oil furnace short cycle

undefinedundefined


recently had my york/beckett furnace inspected and cleaned to be put on a service contract with ET Lawson oil in virgina usa. it was an inspection needed prior to contract. the tech came out and did a complete cleaning and test and found unit to be 80% efficient but he did change the nozzle because the one in it was a .6GPH one and the data plate called for a .75gph one. the unit worked fine before they did their work and when he turned it on it ran and did a short cycle..he stated it was normal and would be ok. he mentioned that it could be the 8MERV filter so after he left i changed it to a 3 MERV and it still short cycles. the unit passed inspection but i did not go with them due to their run around quotes on oil prices....

is there anyting i can do to make the short cycling to stop? the unit is not the orginal furnace in my 1964 brick rancher located in Virginia usa. the temp here is around 30F nites and 50F days. the unit never short cycled till they made their adjustments. the tech also said it could be due to older duct diameter..but like i said it never did it till they came out and messed with the unit. i even tried it without a filter and it still short cycled. he did make some adjustments on the burner too but what they were i dont know.

info on their sticker said unit was 80% efficient, 0 CO , 0 smoke, 500F temp. iam begining to hate oil heat! appreciate any help

 

if it works dont fix it. there must have been a reason for the .6GPH=86400 btu's .75=108000
What is cycling. flame detection. blower ? high limit?
call the guy back he increased your BTU's about 21000
also what degree nozzle. whats the oil pressure
did he do a co test? did he test the stack temp?

good luck

 

thanks for the quick reply, been reading posts here up to page 28 so far looking for similar prob.

whats cycling is the pump/ignitor (i guess) i hear digital thermostat click, pump/ignitor runs till it turns on fan and blows heat through vents, then after about 2 mins the pump/ignitor stops but the fan continues to run and then after about 2 mins the pump/ignitor comes back on and runs for a few mins again then shuts off fan runs still . it repeats the process until the dig thermostat reaches the disired temp. (iam guessing the high temp limit is reaching its set point and shuting down burner till it returns to desired internal temp then resumes heating)

from what i remember (i watched the guy work and he was pretty cool about explaining things)

1)the pump held pressure at 100psi and didnt bleed down

2) not sure of the degree of the .75 nozzle but he did say that the unit called for a .75 not a .6 nozzles and change it out.

3) he did perform a CO test and a stack temp test, the CO was 0, and i believe the stack temp was 500 (iam on duty at firehouse for 24 hrs so i dont have access to the sticker he put on unit) but iam pretty sure it was 500F. he also did a smoke check and visual flame check through access hole.

the tech was a pretty cool guy, but the sales rep and front office people are really crummy people after they gave me the run i didnt persue the oil/service contract...but if they did the work and the problem started after them, are they required to change it back without costing me more money.

thanks again for your quick reply and if you have some "fuel" i can add when i call them it would be most appreciated. back to reading more posts here, by the way this is a really cool site!

 

lol it probably called for a max of a .75gph.......
doesn't mean it has to be that... you use whatever meets your needs.... going to big is a problem since you could damage your furnace.

usually the degree is written on the nozzle along with the size.

 

Without a complaint from you of not keeping the house warm, it was a bad idea to max out the nozzle size. It won't harm the furnace but it will negatively impact the efficiency. You may reduce the stack temp by 50 degrees and lengthen the run time if you go back to the .60 or .65. If it was my house I would have a .50 in there at 130 psi pump pressure and a 5 micron oil filter at the burner. If you have to find another tech, perhaps you could ask for those things. It will make the furnace as efficient as it can be and give you insurance against a nozzle clog with a small size like .50 or .60.

Ken

 

wanted to say thanks to all that have helped me with this problem, you have been more helpful than the company that i called out which was E.T. Lawson in hampton virginia. iam calling out another company tomorrow to remedy this hopefully. as for ET Lawson i called them today and guess what?? since i did not go with them on the dangling carrot contract..they said they could not honor their work they did on my unit when they changed out the nozzle and caused this whole fiasco. (but iam not sure of legalities...but the paper i signed for the work at bottom states in clear writting that there was a 1 year guarantee on work performed to include parts and labor) so after the brush off i contacted the better business bureau and submitted a complaint against them. not sure of what will be done...all i wanted was my furnace to run like it did prior to them. again thanks everyone for the help! james

 

I realize it is water over the dam but I have NEVER seen a fuel burning applicance which produced zero ppm of CO. Either this guy's equipment was faulty, his technique was faulty, or he didn't do a CO test.

 

well i finally got my furnace back to normal after the nightmare, i called out another company and they said that while the firnace called for a max of .75 doesnt mean you have to go with it...and that was the reason for safety tripping causing short cycling. i did submit a complaint to the BBB and did get a bill from the first jokers for 150...and the second contractor charged 99 to come out and change nozzle and do their check...so iam going send the difference in prices along with the second statement. so well see what happens. thanks again for all the help here. pretty cool site and will definately be back..hopefully not in the oil furnace section..lol

 

When you say your furnace 'called for' a max of .75 gpm what you really mean is the maximum limit for the nozzle size is .75. Just like the speed limit is 55 mph, you don't actually have to go 55 mph is that speed is not appropriate for some reason. A furnaces efficiency will increase as the nozzle size decreases but some service techs don't have a great understanding of the big picture so they lok at the nameplate and go for the max. I'm glad you got your situation corrected.

Ken