Weil McLain Ultra 155 Series 3 Boiler Questions

Bluchip

So…
As the subject line implies, I am a homeowner with the stated boiler. I have numerous questions on the operation of said item. Are there knowledgeable folks here with intimate knowledge on the set up and operation of this type unit?
I feel I have the skills needed to perform these tasks but there are specifics that I’d like to know that simply aren’t in the manuals I have access to.
For starters:
Does the controller maintain settings after power outage/shut down?
If they are lost, I have no log of what they were and therefore, cannot restore them.

Is there a reference that can be consulted to help guide one creating optimal settings?

There are many, many more questions I have but we can go from here f anyone is willing to hop in. I cannot ask the contractor who installed this for me in 2013. They cycled out of business some 3 years ago and I don’t believe them to be quite competent anyway. An indicator of their , uh, nonsense is I specifically asked them when it was first fired up what was needed as to maintenance. The 2 boobs shrugged and said “nothing, it just runs”. I maintain and inspect airplanes…nothing just runs!
That was the beginning of a pretty interesting story regarding this boiler. We can elaborate on that story as or if a discussion develops.
Thanks in advance to any forthcoming help!

Bluchip

And our saga continues. 

After discovering the original manuals crammed in the floor joists, I found an unopened bag containing an LP conversation kit. It seems the installer never made the LP conversation. 

I disassembled the gas valve to check for the LP orifice and none there. Never done. So our boiler has been running for ten years set for natural gas while being fed propane. 

So I elected to perform an annual maintenance. The cleaning tool “sword” won’t fit in the upper section of heat exchanger pins. Some are actually melted. I do my best and wash out the heat exchanger and close it up. 

I cannot see the logic in continuing to leave the gas valve set up for NG when I’m on LP. So I installed the orifice  and now boiler won’t light. I switch it back and remove the LP orifice  and it runs. Reinstall the LP orifice and again no light. 

Is it possible that the heat exchanger is so plugged, distorted, and otherwise restricted/damaged that the airflow is restricted sufficiently to the point that the Venturi cannot draw gas. 

Thoughts?

neilc

there may have been different orifice for different elevations,
don't screw with it, get someone there to check it,
tell them you found that bag

pedmec

you have to adjust the gas valve after installing the orifice. you need a professional to come by and perform a combustion test

Bluchip

I am below 5000 elevation and the orifice is not marked HA (high altitude). 

I have tried for 3 weeks now to have the installers ( or their successor) come assess and repair. No response. Clearly this unit has operated out of parameters for 10 years. There is a hole (sealed over with tape ) on the vertical run of flue supposedly where a combustion analyzer probe was inserted and a reading taken. If true, how could readings be correct if boiler set up for NG and being run on LP? I fear my professionals cannot be trusted. 

The boiler is an Ultra 155 series 3 and the orifice is clearly marked 155 LP. I am at 1000 ft above sea level. So no high altitude required. 

I sure wish the local folks could instill some degree of confidence or at least care. I’ll just have to keep making calls and winter is closing in. 

pedmec

you changed the orifice so you changed the gas volume. you need to adjust the gas valve. Natural gas and LP run at different pressures.

Bluchip

pedmec said:

you have to adjust the gas valve after installing the orifice. you need a professional to come by and perform a combustion test

Thank you for the response. I mean not to detract from your comment but I read the entirety of the “LP conversion instructions” sheet  included with the orifice and it makes no mention of any adjustments required. I believe the Honeywell negative pressure valve needs no adjustment between NG  and LP if I understand the manual correctly.  Perhaps there can be adjustments made to the throttle setting. 

However, Weil McLain states that the #1 reason for a boiler fail to ignite is a blockage in exhaust. Thus my query about the heat exchanger being damaged. 

Oh well. We will call another outfit tomorrow and see what comes out of it. 

109A_5

Hello @Bluchip,

I suspect the installers set it up wrong.

Bluchip said:

There is a hole (sealed over with tape ) on the vertical run of flue supposedly where a combustion analyzer probe was inserted and a reading taken. If true, how could readings be correct if boiler set up for NG and being run on LP? I fear my professionals cannot be trusted.

So since it was apparently set up with the wrong orifice and the combustion analysis may not have been done where the manufacture advised. It seems logical it may not work correctly with the correct orifice installed without being set up correctly.



https://www.weil-mclain.com/sites/default/files/field-file/ultra-series-3-ct-manual_1.pdf

May help with your U-Control questions (see the appendix too)
https://www.weil-mclain.com/sites/default/files/field-file/ultra-series-3-CT-quick-reference-guide_1.pdf

There may be other U-Control documents out there or on www.weil-mclain.com.

hot_rod

Lp pressure needs to be checked both running and at rest. It could be a lp regulator isssue

Bluchip

109A_5 said:

Hello @Bluchip,

I suspect the installers set it up wrong.


So since it was apparently set up with the wrong orifice and the combustion analysis may not have been done where the manufacture advised. It seems logical it may not work correctly with the correct orifice installed without being set up correctly.



https://www.weil-mclain.com/sites/default/files/field-file/ultra-series-3-ct-manual_1.pdf

May help with your U-Control questions (see the appendix too)
https://www.weil-mclain.com/sites/default/files/field-file/ultra-series-3-CT-quick-reference-guide_1.pdf

There may be other U-Control documents out there or on www.weil-mclain.com.

I have no doubt of that!
I may have mentioned it earlier, this unit was install and 10 years ago while the house was undergoing a major renovation. Not one person from the HVAC firm ever bothered to discuss the set up or maintenance of the heating system. An indicator to pending issues came at year one. The boiler locked out and screen red calling for annual maintenance. I called them up and when the two fellows came to look at it, they simply reset the reminder, it fired and they left. I cashed after them and asked “ what does the annual maintenance involve?” They shrugged and stated oh not much. They just run.
The excerpt on LP conversion @109A_5 posted is exactly what I read and understood. We have to realize this is a Honeywell negative pressure gas valve. There is no flow until the gas valve electrically opens and there is a negative pressure in the Venturi throat at which point gas is drawn in (not pushed in) and sent to the burner. Or at least that’s what I glean from the manuals and the very many excellent videos Weil McLain has on YouTube. Including this one on the combustion settings and probing as @105A_9 mentioned:

https://youtu.be/Lq_9o0Lp1tE?si=8dmMU2DxxTl8QO85

I do grasp the need to verify gas pressure. I do have a diaphragm gage in inches water column (not the greatest measuring tool in the World but should be reasonably close). I checked line pressure at the drip end of line in the boiler housing prior to entering the gas valve: 10.2”WC. Maybe a tad low but not by much. I gather we are looking for 11. And the fact that the Rinnai tankless heater installed 4’ away is performing fine, I would have to guess we are close enough to have a light off.
Now I will have to plead ignorance on checking the outlet pressure at the gas valve. I’ve read the instructions, force control into high fire, open needle 1/2 turn, insert 9mm hose over the spigot, take reading. But, if there is no flow, will we see a reading? Especially since I cannot get a light off.

This line of thinking goes back to the damaged (heat distortion and contaminants) heat exchanger pins that I witnessed while removing the front plate of the heat exchanger. According to Weil McLain in their video here:

https://youtu.be/NadM96L75oA?si=M6o5XdP3_jC8dnEf

The single greatest reason for ignition fault is exhaust blockage. The unit runs without the LP orifice, so I feel reasonably confident there is no fouling downstream of boiler. I had the front plate off and cleaned the condensate trap hose so it isn’t full of water. Couldn’t the same type of “blockage” situation occur if the heat exchanger is so restricted that the airflow is too slow to draw gas into the Venturi especially with the LP orifice installed (reducing the passage some 85%)? I don’t know. Could it still light without the orifice due to the high line pressure and large passage provided by orifice removal?

We are still contacting service people. The previous outfit called back after 4 days and basically said bug off. The excuse being the guy who knew that line of equipment is no longer there. C’mon. The principals are the same and I’d hazard a guess many boiler manufacturers use this Honeywell valve. Oh well. Thanks folks and onward thru the fog!

HVACNUT

Agree with others who said it needs a combustion test. The gas valve is self regulating but must be properly set up. Now that it's got the smaller diameter LP orifice, the boiler must be fired with a load, then using a combustion analyzer, adjustments are made in high fire to get within the range of the chart, which in the case of the 155 is 10% CO2, <60 ppm CO. Once that is locked in, the boiler gets put into low fire (these steps are taken in the diagnostic section of Installer Setup) and make sure those readings are within specs. This is not DIY. You need someone who is experienced in mod cons, has a combustion analyzer, and knows how to use it.

No hole is to be drilled in the exhaust for the test probe. The Flue gas temperature sensor gets removed and the combustion test is taken in that location. 

Bluchip

HVACNUT said:

Agree with others who said it needs a combustion test.  

Agreed and fully intend to have such service performed… that is when I am able to locate such a rare individual (at least in my locale!). A combustion analyzer of decent quality is not a play toy nor inexpensive. I would wonder if the people I have scheduled for Monday the 30th, have had their instruments calibrated at some point. I have an aircraft maintenance background as well as experience with metrology. Calibration of measuring devices is a rule.
As to location of probe insertion, the W-M video I linked above states that quite clearly. Yet the installers ignored that detail.

HVACNUT said:

Now that it's got the smaller diameter LP orifice, the boiler must be fired with a load, then using a combustion analyzer, adjustments are made in high fire to get within the range of the chart… 

Therein lies my personal curiosity: It won’t fire. How do we get it to fire to test to adjust according to combustion analysis? Chicken and egg.
Reminds me of a garbage Dodge V10 truck I had. It was OBD I which meant you cannot run diagnostics until it is running…but it wouldn’t start. Brilliant.

HVACNUT said:

The gas valve is self regulating but must be properly set up.  

Not to pick nits but there are no further adjustments to be made to the gas valve. Adding the orifice is the only “set up” the gas valve receives (or at least spoken of in any service publications) Any remaining adjustments to get the combustion within specified parameters is limited to mixture via throttle screw. True?

So this brings me full circle. Has the heat exchanger been compromised to the point that it will not flow the needed volume of air during pre-purge to draw fuel and thus provide ignition? An anemometer reading at the mouth of the silencer might help but I see no information on such a diagnostic test.
The unit has been operating without an LP orifice for 10 years. From a thumbnail eyeballing, that is roughly 85% more fuel than designed AND the fuel is LP which has a greater energy content than NG. Surely, the heat exchanger has seen greater than design temperatures. I feel this is true as the face plate gasket was burned thru at top with a full 1” missing. The ground wire for the igniter burned black and terminal insulation crumbled off. The igniter was drooped some 1/2”. The top 4-7 rows of pins in the heat exchanger exhibited melted ends. The W-M cleaning sword cannot fit thru the upper sections of pins due to distortion of pins supposedly because of overheating and sagging after softening. All indications of overheating in my eye. If the cleaning tool cannot be inserted thru the pins as directed in maintenance instructions, is gas flow now restricted thru the heat exchanger to the point that (with the LP orifice installed) fuel cannot be drawn thru the Venturi?
We will see. I have someone coming Monday. I briefed the scheduler that they need to be acquainted with and have intimate knowledge of, a negative pressure gas valve set up and condensing heat exchanger boiler and that we need a combustion analysis performed.
Thank you all again to those that responded!

109A_5

Hello @Bluchip,
If I understand correctly it still presently works without the orifice. So logically it will work if there is enough air flow to support combustion (air to fuel ratio).
I suspect since it was set up incorrectly, now with the LP orifice in place it may be way too lean or way too little throttle for a proper light off.

Maybe (if needed) you can fabricate a temporary intermediate orifice to get things going back in the right direction. But I think you really should not need to.

and/or if the heat exchanger is still excessively plugged up that the negative pressure gas valve set up is not capable of supplying enough fuel for light off with the LP orifice in place. If you can, and if you believe the heat exchanger is plugged up you may want to invent another way of cleaning it.

pedmec

Weil Mclein is stating that the greatest ignition failure with a failed boiler is a block vent is after the boiler combustion is properly set up, not after you changed from a natural gas orifice to a LP orifice, which should have been done at commissioning of the boiler. you need to pay attention to detail. THIS FAILURE IS AFTER ITS BEEN RUNNING. For example, you wake up to 2' of snow on the ground and the vent is covered. Could be birds nesting in the flue because no bird screens were installed.

if your boiler was properly set up, combustion analysis was performed and calibrated, and running then i might look at the blocked vent as a possible cause, but that is done right after installation and part of the commissioning. It's a part of the installation that is necessary. this is why you need to calibrate the air/fuel mixture. you can never get natural gas to meet the same parameters as LP.

hot_rod

You have a tankless on the same LP fuel line? Check the sizing on the piping. If the tankless is firing, and the boiler is attempting to light, measure the LP pressure at that moment. It doesn’t take much of a pressure drop and they will lock out.

HVACNUT

@Bluchip, by "setup" I meant throttle screw adjustments. 
There are tricks to ensure ignition that any decent tech knows, then once it's running, CO2 can be dialed in.

Bluchip

109A_5 said:

Hello @Bluchip,
If I understand correctly it still presently works without the orifice. So logically it will work if there is enough air flow to support combustion (air to fuel ratio).
I suspect since it was set up incorrectly, now with the LP orifice in place it may be way too lean or way too little throttle for a proper light off.

I agree. See further response below.

pedmec said:

Weil Mclein is stating that the greatest ignition failure with a failed boiler is a block vent is after the boiler combustion is properly set up, not after you changed from a natural gas orifice to a LP orifice, which should have been done at commissioning of the boiler. you need to pay attention to detail. THIS FAILURE IS AFTER ITS BEEN RUNNING. For example, you wake up to 2' of snow on the ground and the vent is covered. Could be birds nesting in the flue because no bird screens were installed.

Ah. This is a completely lucid observation. One that must be considered. I’ll shift my think in that direction!

HVACNUT said:

@Bluchip, by "setup" I meant throttle screw adjustments. 
There are tricks to ensure ignition that any decent tech knows, then once it's running, CO2 can be dialed in.

@HVACNUT I figured that was your intention. There’s little else to twiddle with in that unit!

@109A_5 stated, it is likely too lean and has been suggested there is likely a lack of fuel. I am not going to attempt anything to repair this unit until the service person shows up Monday (10/30). However, one could attempt to “choke” the unit like an old carbureted auto engine by partially blocking the silencer intake as W-M shows here:

https://youtube.com/clip/UgkxaqjqcTGxUqTGYkVRwLzybuXSWQtzZNOt?si=Hu8JvzZ6rNSiJ3hi

This would allow a rich mix temporarily for ignition without losing throttle screw setting (though the current throttle screw position is irrelevant now as in the future it will be running with an LP orifice…I hope!).
Thanks again folks. We’ll see if we have heat come next week!

109A_5

Hello @Bluchip,

Bluchip said:

@109A_5 stated, it is likely too lean and has been suggested there is likely a lack of fuel. I am not going to attempt anything to repair this unit until the service person shows up Monday (10/30). However, one could attempt to “choke” the unit like an old carbureted auto engine by partially blocking the silencer intake as W-M shows here:

https://youtube.com/clip/UgkxaqjqcTGxUqTGYkVRwLzybuXSWQtzZNOt?si=Hu8JvzZ6rNSiJ3hi

This would allow a rich mix temporarily for ignition without losing throttle screw setting (though the current throttle screw position is irrelevant now as in the future it will be running with an LP orifice…I hope!).

I wonder how affective that is since I think in this case the venturi needs the air flow (draft and pressure differential) to get the fuel moving. Its not like a piston engine where the vacuum (air flow) is created after the carburation. Maybe it does not matter.

Bluchip

@109A_5
That is one of my thoughts. It is not a positive displacement “pump”. Its centrifugal thus permits “slippage” when blocked. The facts you state are what we see with a lowly shop vac. While it is sucking away, what happens when the intake blocked? We hear the motor wind up. That’s due to no airflow hence no motor load. Likewise if the filter plugs (exhaust side blockage). We usually don’t notice the motor sounds when exhaust blocked since it occurs at a gradual rate. But if you haves used a wet/dry shop vac and the float plugs the exhaust when receiver is full, yes the motors unloads and rpm’s soar. 

If we block airflow on either end of the boiler ducting, velocity drops thus pressure at the Venturi rises potentially causing diminished fuel draw. 

 Reminds me of another little irritation I read about during this ordeal, The boiler “decorative “ cover hasn’t been on the boiler for 2-3 times they visited for various reasons over the past 5 years. They simply walked away. Yet, when the cover is in place CO2 and CO rise .2%   A minor amount but it’s my paid for heated air being burned up. Nobody bothered to advise me otherwise. Oh well. I wonder if the coming service person even is aware of the affect that the cover has on combustion readings. 

That said, could it circle back to my perhaps misguided obsession with diminished flow thru the heat exchanger?
I know, it runs without the 85% smaller area LP orifice. But as this was such a poor installation to begin with, is it possible it still runs without the orifice simply because it is getting such a huge area orifice to draw thru ( of a size good for NG @ 3”WC )?
Perhaps fueling ( now there’s a pun) my twisted theory on a compromised heat exchanger is, I’ve no clue how much adjustment/effect is built into the design of the throttle screw. I get the impression it is a pretty fine adjustment. Meant to move the CO2 one percent up/down. That may be enough, I don’t know. 

We will see. I hope the person coming Monday can instill the confidence with the intelligence that you folks have!
If anyone is interested in our outcome we will post it!

109A_5

Hello @Bluchip,
Yes, would like to know how it all works out. And it may benefit others too.
To me since they set it up without the LP conversion, the throttle is seriously justified at the minimum fuel end of its range. The orifice LP and no orifice NG keeps the throttle in the sweet zone for best dynamic range for burner control.

Bluchip

For anyone paying any attention to this thread, we have a resolution.
As most responders suggested, when LP orifice installed, there simply was too little LP reaching the burner to ignite. The gas valve and source LP pressure and volume is satisfactory and sufficient. If would appear that the original bafoonish installers that failed to install the LP orifice 10 years ago, attempted to adjust the burn via the throttle screw using a flue combustion analyzer so 3’ downstream of flue temp sensor (the Weil McLain recommended sampling port). The throttle screw required 2.5 turns to get the mixture rich enough to light off. The CO2 at that initial firing read 9.0. It needed another 1/2 turn richening to bring the CO2 to 9.8. Recommended is 10 on high fire…I told him to stop there as the manual states adding the cover will make CO2 rise .2%. The service person was unaware of that so we pointed out the chart in the PAPER manual (the pdf version online doesn’t mention this). He didn’t seem interested in taking a low fire reading. We would like to further tune the configuration but we will do that at a later point.
As it runs now, the boiler is quieter and seems happy. If ever (more likely when) the heat exchanger is replaced, I would be adamant on having another analysis taken after installation as I feel current set up may not be optimal for a freer breathing exchanger. Another perhaps crazy thought but can’t hurt.
I had read the manual’s verbal description of what the burner “flame” and surface itself should look like while in high fire mode and never understood it. Prior to the LP orifice installation, the burner would glow orange but the flame was always licking and orange. I gather LP to Air ratio “flammability limits “ is 2.2-9.6 parts LP to air with 4 to 96 (1:24) being ideal for complete burn. Either side leads to incomplete burning. Over 4 to 96 ratio the flame moves from blue to yellow and orange while flames are physically larger in appearance. Based on that I think it is safe to say without the orifice and at the settings it had, the burn was way too rich. I cannot see how they ever got near the CO2 readings that were specified. They likely twisted the throttle screw way in and gave up as it probably was running out of effective adjustment. I suppose it was “close enough” for them and headed off.
With the current configuration, the burner is nice and glowing orange with scattered bright specks here and there and there is a blue “aura” type flame. I believe that is the correct ,or very near to it, appearance. So I would have to say we are all good to go for now.
I am curious now as to what our fuel savings might be. As previously mentioned, this boiler was installed (along with some extra zones added) during a fairly extensive whole house renovation. As part of the renovation, I sought to increase efficiency and minimize heat losses. The original 1938 windows tossed for triple glazed units, insulation in attics, sealing etc. The previous boiler was 1966 Burnham oil fired and fuel costs were $2000/yr. I installed a 1000 gallon propane tank and was ready to spend way less on heating costs. After ten years, it was the same if not more. We will see what yearly but is now.
I have plenty other questions regarding operation settings. As an instance, what would be ideal system temperature? Default is 180F. Would 160 making shorter runs be better or worse? The service person said he liked it at 160. Beats me.
Anyway, thanks folks for the guidance and thoughts! Carry on.

HVACNUT

Both High and Low fire must be checked in Manual Test Mode from the Contractor Menu. Low fire adjustment if needed is not done with the Throttle screw. There's a separate low fire adjustment. 
When was the last time the inhibitor was tested? You're aluminum block won't last long with incorrect pH.