End of Season Report - How's my boiler doing?

MaxMercy

pedmec said:

sorry, you cast iron guys just cant let it go. you just want an easier installation lol.

I install mod/cons all the time and the mod/cons that i have installed haven't failed at 10-12 years. easily get twenty plus years out of it. a properly installed and maintained mod/con will give you comfort and savings for plenty of years. if your getting only 10-12 years then it is not installed properly.

Not being a pro, I can't disagree with you, but I can cite my observations and other anecdotal evidence which seems to support the short life of mod/cons.

My wife's co-worker had a problem with a Buderus in the middle of winter, and he had three different companies come out and check it. None of them could positively identify the problem and only one was willing to order parts to try since there were no parts for that boiler locally. My wife of course told him that I could fix it (God bless her faith in me) because I had installed a new boiler in our home a couple of years earlier. Since I knew less than nothing about mod/cons, I called a couple of people I know and no one was sure what was wrong, so I asked here:

https://forum.heatinghelp.com/discussion/182503/buderus-gb142-no-heat-update-error-codes#latest

My wife's co-worker and his wife were tired of being cold and paying people to tell him that the boiler at 11 years was old and should be replaced, as the repair on his old one would expensive and it might only buy him a year or so.

I was given some advice here and downloaded the manual to bring to his house to troubleshoot, but they decided to replace the boiler since the temp was in the 30s, which they did. I never found out what the problem was with his Buderus.

fentonc

I think "The technicians that will actually come to your house don't know how to troubleshoot your equipment" is definitely a real concern, but I think it is more or less independent of the CI vs Mod/Con vs whatever longevity debate. My 6 year old WM cast iron boiler has a control board in it that I can (currently) order a replacement for online for $200, but I'd be a little surprised if a technician had one on hand (as opposed to an expansion tank, or zone valve or something, which they probably have in their van), or if they could troubleshoot it at a component-level. Will I be able to buy the same controller in 15 years? I think they've already moved on to a different control board on newer boilers (although looking at the newest manual, it looks drop-in compatible).

I think technicians being uncomfortable with them is probably more of an issue than something fundamental about them. If I go the A2WHP route, finding a company that I'm confident can install it correctly and will service it in the future are definitely big concerns, although when paired with an electric boiler for 'backup heat' (or if I leave my old boiler), I think i'd be willing to tolerate more risk on that front.

In_New_England

@fentonc I love your home lab approach to heating system analysis and your data science skills!

It's hard for me to pick a favorite graph, but I'd say that your water temp aligned with firing graph is extremely informative.

Your basement graph shows me that the boiler output is much larger than the radiation because the temperature difference between the In and Out water is pretty small.

I looked at your whole load graph and tried to think what we could do to lengthen the second fire.

Assuming the thermostat was on the whole time, I suppose you could widen the tolerance band, but you are at 20F or so already. Presumably what the boiler is working off is the final mixed water temperature at the boiler inlet.

With a modulating boiler you could perhaps bring the temp down and the firing rate down so that the curve meanders around the limits but the boiler never goes off - that would be kind of an ideal condition in terms of cycling.

I love that dip in the temperature graphs at the start. I'm guessing that's because the circulators are going, and the radiators are cooling the water but the boiler hasn't warmed up yet.

I'd love to be able to do this kind of analysis with the gas boiler I'm going to have installed this year.

Well done.

PS. Do you have thermostat on/off data as well?

fentonc

@In_New_England - Thanks!

I do not have thermostat data (although I do have the circulator status, which is on if any of the thermostats are calling for heat). I designed my setup to be 'minimally invasive', so I didn't put current transformers on the thermostat lines - just two light sensors clipped onto the boiler control board to monitor the 'circulate' and 'fire' status lights, and then temperature probes on the supply/return pipes for each zone. It would have been nice to collect that data precisely for the whole season, but I have logic in the program that's logging all of the data which can do a pretty good job inferring which zones are active by monitoring the change in temperature while the boiler is firing.

The most surprising part was that it actually ran without issue for 4 straight months!

My initial thought was that maybe the circulator was running too slow or something, but I think the low delta-T disproves that theory - there's no way around the fact that the boiler is just injecting heat way faster than anything can dissipate it.

I had mentioned to the guy that services it every year (and installed it) that it seemed way too overpowered, and he mentioned the possibility of capping off some of the burner tubes (I think this is called 'down-firing'?), but I've read mixed things about whether or not that can cause other problems.

On the bright side, I should be armed with excellent data now for possible replacements.

pedmec

as i said in my post, i try to avoid cast aluminum heat exchangers. that is what Bederus uses. the acidic condensate sheers the aluminum off the block and if not maintained will harden like cement. boiler is, from my experience, pretty much dead.

install a gb142 and customer didn't want to pay for the pm. so for 6-7 years it just sat than an ran until one day the boiler failed. opened it up and I couldn't believe it. looked like a block of concrete. i tried to chisel it off but it was nearly impossible to get it back to new. got it working but it was replaced a short time later. never seen a boiler do this before.

Dont know if anybody has any tricks up there sleeve to clean it at that point. i haven't read or heard of anything that you can do. maybe somebody here does. and the weil mclain ultras had issues with corrosion holes forming on the bottom of their cast aluminum heat exchangers. lots of warranty claims that they had to honor. that's why not all mod/cons are the same.

Robert_25

fentonc said:

I'm just an enthusiastic home owner, but I set about trying to understand and characterize the heating system in my house this winter.

Your data collection is awesome. I have thermostat data from my smart thermostat, but the best I can do for my boiler is reading the hour meter and noting it in a logbook. I would like to find some sort of "counter" that can count the burner motor power cycles.

Jersey2

You can get a digital recorder that has the record when it hears sound function(VOX). It's not the best solution though. I put my recorder near the boiler, and a timex watch that beeps every hour to give me an idea about how many hours pass before it runs. The recorder records the beeps from the watch and I note what is the next hour before starting. Listening to the audio is fun, you hear Beep Beep Beep then the boiler going on, then beep beep :-) The recorder will not record the entire boiler run because it gets used to that sound level and pauses, and records again to the sound of the boiler stopping.

In_New_England

@Jersey2 that is ingenious data logging! I thought about attaching a digital thermometer chip to the in and out boiler pipes, a tap on the thermostat line and current sensors on the circulator pumps.

All of these should be existing inputs to the boiler control board and it would be great if there was some way to use the info from the boiler.

fentonc

Doing this with a microcontroller board like my setup is pretty straightforward if you want to collect a lot of data (I used light sensors to monitor the status LEDs because I had some lying around and it was non-invasive, but adding some relays or current transformers would also be pretty easy), but they make electrically-actuated 'pulse counters' for pretty much this exact purpose in industrial settings. Check out this one, for instance. I think it basically just increments once every time it sees electricity on its input.

t300

fentonc, 2 years later, how has the data from your Boilertron helped to optimize your system? Great job on using inexpensive tech to get all this data. I'm building similar system for my modcon, mostly to satisfy DIY homeowner curiosity

hot_rod

JakeCK said:

The issue with modcons is that they absolutely require yearly pm to continue to operate for decades. Which eats up those fuel savings quickly. 375$ a year in savings is nothing. Now I can do my own yearly pm on my almost 40 year old boiler, the only thing I can't do is a combustion analysis. 

Don't get me wrong I like new technology, but going from a ci to a modcon... Is a stop gap measure at best in my opinion. Keep the ci, install a buffer tank and go the air to water HP route. Now you have a dual energy source heating system that is 3x as efficient than the best modcon. 

I have owned a dozen different mod cons in my properties. I've never serviced them yearly? The Laars Mascot went 16 years with just two services. It really depends on what they breath and the burner being dialed in exactly to spec.

If you open one after one or two years and it is spotless, no need to open it yearly. A handy person with a combustion analyzer could do their own disassembly and cleaning. Maybe better that many pros

The bigger killer of mod cons is crappy fluid. Plugging or coating the HX surfaces takes them out quickly. Here are a few different brands, fairly thin metal .040 wall thickness.

fentonc

@t300 - the biggest impact was me just getting a very good understanding of how it all worked. Comfort-wise, I got a thermostat with a wireless sensor for the 2nd floor and relocated the sensor to one of the smaller bedrooms. This completely stops the overheating in the small bedrooms and lets the main bedroom run a few degrees cooler - it was very easy to install and vastly improved comfort. 

This year I built a PLC thing that sits between the thermostats and the boiler which performs zone synchronization, a limited thermal purge and “de-thunking”, where it halts the circulator before shutting off the zone valves. The de-thunking worked perfectly and we haven’t heard it all season, the thermal purge after a run probably helped a little, but I didn’t quantify it carefully, and the zone sync did work amazingly well at extending burn times, but was tricky to get working in a way that didn’t make the house annoying uncomfortable at times. I wound up disabling or minimizing the setbacks more to get the synchronization to work better, so a lot of the savings were probably eaten up by running the temps warmer than I otherwise would have. I have a much better understanding of why it didn’t really catch on (especially during the shoulder seasons).