Oil Aga - Thermostat and Flexatemp question?

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Oil Aga - Thermostat and Flexatemp question?

Postby kilgallon on Mon Nov 28, 2005 7:09 pm

:? I have serviced my 135OCB for five years now and generally get better results than when I paid for AGA engineers service (says my wife!).
A few years back, the thermostat seemed to change when I noticed it only clicked around the 1-mark. After valiant (and valium) attempts to correct this problem, I altered the high fire/low fire screws plus the flexatemp to get the desired results. Thus far, everything has been OK.
I now realise I ought to fix (or replace the thermostat if it is faulty?); also correctly reset the flexatemp (or replace if faulty); and reset the high/low fire screws as necessary.

To start with, I measured the high fire oil flow ( first by lifting the flexatemp manual lever to high fire) into a tube and measuring glass at the oil feed pipe rising into the burner section. This measured between 5cc and 6cc. No matter how I adjusted the high fire screw I could not get the output to the required 8cc.

I have checked and cleaned the oil tank filter, the control valve filter, decoked the burner, checked for levels etc. The low fire oil flow seemed OK at around 4cc.

I have relit the AGA and with further teasing of the high fire screw have managed to get the temperature just under the black line (which is my preferred normal setting) for our house of two adults minus the kids.

I have some OCI literature for the 240VNT control valve and flexatemp 3513 but would appreciate some advice how to reset the flexatemp and also any advice how I should open up and check the oil level or other operational parts of the control valve.

Any sugestions graciously received.
IanK
kilgallon
 
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Postby AGA man on Mon Nov 28, 2005 10:27 pm

Have you ever removed the metering stem from the box to see if there is any dirt in the slot, as this "could" account for not being able to get more cc's out. If the flexetemp clears the pin and shuts completly when turned off it's OK, but don't be tempted to keep adjusting it, just like the low and high fire screws unless there is a lot of earth quakes or you live by the side of a runway you should'nt need to alter them as screws don't turn themselves and once set best left alone and look for other causes.
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Postby kilgallon on Tue Nov 29, 2005 8:12 am

:) Thanks Agaman - Can I take off flexatemp whilst aga still running. Can I then also open up control valve while still running or will I become engulfed in unfriendly blazing kerosene!!
IanK
kilgallon
 
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Location: yorkshire

Postby AGA man on Tue Nov 29, 2005 4:21 pm

You can take the electric top off but if you remove the top of the box the burner will get a little excited and will test your reactions as to how fast you can replace it! so if all is well at this moment leave it untill next service.
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Postby kilgallon on Tue Nov 29, 2005 5:09 pm

I think on an earlier post that Poolman said he had an instruction sheet for setting the bi-metal strip of the flexatemp, which I will contact for.
I am now getting the temperature holding a fairly constant level which must mean my thermostat does work after all. It is set at around 2 which is where the clicking is occurring. I presume that the normal running of the flexatemp would require it switching (?intermittently) from hot (?voltage on via t/stat) to cold (voltage off via v/stat).

Is there an intermediate stage for the flexatemp or does it just switch between on and off, presumably whilst taking a controlled amount of time as the b-metal strip bends under the electrical heat . [My ignorance is shown here due to lack of spec sheet for f/temp].

I might just now need to re-test high fire and low fire flame colour and size to convince myself the aga won't cause meltdown in Yorkshire.
IanK
kilgallon
 
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Location: yorkshire

Postby AGA man on Tue Nov 29, 2005 8:57 pm

The flexatemp is simply a high wattage resistor and a bi metalic rod which when heated expands and lifts the arm so as long as it closes when power is off and clears the pin when power on it will work. They come factory set and any instructions I've seen in the past say not to adjust, but at times I've tweaked them a little but anymore and it could mean it's getting tired.
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Postby kilgallon on Wed Nov 30, 2005 11:53 am

Agaman - I have now taken off f/temp and control valve plate and looked into the abyss!
I concluded that f/temp responds properly to voltage via t/stat and have adjusted actuator pin stop back to what it should be (finally, I hope) i.e. clearing the a/pin when on high fire and closing to a/pin sleeve when on low fire.
My current dilemma is that the a/pin does not fully submerge into sleeve (manually or electronically) - it hits firm metallic resistance with about 1.5mm protruding (1mm of main pin body plus .5mm dome end). I temporarily turned low fire screw up/down to convince myself that this would not alter a/pin position, which I gues is preset with friction clip (which I have never touched -honest)
Is this failure of a/pin to submerg fully into sleeve due to a problem inside control valve such as friction clip or metering stem.?
Thanks
IanK
kilgallon
 
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Location: yorkshire

Postby AGA man on Wed Nov 30, 2005 4:37 pm

Does the Aga go to low fire happily? if so the pin does'nt need to go that low, the pin is basically pushing down the metering stem to reduce oil flow,so if it is set to the correct cc's per min( or untill the desired low fire is attchieved) and this means the pin when depressed is sticking up 2mm then so be it don't worry and be careful you are not looking for problems, if you are sure you have trouble then start from scratch and get all the basics right and then do one step at a time, but don't be tempted to adjust more than one thing at a time.
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Postby kilgallon on Wed Nov 30, 2005 4:48 pm

Thanks Agaman - What I conclude is that the cooker seems now to be alternating correctly between high fire (lever clear of a/pin) and low fire (lever pushing a/pin down to around 2mm of sleeve).
Temperature seems about constant just under black mark, so I will now leave all alone.
On next service, I will recheck for high fire oil flow at 8cc (which I think it is still under but providing the heat our house desires) and low fire at 5cc which is probably close to actual now.
I might dive into oil control at service time and check metering stem and any other "moving parts or chambers (because I hadn't checked these in my previous 5 years diy-servicing.
Many many thanks for your kind input.
PS. I told my wife that I was corresponding on the forum with Agaman in Australia!!. Somewhere on the site I thought that was your location.
IanK
kilgallon
 
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Postby AGA man on Wed Nov 30, 2005 8:48 pm

I wish I was that lucky, I'm still waiting for that agaman to offer a humble POHM a job in the sun.
Don't worry about checking the actual flow rates, go by the results, but it's worth taking the stem out on services.
AGA man
 
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