Replacing my R4184D with a R7284U

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Old 03-21-17, 09:19 AM
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Replacing my R4184D with a R7284U

First of all, thanks for a great forum. Lots of good info on here.

I recently replaced the R4184D primary on my 25 year old WeilMcLean burner/boiler with an R7284U. It is working fine, but I have two concerns.

My old system was intermittent - the ignition ran as long as the burner was running. I set up the new primary for interrupted ignition with 15 second delay. Is there any reason this is not better?

The burner is controlled by the aquastat supplying power to the primary when it calls for heat. The primary then turns on the burner. So now, every time the burner shuts down, all power is removed from the primary and it goes dark. When the system calls for heat, it powers the primary again, it lights up, then turns on the burner after a few seconds. Is this bad in any way for the primary? Is it desgined to be turned completely off every cycle?

I believe I could control it by connecting the aquastat to the "Limit" terminal on the primary. This would require adding another wire, always hot, to the system.

Thanks again.
 
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Old 03-21-17, 04:36 PM
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Several years ago, back when I had an oil burner, I swapped in a R7284U and it worked great.

IIRC, if you want to be able to utilize all the functions that the unit offers, then you will need to run "constant" line voltage in order to keep it powered at all times; the aquastat is connected to another terminal ("Limit" sounds right). In particular, I believe it has something to do with the "post purge" function, which operates after the burner is shut down.

My Carlin oil burner specs called for intermittent ignition, and it had always been set up that way. Like you, once I installed the R7284U, I figured I would try out interrupted ignition and see how it performed.

In my case, it did not work out well. Once the ignition dropped out, the flame was noticeably smaller and smokier, which to me was evidence of an incomplete burn. I put it back to intermittent ignition and left it.
 

Last edited by Rockledge; 03-21-17 at 04:57 PM. Reason: clarity
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Old 03-21-17, 06:49 PM
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Thanks Rockledge. It seems to run fine, but I will watch it tomorrow when the ignition shuts off and see if there is any change. Maybe do a smoke test too.
 
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Old 03-22-17, 08:17 AM
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To monitor, display and record history R7284U's require power to L1 whenever boiler/burner system safety switch is on. Without power there is no display or history. It will not even display
"HARD LOCKOUT".

To start burner cycle, aquastat /out-door-reset control supplies 120 VAC hot to red "limit" terminal on R7284U. Honeywell's use of word "limit" is a classic "half full .... half empty" Honeywell could have labeled it "start" or more neutral "run".

Older dumb controls like the R8182D are simple on-off and do not have microprocessor board watching and controlling things.

Spark is only needed for 15 seconds to start flame. Then CAD cell senses flame. If it ceases shuts down instantly.

Why needlessly run spark for hundreds of hours? In the old days before CAD cells, a temperature activated control on exhaust stack shut down burner after 15 seconds. Back then constant spark made sense. A burp in oil supply might have stopped flame and resulting in an oily mess.

Would suggest reading R7284U Installation data and getting familiar with burner cycles and features. I keep a copy on my boiler. The old controls had one red button to push, this has three and numerous menus to get lost in.
 

Last edited by doughess; 03-22-17 at 11:05 AM.
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Old 03-22-17, 10:22 AM
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Thanks Doughess. It does seem wasteful to be running the ignitor continuously. It's also noticably quieter once the spark shuts off, and saving some electricity I assume.

I have been able to monitor the history, but only if I look when the burner is running. Apparently, it saves the information even without power.

I have the manual, and used it to set up the new primary, but it isn't to clear to me. Ans the schematics are so small I can hardly read them.
 
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Old 03-22-17, 05:02 PM
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Why needlessly run spark for hundreds of hours?
I concur, as long as you can confirm that there is no degradation of the flame. In my case, when I decided to experiment with interrupted ignition, it was easy enough to see that, as soon as the spark cut out, the burner was not running optimally. No other testing was required.

Maybe it was because of how the burner was tuned at the time (by a licensed tech), or because the burner was firing at 2.75 GPH (small apt. building), or some other factors specific to my situation (such as the fact that the burner had been downfired over the years).
 
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Old 03-22-17, 07:01 PM
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I have been able to monitor the history, but only if I look when the burner is running. Apparently, it saves the information even without power.
When there is no call for heat from aquastat the display should read "STANDBY" until cycle starts. If the power is off to L1 there will be no display.

Double check that there is a wire from burner safety switch providing at all times 120 VAC to terminal L1 on the R7284U. A live display is like a pilot light indicating AC power is on
 
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Old 03-22-17, 07:46 PM
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To Rocklege:

The 15 second intermittent ignition is widely used on retension head burners.

If you do not have one, get a Honeywell R7284U with display and history. https://customer.honeywell.com/en-US...d=R7284U1004/U

http://www.supplyhouse.com/Honeywell...ic-Oil-Primary

Watch the display during cycles to find out why it is shutting it down. Obviously something is not set up right in your system.

I am a DIYer not a HVAC professional. Find professionals around here often have a superficial understanding of heating systems. That is why I got involved. Have a high tech background so this is basic physics and engineering.
 
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Old 03-23-17, 06:24 AM
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Thanks again guys. On mine, there is no constant power to the burner. There are only two wires going to it, the hot and the neutral, with a disconnect plug for servicing (the burner swings out form the boiler for cleaning). If I wanted the display on all the time, I would have to run an additional wire to it. It's been runnng fine for 5 days, so I'll probably leave it set up like this.

I also am no professional, but have been frustrated by poor service over the years so I do what I can by myself. This applies to everything around the house and the garage, not just the heating system. It's also nice to have the knowledge and parts, so when something fails in the middle of the night or on the weekend, I can get it going again.

I did look at the flame, and it appears identical with the ignition on or off. I also did a smoke test, and it's not particularly clean. So it's probaby time to get a pro in for a full tune up. I know one guy who's really good, but he's pretty busy. I'll just wait till he's available.
 
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Old 03-24-17, 08:08 AM
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I also did a smoke test, and it's not particularly clean.
With your smoke tester it is easy to adjust burner air.

Most burners have 2 ways to adjust air. A metal band around the body of the burner for major changes and a second for fine adjustments with a round metal plate with pointer behind oil pump.

Loose the screw on the round plate and rotate clockwise to increase air and reducing smoke. Retest and if still trace of smoke open up more. When you have zero smoke , then try turning clockwise a bit to until you see smoke and then back off to zero. (As a guide I use a colored grease marker for each position)

A simple preventive maintenance practice is to use a small test tube brush to clean out dust accumulation in air openings on the metal adjustment plate.
 
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Old 03-24-17, 11:58 AM
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Thanks Doughess. I've been hesitant to mess with that, for fear of making it worse. But I suppose if I mark it, I can always put it back to where it was. I'll give it a try.
 
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Old 04-02-17, 05:00 AM
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Update: I did rewire it, so the primary control is always on, and the limit turns the burner on when called for. I also adjusted the air (got my buddy to come over, who has a CO2 gauge too) and the smoke is zero. Runs like a champ; many thanks to all. Great forum.
 
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