LOCHINVAR PROBLEMS

Hvacman

Do you have picts? Were the install dimensions followed exactly? The only issues I've had with any condensing appliance were due to exhaust recirculation... prevailing winds, building overhangs/ corners, etc. all play a part.

Gerry May

Lochinvar problems

CAn anyone help? We have 3 multiple boiler installations using KBN500 Knight boilers. We've had issues at each of the installations. Our biggest problem has to do with frosting of the intake pipe to such an extent that the intake has plugged, causing "No FLame Running" lockout condition. The KBN500 does not allow for continuous retry and does a hard lockout which requires resetting. This happens consistently when the outdoor temperature drops below 20 - 25 deg.C. We have quite a few days of this temperature here in Winnipeg, so we're running and clearing the vents. Venting is sidewall type termination on 2 of the jobs.....Through the roof on the third. We have taken the bird screens out..which helps alot. We have built an insulated plywood box which encloses both intake and exhaust pipes on one of the jobs, so that the heat emminating from the exhaust pipe transfers to the intake pipe to kinda pre-warm the intake. Only the lip of the intake elbow is exposed to the outside air, rather than the whole elbow. This "modification" has worked perfectly in keeping the intake clear.

Has anyone had these problems in really cold temps? We have no problems with Weil Mclain Ultra boilers, which we also install. Has anyone experienced other problems with the Knights? Lochinvar says: it's venting issue and not the boiler ...too bad so sad.

Any Ideas?

Gerry May

I have pics, I'll post them today..Dimensions were followed EXACTLY as per spec on two of the jobs. The third one was slightly altered to accomodate 12" height requirement above the projected snow line. The basement ceiling is slightly above grade level. We had to turn and extend the pipes vertically on the exterior wall to get the clearance.

The pictures are of one of the installations. I'll post it right away

Gerry May

Pics of the venting.....2 boilers.First picture is blocked vent with birdscreen. remaining pictures are comparative between boiler#1 boiler#2 after we enclosed the set of exhaust/intake on one of the boilers

bobbyg_9

are you having this problem with "both" sidewall terminations? or just the one with the extension for the snowline? How about the roof termination?

Gary Hayden_2

Heat Trace

How about heat trace with insulation around outside until you come up with a better solution.

Ted_9

Recirc

If your using the exhaust to warm or pre-heat the combustion air, then you are definitely recircing combustion gases. Not good. This will cause problems with the boiler.

Gerry May

Both side wall installations are giving us problems with blockage. The one shown in the pics is the modified venting. The other sidewall installation is EXACTLY as per manual and is not as bad, however, we've had to remove the birdscreen altogether. (yes we've tried cutting the screen first to allow for larger air openings in the mesh). The roof termination gives us the same lockout (no flame running), but there is no evidence of blockage at the intake pipe. We've cut the elbow at the roof and looked down....clear. We've also replaced the ventor motor of boiler#1 (rooftop termination) to rule that out. The lockout for the rooftop termination job only happens to the same one of three boilers. It only happens when the outdoor air tenmperature drops lower than -25 deg C. We've tracked this lockout and compared to OAT and wind direction and speed. Wind direction does not affect the lockout condition, only temperature. The sidewall terminations are on the west side of the buildings. Come to think of it, we do have prevailing Northwesterly winds, so yes, that adds to the problems. But again, for all installations, outdoor air temperature is really the only thing that causes the lockouts.

Gerry May

Both side wall installations are giving us problems with blockage. The one shown in the pics is the modified venting. The other sidewall installation is EXACTLY as per manual and is not as bad, however, we've had to remove the birdscreen altogether. (yes we've tried cutting the screen first to allow for larger air openings in the mesh). The roof termination gives us the same lockout (no flame running), but there is no evidence of blockage at the intake pipe. We've cut the elbow at the roof and looked down....clear. We've also replaced the ventor motor of boiler#1 (rooftop termination) to rule that out. The lockout for the rooftop termination job only happens to the same one of three boilers. It only happens when the outdoor air tenmperature drops lower than -25 deg C. We've tracked this lockout and compared to OAT and wind direction and speed. Wind direction does not affect the lockout condition, only temperature. The sidewall terminations are on the west side of the buildings. Come to think of it, we do have prevailing Northwesterly winds, so yes, that adds to the problems. But again, for all installations, outdoor air temperature is really the only thing that causes the lockouts.

bobbyg_9

I agree with Gary (above).

On the lone rooftop intake, if you took a thermography picture, could you visualize maybe the other intakes are warmer via the location in anyway?

Gerry May

You are right, I think there must be some recirc goin on, but the installation calls for

Gerry May

Ted, I think you are correct that there is recircing goin on. This is, I think that the snow build up may be frozen, condensed flue gases? on the cold, exposed intake pipe. That's possible. But.....As per installation manual, we have to be between 12" and 15" vertical distance between the exhaust outlet and the edge of the down turned intake elbow.......which we are. The manual does not specify what distance we can be horizontally between the two pipes. It does show, however, that the intake and exhaust are horizontally next to each other. The only stipulation they show is the vertical separation. Regardlees of the horizontal separation, flue gasses would still be able to recirculate back to intake.
If this is true, ..... how can this be prevented? Any ideas?

bobbyg_9

I think it is because the density difference between the exhaust and intake air.

There isn't any horizontal difference required, but the vertical distance is to utilize the natural movement of different temp./density air. higher temp will rise, lower temp will drop.

Yes, in certain situations, you will have winds causing the exhaust to swirl or be pushed down, this is a problem sometimes (see post from BrianK above).

Gerry May

bobbyg........both sidewall installations are "frosting tp" The extended sidewall installation is alot worse. The roof termination is clear but we still get "no flame running" lockout

mark schofield

cold air locking out

When I use to work (retired now) one of the schools in our system had an Aerco KC gas boiler that would ramp up or down according to demand, set point and outside air. We had problems for about 4 years after installation with the unit locking out when the temperatures dropped. After many calls to Aerco (very supportive) monitoring the nat gas pressure, replacing regulators, ect. (all work done by factory certified tecks or the gas company), I finally cut a diversion into the 10" intake air pipe that came directly from the outside to the burner. Basically, the cold outside air would then come into the boiler room, mix with the warm boiler room air, and then continue back thru the intake pipe to the burner. The problem stopped. There was an issue with a proving switch which reacted too slowly when the intake air was too cold. The warming/tempering of the air solved the problem in this particular case. Something to think about. Good Luck. Mark S.

Phil_17

icing on intake

When my installer put a down-pointing el on the vent for a Knight 210, it locked out right away even tho there were about 3 ft between the two PVCs (sticking out of an old chimney). When he cut that out and did like the company said it worked fine.
It looks as though you installed the vent with a down el in the first picture and I think Lochinvar says thats a no-no. The moisture that produces the ice must come from somewhere nearby and the vent is the 'primary suspect'

Doug_7

Icing Air Intake

Gerry - I agree with Buzz - The flue is too close to the air intake and with the elbow on the end, moisture from the flue is swirling around and condensing in the air intake.

This does not have to be a continuous condition - all it takes is a certain wind condition every now and then, to swirl some flue gas toward the air intake - and you will get problems.

Our KBN-500 ran fine through a couple of weeks of -30 C to -38 C in January with no problems.

In our installation we separated the flues and air intakes by about 8 feet. The flues point straight up - venting about 6 feet above the roof - with no elbows on the end. We want to disperse the flue gas quickly.

Our air intakes are a couple of feet above the roof, above the snow line, and about 4 feet away horizontally.

I try to avoid installing to minimum recommended dimensions.

Suggest you get rid of the elbow on the end of the flue and extend it two or three feet straight up and you should be OK.

You could also consider a 4" x 3" reducer right on the end of the flue. This increases flue gas exit velocity, helps dispersion, and add very little pressure drop. You don't need to glue it.

Doug

Dave Stroman

rich pickering

Same problem over here in Moose Jaw. That 12"-16" inches is a minimum. 4 feet of seperation seems to work. No blockages this year.

tim smith

I would vote for heat tape for now

was there no way to use concentric vent termination, I would say that this would solve that problem also. Tim

The Boiler Dr.

Vent Frost

I've been involved with high efficiency vent issues for years in the 'peg. All of the suggestions above do work -- depending on "installation situations". The best solution I have found is separation. Sometimes it is hard to convince the "enforcing authority" to deviate from published instructions but if you do your home work and practice "due diligence" you will usually succeed. I think there is some specialized resting going on to directly address these issues in our climate as this year has been bad for the frosting condition.
Contact me directly if you so desire

Gerry May

Thank you very much for the input guys. The separation between the pipes makes the most sense in resolving the issue. We'll check with Lochinvar and local inspectors, butI really like this idea. Just coz it's so sensible. I can forsee the problem of convincing the authorities. However, if it works, it works. I'll kep you posted after we do the simple fix.

Thanks again all...Muchly appreciated !!!!

Fern

PEG FREEZING

The actual temperatures including windchill are more like minus 41degrees C basically minus 41 F also. And the spliting of the pipes will possibly prevent mixture into the intake but will not iliminate those temperatures that all the bare pipe is seeing from effecting the blower operation.

There is more pipe on the outside than reccomended on the elaxander pictures and faces North West winds.Added 2 more elbows on the intake equal to additional 14 feet of bare pipe facing the elements. Plus the peices of pipe. Is a matter of more pipe outside Vs the warm pipe inside the mechanical room, kind of like EDR effect?

Fern

There is now available the concentric kit for that KBN500 that was not available at the time of this project that Gerry has discussed here, and do think it will help.

FERN

rich pickering

Concentric will make it worse.

On low fire, there is not enough velocity to get the exhaust gases far enough away. Gets worse the colder it gets because the wind usually dies down. Even with a wind, you have to watch for swirling against the wall.

Go watch the exhaust for a couple of hours at -30.

Been there, done that, could care less about the t-shirt.

My first solution was extending the exhaust vent six feet. Worked great, no ice or freezing issues, even at -40. But the owner didn't like how it looked. 4 feet still works.

BTW, windchill is not a factor.

Tony_23

I agree

When venting directly into the wind or an eddy producing area, vertical seperation is key. Concentric will make it worse. Extend the vent up 3 ft and install a 45 on top. Leave the intake alone. Insulating it is a band-aid on a broken arm. The frost your pic shows is moisture adhering to a cold surface. It's produced by warm, moist air coming in contact with a surface below dew point temperature. That warmer moisture had to come from somewhere. The vent is the only culprit in most cases. The only "windchill" that's causing you problems is the one created by the burner fan.

I would bet the I/O manual states the distances are "minimum", not exact "do not deviate from" distances.

Fern

correcting the vent answer

Seems like everyone is on side here and agrees that the answer is to correct the venting and it will correct the lockout.

But as to the last couple threads on the topic the measurement is minimum 12" maximum 15" between the boiler's intake and exhaust these rae minimums and maximums and are exat so needs to be followed you agree?

As to the measurement between multiple boiler vent arrangements and yes that is only a minimum of 12" from boiler 1 exhaust to boiler 2 intake. It is all about trying to get the requirements met and have the proper operation both have to be obtained. Yest there is a better location for the vents but this is what we have to resolve and working at it!
Thanks,
FERN

Fern

correcting the vent answer

Hi again it seems like everyone is agreeing that correcting the venting is the answer to Gerry's illustrations.

But regarding the last couple of threads on the issue the measurements are 12" minimum and 15" maximum these are exact measurements and need to be followed. The other measurement between boiler 1 exhaust and boiler 2 intake is a minimum only 12" and yes you can spread that appart and may help, but not the invidual boiler's own intake exhaust.

I have attached the two illustrations that must be followed on side wall applications and was mentioning possibly the concentric for his roof project but we are only exploring so far, but we are working on it!

Thanks,
FERN

Tony_23

Well, FERN

Are you with the factory ?

Do you have experience with vent termination scenarios that tend to cross-contaminate ? Or are you just reading the manual ?

Sometimes, "field modifications" need to be made. My advice is based on field experience, correcting problems that were done "by the book", for free.

Fern

No Im not just reading the manual and have videos of all the projectS being mentioned here and this is all part of experience gained from being in the industry for 28plus years. But you have to apply the nmanual to meet the differnt requirements both for design and code puposes as you well know. This is a renovation and there are some restriction on all the reccomendations that are made.

Most of the discussions had here have already been discussed with Gerry and the distribution network and authorities having jurisdiction another body to satisfy!

Thanks,
FERN

jp_2

what happens when

you exceed the max distance between vent and inlet?

I can't see why 15 inches would be Ok but 2 ft would cause problems?????? other than keeping both pipes about the same lenght, and using same # of connections?

Fern

Tony you may be right but there is a process that has to be followed so the corrections are made with all paerties involeved agreeing and the manuals and or bulletins to match it, we just can't re-write manuals and codes to meet our immediate needs can we?

Anyway Sir you seem well educated on the topic and this is all free communication to help I guess!

FERN

rich pickering

I had 3 gas inspectors looking at it at the same time.
(our inspectors all have gas tickets and are usually former gasfitters with many years of experience.) They all agreed that extending the length was no problem.

If ANYONE can tell me why it is a problem, then I'll remove the boilers and install something else.

Doug_7

Extend flue pipe

Rich - Good input.

I agree, extending the flue pipe a few feet solves the problem of icing up the air intake, which is a serious cold-climate problem. We went through -35 to -38 C this winter with no problem (roof termination).

The reason in the factory manual for the 15 inch maximum flue pipe is "Excessive length exposed to the outside could cause freezing of condensate in the vent pipe." Freezing the flue has not posed a problem, but frosting the air intake is a seroius problem in cold climates.

PVC and CPVC are pretty poor heat conductors, so freezing the flue is not a problem. Warm flue gas, with condensed water draining back to the boiler, will keep the flue from freezing - unless you create some bizzare low-point for water to collect.

I am sure both the factory and code authorities will agree that extending the flue a few feet is the best way to solve the problem of frosting the air intake.

Doug

Tony_23

FERN

My reference to free was to callbacks of the same problem. Rectified by field modifications.
I can't believe that there's a code that states the vent HAS to be 15" max from the intake. As long as it's the required distance from windows, doors, gas regulators, etc. I don't see the problem you're having.
Does everything have to be in writing for you, or do you take some chances and responsibility upon yourself ?

And yes, I guess I am educated in solving problems

Gerry May

The frosting seen on the intake can only be caused by moisture condensing and freezing on the cold surface of the intake pipe. For moisture to condense from a vapour, the air must be at a higher temperature. This can only be from flue gases which contain the moisture. I cannot see any other source. This must be from reciculating flue gases. The heat trace or boxing and insulating does not prevent the recirculation. Next time it frosts up, I can take a sample and compare it to other samples of frost found on the exterior of the intake and on the bollards. The lab will tell me for sure if the stuff is condensate from the flue.
If that is the case, then we'll have to do the separation thing.

Stay Tuned

Thanks everyone.

Gerry May

Just double checked the KBN manual. The separation they talk about in the manual is vertical separation between the intake and the exhaust. It must be 12" min and 15" Max. The illustration shown in the manual shows the intake and exhaust side by side. There are no specified dimensions horizontally between the pipes. I think this is where we can get the separation to prevent the flue recirculation.

Joannie_15

Rime Ice

Look up rime ice on wikipedia or something. It might not be flue gases. If it's a very cold climate, maybe it's rime ice.

Doug_7

Vertical separation is better

Increasing horizontal separation is good, but more vertical separation is even better - winds blow the flue gas horizontally more that vertically.

Ask Lochinvar tech service if you can increase the vertical height of the flue by two or three feet because of the cold climate frosting problem. They are very helpful.

Doug

Gerry May

checked internet regarding rime ice. It's something like Hoar frost. I would rule it out because there is no evidence of the frost on other surfaces. The frosty substance we see is only at the location of the venting.....Thanks anyway

eluv8

increase the velocity

I would guess the boiler is running at 20%-40% most of the time. You can try putting a reducer on the exhaust side to increase velocity.