# John Wood oil fired water heater problems??



## scottyk52

I'm having trouble with water temperature settings on a John Wood oil-fired water heater. The original problem was 150 degree water even with the aquastat turned all the way down. So i installed a new aquastat and set the water temperature to 125. Now the problem is, if the tank sits unused all day it maintains the 125 degree water but when its being used and the water heater fires it doesn't satisfy until the water is in the 150 degree range again. This happens whether i have the dial set to the 125 range or to the lowest setting. It is noticed most when someone is showering and the heater fires and produces extreme temperatures. I don't have much experience with oil-fired water heaters as most home around here have gas. Does anyone have any ideas what could be causing this??


----------



## SlickRick

scottyk52 said:


> I'm having trouble with water temperature settings on a John Wood oil-fired water heater. The original problem was 150 degree water even with the aquastat turned all the way down. So i installed a new aquastat and set the water temperature to 125. Now the problem is, if the tank sits unused all day it maintains the 125 degree water but when its being used and the water heater fires it doesn't satisfy until the water is in the 150 degree range again. This happens whether i have the dial set to the 125 range or to the lowest setting. It is noticed most when someone is showering and the heater fires and produces extreme temperatures. I don't have much experience with oil-fired water heaters as most home around here have gas. Does anyone have any ideas what could be causing this??


*Hello! Introduction Requested* 
An intro is requested from all new members. In case you missed it, here is the link. http://www.plumbingzone.com/f3/.

The PZ is for Plumbing Professionals ( those engaged in the plumbing profession)

Post an intro and tell our members where you are from, yrs in the trade, and your area(s) of expertise in the plumbing field.

This info helps members who are waiting to welcome you to the best plumbing site there is.

We look forward to your valuable input.


----------



## waldrop

What kind of oil are u burning?


----------



## scottyk52

The burner is using regular home heating oil... Thanks


----------



## waldrop

Have changed source of fuel oil recently?


----------



## Dplghtg

Where is you'r point of detection is it in the core or it it a strap on aqua stat Core readings will give you a better reading to prevent surge.


----------



## scottyk52

Nothing has changed with the oil. The aquastat is a immersion type so i would believe it would get a accurate reading. It seems as though there might be some kind of high limit or something that i am missing:blink: To me it seems as if the water heater will satisfy at 150 and then once it cools off to 120 it kicks back on.


----------



## OldSchool

I could tell you what to do but I would give you enough information to make you dangerous....

Oil is way different than gas... so unless you are trained for it you would be better off letting somebody that knows work on it.


----------



## vinpadalino

scottyk52 said:


> I'm having trouble with water temperature settings on a John Wood oil-fired water heater. The original problem was 150 degree water even with the aquastat turned all the way down. So i installed a new aquastat and set the water temperature to 125. Now the problem is, if the tank sits unused all day it maintains the 125 degree water but when its being used and the water heater fires it doesn't satisfy until the water is in the 150 degree range again. This happens whether i have the dial set to the 125 range or to the lowest setting. It is noticed most when someone is showering and the heater fires and produces extreme temperatures. I don't have much experience with oil-fired water heaters as most home around here have gas. Does anyone have any ideas what could be causing this??


There's a fixed differential on aquastats(10-25 degrees). Is the water heater have a lot of crap built up on the bottom of the tank? If it's such a problem install a tempering valve.


----------



## scottyk52

Installing a tempering valve is my next option but i was just baffled on why there is such a difference in temperature. I understand there would be some difference in temperature due to the aquastat readings but just didn't think there would be a 20 degree jump.


----------



## vinpadalino

scottyk52 said:


> Installing a tempering valve is my next option but i was just baffled on why there is such a difference in temperature. I understand there would be some difference in temperature due to the aquastat readings but just didn't think there would be a 20 degree jump.


Thats the only control for the temp. How old is the unit? Did you get the right control? Are you in the trade? Were do you live?


----------



## scottyk52

The unit is from 2005. We did not do the original installation. Yes i have my master lic. and all employees are Massachusetts Licensed. I replaced aquastat with same model that was installed with original installation.


----------



## vinpadalino

What size nozzle is in the unit?


----------



## scottyk52

Pretty sure its a .65 nozzle. I was hoping it was just a dial adjustment that i wasn't seeing. This isn't really my area of expertise. I figured it might be a common thing burner techs came across:blink: I will be installing a tempering valve for the safety of the child in the house anyways. I just wish i could have come up with a better explanation. Thanks for your help!!


----------



## Redwood

Soooo anyway what aquastat are we talking about?
Honeywell 4081L.... ?:whistling2:


----------



## scottyk52

yes its the 4081. are they known to have problems???


----------



## vinpadalino

I would take the well out. Check for mineral build up. And flush it out. I've seen water heaters go in 5 years due to bad water. ( Check the hardness, PH, Iron) 
If that well is covered with mineral build up it will throw off the temp.


----------



## scottyk52

The water heater is on a well water so i checked for mineral build up around immersion well . This style aquastat is immersion type so it's all clean and getting direct contact with the water.


----------



## vinpadalino

scottyk52 said:


> The water heater is on a well so i check for mineral build up. This style aquastat is immersion type so it's all clean and getting direct contact with the water.


No way! When you took aquastat out did water come out? Are you a home owner?


----------



## RealLivePlumber

:laughing:
I think you got him on the water well, and the immersion well. 

Good detective work, Vin.


----------



## Redwood

scottyk52 said:


> yes its the 4081. are they known to have problems???


No, But if you have the L4081A1023 or, L4081B1047 models you have an adjustable differential of 10 - 25 Degrees F some of the other models have a 10 Degree F fixed differential...

Check your settings....


----------



## scottyk52

Vinpadalino. no i'm a not a homeowner. Just have never dealt with this style aquastat before. Realliveplumber yes water would have come out if tank was not drained. Take a look at the honeywell 4103a1019. To get a better understanding before chiming in. I'm also pretty sure i know the difference between a well and a immersion well :thumbsup: Redwood i'll take a closer look to see if its adjustable. Thanks !!
*
*


----------

