Does anyone know about furnaces / boilers?

[Nedly]

I am posting this here because I cannot seem to find any decent forum where I could chat with furnace people. Our furnace has had issues for over a year now, and now that we are over 200$ in it still is not working right.

I can get any info that is needed. It runs off of diesel. It fires up, runs for a good 15 mins, then it will not start again, all the while the control box is calling for heat it just does not fire up. Replaced the CAD sensor, replaced the intermittent igniter several times because the first couple were defective, we replaced some other massive control board (the one with error lights etc), replaced the ignition base plate etc, replaced oil filter, checked fuel in tanks, replaced nozzle, then we replaced the copper tube from the tank to the boiler because the original was under cement and we had theory there was condensation.

There is no thermostat, it is jumped so once power is on it is in constant call for heat. We also checked the control box to make sure it was not in a lock out mode. I checked the manual schematics and could not find anything as far as sensors for air / draft, temps, etc, and am not sure how to test any of those...

It is the AF/AFG Beckett Model. We got one of the more basic honeywell igniter boxes.. So I went as far as watching instruction videos on burners and how they work and I still cannot figure out what is wrong. It seems to be some sensor or control board issue as far as I can tell. There is absolutely nothing that happens when it is trying to turn back on after the 15 min run, it just sits there dead, but while it does the reset is down and it is in call for heat...

 

[Rolex]

Does ANYTHING happen when it is supposed to restart?
It's not diesel, just smells like it. It's either #1 or #2 fuel oil.
If the thermostat is jumped out, that eliminates the first possibility. Without seeing it first hand, it's hard to tell what's going on.
If you already replaced the nozzle, replace it again with an OEM unit, not a knock off replacement part.
If you're not getting an arc at the ignitor you have a bad or intermittent transformer.

 

[Nedly]

You are right it is a type of heating fuel. It does absolutely nothing after the first run, it just sits there dead... I tried to test the CAD sensor with my ohm meter and the old ones we had definitely were sporadic and would not hold a resistance under light or not, and the new one was some what sporadic but did have a better reading...

I saw that there are better igniter boxes, can I get just about any? I found another box that was slightly better than the one we have been replacing and it seems to be nearly the same as far as the CAD sensor plugs and thermostat plugs, but it is more expensive, my guess better quality, it had 5+ star ratings, I am wondering if it would be the better way to go...

This is the control system we got.. http://www.amazon.com/Honeywell-R81...r=8-4&keywords=honeywell+ignitor+intermittent

This is the one I am thinking about getting.. http://www.amazon.com/Honeywell-R81...keywords=honeywell+ignitor+oil+burner+control

I checked and they both offer the same timeout rate as far as the 'intermittent' aspect of it...And the power voltages etc seem the same...

 

[Rolex]

I'd recommend going to a plumbing supply house that deals with furnaces.
Bring whatever paperwork you have on your current unit and let them advise you.
How long after it turns off before you can get it to restart? Could be a heat sensor inside the furnace.
What ever you do, don't let it spray fuel into the box when it won't start. Too much fuel in there will cause a real problem when it lights up.
Why is your thermostat jumped out?

 

[Nedly]

I did watch videos that stressed about miss fires and excess fuel so I have been careful there!! It wont run again until it is powered off. I did get this listed on another forum after searching and a guy pointed out that it will run fine after initial power on, lights fine and burns fine through the first cycle, then it sits dead and does not fire up again. If it is powered down and back on again, it will fire and run through the first cycle and then be dead again.

I had the same thought about a temp. sensor too figuring maybe it felt like it was up to temp, but would it be calling for heat if the system thought it was done? That was my theory that maybe that sensor was fine because it does still call for heat.

I found a troubleshooting guide for the "few min run" and it included that temp sensor, but usually if that thing goes off it stops in like a few mins right? Ours runs for a good 15 mins or so.

I think it is the intermittent igniter box, I read online that a ton have known to be defective and that it is actually some cross solder issue where something was placed on the board backwards or something idk..

Going to return another one of these boxes as defective and try again. The thermostat is jumped because it is set up to do forced hot water for heat which we do not use, we only power this thing on for hot showers / dishes etc. We use wood stoves for our heat. The house was previously built by rich people who had this whole set up for fancy stuff like hot tubs / spa's / multiple houses etc...

I have been trying to track down that temp sensor to get a look at it and I cannot find it right now, I looked in the schematics and there is nothing. where would it usually be? Somewhere deep inside?

 

[Rolex]

Sorry, just got back. Forgot to log off.
Has it run normal with the thermostat jumped out in the past?
These units are not meant to run constantly. There would be a sensor in or near the firebox as an added safety if it doesn't turn off by normal means. If it turns off when it should but does not turn back on, something is giving a false read.
Sorry, but I've been out of this for about 15 years now, so the new controls are beyond my knowledge.

 

[Nedly]

So i have to scratch what I said. I have been testing it more today. It does not fire up after poweroff/poweron. It seems like there is some reset getting tripped. It takes several hours wait on or off before it will run again

 

[Rolex]

It could be something as simple as a capacitor that's not bleeding off properly, but no one troubleshoots and repairs circuit boards any more. They just replace the entire unit.
When the furnace reaches temp, a current is sent to a capacitor that stores it and prevents a restart till all the other sensors send the all clear signal to drain the cap, allowing the restart. That's putting it simply, but that's about it.
Since it WILL start and burn clean, it probably wouldn't be the nozzle or transformer, but likely the master control unit.

Here's the entire unit on Ebay for 300. You can also find the control there for 50.
http://www.ebay.com/itm/like/321523397324?lpid=82

 

[Nedly]

I think I might be onto something now. I found a forum suggesting to test the L1/L2 and B1/B2 terminals on the aqua-stat to test and see if either the low water cut off or aqua-stat were having issues and I got a zero reading on the L1/L2 pointing to the low water cut off, but I got the full reading of 120vac on the B1/B2 terminals...

Here's the entire unit on Ebay for 300. You can also find the control there for 50.
http://www.ebay.com/itm/like/321523397324?lpid=82

Thanks for pointing that out!! That is way more worth the price versus buying parts.

 

[Rolex]

I have a complete unit in storage. Not that brand, but the same thing. It will take me 3 days to dig it out and about $400 to ship it.

 

[Nedly]

Yeah right! lol, I noticed the guy on Ebay only wanted 35$ shipping, he must be taking some out of the sale to ship it at that price..

 

[Rolex]

These things are incredibly heavy. The unit I have is for a very large salamander kerosene heater, so the ignition and start switches are all manual. Exactly the same as oil burner assemblies, other than that.

Here's some useful info for you...

http://www.beckettcorp.com/protect/manuals/6104BAFG.pdf

 

[Nedly]

Here's some useful info for you...

http://www.beckettcorp.com/protect/manuals/6104BAFG.pdf

Thanks! I found a manual kind of like this one but it has a little less in it, maybe it is more outdated..

 

[Rolex]

Good luck, and keep me posted on your progress.

 

[Nedly]

I definitely will! I think the plan now is to go out tomorrow and try to find that aquastat component and replace it, then try again...

 

[Nedly]

Ok so I have some news. We drained the low water cut off and shut off its water supply, then tried to fire and no go, indicating the low water cut off is fine. So I received some info from a friend suggesting there were more than one thermostat and jumping the one was only running the high limit cycle and not the low limit. So I investigated further and I see now that the forced hot water lines are still open, rather it is the 'house' based thermostat that is turned down so it never calls for heat. So should we shut off the forced water lines and then turn up that second thermostat???

What is this high limit / low limit process all about? I understand it is fazes...

 

[Rolex]

You should have a control for home heat (wall thermostat) as well as a separate setting for hot water, assuming that what you have is a "Heat exchanger" providing hot water at the tap. You only mention the oil burner unit, not the furnace. If you have a heat exchanger for hot house water it will look like a water tank but there will be a copper coil inside it feeding hot water from the furnace to heat up the water in the tank that now goes to the taps. The water going through that coil is the same water going through the radiators and NOT the water in the tank that goes to sinks and tubs. That unit would have it's own control, circulator pump and zone valve.