Picked up a trick from a firewood sale and went from a 20 degree delta to 28 degree delta. The unit is a Heissheaters.com mid sized unit. It was recommended that I put on a 3 stage circ but I opted to use the Taco 007 I had been using on my (currently off-line) EKO40Super. The trick was in the setting of my ball valve supply flange comming off the circ. I had been running wide open but now I am about 2/3 closed. My setup is very simple and the unit I am using is still a wood hog compared to the EKO but now I think I have a chance of getting to the end of heating season without mortgaging next years wood supply to stay warm (that means going fossil fuel) {sorry all didn't mean to let that slip out I was just elated at the new prospect of the boilers operation}. Since I idled my EKO I wonder if slowing the circ flow down would have shown any improvement on the units efficiency?? Any ideas on that? Thanks ahead of time..Cave2k
28*f delta
- Thread starter Duetech
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
PassionForFire&Water
Minister of Fire
The principal of any boiler or water heater is that:
- you need water
- you need a delta T
- you need flow
- you need time
The amount of heat that is transferred to the water is equal to this simplified formula: Volume of Water x Delta T x Flow
If you have no water you can not transfer much to the water. The more water the better, because you decrease what's called "jacket loss". Jacket loss is important for an outside boiler, becasue you are heating up the outside world, if the boiler is installed inside you take advantage of this heat to a certain extend, if this jacket loss is controlled.
If you increase your delta T by decreasing your flow (or increasing your time the water sees the delta T) your net gain is zero.
From a physics point of view you probably loose a fraction of a % on efficiency because your increased water temp versus your firebox temp decreased.
The BTU's a boiler or water heater can generate is a defined by its construction: ie how well the heat exchanger does it's job, water jacket, firebox temp, ... .
The only thing the user or operator can do is hit the gas pedal more or less, meaning give more or less combustion air.
- you need water
- you need a delta T
- you need flow
- you need time
The amount of heat that is transferred to the water is equal to this simplified formula: Volume of Water x Delta T x Flow
If you have no water you can not transfer much to the water. The more water the better, because you decrease what's called "jacket loss". Jacket loss is important for an outside boiler, becasue you are heating up the outside world, if the boiler is installed inside you take advantage of this heat to a certain extend, if this jacket loss is controlled.
If you increase your delta T by decreasing your flow (or increasing your time the water sees the delta T) your net gain is zero.
From a physics point of view you probably loose a fraction of a % on efficiency because your increased water temp versus your firebox temp decreased.
The BTU's a boiler or water heater can generate is a defined by its construction: ie how well the heat exchanger does it's job, water jacket, firebox temp, ... .
The only thing the user or operator can do is hit the gas pedal more or less, meaning give more or less combustion air.
The boiler I have has no water jacket. It's primarily copper tubing (sparse) in a poorly but self applied insulated (needs more insulation) modified mix-cement enclosure. In this case I would venture that "radiant" (from the fire in the boiler) is allowed to work more effectively (slowing the normal temp swings that a plain steel jacket would have) as the firebox exceeds the average overall jacketed boiler temp scenario (the heat transferto the water happens in the cement walls so the firebox is insulated compared to a jacketed scenario). Said and done reducing water flow increased the boiler temp and that reduced the boilers "call for heat" (which the mechanics of these things do) so I idle more but I idle at a supplied heat that is what I am asking from the unit (so in some degree that equates to improved efficiency). Wood consumption has gone down and realized unit output has improved. I just thought I would share some of my units operating characteristics as I was aked to do in an earlier thread. https://www.hearth.com/econtent/index.php/forums/viewthread/57408/ . Thanks for the formula Marc as I think it says it quite well.
stee6043
Minister of Fire
I think a lot of us toy with the boiler temp vs flow rate gig. That's why Grundfos 3 speed pumps are so handy. I personally slow my circ down towards the end of a burn to reduce mixing in my tanks. But like said above - the net output should be very close to the same since you're simply moving less water, but warmer water.
It's worth mentioning that many of the plumbing purists out there will tell you that throttling flow with ball valves is a bit of a no-no for long term reliability of the valve.
It's worth mentioning that many of the plumbing purists out there will tell you that throttling flow with ball valves is a bit of a no-no for long term reliability of the valve.
Thanks for the input stee6043. I wondered about system longevity and compnent response. My net output has changed as the boiler is not running as hard to keep up and is more responsive to heat demand after periods of inattention like when I have to work over. For comprehensive perspective my boiler set temp is 150f and the circ runs 24-7 (a necessity dictated by design) and is always causing a heat load. Going from a full load (2x day) to a half load (2x a day) and getting nearly the same results makes me grin. With this type of boiler I have sometimes been able to meet heat load a couple of times an hour while idling when there is little wind. The air handler comes on about every 10 min and runs for about 7.5 min with the T stat set for 1/2 degree variant. Loading the boiler full was carry over habit from the EKO40 (which is waiting for a building that insurance won't dump me for) but ended up costing me a lot of seasoned wood. The change in flow rate as an operational approach seems to save even more wood. For the risk of the work of replacement and the price of a ball valve flange versus the work and price of two full cords of wood (per year) I am afraid the ball valve takes the hit. To satisfy the plumbing purists though I already have another ball valve in place down stream and it's wide open. I guess it's hats off to the plumbing parts mfg for job security though.
heaterman
Minister of Fire
Cave2k said:
The best commonly available valve type for "throttle" use is a globe valve. A circuit setter is of course the best but also far more expensive. I have seen both gate and ball valves worn away to the point where they would not shut off the line when used in a partially open state. It's not their intended use.
Hi Heaterman,
How do you think a gate valve would work in place of the ball valve? Thanks for your response.. Cave2k
How do you think a gate valve would work in place of the ball valve? Thanks for your response.. Cave2k
heaterman
Minister of Fire
Cave2k said:
Both gate and ball valves are designed for fully open or fully closed operation. I have seen gate valves with about 20 of the "gate" worn away from running in a throttled position.
In a gate or ball valve the throttling plate or ball sits "across", for lack of a better word, the flow in the pipe. A globe valve is configured in such a way the the flow hits the "throttling" piece face on so flow is more even all the way around the "stop".
http://www.isa.org/Images/InTech/2005/August/20050818.gif
http://www.poolplaza.com/pool-school/plumbing_valves_gate.shtml
How often and how full do you usually load firebox? Others seem to be reporting much reduced wood consumption with half fills. Cracking isnt a issue for you? Appreciate all feedback.
I bought my heater in the fall of 2009 and im still using it today. The company started not to long before that but was told that the founder made several prototypes he used for several years before that. He started out using plain old cement and found out when it was dried over time it wouldnt spall. Mine unit has one or two cracks in the cement but it didnt effect how it ran. The cracks started early and stopped and havent got much worse. I use my unit hard since my 3/4 piping is practicly without insulation( my grass stays green all year and the pipes are 4ft down) and goes 150ft to my 2500sqft house and to my two stall garage. I keep my house at 76f with windows open sometimes. They did upgrade my door and its been good ever since. I do notice that a half fill will last 12 to 14 hours with coals that could even extend my fill times. I will usually rake them to the front and throw a few splits in the back every 6 hours or so. Even though mine is working good i can see why they use a differant kind on "chimney cement" on their standards and 3000 degree refractory on their elite series. I see most of these bloggs are from a while ago and dont see much about the new ones, probably because they arnt having as many problems. I have been to their factory several times and im now convinced that the new ones may be the way to go for outdoor wood boilers. They mentioned that they trade old ones in for the price off a new one and may do so. They have a huge all refractory gasifier at their shop that heats what they said to be 20,000sqft. I saw it in operation burning corn! they also burn sawdust and regular splits I love the fact that in the summer i dont have to clean it out or treat the water to prevent rusting in them. All and all im satisfied with the company. They made me feel important. Anyone that wants to see my old unit may do so.
- Status
Similar threads
