Munchkin 140M, fighting the typical F09. NG fueled

TT_Vert

My first post here and a little disclaimer. I am not a certified HVAC technician but more than competent in the field (They all say that right?) Anyway, I've always serviced this myself and generally when this happens (About once every few years) it's the flame rectification probe needing a cleaning. I annually service this, clean the HX, blow out the condensate and ensure it's clear, clean and test both the ignitor and probe, etc. In this last F9 instance I pulled both the igniter and the probe and cleaned them w/ scotchbrite although both looked good and I did get a spark from the ignitor when outside the machine. Gap was good. It was hard for me to see the spark inside as my sight glass isn't great for some reason. Rectification probe current wasn't great but more on that in a sec. So those attempted resolutions didn't help the F09 so I tore it down, removed the burner and cleaned it and also inspected the flame refractor. I noticed it was a bid damp feeling so I took my heat gun to it and removed the moisture and reassembled. It was fine and fired great for a whole day (A joke). I assumed the ignitor was just grounding out on the wet refractor. Not sure why it was damp to be honest as the condensate isn't clogged and I see no indication of a cracked HX (Perhaps you guys can recommend a way to more thoroughly check for a cracked HX?) I have been monitoring the rectifier current and during those F9 times on initial fire I'm seeing a fluctuation of .4 to 3.6 until it fully lights then it's pretty stable 3.9-4.1 uA. I assume this is due to incomplete combustion and a poor flame. I've also noticed a moaning sound (and a slight vibration from the boiler NOT the fan) as of late only on a cold start (Where it has been sitting a bit). And researching this has led me to a potential AFR issue (apparently these things have a tendency to go lean?). I did look at my exhaust pipe and it's never had a hole drilled to check the CO and CO2 readings. I have purchased a gas analyzer to test this and will have it tomorrow. I also purchased a namometer to see what my inlet/outlet pressure is and to ensure i've got no significant drop in pressure during firing (Not likely but curious). That brings me to my questions..

1. In the installation manual for this it tells me the CO and CO2 specs but I see no mention of what my pressure POST regulator should be. The regulator is a 250P-451 Dungs unit and says MAX .50psi (~13.8" WC) but it doesn't say what the actual regulated pressure is so I don't even know what the actual value should be. I know it's a sealed unit and non adjustable but I'd love to know the desired set pressure of this regulator just for my own knowledge. Anyone know it?

2. I've read adjusting the offset can help w/ the low fire AFR issues, is this factual? I see mention of adjusting the off set here but it is mentioning targeting -.02" WC which I don't know what this is in reference to, i'm guessing it may just be gas pressure offset high fire vs. low fire? Anyone care to explain to me what exactly this offset adjustment does? Do it just mess w/ the fueling during low demand (Idle needle on a carb?)? I will also be playing w/ the main needle to check my high fire gas output (They call it a throttle adjuster in the manual).

3. I have read that swirl plate deterioration can cause similar issues but given this is generally on cold fire only I doubt that's the issue. Opinions? If all else fails I will tear it down and inspect it obviously

4. I see no definition of "low fire" and "high fire". I do know how to get into the test mode to control the fan speed so is low fire just minimum fan RPM and high fire max fan RPM? If this is just fan related is there a specific RPM you guys use for high and low fire gas analysis? How far do you guys drill your hole in the exhaust to analyze combustion? Do you guys generally aim for dead center in the spec window or error to the rich side?

Sorry for the basic questions but before I mess w/ any fueling I need to understand everything fully, i don't need to create a bomb here.

kcopp

What's the age... What does the termination outside look like? Are they close together?
Swirl plate deterioration is a strong possibility.

TT_Vert

kcopp said:

What's the age... What does the termination outside look like? Are they close together?
Swirl plate deterioration is a strong possibility.

The unit is about 15 years old but looks new in/out. The exhaust is 3 or4"" pvc 90 out of unit to a 45 and then up and out the roof. I had no idea where the intake is to be honest. Both are separate 3 or4"" pvc pipes. Would a swirl plate cause intermittent F09 issues? Wouldn't that affect all fueling? Once it's running it appears to have a nice orange flame. I know that's not a scientific way to tell but it's a decent indication of good combustion. Any idea what the minimum current the rectifier must generate to prevent an F09? I was watching it again and it would get to .4 before going F09 on initial fire up.

Here is the exhaust exit on roof.


Also, would you mind telling me what this flathead screw is for on the backside of this dungs gas valve?

kcopp

That vent is also the intake. It prob should have ben a bit higher up off the roof. You dont want the flue gas to be sucked back into the intake. That will deteriorate the swirl plate over time. Improper air/fuel mixture will get you an F09.

Zman

Have you ever replaced the ignitor and probe?
For the combustion numbers, shoot for the middle of the range if the boiler is pulling outside air of average temp. You can go a bit richer if the boiler is pulling warmer (less dense) outside air and leaner if it is pulling colder (more dense) air. You may want to run it a bit richer (within spec) if the boiler is noisy, especially firetubes.

TT_Vert

How could that be possible that both exit out of the same 3" pvc? Two separate 3" PVC pipes exit the room into the attic. Are you saying that they wye back together before exiting the roof? If that was the case wouldn't all intake air be exhaust from the boiler? Update... Jesus I just looked at the exhaust spec on this, **** would they do it this way? How exactly is exhaust gas prevented from being recirculated exactly??? Is that concentric KIT the wye on up? Does the exhaust gas go straight up and out and the intake is coming in from under that bezel?




Dave

TT_Vert

Zman said:

Have you ever replaced the ignitor and probe?
For the combustion numbers, shoot for the middle of the range if the boiler is pulling outside air of average temp. You can go a bit richer if the boiler is pulling warmer (less dense) outside air and leaner if it is pulling colder (more dense) air. You may want to run it a bit richer (within spec) if the boiler is noisy, especially firetubes.

I have not in the last 3 years (Not to say the previous owner hadn't) as when they are cleaned I had been getting the appropriate current reading out of the rectification probe and the spark out of the igniter is very good. There are also resistance value specs for the igniter, i could ohm it out if need be. All of this noise just started when I started getting persistent F09s that I could not fix like i had in the past (Cleaning the rectification probe and igniter). They both looked ok w/ just a bit of what looked like iron oxide (red) tint to them. Generally this will fire most often in winter w/ cooler, denser air. I think to start i'll shoot for the middle as I don't have the diag skills to know exactly when to go richer/leaner. What do you mean by "especially firetubes"?


Thanks
Dave

neilc

that's a pipe inside the pipe,
the exhaust goes up and out the inside pipe, straight up,
the OA is drawn in from under the upside down icecream cone, down to the why inside the roof,
if the assembly isn't high enough above the roof, and nearby ridge or other obstructions, wind swirls and eddies can send exhaust back down the intake, which is not good for the boiler or furnace as others have mentioned, and is shown in your screen shot.

TT_Vert

neilc said:

that's a pipe inside the pipe,
the exhaust goes up and out the inside pipe, straight up,
the OA is drawn in from under the upside down icecream cone, down to the why inside the roof,
if the assembly isn't high enough above the roof, and nearby ridge or other obstructions, wind swirls and eddies can send exhaust back down the intake, which is not good for the boiler or furnace as others have mentioned, and is shown in your screen shot.

Yeah i found a diagram on this "concentric vent kit". From the picture I showed it looks like spec says 10' from the peak if i am understanding this correctly? Or perhaps the top of the exhaust must be higher than any point 10' from it? With that said, if it's within spec would that really cause exhaust recirculation? I mean EGR systems work in cars right? Given this setup has been in place for 15 years I have to assume that exhaust recirculation isn't the issue. Perhaps it has caused an issue w/ the swirl plate but given this is so very intermittent I cannot see that. I'm hoping someone can answer my other questions also.

I just realized the swirl plate is a fixed plate that is referenced to atmosphere. I thought it was attached to the motor and spun. It looks brand new upon inspection w/ all vanes intact.

Dave

Alan (California Radiant) Forbes

On the circuit board inside the Munchkin, is the large transformer red or black? If it's red, you might need to upgrade to a 926 board which has a black transformer. My Munchkin is about the same age as yours and it started throwing out error codes that didn't make sense. Changing the board took care of it.

The pressure post-regulator, i.e. to the manifold should be -.01" wc. That is, slightly negative.

I try not to mess with the offset adjustment because tech. support has told me that it can ruin the valve if you fiddle with it. But yes, the times I have adjusted it is to dial the numbers in on low fire.

4. I see no definition of "low fire" and "high fire". I do know how to get into the test mode to control the fan speed so is low fire just minimum fan RPM and high fire max fan RPM? If this is just fan related is there a specific RPM you guys use for high and low fire gas analysis? How far do you guys drill your hole in the exhaust to analyze combustion? Do you guys generally aim for dead center in the spec window or error to the rich side?

In test mode, arrow down to the lowest and highest fan speeds for min. and max. for combustion analysis. I usually drill the hole just above the boiler, tap it for 1/4" threads and screw in a brass plug when I'm done. Target midpoint, but some Munchies are happier on the rich side.

TT_Vert

Thanks. Mine is red. Given all the things going on I feel it's got to be a fueling issue.  just not sure why I get that moaning sound on cold starts.  Is air volume affected by the rectifier probe current or is that solely for flame verification?

SuperTech

You need to get the updated control.  That will help a lot with the F09 faults. The new control will utilize the igniter and flame sensor for flame rectification.  The control will also increase the post purge time, which will help prevent future problems. 

I really don't like concentric vents with these boilers, too much potential for exhaust gas recirculation.  I'd consider changing the venting to separate intake and exhaust pipes.  

Make sure that your refractory insulation around the burner and igniter/flame sensor isn't loose or damaged.  This can also cause F09 faults.

kcopp

The swirl plate can degrade and effect the way gas and air is mixed. The is is one I replaced last spring. 

TT_Vert

SuperTech said:

You need to get the updated control.  That will help a lot with the F09 faults. The new control will utilize the igniter and flame sensor for flame rectification.  The control will also increase the post purge time, which will help prevent future problems. 

I really don't like concentric vents with these boilers, too much potential for exhaust gas recirculation.  I'd consider changing the venting to separate intake and exhaust pipes.  

Make sure that your refractory insulation around the burner and igniter/flame sensor isn't loose or damaged.  This can also cause F09 faults.

Thanks. I'm not going to start throwing parts at this, just not how I am. I feel we have other issues than control issues right this second. I got the manometer and I'm seeing a static pressure at the inlet port of 7.76" WC. When on lowfire I see 5.8x-5.9x" WC. When on high fire it's around 7.0" WC. I see mention of a spec of a drop no less than .5" WC and then another HTP training vid that said 1" WC. Oddly the munchkin manual states "The gas pressure must remain between 3.5" and 14" during stand-by (static) mode and while in operating (dynamic) mode." so based on this i'd be within spec. I also see : "Is the pressure drop between static pressure (nothing running) and dynamic pressure (unit running) less than 2” W.C.?" which I am. Once I get my gas analyzer later today I'll know more.

So my questions are:

1. Am I really within spec given the drop in lowfire? Everything (Aside from the actual manual states I am not)
2. Is the drop measured at high or low fire?
3. Is this drop directly affected by the "throttle" enrichment adjustment? I was assume if the valve is set too rich it'd cause a more significant drop although I wouldn't imaging it to be THAT much. I have 3/4" pipe feeding this so I cannot see this being the issue but who knows. Nothing else on this feed is on (Dryer) so that's not an issue.

Dave

Alan (California Radiant) Forbes

A 2" drop is more than I like to see. If your 3/4" gas run is long, it may be too small. How far are you away from the gas meter? What is the size of the pipe where it starts at the meter?

You can also call your gas utility company and have them check out their regulator as they often go bad.

TT_Vert

I'll have to check that info but I do know the feed has been fine for 15 years of reliable firing. Wouldn't a pressure issue carry over to my gas dryer and stove? I do know the run is quite long as it's on the opposite end of the house. I checked my offset and it's a perfect -.02. I'll be analyzing the exhaust when I get home later tonight. I did start to hear some gurgling and saw some bubbles in my PEX so I have bled the system. No idea how air would have been introduced so I'll have to keep an eye on that. Ever since I've done this though it's fired perfectly every time w/ no noise at all. The original noise was NOT a boiling sound but the last time it made a noise and sort of pulsated It was a boiling sound so my guess is the circulation pump got a big enough air pocket in it to cavitate and the water in there just cooked (boiled). No idea why that would ever affect firing, perhaps you guys have some insight. Perhaps they are not related, i just don't have the experience you guys to know that. With that said, I'm unsure of the proper purge procedure and I still have some micro bubbles in there that I can see and on occasion hear. My manifolds have a dump/fill valve on the end that a standard hose can attach to. At the top is another vale to open what appears to be a purge valve w/ a very tiny hole.

This is what my logic (Albeit possibly flawed) had me do. I attached a hose to the top manifold hose fitting. I opened the valve to let water circulate. Doing this did get some bubbles out. I then went ahead and closed that and let the system work a bit. I then opened that purge while the boiler was on (Not hot yet) and purged some more air. I still had air in it so I went ahead and opened the dump valve for that manifold and the purge at the same time releasing some more air. I then went to the opposite end manifold and di the same thing. Then I had both purges open at the same time and let the system run for a while. I got to a point where I didn't have any more air coming out of the purges but again I do see/hear some microbubbles Can anyone tell me the proper procedure for doing this so I can ensure I do it as they design? Do both ends need to be bled? I'd assume no bu tit may make it faster? I have read about air separators but I don't know that I have these. I googled them but didn't find much.

Thanks guys, learning a ton more than I thought I needed to on this system.

Dave

neilc

on that water side noise and air,
post a picture or 2 of the boiler, circulator, and tank, all in one big picture so we get a good look,
also show any vents, and their relation to the above boiler, circ, and tank,
what boiler pressure are you set at and showing?

TT_Vert

neilc said:

on that water side noise and air, post a picture or 2 of the boiler, circulator, and tank, all in one big picture so we get a good look, also show any vents, and their relation to the above boiler, circ, and tank, what boiler pressure are you set at and showing?

Will do a bit later. By boiler pressure do you mean water pressure in the pex? It's 15psi.

neilc

yes, the 15

Alan (California Radiant) Forbes

I'll have to check that info but I do know the feed has been fine for 15 years of reliable firing.

Regulators can deteriorate.

Wouldn't a pressure issue carry over to my gas dryer and stove?

Your Munchkin has a negative pressure gas valve which is much more sensitive than your dryer and stove.

I do know the run is quite long as it's on the opposite end of the house.

What model Munchkin do you have? Size matters.

TT_Vert

Its a 140m R1.  In my experience, not with low pressure NG regulators mind you, the failure mode I see on pressure regulators hasn't ever been a reduction in pressure which is stable and repeatable.  It's this a failure mode you guys see in these valves?  If after my combustion testing it's still lean after adjustment I may tear the regulator down to see what's going on with it. They're pretty simple devices.

Dave

TT_Vert

Here are a few pictures. I still have the hose on from bleeding. The metal ducting is from the dryer. I didn't do it so don't shoot the picture taker.  It's a bit tight in here as you can see so getting pics isn't easy.

SuperTech

No offense,  but I am amazed that you are willing to buy a combustion analyzer and devote this much time, effort and frustration in an attempt to perform a DIY repair on a something that you have no experience with and no training on other than watching YouTube videos instead of calling a trained, experienced professional who would have probably had this problem resolved already. 

I understand that you want the satisfaction of fixing it yourself but its obvious that you don't know the basic things about boilers, like how to purge the systems and identify a air eliminator.  Yes, its possible that you can fix it with enough help from the resources available online, but I honestly think you should call a professional service technician who is familiar with modulating condensing boilers. A good pro will not only resolve this problem but he will also be able to identify other issues that will prevent future problems. No disrespect intended but you seem like you are in over your head.  Have you tried using the find a contractor tool on this site?

TT_Vert

SuperTech said:

No offense,  but I am amazed that you are willing to buy a combustion analyzer and devote this much time, effort and frustration in an attempt to perform a DIY repair on a something that you have no experience with and no training on other than watching YouTube videos instead of calling a trained, experienced professional who would have probably had this problem resolved already. 

I understand that you want the satisfaction of fixing it yourself but its obvious that you don't know the basic things about boilers, like how to purge the systems and identify a air eliminator.  Yes, its possible that you can fix it with enough help from the resources available online, but I honestly think you should call a professional service technician who is familiar with modulating condensing boilers. A good pro will not only resolve this problem but he will also be able to identify other issues that will prevent future problems. No disrespect intended but you seem like you are in over your head.  Have you tried using the find a contractor tool on this site?

There is nothing I've not been able to figure out over my life by not just diving into it, reverse engineering it and spending some time grasping the fundamentals of it. The whole teach a man to fish thing. I'm 43 and still have all of my appendages. Ever since I was a kid I took everything apart so it's stuck w/ me the last 35 years and isn't changing any time soon. I've taught myself residential electrical, plumbing and construction by just doing them and understanding the fundamentals (What I'm trying to do here). I got into my life long passion (car racing/modification) out of necessity when I was in HS and needed to get to work and the car we had wouldn't start. First ever thing I did was disassembled and rebuilt a quadrajet carb in a parking lot without ever touching as much as a valve cover prior to that. I was well on my way at that point. I don't just hand off work unless i feel I cannot fully grasp/understand it in a safe manner. There really isn't anything we can't do if we just understand the basics of it and build from there. This system (and the concept of heating water w/ fire) is very simple if not archaic. In fact much simpler than other types of systems I've spent time on. Once i've expended every resource I have I will consider calling a technician in but quite frankly when I'm done w/ this I plan to know every little thing about this setup and probably more than any tech that could be sent out. From every detail down to the resistance rating of each sensor. I've got more education in principles of combustion that pretty much any HVAC guy they could send out. Same for every other sub system here, just not all of them together. it bothers me that people are always so quick to advise someone to "call a professional". Granted I know the customer can get themselves into trouble if they aren't careful but based on my existing post i figured it'd be an indication that I'm well educated enough in general to delve into this.

I've spent a great deal of time researching the system reading and understanding the service manual from basic setup now to intake and exhaust plumbing specs as well as gas line requirements, friction losses due to elbows in both systems, pressure requirements, etc. I did watch a ton of videos to supplement that. and looked at hundreds of posts on this forum and others pertaining to not just Munchkin boilers but other residential heating systems relying on a boiler. My time is valuable but knowledge is power to me. Basically what I'm saying is I feel I'm competent enough to tackle this system. I am asking questions that will help fill in the small gaps in my knowledge that i have not found on the internet. Is the internet always right? No. Am I knowledgeable enough to know if what I'm doing it wrong/dangerous? A majority of the time. Hopefully a few of my remaining questions can be answered.

Thanks
Dave

Alan (California Radiant) Forbes

I like this guy.

SuperTech

I can appreciate your passion for learning about this stuff. I know you already dismissed the recommendation from Alan and myself to consider updating your boiler to the revised control board but maybe you should think about why HTP needed to revise the control board in the first place. Early versions of that boiler, like yours,  were extremely prone nuisance F09 faults. Theres tons of information available about this issue online. It became such a problem that the manufacturer ditched the original control in favor of a better one. I know you think your problem is the gas valve because you were lucky enough to get away without needing the revised control. Maybe its not the problem but you aren't doing yourself any favors by sticking with the R1 control. Either way I hope you get it fixed. Good luck 

JUGHNE

Did you pressure test the water tube HXC?
Isolate the boiler from the rest of the system as much as possible.
You can crank the pressure up to just under 30PSI, close the water supply valve.
Put a dry container under the cond drain of the boiler.
If pressure drops and you get drips into the dry can then it is probably new boiler time.

HomerJSmith

I have covered this so many times in past posts, I'm beginning to feel like Cassandra (Greek Mythology).

F09 error code: a break in the rectification current back to the module. You can read all the causes for an F09 from HTP and go thru them. If you don't have any satisfaction, do the following:

This is probably your cause. There are 4 screws holding the burner tube to the front plate. These do loosen. This causes an intermittent rectification current which can produce a F09. Remove the burner tube and clean the front plate and tube getting rid of the old gasket. Replace with a new and improved gasket and cinch the 4 screws holding the burner tube tightly to the front plate. I use a socket wrench to do it. That's all there is to it.

Do not adjust the OFFSET. This has nothing to do with the F09. HTP gives instructions on how to adjust the offset. It should only be done if the combustion can not be made within the prescribed limits.

I assume the condensate is draining.

TT_Vert

SuperTech said:

I can appreciate your passion for learning about this stuff. I know you already dismissed the recommendation from Alan and myself to consider updating your boiler to the revised control board but maybe you should think about why HTP needed to revise the control board in the first place. Early versions of that boiler, like yours,  were extremely prone nuisance F09 faults. Theres tons of information available about this issue online. It became such a problem that the manufacturer ditched the original control in favor of a better one. I know you think your problem is the gas valve because you were lucky enough to get away without needing the revised control. Maybe its not the problem but you aren't doing yourself any favors by sticking with the R1 control. Either way I hope you get it fixed. Good luck 

Fair enough. Let me think about the logic here a bit if you don't mind. This is my thought process, please feel free to correct me if i'm wrong. I know F09 to be no flame detected. Now the reason for that can be many obviously. But if it's a control board issue, is it normally having to do w/ the rectifier probe current sense circuit or something else? I'll explain this question in a sec.

To prove a flame it uses DC current from the flame rectification probe correct? This value must exceed a certain value after what is it, 3 seconds max? I do not know this value but I assume it is over 2.5-3 uA based on what i've seen monitoring the current out of the rectifier probe. Anything lower would generally generate the F09 for me. So the logic chip programming would look for a certain DC current and it'd be a pass/fail by the logic. In basic terms, IF rectifier probe current >3.5uA THEN go to step 2 (high fire or whatever) and IF rectifier probe Before even getting to ignition
Heating call? Yes, next line
Water pressure good? Yes, next line. No, Error PRO
Flue Temp good? Yes, next line. No, Error F01
Flue pressure good? Yes, next line. No, Error FLU
then we get to the problem area.. I don't even think we can get here until these other values are within spec
Rectifier probe >3ua? Yes, next line. No, Error F09
Ignition.

Then we run into fan, Inlet/outlet water over temp, gas valve errors post ignition I believe (Not sure what control the logic board has over the gas valve but i'd love to have that info if you do?) My guess is it's just a solenoid that is either energized or not energized. Doubt they are doing any PWM here.
Sorry so long winded. I have tons of things circling in my head and trying to orate them all isn't easy sometimes. In my head it's crystal clear, on paper sometimes not so much..

I'm going to go drill the flue and check the combustion in a bit.

TT_Vert

JUGHNE said:

Did you pressure test the water tube HXC?
Isolate the boiler from the rest of the system as much as possible.
You can crank the pressure up to just under 30PSI, close the water supply valve.
Put a dry container under the cond drain of the boiler.
If pressure drops and you get drips into the dry can then it is probably new boiler time.

Thanks for that. I had only had it up to about 12PSI. I pressurized it to 18psi and sure enough a tube has a very visual crack. I pulled the rectifier probe and noticed the refractory material was damp so i tore it back down, pressurized it and it's leaking . I wonder if I did that when i got to a point where the air in the system appeared to be cavitating the recirculation pump. It never got above 200 but that's still mighty warm. Although I cannot see why this HX tubing wouldn't withstand that. I'd love to try to find a replacement HX but I don't know how easy that'll be.. Right now i'm just draining the system in prep to remove it. Sad but at least it's getting warm now and I have time to research something. What would you guys recommend I do? I know people don't like the munchkin but it has been pretty reliable to this point. I am heating a 2,200 sqft garage in one zone and a 400sqft bathroom in the other. I'll probably get a pro out here to do that but I'd like your expert opinions. I'd love one that I could throw a nest thermostat on if possible but given this thing use a slab sensors for one zone and air temp for the other I don't think I can.

Dave

TT_Vert

HomerJSmith said:

I have covered this so many times in past posts, I'm beginning to feel like Cassandra (Greek Mythology).

F09 error code: a break in the rectification current back to the module. You can read all the causes for an F09 from HTP and go thru them. If you don't have any satisfaction, do the following:

This is probably your cause. There are 4 screws holding the burner tube to the front plate. These do loosen. This causes an intermittent rectification current which can produce a F09. Remove the burner tube and clean the front plate and tube getting rid of the old gasket. Replace with a new and improved gasket and cinch the 4 screws holding the burner tube tightly to the front plate. I use a socket wrench to do it. That's all there is to it.

Do not adjust the OFFSET. This has nothing to do with the F09. HTP gives instructions on how to adjust the offset. It should only be done if the combustion can not be made within the prescribed limits.

I assume the condensate is draining.

I can understand your frustration. Know that I have done by due diligence and had eliminated anything very easy/obvious. I came here as a last resort as I see many have the F09 issues but this one was a bit different. In my case I could not see the HX crack until I over pressurized the unit which was causing my F09. My guess is the wet refractory wall was grounding out the ignitor hence the no start after sitting a while. I just wish I knew how it happened and if it was self inflicted.

Funny you mention the burner tube screws. Mine were the complete opposite, I had to get my trusty vessel impact screwdriver out and WHALE on the thing to get them to even rotated 5 degrees. Then I had to work them back and forth and hammer again and again to get them out. I was sure they were all breaking but nope..

Dave

SuperTech

Start with doing heat loss calculations to figure out how many BTUs you require on design days. Proper sizing is critical to efficient and reliable long term operation. Then choose a suitable replacement.  

Why do you want a Nest thermostat? Not a very good choice for a radiant heating system. A mercury T87 is all you really need.  If wifi access to your thermostat is necessary Honeywell makes a version of the T6 designed for use with radiant heating.  

TT_Vert

SuperTech said:

Start with doing heat loss calculations to figure out how many BTUs you require on design days. Proper sizing is critical to efficient and reliable long term operation. Then choose a suitable replacement.  

Why do you want a Nest thermostat? Not a very good choice for a radiant heating system. A mercury T87 is all you really need.  If wifi access to your thermostat is necessary Honeywell makes a version of the T6 designed for use with radiant heating.  

Thanks but that's where I'm out of my pay grade. I'll have the pros take care of sizing.   I was asking more along the lines of a particular brand or design to gravitate towards or away from.   It's all for radiant heat pex tubing.

HomerJSmith

That's my big regret that HTP never provided replacement HXs. Probably a policy decision with the hopes of selling more boilers. But I bet, the new boiler isn't a HTP product. I'm sorry to hear that.

The grounding from the burner tube is thru those 4 bolts. The bolts can be well anchored to the front casting and the burner tube can still be loose. I always used silicone grease on the threads when I re did the gasket.

JUGHNE

I meant to post earlier for the pressure testing, but the discussion has been educational to everyone.
I don't know what the HEX warranty for the Munchkin is, but it may be worth checking out.
HTP might give you some credit towards a new mod con boiler??

They do not make Munchkin's any more but have new ModCon lines available.
The Munchkin was a much maligned product as they appeared on the market.
But they were one of the first innovators of ModCon boilers.
Most failures were from bad installations and lack of maintenance.

So did you have the "coffee grounds" collecting in the heat exchanger?...very common occurrence BTW.
And was there a dedicated boiler pump that pumped into the inlet of the boiler?

I still maintain a 2003 199,000BTUH Munchkin. Wondering when the HEX will fail.
Have changed the blower assembly, it still has the red transformer design control board.
Other than that major replacement, it was cover and target wall replacements and spark and FS probes. It needs opened up at least every 2 years for cleaning.

When it fails I will most likely go with Lochinvar Mod Con. I have one in my house and other places. The main reason for that brand is that is what my supplier (220 miles away) has and maintains parts for.
And of course I have great trust in the installer, everyone here says that it the most important factor......

SuperTech

Someone who cares as much about learning things that will save you money and headaches should care about what goes into boiler sizing. You are going to find out that the majority of professionals won't bother with this critical first step. They will look at the size of your existing boiler and say "this one is X amount of BTUS.  It worked well enough for you, right?"
Its really not that complicated.  Plenty of average homeowners on here figure it out. Its not as complicated as some of the stuff you claim proficiency with.  You can download the Slant Fin app or use one of the other available heat loss calculators online and give it a try.  You might be surprised by the results.  Most boilers are quite a bit oversized for the homes they are installed in. 

TT_Vert

SuperTech said:

Someone who cares as much about learning things that will save you money and headaches should care about what goes into boiler sizing. You are going to find out that the majority of professionals won't bother with this critical first step. They will look at the size of your existing boiler and say "this one is X amount of BTUS.  It worked well enough for you, right?"
Its really not that complicated.  Plenty of average homeowners on here figure it out. Its not as complicated as some of the stuff you claim proficiency with.  You can download the Slant Fin app or use one of the other available heat loss calculators online and give it a try.  You might be surprised by the results.  Most boilers are quite a bit oversized for the homes they are installed in. 

Ok challenge accepted. Downloaded that app and this is much easier than I expected.  I suppose it's just about material efficiency and thermodynamic calculations right?  The app apparently does it all for you so that's nice. Just need to do some measuring and let it eat.  Life has gotten too easy for us.  If I keep this up I may see if I can source a new boiler myself and install it.  

Dave

JUGHNE

If you want the challenge you can always do the long form on paper.

Where are you located? That sounds like a lot of boiler for the floor area.

The main factor is under floor and perimeter insulation.
Did the snow melt away from the outside walls of the garage?

I tried set back tstats for in floor and in wall heating in my house, went back to simple tstats......set and forget it plan.

TT_Vert

JUGHNE said:

If you want the challenge you can always do the long form on paper.

Where are you located? That sounds like a lot of boiler for the floor area.

The main factor is under floor and perimeter insulation.
Did the snow melt away from the outside walls of the garage?

I tried set back tstats for in floor and in wall heating in my house, went back to simple tstats......set and forget it plan.

I'm in Illinois. I just measured and the one garage is 2,021 sqft w/ peaked ceilings starting at 10' and peaking at 12'. The master bath is 325 sqft also w/ 10' walls peaking at 12'. I'm going to input all of these figures as well as window and door opening/materials, roof, etc. here in a bit. I do have one question regarding this calculation. My master bath is attached to the master bedroom and some of the heat from that floor system does heat the master bedroom and I personally like that. The french doors between the two are always open so how should i calculate that door? Not that his matters but In the master bath I've got the radiant heat flooring as well as forced air/heat which I only use the AC part of to cool the bathroom in the summer (Lots of windows in this bathroom). The heat has kicked on a few times when the boiler for the pex was on the fritz but 99% of the time I use the radiant to heat the bathroom. The exact same situation is in the garage w/ its forced air system cooling and the radiant heat flooring doing all of the heating w/ usage of the forced air heat if it's very cold out and I need to quickly get heat back into the garage after i have had the garage doors open for a prolonged period of time.

Dave

SuperTech said:

Start with doing heat loss calculations to figure out how many BTUs you require on design days. Proper sizing is critical to efficient and reliable long term operation. Then choose a suitable replacement.  

Why do you want a Nest thermostat? Not a very good choice for a radiant heating system. A mercury T87 is all you really need.  If wifi access to your thermostat is necessary Honeywell makes a version of the T6 designed for use with radiant heating.  

Well to be honest this entire house is IOT at this point. The only exceptions are the daily driver garage system which is using a HV forced air heating system which I cannot use a nest on and this boiler for the master bath and big garage since it uses a slab sensor. I'm a techie by career so i can pretty much do anything in this house by voice. Open garage doors, turn on lights, lower/raise my garage door screens, lock and unlock the entry doors, set interior temps, check CO levels, check my sump levels and pumping history, etc. It's pretty neat once you get into all of that. I currently have 4 nest thermostats in this house and 5 nest CO testers in the nest app. I also integrate IFTTT applets in to control all of these things based on time, day, temp, geofencing, etc. With that said, the big garage is rarely touched by me as I generally keep big garage around 72' air temp which is usually around 65deg on the radiant heat thermostat. I do have a nest in both the big garage and master for the forced air so I do have the ability to monitor interior temps if need be so it's not really a big thing but given everything else is IOT with this being the only exception I was hoping to get into the modern era with it. No big deal if that's not an option really.

Dave

TT_Vert

JUGHNE said:

If you want the challenge you can always do the long form on paper.

Where are you located? That sounds like a lot of boiler for the floor area.

The main factor is under floor and perimeter insulation.
Did the snow melt away from the outside walls of the garage?

I tried set back tstats for in floor and in wall heating in my house, went back to simple tstats......set and forget it plan.

Sorry missed this. I have about 20" eaves and the snow is never near the house but I don't think it did melt. Seemed highly efficient. There is insulation on all vertical and under floor surfaces under the bathroom. Off hand I don't know the R value but I can certainly check it if it helps my calcs. Speaking of calcs, when you have a peaked ceiling do you just average the height? If I have 10' walls and 12' peak, enter 11'? There is a concrete crawl space under there where the forced air heat/AC resides w/ a drain for the condensate of that system. They did a very nice job. These areas which have radiant heat flooring were built in 2006 and no expense was spared by the builder from what I've seen thus far. As I had mentioned in the post I just posted I pretty much have them both set and NEVER touch them. I had the slab sensor set to 80 deg for the master (netted 70-74 deg air temp in day time (LOTS Of windows in here) and air temp to 65 deg in the big garage which netted 70-72 degree air temp in the dead of winter during the day.



Dave

TT_Vert

Of course the link for the manual for this slantfin app is down right now so I have a few values I'm unsure on but based on best guesses what I got thus far is a total of 84,616 BTUs 68,700 BTUs for the garage and 15,916 for the master bathroom.

The current boiler specs are as follows:
Munchkin 140M ASME Gas Boiler
46,000 - 140,000 BTU/HR Input Modulation
43,000 - 129,000 DOE Heating; 112,000 IBR

Few questions maybe you guys can answer. I know i'm over-thinking this but let me do me

1. I cannot specify garage door openings so I just added doors at the dimension of the garage doors. There is door factor which it appears to take into account window design which is a global setting for all so that will throw off the # some. Also one man is only a partial window while the other larger man door is all glass. Both are double paned but if i I set this it will also set the large garage doors (two 24x8/ doors) to glass doors also I believe. This number changes my BTU calc ~6k BTU when I don't specify the garage doors.

2. The concrete garage floor terminology has got me. This won't be much of a factor IMO but still curious.
My options are on ground or fill or on ground below grade. I do not know the total thickness of the slab but I do know that since there is a lift on ont part of it it has to be at least 4" thick for this lift. With that said I know that one 82.5" side of the foundation has driveway covering it so it's not exposed. I believe a very small portion of the slab is exposed on one long side and one short. The remaining side is connected to the house. Furthermore one of the on ground or fill options mentions edge insulation. Is there any way I can visually verify this? Another setting that probably is insignificant in the overall calculation.