000 BTU per lb. I heat over 2,000 sq ft and have Never used more than 2 bags a day. On the coldest of days. Or 3.33 lbs an hr (26,640 BTU per hr, based on the average 8,000 BTU pellet).

I have a pretty cheap source of bulk coal close by. The long term plan is a boiler with storage that should last a couple days while I am gone. But, that is probably two years away. The free baseboard solution probably makes the most sense until then.

So, how do you get 4 20 amp breakers and only one 2-wire cable running into each end of a run of 30 ft of baseboard heaters? There is an extra conductor inside the run but this still doesn't make sense to me. One pair runs through a single cable to one end and the other pair run runs through a Honeywell box that I assume is some kind of a thermostat relay to the other end? Should of paid more attention when I took it apart 5 years ago...

 

[woodgeek]

-10 and blowin 20+ I am on 12 hour burn cycles and the house drops to the high 60s. But, those are 125 pound loads every 12 hours.

Not judging usage...just trying to estimate your BTU demand. Sounds like your maximum design day is ~10 lbs wood/hr, or ~60 kBTU/hr. This is consistent with a more typical load in January being closer to 40 kBTU/hr. 15 kW of baseboard is 50 kBTU, and sounds like it would carry you most of the time....but not during those howlers. And it would be pricey....but aok for backup.

15 kW of baseboard is ~60A at 240V. 4 20A breakers running 4 units sounds ok....with 12 gauge wiring. Details, can't help you.

 

[SolarAndWood]

Not judging usage...just trying to estimate your BTU demand. Sounds like your maximum design day is ~10 lbs wood/hr, or ~60 kBTU/hr. This is consistent with a more typical load in January being closer to 40 kBTU/hr. 15 kW of baseboard is 50 kBTU, and sounds like it would carry you most of the time....but not during those howlers. And it would be pricey....but aok for backup.

That is what I'm thinking. 30 ft of the old baseboard convectors will have no problem keeping the house at 50 for extended periods while we are gone and make it easier on my wife while I am gone. The long burn cycles with the BK mean that she almost never touches the stove other than the thermostat. Burning 24/7 takes a little planning during the core of the winter without backup heat. I think your analysis is spot on as I have to break out the primo fuel during the howlers and run the stove pretty hard...doing stuff like throwing pine on during the last third of the burn cycle to maximize the amount of heat and limit the cycle to 12 hours.

Now to figure out the wiring of these baseboard heaters...4 circuits with only 4 wires going to the string of baseboard units makes no sense to me.

 

[Highbeam]

4 circuits with only 4 wires going to the string of baseboard units makes no sense to me.

Me either, I suspect that you only have 2 - 240 volt circuits and even then, you would need grounds for modern code, the 2 -240 cicruits would take 4 slots on your panel and some hacks have been known to use individual breakers to save on buying the proper double breaker. I've repaired more than a few mistakes by previous owners. Functionally, the 2 -240 -20 amp circruits would work fine with just the four conductors and no ground as the elements wouldn't know the difference but you'd have no ground protection and the metal cases could be energized in the event of a short circuit.

Nothing wrong with cheap baseboard heaters. They are and always have been 100% efficient, cheap to buy, maintenance free, fueled by the grid with an endless supply, no carbon monoxide worries, no open flame, etc. They just consume a fuel that can be expensive which is a decent investment if you use the electric as backup. Just use a plain line voltage thermostat or a programmable version but skip the bogus modulating novelty stats.

 

[SolarAndWood]

Me either, I suspect that you only have 2 - 240 volt circuits and even then, you would need grounds for modern code, the 2 -240 cicruits would take 4 slots on your panel and some hacks have been known to use individual breakers to save on buying the proper double breaker.

That is exactly what I've got. Each of the 2 cables spans 2 breakers. One cable goes to a Honeywell box that a regular dumb tstat connects to. The other goes direct to the end of the sting of heaters. There is a third wire within the string of heaters but only 2 connecting to each end. I am running a ground as well.

 

[Highbeam]

I have electric wall heaters and the builder had two heaters in one big room. Each on a different circuit. The electrician could not figure out how to make one stat control two circuits so he mounted a pair of stats side by side. Your electrician looks to have made it work somehow with a single stat. Until you figure out how and fully understand it, assure it is safe, I would not energize the ciruits.

 

[SolarAndWood]

I have electric wall heaters and the builder had two heaters in one big room. Each on a different circuit. The electrician could not figure out how to make one stat control two circuits so he mounted a pair of stats side by side. Your electrician looks to have made it work somehow with a single stat. Until you figure out how and fully understand it, assure it is safe, I would not energize the ciruits.

I have that figured out. There are two Honeywell boxes in the basement next to the panel. A 20 amp circuit comes into each of them from the panel. The tstat comes into one and then is jumped to the other. Tested the lines that come out of each and both turn on and off properly with the tstat.

I just need to break my string into two and use those two lines.

 

[woodgeek]

Ah. Sounds like you just have to gang the b-boards to work in two groups of 240V 16A (max).

 

[SolarAndWood]

Ah. Sounds like you just have to gang the b-boards to work in two groups of 240V 16A (max).

Yep, they are set up that way. Just need to get that second zone feed run over to the heaters. Kind of scary to think that they had 40 amps of breaker running on 12 wire. Good thing that old cloth insulation does a good job dissipating heat.