Oil furnace lift / realistic heights?...

swihart_art

SHORT VERSION: How high can a 1 stage pump lift in 3/8 and 1/2 lines with1 or 2 line runs?... 2 stage pump?

A LOT of conflicting info out there... read on for full overview...

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Hello All,
Just joined... found your site after searching for info on a lift question on an addition we are building...

Here is my scenario, appreciate any advice / guidance I can get please...

Existing 1 story house sits just above grade and has an oil furnace in the small "attic" from 1970's... reliable old dog up there and we love her.. 2 pipe installation with 3/8" lines, tank sits outside about 15' over / through wall and then 12' down to 275g tank...

We built an addition just beside (on the non tank side) on 10' stilts ...due to the creek flooding we experience and connected the 2 with a staircase.

I plan to install a 125,000 btu oil furnace in the "attic" of the addition which is pretty much the 3rd floor with full ceilings in a utility room... I plan to T off of the existing furnace line in the "old" attic and continue that line out of the wall and up into the addition to feed the second burner in the addition in the attic...

Here's my question, the second new furnace would be about 22' above the tank... lotsa searching (manuals etc) tells me that 18' is the max that a suntec 2 stage can lift the #2 oil in a 1/2" / 2 line system... but I am finding conflicting information on this and some claim that 22' lift is no problem... even for single line systems... is this true?...

I want this to be as safe as possible and of course a no-headache operation install... no compression fittings... I plan to flare them...

Again, I appreciate any advice I can get on how to accomplish this...

pecmsg

My Question is how did you come up with 125K?

That’s huge!

swihart_art

2400 sq ft addition in northwest pa... it is huge!!...

swihart_art

there are tons of windows / 2 sets of french doors so that also factors in...

EdTheHeaterMan

fuel pump answers are right here https://s3.amazonaws.com/s3.supplyhouse.com/product_files/B2TA-Bro.pdf

EdTheHeaterMan

OK, so I had a builder call me with your same situation. No research was done, the oil furnace was installed in the attic and the tank was buried. So the burner would not operate for any length of time without problems. After the fact, I was called to resolve the problem because, no one else could!

I recommended a lift pump installation, The builder did not want to pay for it and the homeowner did not want to pay for it. So I tried something unconventional. The tiger loop Fuel Deaerator uses one line from the tank to the burner. The lower flow rate thru the fuel line allows for lower friction loss thru the tubing. This effectively reduces the vacuum required to lift the oil to the attic. At the burner, a fuel deaerator will convert the piping from single line to a self-air-purging 2 pipe design.

Bottom line, for less than 1/3 the cost of a lift pump system the burner is operating. I got paid, The builder is happy and the homeowner is happy. After 3 years the system was still working. That was 12 years ago. have not heard from them in 9 years, but I'm sure I would have if there was a problem. OR. they had a problem in year 4 thru now and a lift pump was finally installed by others.

swihart_art

Thanks for posting... I've seen those tables before and it says 18' max but I've read on here and other sites that people have installed higher than that... I'm just trying to get more opinions on why the manual states a max... but sometimes real world experience proves the manual wrong...

I'm hoping someone on here can elaborate if they've installed higher with success and maybe why the manual is wrong or is it just so they can cover their butts and list a conservative max...

swihart_art

That's the type of info I'm hunting Ed!!... I wanted to use a tiger loop after researching to keep air out anyway but kept running into the height problem everywhere Iooked for info...

Very useful info on the vacuum friction loss... I am still researching if I need check valves etc and where the go inline... also plan to install the fire valve just inside the wall where it comes in...

Was it a single or 2 stage pump if you can remember... I really do appreciate your time...

Jamie Hall

You see the same sort of thing in all sorts of applications. The manual will give the engineer or in this case the installer a figure for something which everyone can be reasonably sure will work reliably. It always has a safety margin built into it. What this means is that sometimes, but not always, you can push the envelope beyond what the manual says and get away with it. How far beyond? Unknown. Will it work with your specific application and arrangement? Also unknown. Doing it this way -- with a conservative manual figure -- is, in a sense, "covering your butt". On the other hand, you do have to realise that if you are confidently told "oh we don't have to worry about that, we do 25 feet all the time" and it doesn't work in your specific application, you are not going to be a happy camper and your lawyer will be a very happy camper. The contractor or engineer will be out sometimes major money, not to mention reputation. You will find that the appetite for risk in terms of pushing beyond the manual or manufacturer's specifications varies widely.

STEVEusaPA

You can try to use a 2 stage pump. But a booster pump, small day tank is an easy, solid solution.
You can't defy the law of physics, and too much vacuum just creates problems, and excessive wear on the fuel pump.

swihart_art

Point well taken Jamie although I stay away from lawyers when I can....lol... not that all are bad but I'm just not that way, I prefer to do my homework and make an educated decision and then move forward... if there are issues, guess I'll have to figure it out... I've read about the booster pumps as a backup plan and also tanks in the attic but something about storing fuel up there, even 5 gallons seems sketchy to me...

swihart_art

Thanks Steve... can you recommend a booster pump if needed?... good day tank?... I'm searching for photos of a setup like this... I'm concerned about a fuel tank up there...

I read an article a few hours ago about how too much vacuum (above 12 i think) starts to "rip apart" the oil into hydrogen / sulfur etc and causes air problems too... like you said, hard on pumps and loses prime...

KC_Jones

125k for 2400 sq ft

Did you forget the insulation?

Do the heat loss calculations I think you will be surprised.

swihart_art

Hello KC... this part has been driving me nuts!!... the info out there on this is equally confusing as lift heights... depending on where you go the results are very different... many sources say that for Zone 4 you need 45-50 BTU per sq ft... that is where I get my figure... I welcome any info to help me figure this out to get it right...

Here is more info... 2x6 walls with R 19
Attic ceiling is R 38
Foam around windows / doors / outlets but not completely air tight.

I consider it average insulation compared to other builds with all foam or r 60 in the attic...

I do understand that you have to factor in the efficiency as well and most oil furnaces now are 80% or so...

I've also found sources saying that the pros use Manual J so I'm looking into that now... I designed the house and have the drawings so I know every detail as far as window sizes and values of the windows / doors etc as far as their efficiency...

swihart_art

Is this a good source to get some furnace sizing info?...

https://www.loadcalc.net/structure.php

Jamie Hall

@swihart_art -- there is a very easy to use on-line calculator for heat loss from Slant/Fin: https://www.slantfin.com/slantfin-heat-loss-calculator/
It's available from them both on-line and as a downloadable app -- if you are more 21st century than I am. Easy to use, although sometimes one has to do a little thought about exactly what to enter (cathedral ceilings are a bit confusing!). Works well, and is quite reliable.

Use it. You will find that your 45 to 50 BTUh per square foot figure is very pessimistic! Or conservative, depending on your point of view. With your insulation, I'd be a little surprised if you didn't come up with about half that.

On figuring efficiency. Almost all boilers and furnaces publish both a BTUh input figure and a net BTUh output figure. The latter takes into account the known efficiency of the boiler or furnace, so it saves you some figuring. Might as well let the manufacturer crunch the numbers...

swihart_art

OK... thanks to all who have followed this and have commented / helped out...

I went to
https://loadcalc.net/structure.php

Punched in my numbers and this is what it spit back out...



Roughly 70,000 BTU heating is required if this is accurate... (nowhere near 45 - 50 BTU's per sq ft) 37,000 cooling...

So it appears as though 125,000 btu furnace is too much at 80% eff and would result in uncomfortable space and a short cycling unit which is no good either... A 95,000 BTU furnace should be enough to heat this space at 80% which would give me 76,000 BTU...

HVAC is my weakest link in my home design / building knowledge so I am learning as much as I can to apply that knowledge to my house project and it is the next step in the process...

Folks on here were absolutely correct and I'm glad I came here to ask people who know instead of wading through the web and all of its inconsistencies... go to the ones who know and work to find the info I need is my attitude...

My next step is to go to the link that Jamie posted to cross reference this result...

I hope that others may have learned something from this thread if they are in the same situation... I'll post updates on how I handle the lift situation as it develops... I plan to try the tigerloop single line method posted by Ed to see what happens... our existing furnace is a single stage pump (old at that) and never had a problem in 25 years lifting oil 12 feet into the attic so I'm hoping a 2 stage pump on the new unit will bring it up the additional 12 feet with the tigerloop installed...

EBEBRATT-Ed

What @STEVEusaPA said. You can't defy the laws of physics. Weather you use single pipe, two pipe or a tiger loop when you get north of 12" of vacuum the oil will foam and cause issues.

1' of lift is 1" of vacuum, 2' of horizontal is 1" of vacuum. Filters and valve add resistance.