Well,That Didn’t Last Long

[Rrm8711]

Backstory & an update.

A month or so back, replaced an older Takagi TK3 LPG (This is an LPG unit straight out of the factory- not a conversion model)-was installed by the previous homeowner.
Replaced w/a Takagi 310 because it fit right in where the old one was- didn’t have to adjust mounting or ANY connections.
This model out of the factory is natural gas.
LPG conversion is required -taking off the manifold plate and installing LPG nozzles- no big deal.

Got it converted, mounted, everything hooked up, Dip switches set per instructions: LPG, altitude, venting system.

After employing 2 technicians, many calls to Takagi tech-support, replacement of 2nd stage regulator (Measured in at 11.12”) and Takagi sending a new gas valve assembly including new LPG conversion nozzles, unit would randomly fire up but never consistently. Code 111.

Takagi finally sent out a new water heater.

I installed the new one; not that difficult.

Inlet static and dynamic pressure came in where they should: 11.11” & 9.70”

Fired the unit up & worked the first time like a charm. I figured great, we’re in business.

This lasted for 3 days.

Then it started hot, cold & occasional trouble code 991.
Called tech-support, gave them all the numbers, then they instructed me to go to diagnostic mode #16 , which is the air fuel ratio, which I did and it measured right where it should be: 6.
Tech-support (TS) was baffled.

TS then wanted me to send pictures of the set up , including the intake and exhaust application.

This vent set up is single pipe with room air intake.
The current set up: EXHAUST IS ALL SINGLE WALL GALVANIZED. This was the old set up ,nothing was changed.

A 4” collar sleeve fits very tight over the 4” water heater exhaust pipe. The other end of the collar expands to 6” and connects tightly inside a 6” adjustable 45° connector. The 45 then connects tightly to a 6”, 10’ straight pipe with rain cap.
The intake is room air intake and has a 90° elbow on it.

After sending the required picture to TS, they thought the venting set up was suspect and wanted to see if the unit would run disconnected from the current venting system.
I don’t buy their leariness as the TK3 ran fine for 20 years and this current 310 ran fine for 3 days.

So yesterday, ran the unit disconnected from the exhaust venting.
Same problems: random hot & cold and code 991.

Yesterday during this process, I took pictures & sent them to TS via email: altimeter reading, DIP switch settings, inlet static & dynamic measurements, air/fuel ratio measurement, running, leading to not running, leading to trouble code 991.

As mentioned before, it ran fine for 3 days
Will be interesting to see what TS reply is.

Unless TS comes up with a remedy, I will be looking into out of the factory LPG units (no conversion models).

If I knew then what I know now….
Sheesh.

 

[Fitter30]

First post 24 and 28 stated the gas pressure was lower at the 2nd stage reg than at the heater don't how it could be. Want some pics of the venting both sides in and outside. Never answered my question if venting was located same side of house.

 

[Sponsor]

 

[Rrm8711]

First post 24 and 28 stated the gas pressure was lower at the 2nd stage reg than at the heater don't how it could be. Want some pics of the venting both sides in and outside. Never answered my question if venting was located same side of house.

 

[Rrm8711]

New 2nd stage regulator was installed a few weeks ago. Out of the factory, Rego presets their regulators at 11” - this one was there.
Manometer readings of old one were a bit all over the place. I haven’t dissected the old one yet- will be interesting to see inside.

Current inlet static and dynamic measurements: 11.11” & 9.70”, so no issues with LPG pressures,

When I try to post a pic, it says file is too big for the server, so I can’t send any pictures.

As far as venting: single pipe exhaust with room-air intake.
Exhaust is galvanized, straight 10’ length, 6” diameter with a rain cap: straight through the ceiling, straight through the roof.
Intake Is room-air intake that has a 90° elbow on it to keep debris from falling in.
So if you were looking at the w/h straight on, on the right- 10’ pipe would be going vertical as mentioned; on the left is the intake w/a 90° elbow attached.

 

[GReynolds929]

Page 13-25 of the installation manual dictates the venting requirements. It requires class 3 venting which means non corrosive materials and gas tight connections. This is usually stainless steel with gaskets at each connection, the manual list 4" Z-VENT, or NovaVENT. No galvanized steel, or aluminum B vent. Max exhaust vent length is 60' with no more than 6 90's. Each 90 removes a specific length of vent. How is the make up combustion air getting into the room?
The gas pressure drop of 1.41" wc is almost triple the recommended sizing drop. Sounds like the gas piping might be undersized. Most appliances have a 13" wc limit. If it were me I would also bump the regulator up to 12.5"-13" wc.

 

[Rrm8711]

Page 13-25 of the installation manual dictates the venting requirements. It requires class 3 venting which means non corrosive materials and gas tight connections. This is usually stainless steel with gaskets at each connection, the manual list 4" Z-VENT, or NovaVENT. No galvanized steel, or aluminum B vent. Max exhaust vent length is 60' with no more than 6 90's. Each 90 removes a specific length of vent. How is the make up combustion air getting into the room?
The gas pressure drop of 1.41" wc is almost triple the recommended sizing drop. Sounds like the gas piping might be undersized. Most appliances have a 13" wc limit. If it were me I would also bump the regulator up to 12.5"-13" wc.

Thank you for your reply

Venting:
Manufacturer “recommends”, not requires cat. 3 venting.
Instructions don’t prohibit any specific materials.
The current set up worked for a Takagi TK3 for 20 years. In the TK3 manual, it also
recommended cat. 3 venting. For whatever reason, the previous homeowner and installer did not go that route.

The current exhaust system is as mentioned previously: 10’ long with 1 45° connector at the w/h exhaust vent collar. So I’m safe with that as far as you mentioning the max 60’ length & numerous 90’s.

Combustion air:
Air is supplied by where the water heater is mounted: in a 13’x 8’ laundry room; it’s open air, non-restrictive, just like walking around in my house.

Gas pressure drop:
Takagi manual indicates pressure drops that “exceed” 1.5” wc should be addressed. My pressure does not exceed that.
I gave static & dynamic #’s to Takagi tech-support and they were not concerned.

Gas piping size is 3/4” feed to the water heater.

Bumping up the regulator:
Takagi tech-support strongly indicated inlet static pressure be at 11”wc.
That # is right in the middle of the 8”-14” range specified in the manual.
So until this problem is remedied (getting the water heater to work properly), I’ll go with their recommendation(s). If they recommend another setting, I’ll do that.

In review:
The current set up worked for the TK3 & ran for 20 yrs.
Then, the first Takagi 310 that was installed a couple of months ago would randomly fire up and run long enough (10-15 minutes) with hot water to fill up a bathtub and at a different time, take a shower with no hiccups or interruptions. It would just not fire up on a continuous basis & code 111.
Now, the current Takagi 310 that was installed 3 weeks ago fired up right out of the starting gate with no problems and worked for 3 days straight, providing showers with no interruptions or hiccups.
Then the fluctuating water temperatures and occasional trouble code 991 started.

TS at Takagi wanted me to disconnect the exhaust venting system from the water heater & run it.
I did that this past Saturday and the same problems occurred: fluctuating temperatures and an occasional 991 trouble code.

So with the unit disconnected from the exhaust venting system & running, it STILL has the same problems occurring; it seems that the venting system is NOT the problem due to the w/h still not operating properly while being disconnected from the exhaust venting system.

My question is why would a Takagi TK3 run fine for 20 years, then 1 Takagi 310 would sporadically run & provide hot water for 10 to 15 minutes straight, and finally, why a 2nd Takagi 310 would fire up on initial start up and then for 3 days run flawlessly and then start having problems.

I “took” photos instead of using existing pic’s and that seemed to work, so here are some pic’s.

 

[Jeff H Young]

Page 13-25 of the installation manual dictates the venting requirements. It requires class 3 venting which means non corrosive materials and gas tight connections. This is usually stainless steel with gaskets at each connection, the manual list 4" Z-VENT, or NovaVENT. No galvanized steel, or aluminum B vent. Max exhaust vent length is 60' with no more than 6 90's. Each 90 removes a specific length of vent. How is the make up combustion air getting into the room?
The gas pressure drop of 1.41" wc is almost triple the recommended sizing drop. Sounds like the gas piping might be undersized. Most appliances have a 13" wc limit. If it were me I would also bump the regulator up to 12.5"-13" wc.

sound like some valid points I did see in one of the instructions not to oversize the vent . If the tech guys have no answers at all I dont see how trying a pressure increase can hurt withen specs? and 1.5 or even 1.41 w/ c drop sounds like a lot.
I see Op has tried disconnecting vent with no help. only thing hasent been concidered is contaminated fuel, or dumping takagi for another brand

 

[Rrm8711]

sound like some valid points I did see in one of the instructions not to oversize the vent . If the tech guys have no answers at all I dont see how trying a pressure increase can hurt withen specs? and 1.5 or even 1.41 w/ c drop sounds like a lot.
I see Op has tried disconnecting vent with no help. only thing hasent been concidered is contaminated fuel, or dumping takagi for another brand

Thx for the reply.

Yes- If the tech guys can’t come up with something solid, what would it hurt(?) to increase the pressure as you suggested.

Yes- I separated the w/h from the exhaust vent per tech-support as they wanted to see if the unit would run without the exhaust system connected ( it didn’t & had the same problems) as they thought and/or think the exhaust system is suspect. I think that’s a bunch of nonsense. Pain in the patootie un-mounting and mounting the unit solo.

I think with Takagi, this specific model comes out of the factory for natural gas and an LPG conversion kit is provided.
I think that’s where the problem is: the conversion kit and then the PCB/computer having a hard time matching up with one another.


And yes, I would definitely consider a different maker and I will only consider an out of the factory LPG unit- NO CONVERSION MODELS.

If I knew then what I know now- what was I thinking! Lol

 

[Fitter30]

Your roof looks like if not close to a 12x12 pitch and your what 15+ ft from the peak? Did tak ask for pictures of the flue? I would want a pressure reading between air inlet and the flue. 991 code failed five times to ignite. Since the flue is disconnected take mirror and a good flash lite see if can see the flue cap? Two units doing the same failures there's a common problem.

 

[Rrm8711]

Thx for the reply.

Yep- 45° on the roof, 10’ from peak.

Tech-support inquired about the exhaust vent & possible blockage. I told ‘em it was clear as a bell.
Here’s a picture.

Not sure how to measure the pressure between the air inlet & the flue- how would you do that?
& for curiosities sake, what would one be looking for in that measurement between them?
And for more definitive info, that exhaust vent pipe/flue is actually 8’6” long from the bottom to the rain/flue cap; not the 10’ I guesstimated.
No flashlight needed.

The units don’t/didn’t have the same failures.
First Takagi 310 had trouble code 111= Ignition Failure. Technician did check the high limit switch and cleaned up the rods, checked the connections, etc., but to no avail.
The current Takagi 310 has trouble code 991=Imperfect Combustion.
Tech-support had me check the air fuel ratio and it came in fine, per the diagnostic mode:6

 

[Jeff H Young]

what ever happened to warrantys?

 

[Rrm8711]

what ever happened to warrantys?

Takagi tech-support has been real helpful and they did send me out a new unit.

Tech-support did explain to me their flue application requirements.
4” diameter is required to get the exhaust gases expelled properly. Any bigger diameter flue & the gases will kind of sit stagnant, not rise and expel properly.
So my ignorant self learned something new today.

My current flue is 6”, so I’m gonna get a piece of 4” stainless steel and feed it down through the current 6” and anchor it at the rain cap, this way I don’t have to demo the 6” exhaust system.

Hopefully this will get my water heater up and running.