Does this pipe layout count as vertical or horizontal

dmaclaren said:

I am having a heck of a time figuring out which way I want to set up my system. The best location for ease of running the duct would require more than allowed for a horizontal run. The question I have is how is a 45 degree run calculated as?

The Harman PF100 states it can go 18' for a horizontal run and 30' for a vertical. Then, each 45 or 90 subtracts from the length allowed. But, how is a 45 degree run calculated as?

I have attached a picture

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Both.

Measure the horizontal displacement multiply that by 1 and measure the vertical displacement multiply that by .5 add the two together and call it close enough..

ETA: What is preventing you from going straight up?

dmaclaren said:

Everything above it is causing the issue.

So I am a little confused about that calc. the displacement is, horiz. for ex, the length that would be from o45 to the other and the vert is the same but in height.

So, that end number, that is what it would be for a Horiz. run? Then what would I do on the two 45's, count them as they would be normally?

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The two 45 degrees add 6 to your EVL calculation.

If you measure the horizontal displacement of that slanted pipe and add to it one half of the vertical displacement of that slanted pipe you'll be darn close to the EVL of the slanted portion of the pipe.

dmaclaren said:

So, it sounds like as long as I have a 45degree slant, it won't count as part of my total Horizontal run which is limited to 18'.

Or is this not correct?

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Not correct.

Normally venting limits are based upon EVL (Equivalent Vent Length) each component of the system has a fixed EVL assigned and nonstandard components are calculated based upon the sum of their vertical and horizontal displacements, with a unit(foot) of vertical displacement having half the EVL of the same unit (foot) of horizontal displacement.

They also have other requirements based upon what the blower is capable of.

Sometime tomorrow I'll download the manual for the PF100 and look at the venting information.

OK, I downloaded the install manual, did a bit of reading, and find Harman has a different EVL calculation method it is tuned to 4" pipe for the furnace and weather or not the bends are horizontal or vertical.

Their overall length limits already take into account one 90 degree bend or one T.

There is a total limit of 30 feet at sea level (this is the so called maximum vertical run it is also the maximum number of feet allowed in the run and is valid only at sea level), a horizontal run of 18 feet is the maximum length of horizontal pipe and also the maximum number of feet allowed, this is valid only at sea level)

So if you provide the exhaust parts and their length starting after the exhaust outlet on the furnace I'll do the calculation for you.

Since you say you are on the sea coast we will take those as or limits. I'll show my work.

Oh before I forget it, be certain to pay attention to the requirements on the convection blower, it must work against pressure, free air operation is a no no.

dmaclaren said:

Great, I will work up what I was thinking. One thing, does this mean that the 45 length, between the 45 elbows will count partially to the horiz length?

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In a single word yes.

If the pipe is at 45° then

EVL = L * (0.5* sin(45) + cos(45)) = 1.06 * L

Where L is the length of the 45° section

Close enough to just use the pipe length.

Aaron

No throwing bricks at the guy who still remembers Trig - unless they are BioBricks, of course

dmaclaren said:

so I believe the EVL is 30' and the max horiz is 18'

So, I still have the question of the EVL of EVL = L * (0.5* sin(45) + cos(45)) = 1.06 * L

is that added to the 30' or the 18 horizontal? This is my confusion

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Do not think of EVL in terms of the 18' and 30' figures.

Just let us have the lengths and fitting types and a calculation will be done showing each step and the end result.

From the manual:

Each Vertical ---- 90 deg. or T subtract 2.5 feet
Each Vertical ---- 45 deg. subtract 1.5 feet
Each Horizontal - 90 deg. or T subtract 5.0 feet
Each Horizontal - 45 deg. subtract 2.5 feet

My guess based on the manual those two 45 elbows are going to subtract 4 feet from that 18 foot horizontal run.

dmaclaren said:

I think we are going two different ways. I really only care if I am adding to the Horiz. specifically.

I can have a total run of no more than 30' and no mroe than 18' can be horiz is how I read it.

So, the loss on the vert. 45's is a non issue as I am under the 30'. I just need to know for terms of Vert and horiz is that the two 45's and the 45 degree pip run in between don't actually add to the overall Horiz length.


If the 45's and the 45 degree length are counted as a vert. run, then I am good as long as my horiz is under the 18'

So the simple question is does the two 45's and the angled length between count as a horizontal run at all, even a percentage.

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That angled length counts as both.

Look at it this way your venting can not exceed the equivalent of 30' of 4" pipe.

Each fraction of the run that is vertical counts as 1' per vertical foot of run and 1.66667' per 1' of horizontal run + the figures given in the chart on page 11 for the pre built elbows.

Once this figure exceeds 30' you are going to have problems.

The problems will be poor burning, excessive ash production, possible vacuum errors, possible combustion blower shut downs or burn outs, and the horizontal portions of the run (which by the way must have a slight rise to them) will fill with ash faster than the vertical portions.

I would never run a long horizontal run even if the combustion blower could handle it.

SmokeyTheBear said:

Look at it this way your venting can not exceed the equivalent of 30' of 4" pipe.

Each fraction of the run that is vertical counts as 1' per vertical foot of run and 1.66667' per 1' of horizontal run + the figures given in the chart on page 11 for the pre built elbows.

Once this figure exceeds 30' you are going to have problems.

The problems will be poor burning, excessive ash production, possible vacuum errors, possible combustion blower shut downs or burn outs, and the horizontal portions of the run (which by the way must have a slight rise to them) will fill with ash faster than the vertical portions.

I would never run a long horizontal run even if the combustion blower could handle it.

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I agree. :cheese:

This sure is a confusing one, Im just reading and trying to get a venting education. But personally looking at that diagram with the long horizontal run I wouldnt be comfortable with it. I'd have the stove close to that wall and go out and up to get an efficient draft and your stove would be a happy one. I agree with Smokey , too long of a horizontal run will cause a lot of problems. If you had 18 feet of horizontal pipe and the power goes out, be prepared to open all your windows.


That said this is an interesting thread to learn from. It will be interesting to see what the final outcome of the layout is.

Without seeing what dmaclaren has in his house it is confusing. When I installed my PF100 I had in mind what is the shortest run of venting I could make. Mainly because of cleaning and the stuff is prone to leaks not mention ridiculously expensive. The unit doesn't seem to mind the extra duct work length

dmaclaren said:

Interesting, I re read your post. 1.666.. I was going up 2' then 18' horiz. If that 18 is the equiv. of the 30 vertical then I have to change my plan and go
with a 45 out of the unit, some vert length, then another 45 into the horiz to shave that 2' length from having a EVL run of 18h + 2v or 32'.



Interesting

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Now Harman has a high altitude fan blade for that combustion blower, what that would do I don't know. Likely getting that information from Harman would be the equivalent to pull a tooth out of a rabid snarling dog. Maybe one of the techs that service Harman stove could provide you the answer.

Once again, I wouldn't want to deal with a long horizontal run, but that is me.

the high alt fan is just a double paddle fan blade, its actually standard on some units. I'm not sure what effect it would have. Likely create a bit of back pressure in the exhaust, possible tripping the vac sensor. I've seen some of these units with lots of pipe on them, but nothing with that much horizontal in one shot. I would stick with the 2 45's rather than the T. You should be able to clean the pipe in 1 shot from the outside by removing the combustion blower. If you're lucky then it will probably work ok, but you'll have to clean frequently, if you're unlucky then thats a very pricey venting experiment. Might be worth it to change the duct rather than risk the unit not liking the venting IMO.