Greenwood Furnace Advice - water heater? overheat loop? neither?

[jbeamer]

For those of you who helped me back in the late fall, I just want you to know that I had a successful heating season. I definitely understand my furnace a lot more now than when we started (thankfully!)

As we approach warmer weather, I am in a bit of a quandry. As you know, warm days make it more difficult in preventing the furnace from overheating. I have managed okay so far, but have had a few times where I've gotten in trouble with higher temps. At least now I know what to do to quickly return things to normal.

Previous posts have suggested putting in an overheat loop (I don't know what that would look like for me, but supposedly there are articles on this forum explaining how to do it). I'm also wondering if attaching a water heater to the loop would be a solution (we run out of hot water at times so this would help this problem as well).

My third option (for the summer at least) is to shutdown the system all summer long and just run oil - but, based on the amount of oil we used last summer (our first in this house), I dread the thought of this expense.

Hopefully there are some folks who can weigh in on this issue and give me some advice.

Thanks!

 

[Singed Eyebrows]

I know storage isn't recommended for these boilers & the shoulder seasons is where this really helps. I would try the water heater, get a large one & if thats ok consider looking for a 500 gallon propane tank, Randy

 

[muleman51]

If you are going to run it all summer ( I don't) I would definitely add storage. I have 1000 gallon storage on my Adobe, same boiler as your just different color. Storage makes the boiler work much better, you can burn full complete fires, this eliminates a lot of issues and you would be hard pressed to over heat it.

 

[mole]

I agree with muleman. Summer hot water is easy with storage. I do about an 8hr burn every 8-10 days. That beats $50/mo for electric.

 

[jbeamer]

Pardon my ignorance (I'm still learning), but how do you tie the storage tank into the system? As of now, my boiler feeds into an oil furnace. Do you put the storage tank near the boiler? underground? in your basement? And, am I correct in saying that the boiler then works to heat the water in the storage tank (thereby providing a pretty limitless supply of hot water)?

Why aren't storage tanks recommended for boilers?

Thanks for the insight!

 

[Singed Eyebrows]

Pardon my ignorance (I'm still learning), but how do you tie the storage tank into the system? As of now, my boiler feeds into an oil furnace. Do you put the storage tank near the boiler? underground? in your basement? And, am I correct in saying that the boiler then works to heat the water in the storage tank (thereby providing a pretty limitless supply of hot water)?

Why aren't storage tanks recommended for boilers?

Thanks for the insight!

Your boiler is piped into the storage tank top & return to the boiler is from the bottom of the tank. System water is pumped from the top of the tank to the emitters & return to the bottom of the tank. The tank should be as close to the boiler as possible. You will have limitless hot water.... as long as there is wood in the boiler,lol, Randy Storage tanks are recommended.

 

[woodsmaster]

In general storage is recommended. Not supposed to be necessary for greenwood ,but I think it would definitely be a plus if using in the summer.

 

[flyingcow]

storage is nice

 

[jbeamer]

Is there a "rule of thumb" to follow as to how big a tank you need for a certain sized house?

Also, when you have the storage tank attached, do you go through a good bit of wood each day (it would seem that would be the case)? I'm a little confused by the comment about doing an 8 hour burn every so many days.

Thanks again for the expert advice. I'm just trying to understand this as much as possible in order to make my decision.

 

[woodsmaster]

Is there a "rule of thumb" to follow as to how big a tank you need for a certain sized house?

Also, when you have the storage tank attached, do you go through a good bit of wood each day (it would seem that would be the case)? I'm a little confused by the comment about doing an 8 hour burn every so many days.

Thanks again for the expert advice. I'm just trying to understand this as much as possible in order to make my decision.

with storage you go through a good bit of wood when you fire the boiler to heat up the depleated storage and satisfy loads ,but you may only have to fire once a week in the summer to supply your dhw depending on tank size. the water in the tank is never actually used, it just transfers heat to other water via an hx. I dont Know of a rule of thumb for sizing. It depends on your demand (btu's / hour used) and how often you want to fire the boiler. Hope this was helpfull. J.T.

 

[heaterman]

Is there a "rule of thumb" to follow as to how big a tank you need for a certain sized house?

Also, when you have the storage tank attached, do you go through a good bit of wood each day (it would seem that would be the case)? I'm a little confused by the comment about doing an 8 hour burn every so many days.

Thanks again for the expert advice. I'm just trying to understand this as much as possible in order to make my decision.

At minimum your storage should be big enough to hold all the heat from a normal load of fuel. Average btu/pound being about 8500 you would use the number of pounds in your fuel load times the efficiency of your Greenwood (?) to arrive at actual output.

Let's assume you use a 100# load of wood in this example.

Step 1: 100#'s of wood x 8500btu/pound = 850,000 btu. Assume the Greenwood is 70% efficient with a nice continuous burn so 850,000 x .70 = 595,000

Step 2: 595,000 / 8.33 (weight of 1 gallon of water) = 71,428

Step 3: assume you can work with a 70* swing in your storage (200* down to 130*) 71,428 / 70 = 1020 gallons of storage capacity.

Now.......that's the input side of the equation. The other thing to consider is what you need for daily output along with the standby loss of your storage. For the first part, there are lots of facts and figures available on the DOE website that will tell you the DHW "load" created by a family. From that you can get a handle on the btu's per day you will need to supply hot water for washing, cooking and bathing.
AFA the standby loss from your storage is concerned, that is a variable that is very controllable by you and can be made as small a factor as you want it to be.

My personal experience has been that 500 gallons is pretty much the minimum amount of storage for most wood boilers. Anything less and burn efficiency starts to go down due to cycling of the fire and/or less than optimum fuel loads.

PS: There are a number of reasons that the smallest Garn holds about 1500 gallons of water......