High Wind causing Limit Switch to Trip now glacier after installing elbow pvc help!

[mettao]

Hi Everyone,

I live in Northern Minnesota and 282 feet off of Lake Mille Lacs (big lake) on 3 sides SO, the wind can get real bad
from the North and Northwest primarily but can come from the South and East (kinda rare but does happen.) I don't have much for wind breaks and would take years for trees to grow tall enough to help.

I live in a Manufactured triple wide home where the exhaust vent is "roof terminated," and can not be moved without great destruction. The vent limit switch tripped once and was replaced but service guy suspected wind and I agree as it was 50mph and gusts to 80mph at times.

SO...he recommended that I install a pvc elbow and point it to the east...I did and it helped however winter came and now I'm knocking down little pointy glaciers from the dripping condensation coming out of the vent. Can't tell you how dangerous it is to be out in -14 weather let alone finding a good spot to plant your extension ladder so it's stable

The vent resembles a candy cane top so the dripping is straight down to the shingles and builds it's way back up to the opening of the pipe...I haven't let it go so I do not know if it would in fact grow up far enough to actually block the vent but I didn't want to take the risk and lose my very necessary heat.

I gotta come up with something that will block the wind, YET allow the condensation go back down the vent and allow the pump to shoot it down the drain. I'm thinking of cutting a pipe in half lengthwise and somehow securing it so that it will shield only the wind from the N, NW and yet leave the pipe open and able to vent.

I'm looking for any advise you have, I've looked at "high wind vent caps," but I'm concerned that they will freeze up and clog on me? I'll await your responses and greatly appreciate your expertise and time, thanks.

[martyinlincoln]

Your guy should be able to talk to tech support. Using an unapproved termination isn't something I would do.

[pacnw]

since this unit is vented in pvc/abs, you CANNOT use a metal cap on it as it will rust among other reasons!!

can you post a photo of what it looks like?

I have not heard of a vertical pipe having winds affect it, but horizontals most definitely.

[beenthere]

Sounds like a single pipe system. Whee is the combustion air coming from.

[BadgerBoiler MN]

Some units must have both terminations on the same load plain (wall or roof). If it is the roof, then the exhaust straight up and the intake "candy-cane". This arrangement keeps the PS happy as no differential pressure is possible unless blower induced...happy pressure sw.

If you only have one pipe, get two if the the manufacturer allow it of course.

[mettao]

Some units must have both terminations on the same load plain (wall or roof). If it is the roof, then the exhaust straight up and the intake "candy-cane". This arrangement keeps the PS happy as no differential pressure is possible unless blower induced...happy pressure sw.

If you only have one pipe, get two if the the manufacturer allow it of course.

Thanks for the reply. I do have two terminations on the roof and the intake already had a pvc elbow "candy cane," config on it (but since it's the intake it doesn't give me any problems with condensation.)

The icing/glacier problem only began after putting the same pvc elbow configuration on the exhaust pipe for the high wind issue. So, while it fixed one issue (vent switch tripping) it has caused another with dripping condensation freezing and building up on the roof.

I keep plugging away for a solution & did an internet search, found what's called a "Concentric Vent Kit," now I'm wondering if this might be a solution? This is where expertise comes in handy Thx again.

[pacnw]

The concentric will change nothing from the original configuration other than combining it onto one.
You should NOT have both in the candy cane shape, it will cause more issues than it fixes!!

[OldSchoolMech]

Can you call my boss and tell him how dangerous it is to work in -14 on an extension ladder?

[mettao]

since this unit is vented in pvc/abs, you CANNOT use a metal cap on it as it will rust among other reasons!!

can you post a photo of what it looks like?

I have not heard of a vertical pipe having winds affect it, but horizontals most definitely.

I posted a picture of both the intake and exhaust pvc pipes and you can see the condensation blowing out of the exhaust toward the easterly direction if you look closely (it's 12 above so we're having a heat wave.) You can also see a small glacier that's beginning to develop on the shingles, I already knocked the taller one down 3 days ago.

Like I said it gets so tall that I'm afraid it will actually go high enough to close off the opening of the exhaust (just didn't want to let it go that far..might not actually happen or cause a problem.) Everything works with this configuration, no problems except the glacier.

I could just run heat tape up there and plug it in every winter so no glacier but I'm hoping for another solution, such as just a pvc pipe cut in half and attached to the top of the existing pvc thus blocking the wind but allowing fumes to escape and condensation to run back down pipe to the drain? Hope the pic comes across and is helpful, thx.

[martyinlincoln]

So why is the vent pointing down if the guy said point it east?Just so you know...many mfr's make high wind kits. That's why I wrote your guy should be able to talk with tech support.

[beenthere]

So when the vent limit switched tripped. It was the first time you were having wind gust?

[pacnw]

I am curious just what limit tripped after seeing the photo.

I am leery of the height on the intake. Per mfr instructions, it should be above snow level and in your area as described I wonder if that is tall enough.

It also appears to have frost on it. Is there a screen of some sort on it, because that is not recommended either and can cause issues.

Is the ice you are referring to at the coupler or from the end of the last elbow? It looks like there is some at the coupler which to me indicates that it is just slipped on there and not glued. This allows the exhaust to flow out there as well as the end.

If this were my house, I would assure the intake was screen free and well above snow level. I would not use anything other than a 45° elbow on the end of the exhaust.

Depending on the actual snow level, a concentric may be out of the question by design.

[tiger man]

I posted a picture of both the intake and exhaust pvc pipes and you can see the condensation blowing out of the exhaust toward the easterly direction if you look closely (it's 12 above so we're having a heat wave.) You can also see a small glacier that's beginning to develop on the shingles, I already knocked the taller one down 3 days ago.

Like I said it gets so tall that I'm afraid it will actually go high enough to close off the opening of the exhaust (just didn't want to let it go that far..might not actually happen or cause a problem.) Everything works with this configuration, no problems except the glacier.

I could just run heat tape up there and plug it in every winter so no glacier but I'm hoping for another solution, such as just a pvc pipe cut in half and attached to the top of the existing pvc thus blocking the wind but allowing fumes to escape and condensation to run back down pipe to the drain? Hope the pic comes across and is helpful, thx.

I would cut that elbow off asap on the exhaust, and get a bushing that is 2 inch, to 1 1/2 inch then a foot long piece of 1 1/2 pvc. The tech who was there should have done something like this, or find the reason the vent limit is tripping. Have him perform a combustion test as well

[comfortdoc]

What is the brand and model number of the furnace, and what is the total length of vent pipe?

[mettao]

What is the brand and model number of the furnace, and what is the total length of vent pipe?

The brand is: Intertherm/Nordyne
Model is: M3RL-080-A-BW +90

I can't tell you the exact total length of the vent pipe but it's gotta be 10 foot or more..I've enclosed a picture showing the pipes from a distance. Again, the intake pipe had a (what I'm calling a 90 degree) pvc elbow on it when I moved in...BUT the exhaust had nothing..it was just straight up in the air (no slope that I could tell) and when the vent switch tripped, everything, including compression tests etc were performed and the conclusion from the two techs was that it was either a faulty switch or off the top of his head it was a high wind (which there was gusts to 80 mph prior to tripping.)

I'm the one who put a 45 degree elbow but just before snowfall I thought I should make it a 90 degree (just like the intake and point it easterly)...didn't think about the fact that the water would drip down at the time but in my defense I don't work with this stuff nor was I familiar with the winds up here.

There is a couple areas where icing is occurring where it can seep out but that really doesn't seem to be problematic..I could seal that better but still the whole design is not right. I could put it back to just a 45 degree config BUT I think that will still allow for dripping and growing ice? I could put a high wind vent on but I think I would need to block off one side of it due to N & NW winds and I know that metal will rust and stain the roof..that's all I know at this point. I wish I could describe the config I think would work which would just be extending the straight pipe up say 10 inches but doing it with only pvc that's cut in half and attached to it...would block the wind but allow condensation to fall back down pipe. Hope this helps and really appreciate all the advise I'm getting on this forum, you guys are great.

[mettao]

I would cut that elbow off asap on the exhaust, and get a bushing that is 2 inch, to 1 1/2 inch then a foot long piece of 1 1/2 pvc. The tech who was there should have done something like this, or find the reason the vent limit is tripping. Have him perform a combustion test as well

I agree that the elbow will have to go but I'm left wondering if I do what you suggest above how this will help keep the wind from cutting off the exhaust from the 1 1/2 inch pipe, I realize going to smaller diameter would help if it was freezing inside the pipe but that is not an issue it's the negative pressure (if I'm saying that right) overtaking the positive outgoing exhaust. The height of the existing pipes is ok and with the way the wind blows at times the snow doesn't build up or stay on the roof it blows off and if it didn't I would have to get out the roof rake, but so far no issue with any blockage from snowfall, just wind. Thanks.

[beenthere]

Have you had 80 MPH gust since you put those ells on? If not, the you don't know if its helping.

Wind gust should open the pressure switch. So I doubt you had a tripped vent limit switch from wind gust.

Did you power go out anytime close to when you were having those wind gust.

[mettao]

Have you had 80 MPH gust since you put those ells on? If not, the you don't know if its helping.

Wind gust should open the pressure switch. So I doubt you had a tripped vent limit switch from wind gust.

Did you power go out anytime close to when you were having those wind gust.

Yes we have had several strong winds and the vent limit switch did not trip, so I believe the elbow fixed the problem...I may have made the elbow curve too much thinking a little more would be better and hence creating the glacier growing on the shingles but need an idea for a better design for next winter (and hope it doesn't create another problem like this idea.)

As for any power outage, I do understand that it could cause the vent limit switch to trip (I was asked that by the tech at the time) but none had occurred around that time.

I missed answering this on a previous response, but there is no screening material in either the intake or exhaust, just fyi.

Appreciate your response and working with me on this.

[comfortdoc]

Find an installer that is very familiar with that furnace. Be certain the vent size is correct for the length, and the position of the pipes is correct. Then have them look for the manufacturers recommendation on insulating exposed pipe for your outdoor conditions. If the manufacturer does not have guidance, check with your local building inspectors.

[Chuck]

The vent limit trip is a very common problem on that model and has nothing to do with the termination or the wind.

Your technician is fixated on the venting and overlooking the real problem.