Heating Help

Rinnai E110CP explosive ignition and low heat

Background:
I converted from forced hot water via oil to forced hot water via propane this past spring.  My installer put in a Rinnai E110CP burner which also functions as tankless hot water for domestic.
My house size is approx. 1800 s.f. single story.  I had an energy audit and they found ample insulation and adequate baseboard length and I have low E windows.  I am aware that gas fired versus oil fired is different and that oil is a quicker & hotter heat, but I have a couple issues I need answers for.

First issue I experienced and one that is most concerning to us, is that upon cold ignition, the burner basically explodes.  Very loud, shakes the house.  I've had Rinnai's N. American Boiler Service Manager at my house 4 times now and my installer's been there well over 10 times.  They've tweaked settings, ignitor gap etc... to no avail.  Finally, my installer (who's been fantastic) convinced Rinnai to replace my burner, which they did.  Unfortunately, the "new" burner had a broken plastic housing holding the computer circuit board so the re-used my old board.  Question is, Can this board be the problem as it's still "exploding" and as of late I've no success with Rinnai even answering my inquiries.  Their Service Manager even took an audio of the explosion to send to the factory but still no response.  We've tried 4 different propane supplies so we know it's not an over methanol issue.  I'm at wit's end here.  One fix which seemed to work was when the Rinnai S. Mgr added an additional metal deflector plate to the burner housing causing more turbulence of the air/gas mixture, making a better mix.  Unfortunately, Rinnai considered that an "unauthorized field adjustment" and he had to remove it.  I've been told that the Rinnai burner will expel any gas mixture if it doesn't ignite properly, but I've also been told that it's not supposed to explode like it is...  We're not real comfortable
Second issue I'm experiencing is that it takes approx 1 1/2 to 2 gallons of water flow via sink or shower/tub (no more than 20' from burner 1/2" insulated copper pipe) to get hot water.  Is this normal for a gas fired burner?  My old Burnham oil burner was easily twice as quick and twice as far away.
Last issue I'm experiencing is that even after setting the burner back to factory default, I don't get hot baseboards.  Example.  20 degrees outdoor temp.  At 4:30 AM my thermostat goes from 62 degrees F. to 70 degrees F.  My old oil burner would get the house to temp in approx 40 minutes.  With my Rinnai, at 6:30 AM, a full 2 hours later, it's still only up to 68 degrees F.  I do have an outdoor sensor which has already been replaced, but if it's 20 degrees outside, shouldn't this burner come full on and give full heat?
Any help and/or answers will be greatly appreciated.

Thanks

Re: Rinnai

Don, where are you located. I'd like to try and get you some assistance with this issue.

Explosive Ignition et-al.

Think about all the money you spent to save money and you get an exploding bomb in the house. Setting off a cherry bomb in a can  in your house must really get your attention.
Back in the old days, when consumers like us had some government enforced protection, a manufacturer would have had some concern about a defective product and done something about it. With as many "eyes" that have looked at this and not found a solution says that there is something wrong with this and has a factory defect that the company should resolve. All the Rannai equipment I have heard about and seen has been very reliable. If this unit acts as you describe, the company should replace it with a new one and see if the problem goes away. If it does, then the unit you have has some defect that is difficult to pinpoint. They should have their engineers take it back and figure it out. They shouldn't be expecting we installers and technicians to be doing their troubleshooting for them. And when we come up with an idea or cause, they give us an argument. These boilers and equipment have inherent problems. Which you have described in yours. You never had those problems with your oil boiler and tankless. Too bad the salesperson/installer didn't suggest a conversion power burner in your old boiler.
There is only one cause of cherry bombs going off in a boiler. Delayed ignition. Either from the gas valve opening too soon or the igniter not working properly. Or the air fuel ratio not proper due to improper mixing.
Good luck.

Outdoor Stat

Bypass the outdoor stat that will solve your heating issue.As for the 1 1/2 to two gallon of water usage before heating up is really not bad, cheaper then a recirc loop.
Has anyone done any combustion analysis to find the reason for the delayed ignition?
We have installed several of the rinnai E110 on natural gas with no issue as of yet.But heck its a machine and they all will have some issue down the road or right out of the gate Thank goodness or I would starve..lol
Happy holidays everyone..

Thanks

First, many thanks for your responses and help.
To answer a few questions.
Yes, I've had every combustion test, air mixture test and pressure test known to man done to this unit.  As mentioned I've had the Senior North American Rinnai Service Manager out 4 times along with my very competent installer / techs who worked with the Rinnai tech service multiple times.
Rinnai has replaced my original burner, but, as mentioned, because they sent a "display model", there was a broken clip holding the computer board so they re-used my old computer board.  After all of the testing that has been done and all of the adjustments made, I'm of the opinion that my original computer circuit board is the culprit, possibly causing delayed spark/ignition.  One thing I did find out was that Rinnai uses a carbon impregnated string ignition "wire" which when replaced with a Honeywell aftermarket wire did improve the ignition somewhat.
What I found interesting was that Rinnai would not allow the "field adjustment" that fixed my issue (the deflector plate) and that they've not responded to the audio file that was sent to them.
I believe, after the holidays, I will ask for a new computer board and will post my results.
I do have one further question regarding the baseboard water heat.  If, I was to deactivate my outdoor sensor and continue using my programmable thermostats as I did with my oil burner, will the efficiency of the gas fired burner drop dramatically?
Lastly, a conversion burner was not applicable in my case as my old oil burner was on it's last legs.

Many thanks again & Happy Holidays!

Banging Heads:

Carbon based ignition wires in cars were supposed to stop electrical interference in radios. If you had a performance car, it was the first thing you replaced and went to solid wire core cables. In the days of the Muscle cars, who was listening to the radios when you were banging gears with someone else beside you, trying to go faster than you?
All the ignition wires I see are solid wire core cables. But

Hope the board does it

But if not, I wonder if you have a venting problem.

I had a customers furnace once (15 years ago) that had similar trouble. We followed all installation guidelines to a tee. In this case the application was borderline, between 2 and 3 inch flue and combustion air piping and we figured we'd be safe with 3 inch. The manufacture was of no help. (this was before combustion analyzers were common)

We eventually figured out the amount of air coming into the burners was too much, or moving too fast, and preventing normal ignition. What we ended up doing was adding restriction to the intake air, and the problem went away.

I'm not saying the problem is the same, just pointing out there is more to combustion then the unit itself. A lot of service personal have a tendency to focus on the equipment, and more or less have blinders on and not notice what the unit is connected to.

Draft:

Interesting observation of yours, FF. We sootsuckers are well versed in high draft issues. Especially if you live and work in an area where the wind can blow the rectal orifice out of a dairy cow. And that wind will blow from any direction at any time of the year.
Sealed combustion in oil seems to have been a disaster. I often wonder about why gas sealed combustion doesn't in fact, have the same problems. Oil shuts off on safety. Gas will recycle. As long as it keeps running, you never know it had a problem.

You might try this

I worked with Rinnai as their rep for many years. I no longer do so, but over the past few years since the intro of the boiler, I solved ignition issues, delayed and no fire, by changing the gas supply. Turn off the gas cock and tie in a 20 lb cylinder of known good gas at the drip leg for the test. Certainly, I cannot say it is the gas, but with a new tank set, the change has worked. At this point, after all you have gone thru, it is worth a try.

Gas change

We've actually tried 3 different tanks of gas so far.   Initially we had a 100 gallon temporary tank, then we had my 500 gallon permanent tank and during one of the tech calls with the Rinnai rep, we used a 20 gallon drop tank.  All had different gas fills so that we could eliminate over methanoled gas.  Since May I've had 2 refills, each at about 100 gallons so I'm pretty sure we can eliminate the gas or tank as the issue.

Thanks for your input.

sensor

Hi Don.let me say we are still in the learning process with this type of equipment.
let me first explain my reasoning for jumping out the outdoor sensor.My understanding is that it will monitor the outdoor temps and will increase the btus after a certain amount of time.Example..start in low fries and will ramp up the btus after lets say 30 mintues.Now when i spoke to my rep about setting the curve on outdoor reset he was kind of vague about it and i got the feeling that he was not sure himself.So i still in search of on this issue.I was told to bypass the stat bc I really did not need it being i was in a warmer climate and its more for people of north.LOL.I was like heck people up north have no need for it bc they will be running at design temps most of the winter anyways.
Ok enough of that.I have install one on a lowmass emitters with copper baseboard with outdoor stat connected and its would not bring up the temps quicker enough.So i bypass the stat and all is well.
The second one i have high mass rads with outdoor stat connected and it does a wonderful job maintaining temps and comfort.
Bear in mind that my results just show that every house is different and their is so many variables that changes things.that why we have to always look pass the nose on one face.
I think you would be far better at this time to install the programable stat and bypass the outdoor sensor.And no your effiecency should increase being you have it held out for awhile.and you are coming out of setback.now as far as fuel comsuption that another story best left up to the pros in your area.
Hope this helps. 

Setback

Your setback is too much with outdoor reset I have found 8 degrees to be too much. Your boiler runs at a lower water to save you money which is why it is taking too long to catch back up. I use the set it and forget it with outdoor reset let the boiler do what it is supposed to do. If you still want to setback your thermostat try 4 degrees and experiment with it but 8 degrees will take a while to come back up.

Update

Update.  Feb, 2nd.
Replaced the computer board shortly after the first of the year.  No change.  Still explosive on cold fire.
After threat of legal action, Rinnai finally sent a factory fresh new boiler versus the display model last time.  It was installed yesterday.  This morning..."BOOM"  same thing.
3 burners, 4 different fuel supplies, this has to be an issue with air intake.
Interestingly enough,  this brand new factory unit wouldn't ignite at all at first and my techs had to tweak the air/fuel mix ratio to get it to ignite.
I would have to give Rinnai a failing grade for both manufacture and customer service.
As far as low heat, we're learning to live with colder than oil heat and much, much slower hot domestic water.

I presume....

The flue pipe is the concentric Ubink pipe? How long? How many sections? It is possible there is a rolled o-ring causing cross contamination? Very odd. all those changes and still an issue... Where in the house is the boiler located? What side of the house? Do you get a lot of wind?
I agree on the set back... if the boiler has outdoor reset set back  tstats are a poor match.

It would be a shame

To blame a company for your issue when you could still have a install or distribution issue..
If it was a venting problem then it could easily be detected by watching your co action during the run cycle.If it were a fuel issue then o2 numbers and stack temps would be off.
It only does it on a cold start but does not after it warms up? Would you care to share any test numbers with us?

Numbers

I would love to share numbers, but I don't know them, being a homeowner and not a tech.
What I can tell you is that two of my techs used two different analyzers to test and tweak and in their eyes the numbers were correct.  I do know that the factory settings for this burner were so far off that it wouldn't even ignite until they changed them.
The Rinnai Senior Service Manager also said numbers were correct the 4 times he was out here.  They also did a atmospheric (?) test and gas pressure test and both were ok.
As far as fuel, as I stated earlier, we've had 4 different fuels including a drop tank so those issues have been eliminated.
The unit is located on the north side of my basement.  Mounted on the wall with an intake/exhaust pipe that goes up approx 8" into an elbow and the out through the wall so I'm not pulling or pushing air/exhaust for more than a couple feet .
This being the second night of the brand new burner, it was decidedly quieter on startup than it was the first night.  I am going to monitor it for a few days before claiming victory or defeat (again).  Many thanks for all your input and suggestions.

now we are getting....

somewhere.
 The north side of a house is prob the worst side to locate a boiler boiler w/ a direct/ concentric vent. The wind blowing can give you all kinds of issues.Delayed ignition just one.