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Will your heat keep up?

Started by r.man, January 23, 2013, 12:53:23 PM

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woodmills1

not to help the stove keep up, but maybe help it keep from getting behind in the first place.  It would have more stored BTU's.  I don't think it would provide much of a cushion but my system has less than 200 gallons as it is.  Mine only gets behind when the wood is low.  If the stove is charged the house is warm.

when it is below zero day and night for a few days, the chance of me either sleeping to long or being away is real so the wood can burn low

my house demands heat, so about an hour after low wood the water temp is going down fast
James Mills,Lovely wife,collect old tools,vacuuming fool,36 bdft/hr,oak paper cutter,ebonic yooper rapper nauga seller, Blue Ox? its not fast, 2 cat family, LT70,edger, 375 bd ft/hr, we like Bob,free heat,no oil 12 years,big splitter, baked stuffed lobster, still cuttin the logs dere IAM

Holmes

 A 500 gallon storage tank will have 4,150 lbs.of water in it. If you heat it to 180 degrees you will have  around 70 degrees of usable stored heated water. {180* to 110*}     70x 4150 =290,500 btu's of stored heat .  That stored heat will help the boiler keep up with the overwhelming heat loss. I think he would need a 1000 gallon storage tank to get thru the minus 40 weather.   I hope this helps.
Think like a farmer.

Ianab

If you can store BTU's in a hot water tank, this means you have a reserve of heat for times of peak need.

Then the furnace need only produce the average BTU's needed over the day. During warm times the furnace still runs at a higher burn and stores heat for the coldest time of the day.

It allows a smaller furnace to actually provide more BTU's over the course of the day, even if the peak isn't any more.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

r.man

Short term help only. Which is why an extra tank would need to be valved so that it could remain cool after giving up its stored heat. Same premise as the batteries on an off grid system. I have wondered whether a large heat mass would be better. Maybe instead of insulating immediately below a concrete slab the insulation should be 4 ft down with a set of heat pipes there to heat the gravel mixture below the floor. Harder to control, probably quite a learning curve but the same principle as a masonry heater, large mass slow release of heat.
Life is too short or my list is too long, not sure which. Dec 2014

Holmes

A heat sink might be a good idea if you could load it up before the cold snap arrives.
Think like a farmer.

sprucebunny

I use the heat sink idea by heating my 6" slab in the downstairs with the radiant oil furnace before a cold snap. I can get the slab up to 75 in just a few hours. Then the warm air from the wood stove system will keep it from dropping fast or the slab will keep the whole house at a bearable temperature for a couple days at more moderate outside temps without using the wood stove at all.
MS193, MS192 and an 026  Weeding and Thinning. Gilbert Champion sawmill

r.man

That's what I am talking about but imagine your slab being 4 ft deep.
Life is too short or my list is too long, not sure which. Dec 2014

stumper

OK I get your concept.  Create a big heat storage and keep it warm until the cold hits, then drain the heat from it, isolate it till it warms up, and when warm reheat it.  Yes I can see that could help for a quick hit cold snap (one night). 

It would be of little help in my area as when we get cold snaps they last for several days. 

Now on the other hand, it could be of use in the summer time when I only heat my domestic hot water.  If it were large enough I could fire the boiler bring everything up to 190-195, let the fire go out and run off the store heat till the temp got down to stay 160 (my hot water is set at 140 and if I recall 160 was as low as I could set the heat setting on my furnace without changing out the controller).  Assuming minimal heat loss, 1000 gallons of heat storage would give me about 300 gallons of usable hot water (about 3 days with my family of 4). 


John Mc

Stumper -

That's exactly how systems which are designed with large storage tanks work.  I believe this set up is much more common in Europe than in the US, though we are seeing more of them with large storage tanks (some in basements, some buried underground).

The reasoning behind it is more for efficiency improvement and pollution reduction.  In general, wood boilers burn most efficiently and cleanly when they burn long and hard (at something approach the max load the boiler can handle).  A big storage tank allows you to do this, rather than having a bunch of short-duration and/or low-output fires.

A side effect is that this also allows a system to absorb short duration peak loads which may be above the boiler's rated output.  A sunny day/frigid night, or even a couple of frigid days can be "bridged" with this system.

Industry "Best Practices" for  commercial scale wood chip boilers (I'm talking 500,000 to million BTU and larger systems) do not use a single boiler designed to handle all of the peak load (at least not here in New England or in similar climates).  Typically, the boiler will be designed to handle 60-70% or so of the peak loads, with the peak being supplemented with other heating sources (sometimes even a smaller wood chip boiler).  Wood boilers do not have as good a "turn-down ratio" as oil or gas boilers.  A very well designed wood combustion system (I'm talking about computer controlled, larger scale systems here) will only turn down to about 30% output before it loses a lot of efficiency and burns rather dirty, making it unusable in the spring and fall. 

As it turns out, a system which employs wood chip boiler sized for around 65% of peak load here in the northeast, and supplements with fuel oil will actually burn LESS fuel oil than a system where the wood chip boiler is sized for 100% of peak load with a smaller oil burner for the "shoulder heating seasons" in the spring and fall.  This is because the larger system can't "turn down" well enough to burn reliably, efficiently, and cleanly enough to be used in the spring and fall.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

r.man

I would think that cooling and heating systems are the same way since some employ two stages to achieve full load.
Life is too short or my list is too long, not sure which. Dec 2014

stumper

I have heard of this heat storage for solar systems, so I did a quick search.  http://www.americansolartechnics.com/index.html this site has insulated storage tanks.

snowstorm

if its 20 below and the wind blowing the temp in the house will drop to 67. i think its mainly because i am asking to much from the in floor heat. the house is a cedar log cabin 30x56 with 17' ceilings the garage is 40x40x15. i use a taylor t1000 it holds about 900gal of water. works well

r.man

Snowstorm, I wonder what it would have gone to if it had been -39 F. At -20 is your system cycling at all?
Life is too short or my list is too long, not sure which. Dec 2014

John Mc

Quote from: snowstorm on January 30, 2013, 05:20:08 PM
if its 20 below and the wind blowing the temp in the house will drop to 67. i think its mainly because i am asking to much from the in floor heat. the house is a cedar log cabin 30x56 with 17' ceilings the garage is 40x40x15. i use a taylor t1000 it holds about 900gal of water. works well

So is your boiler running flat out, and just can't keep up, or is it doing fine but you just can't radiate enough heat into your house?
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

snowstorm

i think i am just asking to much from in floor heat. too much air space to heat . the garage with 2 modines would stay at 70 all winter if you wanted

John Mc

I'm not sure how airtight your house is, but my in-floor heat has no problems keeping up (on the days I'm not heating with my wood stove).  If you've got air infiltration issues (leaks around wind and door framing, or other areas), that's the first place to tackle, then adding insulation where it may be lacking.

I'm not sre wat temperature you are running for the water on your in-floor heat, but if you are not already at the upper limit of what is safe, you may want to try tweaking that up a bit by adjusting your mixing valve.  I know you've got to be careful of not trying to drive too much heat through wood floors... tile or cement can take a bit more.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

doctorb

I strongly agree with John Mc.  Lots of variables with radiant heat, but once the material of that floor gets to temp, it should hold the room temp unless heat loss is excessive.  What temp is the floor water, and what temp is the water returned to your stove?
My father once said, "This is my son who wanted to grow up and become a doctor.  So far, he's only become a doctor."

beenthere

Seems from the beginning, that r.man's problem is the burn chamber in his OWB is just too small to hold the amount of wood that will keep him in hot water all night.  It's a size problem at the OWB.
r.man doesn't want to get up in the middle of the night, and I don't blame him as he has to go outside.  :) :)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

r.man

Most of the time in very cold weather my owb will not hold enough wood but at other times it hangs up the wood, either on the sides or the ramp or it plugs the grates with ash. Nothing like a cool house, a cool tank and wood sitting in the firebox unburnt for some reason.
Life is too short or my list is too long, not sure which. Dec 2014

Ivan49

Been watching this for a while. I have a WoodMaster 4400 and it keeps up fine. We have years ago had temps as low as -20 with on heating problems . I run the temp on the out door stove at 170 and we keep the house at 73. Last week we had several nights below 0 and on one night the temp was -4 or 5 with awindchill of -25. Got up in the morning and my wife says something os wrong with the wood furnace. I asked her why and she says the house is 88 degrees. I now knew why I woke up sweating. She said I looked out side and the furnace is 170 degrees. I told her to invite our friend over for a summer cook out as they keep their house 65 degrees. What had happened was the furnace blower on the gas furnace the contacts had stuck and would not shut off. Easy fix and then the furnace did not turn on again all day 

coxy

i have a cb that holds 400 gal of water it heats my house and my dads but whene it gets real cold my house gets a little cold dads is like going to afraca ido bump my water temp some times up to 200 but if the wheather turns it will make it boil over  i have learnd a lot of differnt things to try from reading all the post thanks for all the tip  and keep them comming  :) :) ;D

doctorb

Quote from: beenthere on February 03, 2013, 01:30:50 PM
Seems from the beginning, that r.man's problem is the burn chamber in his OWB is just too small to hold the amount of wood that will keep him in hot water all night.  It's a size problem at the OWB.
r.man doesn't want to get up in the middle of the night, and I don't blame him as he has to go outside.  :) :)

Maybe another way to work around the nighttime problem is to raise the temp in the house during the day by 5-10 degrees.  That way, when you drop the thermostats at night, the OWB will kick on less often as the house has to cool down before it gives the signal for more heat, and thus more wood consumed in the small firebox.  Just a thought.
My father once said, "This is my son who wanted to grow up and become a doctor.  So far, he's only become a doctor."

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