# Gas boiler & Rinnai strangeness



## futz (Sep 17, 2009)

*Rinnai strangeness*

Here's a fun one for you all to puzzle over:

House (about a year and a half old) is hot water heat w/standing pilot boiler. It has a Rinnai R94-LSi tankless for hot water. 

Today I get a call - they have no hot water and the heater is throwing a #12 fault. I get there and it seems normal except it won't stay fired. Kinda kicks on and right back off and displaying 12.

I look in the manual at the long list of stuff that can cause a #12 fault and start at the top of the list. I turn up a thermostat to fire the boiler to confirm there is gas. The boiler fires normally, so I turn that back down.

Then there is an interlude of stupidity and frantic floor scrubbing - the bucket I grabbed out of the truck to use as a ladder had paint in it under the dirt and sawdust! Sigh... 

Back to the heater. I kick on the hot water and the Rinnai fires up normally and never screws up again. I try it many, many times and it's fine now. WTF? Fault is gone for now, but you know it's gonna come back...

Then HO mentions that the boiler pilot has gone out something like three times over the past year and he just re-lit it each time.

At this point I'm really starting to look suspiciously at the 2 lb gas reg. Didn't think of it at the time, but I probably should put a manometer on the downstream side of that reg and see what it's putting out. Or maybe just replace the stupid thing - I've never seen that brand before - some furrin thing.

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Probably not connected, but he complains that every so often the Rinnai makes a loud noise like "furniture being dragged across the floor". It has never done it while I'm there though, so I'm at a loss about that.


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## 1703 (Jul 21, 2009)

futz said:


> Probably not connected, but he complains that every so often the Rinnai makes a loud noise like "furniture being dragged across the floor". It has never done it while I'm there though, so I'm at a loss about that.


Try this:

http://www.plumbingzone.com/f2/rinnai-issue-10885/


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## futz (Sep 17, 2009)

Colgar said:


> Try this:
> 
> http://www.plumbingzone.com/f2/rinnai-issue-10885/


HOLY HELL! I sure hope it's not making a sound like that! :laughing: Wow! That's crazy!


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## OldSchool (Jan 30, 2010)

Could be the flame sensor rod.... try cleaning it with sand paper


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## futz (Sep 17, 2009)

OldSchool said:


> Could be the flame sensor rod.... try cleaning it with sand paper


It could be, but I just find it hard to believe that an 18 month old flame rod is already so dirty that it's not sensing properly. There'd have to be something else really wrong to cause something like that in such a short time. That said, if they call again I'm gonna for sure have a look anyway.


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## OldSchool (Jan 30, 2010)

futz said:


> It could be, but I just find it hard to believe that an 18 month old flame rod is already so dirty that it's not sensing properly. There'd have to be something else really wrong to cause something like that in such a short time. That said, if they call again I'm gonna for sure have a look anyway.


I would say instant flame failure would be flame sensor or control board issue.... I have had lots that it would work for a while and then at times it would not work,,,, took out sensor rod and clean it up... there seems to form some kind of oxidation on the rod and current can not go through it and at times it does.


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## futz (Sep 17, 2009)

OldSchool said:


> there seems to form some kind of oxidation on the rod and current can not go through it and at times it does.


Hmm... Most flame rods are good for many many years without any trouble at all. Something to do with the sealed combustion chamber, ya think? - but there's still plenty of air moving through there...

I think I'd be more inclined to look for bad wiring connections outside the comb chamber, or, like you said, maybe something not quite right with the control board or the connections to it.

Anyway, if they call again the flame rod will get looked at immediately.


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## ckoch407 (Sep 30, 2009)

Sounds like bad control board.


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## BROOKLYN\PLUMB (May 21, 2010)

futz said:


> Hmm... Most flame rods are good for many many years without any trouble at all. Something to do with the sealed combustion chamber, ya think? - but there's still plenty of air moving through there...
> 
> I think I'd be more inclined to look for bad wiring connections outside the comb chamber, or, like you said, maybe something not quite right with the control board or the connections to it.
> 
> Anyway, if they call again the flame rod will get looked at immediately.


I've found the flame rod issue is more prevalent with sealed combustion due to moisture levels being way higher starts off with a whitish coating and can eventual just become a nub before complete failure. But grounding is also an issue make sure your grounded

Sent from my EVO 4G using Plumbing Zone


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## ZL700 (Dec 8, 2009)

Many people apply the wrong regulators. A appliance reg may have been used, and it cant respond quick enough the high *sudden *gas demand for the tankless which may explain the boiler pilot outage.

Always use a "line" regulator when tankless is involved, even though it is applied as a appliance regulator.

The Maxitrol "blue-top" works best. P# 325-5AL

2# to 7-9"


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## futz (Sep 17, 2009)

ZL700 said:


> Many people apply the wrong regulators. A appliance reg may have been used, and it cant respond quick enough the high *sudden *gas demand for the tankless which may explain the boiler pilot outage.
> 
> Always use a "line" regulator when tankless is involved, even though it is applied as a appliance regulator.
> 
> ...


I didn't know there were different types of reg. But your explanation nicely fits the symptoms. What's the difference between an appliance reg and a line reg?


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## ZL700 (Dec 8, 2009)

futz said:


> I didn't know there were different types of reg. But your explanation nicely fits the symptoms. What's the difference between an appliance reg and a line reg?


While performance charts will show appliance regulators of certain IPS sizes capable of handling Btus of Tankless, what they cant do is supply the sudden demand commonly occurring with a Tankless unit. This sudden demand of going from low to high fire suddenly results in a lull in delivery of the appliance regulators. When ever you have a fan and gas valve/burner that must be in sync and they are not, with a lack of sufficient gas, the exhaust fan, in rinnai's case sucks the flame out. 

With the boiler pilot close by, the rinnai demand causes sudden line pressure drop, snuffing out the flame, or at least I suspect that now knowing how improper regulators react. 

The big difference being reaction time between the two, besides a line regulator typically cost 3x more.


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## futz (Sep 17, 2009)

ZL700 said:


> While performance charts will show appliance regulators of certain IPS sizes capable of handling Btus of Tankless, what they cant do is supply the sudden demand commonly occurring with a Tankless unit. This sudden demand of going from low to high fire suddenly results in a lull in delivery of the appliance regulators. When ever you have a fan and gas valve/burner that must be in sync and they are not, with a lack of sufficient gas, the exhaust fan, in rinnai's case sucks the flame out.
> 
> With the boiler pilot close by, the rinnai demand causes sudden line pressure drop, snuffing out the flame, or at least I suspect that now knowing how improper regulators react.
> 
> The big difference being reaction time between the two, besides a line regulator typically cost 3x more.


Well that sounds right. I'll look into it. Anybody who remembers me posting pics of this system (first one I posted) will remember me and other posters going back and forth about the gasfitter's lame workmanship. The reg he put in there is some weird foreign thing I've never seen before. I think I'll try replacing it with something else (a Maxitrol Blue Top?) and see if he never calls again. 

EDIT: Here's the pic with the reg in it.










EDIT 2: Found the original hi-res pic and cropped the reg out in full resolution. It's still not a great pic, but it's all I have.








EDIT 3: Went to Maxitrol's site (the "Lever Acting Regulator" page) and sure enough, you're right, there are Appliance regs and Line regs listed. Good to know. If this cures the problem I'll be hounding the gasfitters about it from now on. More and more people are demanding tankless heaters these days, and I sure don't need the callbacks.


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## plumber666 (Sep 19, 2010)

Two regs on a system like that.The pressure drop to the boiler when the Rinnai kicks in is 105%.


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## Walt (Mar 12, 2011)

what about the venting on these units? are they separetly vented? is one power vented or both, or neither?


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## Walt (Mar 12, 2011)

just saw picture, is there a condensate on vent, does that even matter.


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## futz (Sep 17, 2009)

Walt said:


> what about the venting on these units? are they separetly vented? is one power vented or both, or neither?


Separately vented. Rinnai with Ubbink concentric vent. Boiler to roof with B-Vent.



Walt said:


> just saw picture, is there a condensate on vent, does that even matter.


Rinnai vent is long and carefully sloped. The condensate drain hadn't been piped when that pic was taken.


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## futz (Sep 17, 2009)

Changed the reg today. We shall see how it performs.

Pulled the flame rod and had a look. It was a bit frosty white. I doubt it was enough to be the problem, but I cleaned it anyway.

Found the noise problem. I had everything shut down to do the reg change and heard a loud "bddddddddt" from the B-Vent - more than once. I'm thinking, "WTF? That sounds awfully familiar!". I go out to the street and look up at the B-Vent. There's a bird sitting on it. While I'm looking the stupid woodpecker gives the rain cap another "bddddddddt". :laughing::laughing: Guess that's why it never made the noise while I was there before - it was always early evening (almost dark) when I showed up before.


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## sdalla1 (Mar 30, 2011)

Did you check the gas water colum ?


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## sdalla1 (Mar 30, 2011)

two regulators on one appliance could be an issue


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## SPH (Nov 4, 2008)

futz said:


> Changed the reg today. We shall see how it performs.
> 
> Pulled the flame rod and had a look. It was a bit frosty white. I doubt it was enough to be the problem, but I cleaned it anyway.
> 
> Found the noise problem. I had everything shut down to do the reg change and heard a loud "bddddddddt" from the B-Vent - more than once. I'm thinking, "WTF? That sounds awfully familiar!". I go out to the street and look up at the B-Vent. There's a bird sitting on it. While I'm looking the stupid woodpecker gives the rain cap another "bddddddddt". :laughing::laughing: Guess that's why it never made the noise while I was there before - it was always early evening (almost dark) when I showed up before.


Why 2 regs? Should just have a lbs to inches. Also I have found the Aura regs to be crap with on demand heaters. Best to go with the maxitrols.


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## futz (Sep 17, 2009)

sdalla1 said:


> two regulators on one appliance could be an issue


The second one was supplied by Rinnai. Drops 7" to 3.5" I guess.



SPH said:


> Why 2 regs? Should just have a lbs to inches. Also I have found the Aura regs to be crap with on demand heaters. Best to go with the maxitrols.


What's an Aura reg? Never heard of them.

What I took off was a Pietro Fiorentini F3T05230ANYR. I replaced it with a Maxitrol 325-5AL. 

Haven't heard back from him so far, so maybe it's cured. It's not something that happened very often though, so I'm kinda holding my breath. If I haven't heard from him in a year then I'll consider it fixed. I've been lazy about invoicing him. I'll ask him how it's behaving when I drop it off.


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## Tommy plumber (Feb 19, 2010)

ZL700 said:


> Many people apply the wrong regulators. A appliance reg may have been used, and it cant respond quick enough the high *sudden *gas demand for the tankless which may explain the boiler pilot outage.
> 
> Always use a "line" regulator when tankless is involved, even though it is applied as a appliance regulator.
> 
> ...


 




Thanks for the information, good to know...:thumbsup:


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## futz (Sep 17, 2009)

After removing and replacing that regulator I gave it to my gasfitter friends, since it was in good shape still. I do so little gasfitting anymore that I'd never use it up.

Several weeks passed and I ran into them at a job yesterday. The young fitter guy said that the reg turned out to be some kind of high pressure industrial thing that required something like 5.5 lb. minimum input pressure. Well no wonder it didn't work right! :laughing::laughing:


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## andy (May 22, 2011)

I have had issues with flame sensors when the unit is near the water. The unit draws air for combustion from outdoors,and the dampness from the water may cause the flame sensor to collect a build up on it sooner than a unit that isn't installed near water.


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