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Boiler not providing enough heat.

Started by stumper, December 14, 2013, 10:58:27 AM

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stumper

Well a strange thing has happened.  The boiler is not providing enough heat to keep the oil boiler off (central boiler E2300).  Dang*%#*&^)** another issue with the boiler.  Fire out? or other?

Bundle up and go out.  Huhh??? Boiler is up to temp.  Yes it is calling for heat but its at 182.  Oh darn, the dumb operator forgot to bump up the pump speed, must have left if on low or medium.  So I dig into the back, remove the insulation and, Huhh??  Pump is on high.  Still had the boiler come on twice.

It turns out the line is just not providing enough BTU's into the house with this snap of bitter cold.  When I have several zones calling for heat cold water from these zones dump in cold water faster than the wood boiler can through the 1 inch thermo pex.  I knew this could be a problem, but the cost of the 1 1/4 inch and the mods I would need to do to the boiler stopped me from installing the larger pipe.  I have now bump my wood boiler temp up to 195 degrees.  This will provide increased BTU movement and a larger buffer before the oil comes on.  I have done this during past cold snap to improve efficiency of transfer, but not because I "needed" to, or so I thought. 

Thankfully we have about a foot of snow coming in to help insulate the house, and we only have cold like this for 2 to 3 days in a row a few times a winter.  Mental note, when the temps drop below 0 bump the temp on the boiler.

r.man

Can you disable your oil boiler and allow a slight down trend in a zone?
Life is too short or my list is too long, not sure which. Dec 2014

thecfarm

The money factor does get in the way at time with most of us. I hope this cold won't last for long. January cold is not far away.  :o
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

doctorb

One of my boilers used to do that.  I just turned down the aqua stat temps on the indoor furnace/oil burner so it never got the signal to kick on.  Do it on an annual basis now.  Just turn the settings lower and you won't be burning any oil!  The heat is fine without the oil burner.
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."

stumper

I could but I would need to turn down the temp of the hot water as well.  My hot water is set at 150, my oil boiler at 170, so I have decent efficiency in heat transfer to my hot water. 

Much easier to bump the temp up to 195 on my wood boiler.  I seem to have less creosote build up at the higher temp, which is another benefit to raise it.  Shortens my scraping time when the Kee-Kee bird is flying.

JJ

I run my e-2300 at 189F with oil furnace at 175.
Runs better little hotter, but I also have pretty big pump (24 gpm if I remember) on 1" thermo-pex.   Keeps up fine

         JJ

woodmills1

If it was easy everyone would be doing it



9 seasons here...............bumped the water temp to 195 and the house went from 65 to 68 in 3 hours............more wood ina stove though


it is amazing how much warmer 10 inches of snow will keep my house
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

JJ

The wrap around pump I have (on water manifold side) is variable speed, and in this cold weather, I have to run on high.  do you have aqua stats on all 4 sides of heat exchanger?
This will tell which side needs more flow.

             JJ

stumper

No heat exchanger. 

Bumping the wood boiler temp seems to solve the problem.  I always knew that the that the pipe was a limiting factor but because I had raised the boiler temps with cold snaps in the past the limitation had not come to light.




doctorb

Do you have temp guages on the inflow and outflow lines coming from the OWB in your basement so you can see the real temp delivered to your oil burner?  I have always operated my 2300 at 185-195 deg.  This is becasue I have a long underground run to the house (300') with 1 1/4 inch pipe.
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."

stumper

Well that is a yes and a no.  Yes, I have lines temperature gauges going in and out, but they are at the wood boiler.  So to read them I have to open up the back and remove the insulation to read the gauges. 

When I have checked them in the past they have normally been from 0 to 4 degrees apart.  I am sure the zero was when there was no call for heat, and I would only be seeing the line loss.  As my line is only about 70 feet, buried below the frost, and has several inches of extra foam insulation (and under drainage) my line loss is less than what my gauges read.  Honestly, I have not read them when it was below zero and calling for lots of heat.

If the snow ever stops maybe I will check them today.  It is a balmy 9 degrees but with my wife doing laundry there should be a call for heat.

Holmes

If you have a 4* difference and your house was warm that would be great. With a 4* difference and the house is cold,
1 the heat is being delivered from the boiler to the house
2. the heat is not being exchanged to the house side
3. is the heat exchanger air bound or is that the boiler?
4. is the circulator that drives the water thru the boiler Working?
5 is there an aquastat for the above circulator and does it work?
6. piping in and out of the house boiler can be in the wrong place and you will get minimum heat exchanging
Think like a farmer.

gspren

  How do you operate with no heat exchanger? Usually the OWB keeps the water in the oil boiler hot using a heat exchanger so cranking down the oil kick on temp wont affect hot water unless the OWB just cant keep up, at least that's the way I've seen them and mine works well with the oil kick on down at 140.
Stihl 041, 044 & 261, Kubota 400 RTV, Kubota BX 2670, Ferris Zero turn

stumper

1. yes
2. No exchanger
3. No exchanger
4. Yes
5. No
6. Nope.  Pipes are correct.

I only have the problem when multiple zones are dumping cold water in at once.  Up to the other day I have only had this issue if the fire went out or I shut the boiler down for cleaning.  At those times I had all zones calling for heat at once.  There is no way that a 1 inch line can move enough hot water to overcome 5 zones dumping in cold water.  At those times if I cycle the emergency switch (oil boiler and circulator pumps) on for a minute off for a minute several times I can get the cold water out of the pipes and the wood boiler can keep up.  During normal operation and normal winter temps say above zero there have been no issues with the wood boiler temp range of 180 to 185.  The other night I had temps well below zero.  Since bumping the wood boiler temps up to 190-195 no issues with the lower temps.

My wood boiler is piped directly into the oil boiler.  Same water circulates through both.  Yes lowering the oil boiler aqua stat would solve the issue as long as the wood kept up.  If it did not due to what ever, the circulator for the hot water could call for heat continually and potentially cause an issue.  Bumping the wood boiler temp causes no issues and solves my problem.  I just need to remember to bump the temps when it gets real cold.  If I were in a colder region than I would be more concerned. 

That said I would recommend the installation of the 1 1/4 inch thermopex with its 50 percent more capacity.


Holmes

 OK  2 more things before you change the pipe  If the feed ties into the front of the house boiler and the return ties into the back of the house boiler directly in line with the feed you may not get as much heat transfer as you should. I've had that happen.
The 1" pipe can carry all the btu's you need with a "bigger" circulator.  1" is usually good for 12 gpm or 120000 btu's  a larger circ  009? could deliver 20 gpm or 200,000 btu's thru the 1" pipe.. I did not do the math on this it is for example only at this time.
Think like a farmer.

stumper

My inlet and outlet are both in the back.  Hot in on top cool out on the bottom. 

I do have a slightly oversized three speed pump (Grondo? 17 gpm?).  I do not remember the GPM now but I beleieve it was slightly above what Central boiler called for. 

If I recall my oil boiler is 250,000 btu, and my e 2300 is 180,000, so the limiting factor will be the pex.

I have no intension of changing out the pex until I have a real problem with it.  I just need to remember to bump the boiler temp for cold snaps.  Running 190 to 195 range has gotten me through 20 below nights in the past with out any issues.

If I do have any issues this winter I will look to rebuild the pump.  I run my boiler 6 month or more a year to this has been running continually for more than 2 + years (4 * .5=2).  While I expect more life it may be getting tired.

AnthonyW

Why would you think the 1" line is the limiting factor? Most forced hot water piping I have seen are 1/2" and or 3/4" copper pipe. Not being familiar with your specific model OWB, what is the diameter are the connections on the side of it? 1" or 1 1/4"?

You mentioned that when you have checked the gauges, you have noticed them to be 0 to 4 degrees difference. What are the absolute/actual values of each? If they are above 150, then you are not getting the heat to the house. If you are not seeing that much or more of a difference then you are not "exchanging" the heat from the furnace piping with the air in the house. Are you sure the zone valves are working properly. I have had problems with both the zone valves sticking and the circulator pump becoming air bound (remember that circulator pumps cannot pump air).
'97 Wood-Mizer LT25 All Manual with 15HP Kohler

doctorb

Lots of good opinions here, IMO.  I think that Holmes may have the answer,  You may not be getting enough mixing of the cold return to the boiler jacket before the cold water is returned to the stove.  Your temperature fluctuations to the boiler may be too great.  I also don't think it's the diameter of your pipes, although enlarging the diameter may be one solution tothe problem.

Many different solutions are possible fixes for your issue, an have been mentioned.  I think your situation is good support for using a heat exchanger.  The mixing of the water temps would make the drop in temperature smoother.  Separating the two systems permits one to continue to run while the other is undergoing maintenance of is leaking.  May I ask why you did not install one initially, if there was a reason other than cost.  How does the pressurized system in you home work with the open system from the OWB?
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."

stumper

Well I have 5 zones that run through a manifold into and out of the boiler.  Each zone is at least 3/4 of an inch pipe.  I would say the manifold is 2 inches plus.  As I recall 1 inch pex is approximately equal to 3/4 steel or copper.    I guess it is just an assumtion on my part but if I have two of the zones dumping in cool water at say 130 degrees average (could be as low as 65) and one line from my boiler dumping in water at 180 degrees.  The average temp of the three will be less than 150 degrees and my oil boiler will be kicking on as soon as the boiler and water in it cool to the average of the three.  As 1 1/4 has about 50 percent more capacity the average temp would be higher and it would take longer to have the oil boiler call for heat.  Similarly bumping the heat of the wood boiler also pushes more btu's through the pipe.

I have depressurized my home system.  My oil furnace and circulator pumps sit at a lower evelavion than my wood boiler.  This results in about 5 to 6 psi of pressure in my oil boiler.  As my circulator pumps push away from the boiler there are no issues with "depressurizing" the system.

I may have forgotton something since thermodynamics but direct water to water should provide a better exchange thanany heat exchanger could, especially since the same inlet and outlet to the oil boiler would be used. 

I can throw a couple of valeves and isolate the wood from the oil if I need to work on the wood side. 

Hilltop366

Seems to me I have heard of mixing some hot in the return line to prevent oil boiler short cycling when talking to a plumber I had hired years back.

It may work in this situation to prevent your oil burner from coming on by tempering the return line temp and allowing the wood to keep up by preventing the sudden demand situation when multiple zones are on.

AnthonyW

Quote from: stumper on December 16, 2013, 12:45:04 PM
Well I have 5 zones that run through a manifold into and out of the boiler.  Each zone is at least 3/4 of an inch pipe.  I would say the manifold is 2 inches plus.  As I recall 1 inch pex is approximately equal to 3/4 steel or copper.    I guess it is just an assumtion on my part but if I have two of the zones dumping in cool water at say 130 degrees average (could be as low as 65) and one line from my boiler dumping in water at 180 degrees.  The average temp of the three will be less than 150 degrees and my oil boiler will be kicking on as soon as the boiler and water in it cool to the average of the three.  As 1 1/4 has about 50 percent more capacity the average temp would be higher and it would take longer to have the oil boiler call for heat.  Similarly bumping the heat of the wood boiler also pushes more btu's through the pipe.

I have depressurized my home system.  My oil furnace and circulator pumps sit at a lower evelavion than my wood boiler.  This results in about 5 to 6 psi of pressure in my oil boiler.  As my circulator pumps push away from the boiler there are no issues with "depressurizing" the system.

I may have forgotton something since thermodynamics but direct water to water should provide a better exchange thanany heat exchanger could, especially since the same inlet and outlet to the oil boiler would be used. 

I can throw a couple of valves and isolate the wood from the oil if I need to work on the wood side.

It seems like there should be plenty of heat. There is probably a small nuance with the system that we are overlooking.

Are the oil and wood boilers in series or in parallel?

I am picturing all the zones go into two manifolds, one from the furnaces, one from the zones back to the furnaces.

Do you have a loop that heats, when no zones are calling for heat? The water in the OWB jacket should be toasty hot with plenty of heat for instant demand. If you have this loop, does it include the manifold?
'97 Wood-Mizer LT25 All Manual with 15HP Kohler

stumper

I would say series.  The wood boiler heats the oil boiler the zones draw off the oil boiler.  No loop that heats when no zone is calling for heat.

It was -14 this morning and no issues, with the wood boiler set at 190 to 195. 

Your comment does point to another possible solution.  If I replumbed to that I was draw my return to the wood boiler from the return manafold from the house than I would be pulling some of that cold water directly to the wood boiler when I had zones calling for heat.  When no zones wher calling for heat it would be very similar to what is happening now.   

AnthonyW

Quote from: stumper on December 17, 2013, 07:28:54 AM
Your comment does point to another possible solution.  If I replumbed to that I was draw my return to the wood boiler from the return manifold from the house than I would be pulling some of that cold water directly to the wood boiler when I had zones calling for heat.  When no zones were calling for heat it would be very similar to what is happening now.

Sorry stumper, I didn't follow that.

Does the circulator pump on the OWB run all the time or does it only run on demand?

If you don't have at one loop that is always open, then the supply and return loops are deadheaded and stagnant. If you added a loop that was open when no loops called for heat, and closed when a zone needed heat, it would keep your supply and return loops warm and ready to take the load.

Right now when a zone demands heat you have to:
(1) heat all the water in the zone
(2) heat all the water in the loop
(3) heat all the water in the manifold
(4) And if the furnaces are in series such that the water flows through the oil boiler and then the OWB, you have to heat the jacket in the oil furnace and all the water in the jacket of the oil burner.

I can't help but think the reason the increased temperature works so well is because it helps provide more BTUs to heat ALL of your load.

Since the heat source in the OWB (fire) does not start and stop like to oil furnace, you are not wasting any heat in having this loop. You wouldn't happen to have drain valves on the manifold that you could temporarily hose together and crack the valves to keep the water circulating, do you?
'97 Wood-Mizer LT25 All Manual with 15HP Kohler

beenthere

QuoteYour comment does point to another possible solution.  If I replumbed to that I was draw my return to the wood boiler from the return manafold from the house than I would be pulling some of that cold water directly to the wood boiler when I had zones calling for heat.  When no zones wher calling for heat it would be very similar to what is happening now.   

I'd say you have found, or now know your problem. I suspected such but could never quite get it fixed in my mind what you had for a design.
Returning the cooler water from your runs to the oil burner, the cooler water never (or likely) makes it back to the wood burner unless you make it happen.
I have valves to turn on/off to force the system into wood only, or gas only, or if in series the return water goes only to the wood fire first, then on to the gas if I want the gas to pick up any slack.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

doctorb

Quote from: AnthonyW on December 17, 2013, 07:44:52 AM
[Does the circulator pump on the OWB run all the time or does it only run on demand?


This is key.  I have also had a difficult time envisioning exactly the design and functionality of your system.  I imagine that the OWB pump runs continuously through the oil burner jacket, and the zone circulator pumps kick on when heat is demanded from a thermostat.  When cold water is returned to the oil burner jacket, it's "available" when any zone kicks on to be recirculated back into the house.  Why would 60 degree water ever be returned to the oil burner on a cold day?  If your thermostat was set at 65 degrees, wouldn't the water temp in your baseboard heating loop be higher than that?  Now, maybe, if you had the thermostat turned off, the water would cool to that temperature or even below, but after the thermostat kicked on to maintain a certain room temperature, it should never really get below the room temperature, as the air cools faster than the water.  Is the cool water from a radiant heat loops) with a recirculating loop to lower the temp of the circulated "hot" water?

I have to agree with beenthere, the cool water return is not efficiently getting back to the OWB, lowering the temp in your oil burner jacket and being recirculated to other zones, when demanded.

Glad all is working well with the higher OWB temps.  -14 is real cold to this Mid-Atlantic dweler
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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