Oil boiler aqua stat issues - need replacement advice

[mustash29]

Personal background - 10 yrs Navy Electronics Technician + 25 yrs trash to energy power plant. Good working knowledge of electro-mechanical, digital and hydronic systems.

Built the house in '96, been here ever since. Appliances are all vintage with very few repairs / replacements, so most everything is 28.5 years old.

Burnham oil boiler with internal DHW coil, Beckett burner, Honeywell L 8124 A/C triple aqua stat set to 150 low, 10 diff, 180 hi limit and 2 zones of baseboard heat. This works well for us 24/7/365. Oil does the DHW and shoulder season heat with T-stats set to 69. When below 40 deg we have the wood stove going. Typical oil usage is about 1 gpd. During extreme cold snaps (teens and below) the oil will help out as needed.

Everything has been normal so far this fall and winter, although I have heard a bit of buzzing/vibrating noise from the circulator relay at times. It has a little counterweight on it that may be causing the noise, but the relay contacts themselves have not been chattering.

Recently went through a warm spell for several days in SE CT so the stove was cold and we were on oil. No issues.

No issues with my shower Thurs morning at 0400 but wifey said hers was a bit chilly at 0600. She got home at 1715 to a house at 58 deg with high winds and a cold front moving in and said WTF? and lit the wood stove. I got home at 1900 and heard the bad news. Investigation reveals the oil boiler stone cold at 70 with the fire eye tripped. Reset fire eye and it took off ok, heated up ok, got above setpoint, then circulator started ok since the house was still at 64 but it continued to fire to over 200 when I shut it down.

Cycled the low limit setting. It clicks on and off.

Cycled the hi limit setting. It doesn't click on/off, so it seems like it's stuck on and allowing the boiler to overfire to a high temp.

Opened breaker, pulled knobs off aqua stat, removed 3 screws, removed cover, found white crusties, (evidence of slight water contamination from a slightly leaky DHW fitting) and a brown sticky substance (solder resin?). Cleaned this up with electrical contact cleaner. Looks brand new again. Re-assembled. Low limit seems to work ok. High limit seems way off, it still wanted to overfire to 200 deg. Shut it off for the night.

Turned it on and watched everything as she showered Fri morning. Low limit / diff seem to be working ok. Still not sure if high limit is AFU / reliable since the house is warm due to wood stove.

Question - Replace 28.5 year old Honeywell L 8124 A/C triple aqua stat with identical replacement? Maybe more reliable. Maybe longer lasting but looks like about $100 more.

What to use? Replace with newer digital/electronic version? Apparently, Honeywell is now going by Resedio. What's up with the name change? New ownership or what? Are they still any good?

What's better, old school electro-mechanical or new school digital/electronic. Probably got my $$$ worth out of a 28.5 yrs unit but what should I replace it with?

 

[brenndatomu]

Honeywell is now going by Resedio. What's up with the name change? New ownership or what? Are they still any good?

It still being spec'd/used commercially, so must not be too bad...we haven't had any issues with the one we installed with a burner upgrade on our 650k BTU boiler at work back in 2018.

What's better, old school electro-mechanical or new school digital/electronic. Probably got my $$$ worth out of a 28.5 yrs unit but what should I replace it with?

I'm sure much of the new electronic stuff may be fine (assuming you have clean/reliable power) but the track record of your old one says a lot...I'd probably tend to stick with that, unless you have some other reason for wanting to go to electronic.

 

[mustash29]

The original L 8124 A/C is easy to set up and adjust, but it lacks modern efficiency features. While the mechanical controls may be more reliable, they are also not as accurate. I think my work background and OCD requires something better. An "identical" replacement would be the Residio L8124A1007/U.

All of the electronic units have replaceable temp sensors and can be remote mounted which appeals to me so I don't have to crawl on the floor to read/adjust it, will get it away from the DHW piping should a leak develop and get it away from the access cover for boiler flue pass cleaning.

The Residio L7224U1002/U is an electronic upgrade and is ODR capable with the extra module.

https://digitalassets.resideo.com/damroot/Original/10011/68-0281.pdf

Page 5 describes the adjustable features.

The Hydrolevel Hydrastat 3250 Plus can do ODR but has "thermal targeting" that simulates ODR based on boiler firing history.

https://hydrolevel.com/wp-content/uploads/2024/04/HydroStat-3250-Plus-Instructionsweb-032724.pdf

Page 7 describes the adjustable features.
I think it's rather goofy that the set point knobs are also used to access the menu functions so after any adjustment you have to reset your desired setpoints.

The Beckett AquaSmart 7610A0001U is looking like a very strong contender.

https://tggcdn.azureedge.net/tggakeneoassets/productinstallationsheets/1/c/f/b/1cfb5e92041e4bf3cb2b8d4f0b0c06913abb635c_InstallSheet_BEC7610.pdf

Page 19 describes the adjustable features.
Backlit LCD digital display with LWCO status and touch pad buttons for programing.
Stores history of the last 9 firing cycles. This is almost like having a display trend, so it satisfies my OCD.

 

[mustash29]

Wound up going with the Beckett AquaSmart 7610A0001U. Wifey's cousin works at the local plumbing supply store and had one in stock for only 3 bucks more than a popular online retailer. Very happy with it so far.

Beckett claims 10-20 % oil savings due to their "heat manager" program. Probably won't qualify for any rebates due to it being self-installed but they guarantee 10% savings or they refund the purchase price. Got to love that kind of faith in your product.

We've had the wood going for 8 days straight and so far over the last 2 days the AquaSmart is almost always kicking into economy mode where it lowers the high limit when not constantly getting a call for heat so this saves standby losses up the flue.

I'll be interesting to see what the oil usage spreadsheet shows over the next year.

 

[mustash29]

Since installing this on Jan 7 I have been visiting the basement and boiler frequently and paying close attention to how things are operating.

The old Honeywell L 8124 A/C aqua stat used to short cycle where on a call to heat it would fire the burner for a short time, shut it off and then refire it again for a longer cycle. This used to drive me nuts. Not anymore. Since installing the new Beckett AquaSmart 7610A0001U everything is working well. The burner fires to meet the high and low limits, the circ runs to keep the zones happy and the internal DHW coil is making nice hot showers. Temperature control is much tighter and compares with the manual temp guage pretty well.

I heat mostly with wood and don't use very much oil. The last complete PM was done on Dec'13. New transformer (old one failed), new fuel nozzle and new tank filter. The pump strainer was cleaned, ignitors adjusted, heat exchanger cleaned, combustion checked with instruments and smoke check done. A complete professional PM.

Due to life, loosing 2 parents, a beloved Sheltie (who was replaced with 2 new brothers) and some other family health issues I got busy and ignored the boiler for 8 years. After 4200 gal of oil throughput the tank filter clogged up. Changed tank filter and cleaned pump strainer on Nov '21. Oil throughput since then is 1000 gal, which I figure is about what this house would use in one year if I was not burning any wood. Overall combustion seems normal with no issues like soot buildup, stink, puffing positive, etc. Oil use is very normal at about 1 gal per day on an annual average due to standby losses, DHW, shoulder season and supplemental winter heating.

There have been a few times in the last 3 weeks where I found the boiler colder than setpoint with the 28.5-year-old Honewell R4184D 1027 boiler protection relay tripped, usually in the morning when I reload the wood stove and do my basement / boiler tour. Each time I hit the reset it takes right off and fires normally, but this past weekend the issue began happening more frequently.

So it's time for some boiler TLC. A few weeks ago I checked the ignitor tips and found them to be burnt up a bit and slightly out of alignment tolerance, so I made some tweaks and cleaned a very slight layer of haze off of the fire eye with 91% isopropyl and Q-tips. Yesterday the local supply house hooked me up with a new tank filter, pump strainer, fuel nozzle, fire eye, ignitor tips and the super easy to use Beckett Z tool for only $67 after contractor (family) discount.

Yesterday morning we hit a low of 2 deg, had a slight breeze and it only got up to the low 20's. I headed to work at 0445. She headed out at 0650. I get home at 1830 and walk into a serious WTF issue.

Wood stove is down to a handful of small embers. Kick start stove with kindling and propane torch and toss in the oak. We are now making heat.

House is at 63 deg with both zones calling for heat. Zone 1 is kitchen, dining and living room. Zone 2 is 2 small front BR's, MBR, master bath and rec room/mud room/walk out basement where the wood stove is. The house is a tri-level so half of it is like a typical raised ranch. My big concern is that the 2 small front bedrooms are cantilevered and overhang the garage by 4' so these heat pipes are a potential freeze issue during extreme cold snaps if zone 2 goes cold or dormant. This is why I let the oil do the backup when we are below 20 deg and especially during polar vortexes.

The boiler is also at 63 deg, because the 28.5-year-old Honewell R4184D 1027 boiler protection relay tripped again. Time to find a replacement ASAP.

Then I find the silver lining that brightened my crappy evening. The new Beckett AquaSmart 7610A0001U had kicked into "Freeze Resistance" mode. This is triggered when a zone is constantly calling for heat for 3 hours or when the controller is in lockout / alarm for 3 hours. The house is cold, the zones are calling so the circ stays energized to maintain flow. When the boiler tripped and cooled off below the low diff setting the old school "dumb" triple aqua stat would have went into DHW priority mode and locked out the circulator and stopped flow through the zones, potentially allowing for a freeze up.

Now I'm curious as to how the AquaSmart is going to recover. Reset boiler protection relay. Boiler fires right up and temp starts climbing although it was slower to recover than normal since the zones are still calling and the circ is still running while the boiler temp is climbing up through the condensing region. The protection relay tripped several more times during this long run up to the high limit and subsequent re-fires as the house heated up and the zones became satisfied. On a few of the trips it would not reset immediately, like a hot breaker or thermal overload that needs time to cool down before it will reset, so I know it's very tired and very near death.

It's been a long, cold, frustrating day at work and more BS when I got home so a few well-deserved wobbly pops and I take slumber on the LR couch.

I wake up at 0300 to go potty. Once again protection relay is tripped, boiler temp way down, AquaSmart in Freeze Resistance mode. I'm still in "curiosity killed the cat" learning mode so this time I cycled power to the entire boiler with the local kill switch and reset the protection relay. This rebooted the AquaSmart which reset the Freeze Resistance mode so the boiler heated up quicker through the condensing region to low limit to satisfy DHW, then energized the circ to heat the zones and continued to heat up to high limit, like it does during normal operation.

Sorry for the long babble, but it's fun to learn the quirks and benefits of new equipment, especially when they have very pleasing benefits and performance. I'd hate to think how costly and aggravating frozen pipes in my garage ceiling and front bedroom overhang would have been.