oversized oil boiler - what to do?

ice4life1417

after a good cold snap i can pretty much guarantee my boiler is so ridiculously oversized it's not even funny.



symptoms: 3 minute fire time is the longest the burner has fired. circulator continues running and if necessary the burner will fire again usually for 2 minutes at a whack after the initial 3 minute. around 3 min is the longest burn time even when showering, it's ridiculous. the aquastat is satisfied so quickly i can't remove BTU fast enough.



HL 175 HLd : fixed at 10



LL 150 LLd : 10



approx 64 ft of rad on the first floor and 70 ft of rad on second floor



wtgo-3 with beckett AFG : 0.85 GPH



tankless coil - considering moving to indirect or something else altogether.



I'm sure it doesn't help that my wife and I are comfortable at 64 on the first floor(60 overnight) and 63 on the second floor.



______________________________________________________________



What do i do to make this boiler work efficiently in the space?



Sure, it's a drafty house, but I don't leave the doors open and heat the neighborhood.

Charlie from wmass

How many square feet of house

are you heating? I am guessing the feet you refer too is lineal feet of baseboard. It maybe you could use a buffering tank and an outdoor reset to give longer run times on the burner.

ice4life1417

square footage

so sorry i left that out.  1800 sq ft.  and yes, the other measure is linear feet of slant fin baseboard.

yes...i am heating.  Run times are really short considering I've gone through over 1/2 a tank of oil since the last week of October. 

Robert O'Brien

A few things

The firing rate can be reduced,this requires someone with an analyzer who knows what they are doing. A reset control,I'm partial to the Beckett AquaSmart for these type applications,a HW AquaReset or Hydrolevel Fuel Saver will work as well. As long as you can cold start or warm start the boiler,an indirect will be a big improvement as well

Fortunat

junk it ?

Well, my first piece of advice would be to junk the boiler and get something modulating and correctly sized to the load. But I assume you'll tell me that isn't an option so:



-Have you considered downfiring the boiler (replacing the nozzle with a smaller one). That is an option in some cases, effectively making the boiler a bit smaller. It would probably necessitate cold starting the thing and adding an indirect though, as a smaller nozzle mights struggle to maintain the tankless (you should do this anyway).



-Its not a total solution, but a burner control like the Intellicon HW + would certainly increase the run time of the boiler and reduce burner cycles somewhat. We've seen them save up to 30% of an annual bill (8-12% is more common) in cases where a boiler is oversized for the load or where many small zones result in lots of boiler cycling.



but what do I know...I'm just a solar guy....



~Fortunat

www.revisionenergy.com

ice4life1417

replace

100% I would love to just junk it.  BUT... it's only 4 years old and that would be awfully wasteful.   

how small a nozzle can i put on the Beckett AFG with the WTGO-3?   Will doing this hurt efficieny ratings?     here i am worrying about efficiency ratings when the unit is currently running at like 20%. 

cold fire a cast iron boiler?

Robert_25

2 minutes is short...

Are your baseboards 3/4"?  What do you have for circulator(s)?  You can't get much smaller in the world of oil boilers.  Your baseboard load is small, but I still wouldn't expect the boiler to short cycle that badly. 



I installed a Beckett HeatManager on my oil boiler to cure short cycling; it worked as advertised, but I don't know how it would play with a tankless coil.



-Rob

ice4life1417

taco

3/4" baseboards

taco circulator that came prepackaged with the WTGO-3

ice4life1417

taco

3/4" baseboards

taco circulator that came prepackaged with the WTGO-3

ice4life1417

coil schmoil

what does the tankless coil play nice with!?! rhetorical ... i hate that freakin thing

billtwocase

Nothing wrong with that boiler

A plus would be a Carlin EZ-1, make sure it is set up for rear flue, and have it professionally downfired, and a Beckett heat manager might help . Buy some time with it, have an indirect installed so you can add ODR to it. 

Charlie from wmass

so you know what a coil can do

My fathers house is 3600 square feet total and three bath rooms. Even with my four sisters we never went through 1000 gallons of oil a year. I still take two showers a day every day. The coil does not make the system the total oil hog you would think. I am curious as to what the boiler piping looks like.

Ironman

Aquastat

Have you checked the differential setting on the aquastat? Try increasing it .At a firing rate of .85 @ 100psi your input is 119mbh. At 80% efficiency = 95.2mbh. Your rads have an output of 67mbh @ 170 deg. average. So your boiler is about 1/3 over-sized. Not enough to cause the kind of short cycling you're describing in very cold weather.



Down sizing is a good idea and should be easy for a pro. Just be careful not to let stack temp get too low and cause condensation in the flue. I second the motion for an indirect and reset.

ice4life1417

zone

i assume the design temp is 4-7 F outside and 70 F inside where i live.  during the day we keep the 1st floor at 64 and the second at 63.  the second floor rarely calls for heat so it's only the fintube from the first floor calling, which is 36000 btu/hr load i think. 

***could that be the major cause of the short cycling?  one zone running at any given moment? 

ice4life1417

zone

i assume the design temp is 4-7 F outside and 70 F inside where i live.  during the day we keep the 1st floor at 64 and the second at 63.  the second floor rarely calls for heat so it's only the fintube from the first floor calling, which is 36000 btu/hr load i think. 

***could that be the major cause of the short cycling?  one zone running at any given moment? 

ice4life1417

piping

I don't have a picture to send but i can describe the piping for you Charlie.  the pic i attached is not my boiler, it's someone else's with the same piping, right down to the incorrect heat drop for the mixing valve off the coil.

pressure regulator and backflow preventer on cold supply coming in which connects with the main line return to the boiler.  air vent and diaphragm expansion tank hung off the top of the boiler.  supply line to taco pump(prepackaged) to 2 Erie zone valves.  one zone to first floor and one to second floor.  both zones return on the opposite side of the boiler

Charlie from wmass

one zone at a time will

cause the burner to short cycle. As the other guys said a professional should be able to down fire the burner and watch he does not do it too far. The boiler is as small as they get for oil from Weil McLain so the boiler choice is not truly the issue but an indirect would be needed when you down fire the burner. There are other things like buffer tanks that can be added but keeping it it simple is better when you have no idea who is going to be working on a system in the future. Rough idea of what a buffer tank looks like here http://www.cemline.com/products/steeltank/sebmenu.asp

icesailor

Oversized boiler

Where did you come up with the number of 20% efficiency?

I have the exact same boiler with a Carlin EZ-1 and get 86%+ when it is running. After two years of year around running for heat and domestic hot water. I think you have been reading too many Popular Science and other information from "Experts". (Defined by me as being "X" is an unknown quantity and "Spert" is a drip under pressure.)

My take on this screed of boilers are only efficient when they are running so lower the output and it will run longer is a contradiction. The boiler and heating system are supposed to be designed for the coldest day it will encounter in a day. As far as I know, we haven't hit that day yet this heating season. So your heating system is over sized. For heating. Someone mentioned that your system is 1/3 over sized or 33%. The extra is being used for domestic hot water heating which is a base load that is there 24,7, 365. You are also keeping your house at a temperature that is above the design temperature for inside temperature. When you hit that design day, you or your wife get in the shower and see how long the burner runs and if you get enough hot water.

I have set back thermostats with 5 zones. Two zones are set at 50 and the other three are at 68 when on and 54 when off. They are off, 14 hours a day. It's 23.2 degrees out now and 68.5 degrees inside. The burner came on a few minutes ago and shut off after three minutes. It started a few minutes later. It was another zone calling. I heard the circulator stop. And start.

You need to (but won't) look at it as that the burner extracted BTU heat from the fuel and stored it in the water in the boiler. It is being stored for future use.

I find that with this boiler and others that I have installed or worked on, I will get the best combustion numbers the closer to the boiler rating number. When I drop the nozzle to down fire it, the efficiency goes down. If you fire that boiler with a .75 GPH nozzle, you may find yourself with low hot water performance.

And finally, if you have digital thermostats, they can be cycling too much. They can be set. They may be set improperly.

icesailor

Boiler Twin:

Ice,

Be glad you don't have that POS burner on the boiler in the picture. A bigger piece of junk hasn't ever been made. And after putting them on many of their boilers, they stopped making them and parts are unavailable.

icesailor

Oversized:

The EZ-1 is the way to go. Get the "Burner in a box" for a GO-3 from your supplier or Carlin and it is a bolt on deal. All you need to do it adjust and combustion test it. Get it with the 602000 control and you will be living large and in style.

ice4life1417

downfire

So, I will be downfiring the boiler next week. how far do you think would be too far. i'm willing to suspend the home heating needs for a 15 minute shower by turning the thermostats down. also, I just started using the wood stove so the boiler is only really necessary as a supplement overnight and for hot water.



if i had an indirect, what do you think would be a fair nozzle to put on there knowing that:

desired temp is 65, outdoor design temp is 4-7, i'll be running a wood stove during the coldest days anyway.

**all things the same, what nozzle would you suggest knowing i have the coil?

World Plumber

What head on the burner

What head on the burner? This need to be set up by someone who knows what they are doing. You may need a low fire baffle and different static plate.  I down fire often with good results. You have to get the firing rate right so that you maintain boiler temperature but are not constantly against the limit. Find a good burner tech and have him set it up. That should have been done when it was installed. Once you match the output of the boiler to the house it should run well. As long as the boiler is remotely close in size they should be able to get you running right. I looked back you do say Beckett AFG the specs show you should change the static plate to drop to a ,75 anything lower you should change the head, You will need the low fire baffle. You just need an oil guy who knows what he is doing. Beckett teaches all this in their factory training.

ice4life1417

burner head

L1 head

Robert_25

Smaller than 0.85

If you intend to downfire the boiler to something less than 0.85 GPH, I would plan on keeping some spare nozzles and filters on hand.  Nozzles that small do not tolerate dirty fuel, and if you have an old tank the problem is even worse. 



If you are considering adding an indirect, I would question firing the boiler below 0.75 GPH.  A 30 gallon indirect will take about 90k btus/hr to achieve rated output.  As for the short cycling from the two zones, a buffer tank or control that varies the differential (Heatmanager, Aquasmart, etc) will take care of it.



-Rob

mark schofield

teckmar ?

I have the same boiler (with the Carlin EZ1) and added a Honeywell AQ475

outdoor reset about 4 years ago. The

literature says that the differential when calling for heat is also

controlled by the AQ475 for longer runtimes. The literature for a

Teckmar 256 seems

to say that the differential when calling for heat can be manually set. I

changed from top to rear flue as billtowcase suggests and the stack temp dropped fro 450 to

390. The original nozzle was .95, and last year when the serviceman did the tuneup with the digital meter he changed it to .85. I guess 390 is as low as I could safely go. I get frustrated with the short runtimes also, but aside from buying a new smaller boiler (Basi?) and adding an indirect, there's not much more I can do. The teckmar controllers aren't that expensive. Possibly one of those might help if you can actually up the call for heat runtime differential.

Eric_32

What brand...

 of thermostat are you using? I have had problems with some Honeywells causing some systems to short cycle. They do not have an adustable differential.

However if the zone is still calling after the burner is off then it is probably bouncing off Hi limit, not short cycling from the tstat.

Do you have zone valves for each zone and share a pump or separate pump for each zone? If zone valves, maybe the pump is having issues and not working correctly, the zone valves open and gravity heats the house, boiler bounces off hi limit because the pump isn't dumping the heat like it should.

64 and 70' zones are good size and should take good good bite off the water temp of the boiler when it calls.

I would investigate either a pump problem or restriction somewhere.

ice4life1417

tstat

the tstats are honeywells but i can tell you the boiler bounces off the high limit constantly. I've done a good amount of monitoring and 9 out of 10 times the boiler hits high limit before the tstat is satisfied.

I did investigate a possible pump or restriction issue and i do not believe this is the case. the return side of both zones gets super hot pretty quick. zone valves with one pump r in use currently.

icesailor

Oversized Boiler:

You know Ice,

I don't think that you quite understand one of the functions of a boiler. It is to save recovered heat from the fuel. The heat is transferred through the boiler casting to the water in the boiler. The heated fluid is transferred to the heat emitting units where it is swapped for the colder air in the room around the emitters. Heat flows to the cold. A warm air furnace has virtually no heat storage capacity where a hydronic boiler has storage capacity. You expect your boiler to do something that no hydronic boiler was ever designed to do. Going off on High Limit is a normal part of the operation of a hydronic boiler You seem to be someone who really wants to save money. That you are willing to spend a dollar to save a dime. Most of the people I deal with will spend a dollar if they will save ten dollars a year.

You need to get a price to put in exactly what you want. Scrap that grossly inefficient heating system, the same one that I have and know that I would never be able to justify changing it, and see for yourself. You want perfection. There is only one being that is perfect and I don't think you are Him. If you came to me with your problem and you gave me all the stuff you have mentioned here, I would wish you health, happiness and long distance. After over 40 years in this business, I chose what I have, the same as you have except with a storage tank.  I could have installed anything I wanted. The biggest bang for MY buck is what I have. For less than $1000, you could have something as economical as I have. Wait until you get a price on a Mod/Con LP gas with an indirect, indoor/outdoor reset and all the toots and whistles And how much you will save over time compared to your investment.

What you pay for is the fuel and the BTU content of the fuel. It's the equipment that transfers that heat into the structure for use.  That's all and nothing more.

Charlie from wmass

Buffer tank and more radiation

the only way to save money and get a longer cycle is to increase the radiation to get more air out to the room from cooler water. The buffer tank will give a longer run due to storing the heat in the higher mass it provides the system. It will also allow the system to run at lower temps while not sending cold water through the boiler. A boiler that is turned off is 100 percent efficient. You can also use a heat manager to use up the heat stored in the mass Icesailor is talking of.

World Plumber

L1

If you have a L1 head a tech with Beckett knowledge should be able to set it up with just adjustments and a selection of nozzles. 

World Plumber

High limit

Try spacing your limit out some more. Take your high limit up to 190 .  25 degrees isn't much for a burner that size with a small load.



It sounds a lot like the one I did on New Years day. Same boiler kept the pump pressure and brought it down to a .65, But you need to make a lot of adjustment that you need equipment to do so get a good oil tech. Has the oil pressure been checked? If it's over 140 it's over firing. If you get someone who knows what he is doing he can dial it in for you. 

ice4life1417

scheduled

i have a tech coming out on friday for a routine service.  the downfiring is included as a part of that service so I'm not spending any additional dollars on that and I am getting a professional to do it.  i wouldn't dream of trying to set up the burner without the proper equipment.  thanks for the advice to all. 

my plan through next summer. 

**downfire the burner

**add outdoor reset or heatmanager/intellicon HW+ (haven't decided yet)

**add indirect remotely at pex distribution block 

**set up boiler to cold start - anyone know of some good diagrams out there for proper piping for cast iron cold start or will my piping be fine???

???any other things i could do to maximize efficiency as part of this plan or does it sound pretty good????



@icesailor - I really don't know why ur post is so confrontational.  i'm looking for professional advice from professionals so I can make an informed decision.  Please stick to providing professional advice and keep your personal opinions to yourself.

World Plumber

Piping

Do you have a bypass if so adjust your balancing valve to maintain 140 and  your piping should be fine.  If not it would be best to add a bypass so the boiler doesn't condensate. An thermostatic return/bypass valve would be even better.   If you go with an indirect. I would recommend a priority zone control.

Patchogue Phil_2

differential

ice4life



You might want to check out this explanation



http://www.heatinghelp.com/forum-thread/63373/Triple-acting-aqaustat



Besides having very small amount of baseboard to heat,  your differential setting of just 10* will contribute to short cycling.



A buffer tank for the boiler water (not the domestic) might prove to be very efficient.  Probably very costly too.



Safely down firing by a pro and also adding storage for your domestic needs may be a more economical solution. 



Even if you just "extend" that domestic coil by having it feed into an electric WH (electric elements stat turned down to say 125*).  The boiler coil feeds the storage tank with ~160* water.  Keep boiler above 140/145* with a 20* differential.  LO of 160*,  boiler kicks on at 150* for domestic,  OFF at 180*.  HI protection at 190*.   Longer,  fewer burn cycles.  The electric elements will never come on,  except maybe if you are running two very hot showers for a looooong time and the dishwasher at same time.



For heat calls,  the burn cycles will run as long as the room stat(s) call for heat.



Are the circulators wired directly to the triple aquastat?





Your mileage may vary.  Get a real pro though.