Boiler that is approved to vent down and out

Danny_Jr

Quoting a replacement of a Weil Mclain HE4 The unit is vented in B-Vent downward and across through the floor joist to the outside. It was not approved for that type of installation, but it, and a second one identical, have been in place for 25 years. Venting any other way is going to be ugly. Trying to find a boiler that is UL listed for that venting configuration.

Thanks,

Dan Wood

SuperTech

I can't imagine any boiler being approved to be vented in such a fashion. Seems dangerous.

pecmsg

NG or LP 90+ is all I can think of

Danny_Jr

pecmsg A condensing unit would be fine. But everything I looked at goes up and out. And yes Super Tech I agree. But it's hard to tell them it's dangerous when they have had two of them for over 25 years. I will not repeat the same mistake.

STEVEusaPA

None that I know of...but I don't know much .
Just because it 'works' doesn't mean much in the event of a problem-CO, fire, etc.
You're on the hook, and probably without your insurance company backing you.

pecmsg

Danny_Jr said:

pecmsg A condensing unit would be fine. But everything I looked at goes up and out. And yes Super Tech I agree. But it's hard to tell them it's dangerous when they have had two of them for over 25 years. I will not repeat the same mistake.

You can go Down then horizontal just not back up again.

Print out this on CO alarms and give them a copy.

Ironman

Code is code; physics are physics; manufacture's instructions are to be followed.
Just because it was done wrong is no justification or president for continuing to do it wrong. If a man robbed a bank 25 years ago and wasn't caught, would that give him a license to do it again?
I'm sorry that I don't have anything better to offer, and IDK of any manufacturer that would approve of such an installation, but please don't let a customer back you into that corner of repeating the error.
"You gotta know when to hold 'em and when to fold 'em and when to walk away."

EBEBRATT-Ed

@Danny_Jr
@Ironman is right

Why not call the mfg of a condensing boiler and ask?

I don't see why a condensing boiler could nnot be installed this way as long as the flue is drained on the lower level...with a trap and a condensate pump

mikeg2015

Condensing boiler should be fine this way. So long as the pipe size and equivalent length are respected. I had to vent kit down to a tee then Jonas I didn’t have enlightened rise to Vent out a sidewalk since broiler was blunted too high.

Icarus

^Huh? A bit of auto correct?

Danny_Jr

Your Input is appreciated. Unless the customer is willing to do something that is going to be ascetically ugly, ( in order to install it in approved manor) I will probably walk away from this job. I would call Lochinvar etc. but I know what they are going to tell me. "If it isn't in the manual, they can't put their blessing on it"

PerryHolzman

Many years ago (est 10-13 years ago) I had a long phone discussion with the USA Viessmann Engineering Manager. We were mainly talking about materials of construction and other challenges that boilers face... and I recall him mentioning that they had done some work with people in the USA with unusual venting considerations. My vague memory was venting down and out was mentioned as possible if done right.

So, you might wish to call Viessmann and contact the US Engineering Manager - and ask them about the possibilities. They might have a workable answer (even if its not in their manual).

Something to consider though. The condensate from a condensing boiler is usually slightly acidic. If its running downhill to outside there needs to be a way to capture it and neutralize it. In a normal Vitodens installation it runs back to the boiler.

Of course, you would also have to come up to speed on the Vitodens boiler.

I hope that helps,

Perry

rick in Alaska

Seems to me that if the low point of the vent had a way to drain the condensate, that it would not matter if it went down. But, as they say, it is up to the manufacturer to approve it.
Rick

Alan Welch

Any possibility of locating the boiler in another better location, and connecting the existing supply and return at the present location?

Tom_133

What about a boiler that starts with a really low flue and air connection, like an HTP phoenix or GV90+? Could you start low and pitch up to not make it look too bad?

Ironman

The problem with attempting this is that all boilers that operate with a negative pressure gas valve only have a slightly positive pressure flue vent. The flue relies upon the upward pitch of the pipe to properly vent. They shouldn't be confused with "power vented" appliances even though both are cat4.

Henry

HTP has an approved method of venting under obstacles. One has to put a drain tee at the low point.

Ironman

> @Henry said:
> HTP has an approved method of venting under obstacles. One has to put a drain tee at the low point.

Can you post the document?

Henry

I will find it and post it

Henry

Here it is from the factory

Ironman

I remember seeing this drawing many years ago. I'm not sure if it would apply to what is being proposed in this post. Clearing a beam is one thing, going down several feet below the boiler may be another.

It would be worth a call to HTP to see what their engineering department says. If they approve it, I'd getting in writing with an actual drawing that has the dimensions of how it's allowed.

There was an OP on here several years ago that had constant problems with a Buderus GB142/60 that he had installed himself and it kept locking out on ignition of flame failure. The post went on for a long time getting bits and pieces of info at a time from the OP. It was finally revealed that he had piped the flue downward for about 10' like what's being proposed here. Buderus engineering said absolutely not to that arrangement and that was what was causing the lockouts.

As I recall, when the OP was told this, he was gonna pull out the over-sized GB142, sell it on the Internet, and put in a TT instead because their I/O manual didn't specifically forbid such a venting scheme.

Danny_Jr

Ironman, thanks for the additional input. I think we might contact HTP. I used to handle TT. But they dropped my favorite distributor and I have moved on to Lochinvar. I might check with TT as well. But you called it right, it would go down just below the floor and terminate straight out the sidewall about 10' from the boiler. I had not considered the affects on the negative pressure gas valve. I could see a trapped condensate tee just below the floor might work. Possibly insulating the vent to reduce condensing. (it would be in an unconditioned crawl space in northern MI)

GroundUp

I made a call to HTP about 9 months ago for this very reason, as HTP was my go-to at that point, and they were very adamant there could be NO drop in elevation between the boiler and termination, under any circumstances, or warranty would be void. This was a UFT-80W so maybe it differs with other units but that's what they told me. I needed to get under a beam very similar to the drawing, not drop to a crawlspace like the OP. Good thing the UFT has top piping connections is all I can say about the solution to that issue