Veissmann vs Furnace

Weezbo

S Ebels

Heating system overhaul/redesign

Not a fair comparison technology wise but this gives a good illustration of what you can do with a couple good boilers and as little expertise as even I possess.

We replaced a forced air system in a 1950's construction building that is 13,800 sq ft last year. The building was heated by a forced air system with underground ducts (tunnels) delivering heat to all the rooms. We cut out the old furnace (5,800# of scrap) and replaced it with the following equipment. 2 Viessmann VB2-63 boilers (300,000 input) were chosen for their abiity to work with any water temp. This was important because we were installing Vasco and Radson radiators with TRV's in each room and I didn't want the additional expense, maintenance and installation cost of VSI or mix valves. The township board wanted something that would last another 30+ years but didn't have the budget for a Vertomat. The need for a large air handler in the gymnasium dictated the need for the ability to hit 200* at outdoor design temps. That being the case, most of the small condensing type boilers were eliminated.

We set up the system into 3 zones for the rads and 1 zone for the air handler. Each rad in the classrooms and meeting rooms has a TRV as opposed to the old system which had one thermostat for the entire building. In addition to the TRV's we added a programmable thermostat for each zone which kills the corresponding circ during nighttime and weekend setback periods. The rads on the third zone (the gym) provide about 60% of the heat required so we let them run constant, just working with the outdoor reset. The 4th zone is the 7 1/2T AHU for the gym which is basically a second stage and is controlled by it's own programmable stat. We also installed a Takagi TK1S instant on water heater which is perfect for a building that see's only 6-8 hours of use per day. (No sense keeping 80 gallons of water hot without needing it)

I now have a years worth of data for utility bills to compare how we came out. I told the customer that I would be happy with a 20% reduction but I'm pleasantly surprised at how well it works. I figured there would be not only a reduction in CCF of natural gas but also a little decrease in KW. This is because the old furnace used a 5HP blower (24 amps @ 220V) to deliver the heat to the rooms and we are circulating the whole building with a total of 10 amps including the AHU.

Here are the numbers

Old system June through May, 11,993 CCF gas @ $.82 = $9,834.26. New system for the same time period, 6,419 CCF @$.82 = $5263.58

Electrical, (this is for the entire building) Old system 20,072KW @ .08 = $1,605.76. New system 15,522KW @ .08 =$1,241.76 The electrical and gas savings are even greater than shown because of increased lighting and heating loads in the recent year time period due to higher occupancy.

These numbers for the old system are for 2002-2003 which is the last heating season it ran 100% of the time. During 2003-2004 I manually lit the old girl once or twice a day from November on til spring.

When you total that up, I think it comes out to around a 43% reduction in utility costs. This is a good thing, but the building occupants are thrilled to the core with the comfort level now as opposed to the old system. They told me the building has never heated as evenly and felt as good as it did last winter. The old system was either scorching them or letting them freeze.

I have to round up the degree day data for the two years to compare apples to apples but I doubt if there is more than a 5% variation.

I'm pretty tickled with the way the whole thing works and they are smiling because they are saving just shy of $5,000/year in utilty bills. That percentage is going to add up quickly when you factor in a 3-5% per year increase in gas and electric costs. I'll post some pics tomorrow.

PS: Just to illustrate how little demand there is for the full capacity of any heating system, stage 1 has 1243 hours on the burner and stage 2 ran for only 102 hours.

Mark Hunt_2

Kudos Steve!


Even a "little" expertise can make a HUGE difference.

Looking forward to the pics!

Mark H

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jerry scharf_3

you do yourself an injustice

When you say "as little expertise as even I possess." Your humility is nice but it is not right. You have a clear understanding of heating as a system, and it shows in everything from design to equipment to analyzing the results. great work!

I'm fascinated by one piece of data. Your number that 60% of design day load supplied the room about 92% of the time. This says that the computed load is significantly greater than the actual load (maybe by 25%.) I'll start another thread to take this further.

jerry

Constantin

Great Improvement!

I remember reading about the beginnings of this project... Congratulations to you and your staff not only for creating a comfortable solution for the local district but for creating one that saves them a lot of money as well. The 40% reduction in consumption jibes with Mike T's experience when he went from an atmospheric 80% boiler to the Vitodens + TRV's.

So, given that you know the installed cost, the annual savings, etc. what is the payback on the investment even if the fuel prices don't change?

Nick Dearing

Great savings

Very nice job. I bet they are thrilled. Remember it's KWH not KW. Big difference. LOL :-)

S Ebels

VB2-63's and AHU

Community center Vitola's and American Standard AHU

The duct coming off the top of the AHU is the supply which still utilizes the old cement chase to the gym. Our radiator piping also runs through that chase. We sawed a 20"x42" hole into the cement floor under the AHU which sits directly on top of the existing return for the gym.

S Ebels

Lee Brooks' headers

Headers courtesy of Lee Brooks. They came through exactly as ordered and work great! Thanks Lee!

The headers are 2" pipe with 1 1/4" tapping spaced as ordered.

S Ebels

Near boiler piping

Near boiler piping. Main supply and return are 2" copper with the zone piping running from 1" to 1 1/2". I don't know if we would have attempted this job without doing it in Propress. Any other method of joining the piping in the tunnels would have been nearly impossible.

At the bottom left, you can see the AHU supply duct elbowing into the old chase/duct. Mark was all the way back in the end of the chase running pipe, about 150', and two 90* turns while Drew and Matt were torching the old furnace. They had a "slight" mishap with a big chunk (about 500#) of the HX on the old furnace which fell on a well tank and snapped off the pipe.(But Dad, it was an accident!) Water was shooting to the ceiling, flooding the floor which was covered with extension cords AND the cord to the light set which Mark had with him in the back of the tunnel. The boys yanked all the cords out to keep from becoming an unwilling current path themselves. If you ever see Mark, ask him how dark it is at the back of a 150' long, 28"tallx36"wide tunnel when the lights go out, then start feeling water running around your hands and knees. We all had a good laugh over that.

S Ebels

Vasco classroom radiator

This rad is about 13' long and cranks out 32,000 btu's at design. I've seen the little kids that attend HeadStart program there all lined up in a row sitting on the rad after coming in from playing in the snow.

Takes 3 guys to carry it and we had to slide it in through the window because it was to long to turn the corner from the hallway into the classroom. They are the M1 Abrams tank of radiators. HEAVY!

You can see the registers for the old forced air system along each end of the rad. The chase (duct) runs directly under the rad.

S Ebels

Radson radiators

Gym rads are Radson 33-600x1500 and do just shy of 18,000 btu's at design temps. I wanted to keep the gym fairly warm all the time with that much concrete and brick in it. If you let a room like this drop way down during setback, you can bring the air temp up but it still feels cold due to all the cold mass around you. I sized these to provide about 60% of the heating load in the gym as they ride along on the reset curve. The AHU is the "second stage" that runs on its own t-stat.

S Ebels

Boiler room piping

I gotta say my hat is off to my guys Andy and Mark. They hung just shy of 2,900 ft of 1 1/2" copper in the "tunnels" under the building. All of it had to be cut into 6 and 7 foot lengths to make it around the corners in the cement duct. I bought three $80 sets of knee pads from Duluth Trading for the job and they saved our knees and shins bigtime. We had a 36" fan blowing into whichever tunnel we were working in to keep the dust blown out ahead of us and help with cooling. The opening on the far right was the supply for the East wing of the building and the left one was the return. It was so narrow in the last 50' of the return that Andy had to lay on his side with his belly touching one side and his back touching the other in order to get the tube to the last of the classrooms. All three zones are reverse returned in the tunnels. No other balancing was needed. Zone 1 to the 4 classroom is just shy of 1000' of 1 1/2" doing about 13 gpm with a 26-64 on it. Zone 2 has 13 rads on it in smaller rooms plus the main hallway with a 15-58FC doing 10 gpm roughly. Zone 3 is the gym with a 15-58FC on speed 2, approx 8GPM. The AHU needs a 26-99 to overcome the head in the coil and deliver the required 22GPM.

I'm sure that someone will say something about insulating the pipes. They will be left uninsulated because if we wrapped them it would freeze the water lines in the mechanical room. We would have to add a radiator in there to prevent that so I elected to just leave them bare. The Vitola's lose practically zero heat. Besides, I think if we heated the mechanical room it would upset something else we have going on there.

I had a hunch that leaving the pipes bare in the chases would provide the building with another benefit. It turns out that it works beautifully too. There is no provision, nor had there ever been any, for ventilation air. By leaving the pipe uninsulated, the heat lost in the chase creates a natural convective airflow throughout the old duct system. There's a 5 sq ft louvered opening in the mechanical room intended for combustion air. This cold fresh air spilling into the mech room gets drawn into the chases by the heated air exiting out the other end, into the rooms. All the registers are still functional in each room and a smoke test showed that it only takes about 10 minutes for the air from the mechanical room to reach the far end of the building. This provides a nice natuarlly tempered air flow to all areas of the old building.

S Ebels

Jerry

I'm not following what you're saying with the 60/92 thing. Maybe I need to restate to make clear what I'm trying to say. The rads in the gym, riding on the selected reset curve, will provide about 60% of the required heat at any outdoor temp. What this means in real life operation is that they will maintain the gym at about 58-60* whether it's -10* or 40* outside, running constantly. If you look closely at the gym rad picture you'll see there are no TRV's on the rads. Don't need them because they would never shut off to begin with.

What the rads do is provide a little constant heat in the gym to keep the block and cement halfway warmed up. The AHU is needed to achieve 70* indoor even if its 45* outside.

Any clearer?

DanHolohan

This is the sort of thing

that cries out to be in On the Job. Others (especially homeowners) would read it and in this way we could make a difference.

I wish you would consider submitting it, Steve. Thanks.

S Ebels

Total installed cost

Was just over $105,000. If fuel prices stayed the same, the investment would come back in 21 years. If you factor the interest you could earn on 100K if you banked it, the payback would be much longer.

The event that precipitated the whole job was the complete failure of the HX in the old furnace. (All through the winter of 2003-2004, I went and manually lit the burner every day in order to be able to monitor the CO level in the building. I didn't let the furnace start and run automatically) When we cut it up we found 7 different spots that had been welded up. There were 4 cracks that were not welded and two of the ones that were, had cracked again. Some of these cracks were 3 feet long and wide enough to stick your hand in. Some had obviously been there for years. (The school system that owned the building previously was really up on their maintenance and cared about the kids, don't you think?)

When you factor in an annual increase of 5% the payback drops to 15 years. Consider also that repair costs will be negligible during that time period when compared to practically any other type of system we could have installed and you can probably chop another 2-3 years off that.

Going with a cheaper boiler/control setup would have dropped the total price of the job less than 10%, maybe 15% at the most. Why not have the best?

Another F/A system with a single thermostat for the whole building was ludicrous IMHO.

S Ebels

How do I do that Dan

Do I have to repost the whole thing over there? Or could it be copied and moved?

signed

your semi-computer illiterate friend

Steve

DanHolohan

Just cut and paste

to email what you'd like to have appear, Steve. This nice thing about On the Job is that it doesn't fall off after several, as do Wall posts. By using this feature of the site, you'll be affecting more people as the years go by.

Thanks.

S Ebels

Cross your fingers

I'll try it tonight.

hr

Right down to the gas piping

this job screams top quality!

hot rod

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S Ebels

Gas piping

The old meter was inside the mechanical room and I thought while we were at it, let's move it outside. So I called the utility compnay and made arrangements to move it. They updated the whole service, regulator and all and were great to work with. We had a problem with gas pressure fluctuating and to prove it to the gas boys I installed those two WC" gauges in the line. When both boilers would fire the pressure would drop below 3". At first the gas guys said "I doubt it" but when I showed them what was happening on the gauges they installed a new regulator.

BTW, for all you Viessmann fanatics out there, the burners under those hoods are the new Vitoflame 300 series. They are without a doubt the sweetest running, cleanest burning flamethrower I have ever had the joy to work with.

Sweet_3

S.E.

What a great job. You and your crew are top notch, looks like it was alot of fun, well worth the effort I'm sure. Wow!!

S Ebels

FYI

Both boilers run from the high 85% to low 86% range sepending on system water temps. CO levels are 0 (that's zero, none, zilch) to 2PPM. Net stack temp is 270-280* with 140* system temps. CO2 is 9.2% to 9.3%. O2 runs 4.5.

S Ebels

Do you see what's going on here?

I put this post up here because it illustrates something perfectly.

We removed a heating system that had a tested combustion efficiency of 78% and replaced it with one that tests 85-86%.

That's only 8% better efficiency...............

Yet the fuel comsumption in the building dropped 43%!!!

What's going on?

I'd like the homeowners reading this who are pondering replacing their old equipment to be able to grasp how a system is supposed to work.

Weezbo

not to Play the Defender buh ,..One can only Wonder ...

How much it will save on the future health of the occupants costs in medical bills and longevity....how does one actually calculate That relavant though often overlooked piece of information in the calculation on R.O.I.....and too, The aspirations Vs Inspiration of the potential of the occupants..........i have what i feel is a relavent question ...wouldnt one feel like they were being held hostage in a building (without thier knowledge) to later find out just how dubious of integrity the previous heating system "preformed"?

Weezbo

Yah Buddy The breadth of thier minds need a breath of

fresh air , that will help get some oxygen to the brain and aid them in thier ability to do math again *~/:).............It suprises me to find that something i installed last year ,which i figured would result in about a 15 percent savings is half of the previous years consumption...man this co must be cloudin my brain ))

DanHolohan

Never got it.

Hope you can try again. Thanks.

Constantin

Congratulations!

I knew that the system had to be replaced, but it is always interesting to note whether the new system on its own manages to save the client money. Never mind the added bonus of the building occupants actually being comfortable!

The pictures speak for themselves, as they illustrate your attention to detail. The Propress fittings and the unistrut hangers on the walls make for a very neat installation. On the near boiler piping picture, it is interesting to note how the pipe sizes increase a notch once they come out of the header.

It's also neat to note how you took advantage of the natural convective flow via the ducts to get air into the rest of the school. Does it return to the mechanical room?

Steve Ebels_3

OK

I'll answer my own question. Maybe it should have read, How do you get a 43% improvment in efficiency with an 8% increase in burner efficiency?

1.The old furnace was operating on a single thermostat for the whole building. Pretty much anyone should realize that a great deal of efficiency can be gained by zoning any building and providing the ability to "turn down" rooms which are not in use. The same holds true for 80% of the houses I have ever been in. Think about your own home. How many rooms do you actually use and need to maintain at 70* all day, every day.
Zoning should be mandatory in any house over 1,200 sq ft IMHO. When used correctly it can really make a difference.

2. Matching the firing rate to the actual requirements of the building. In this case the old furnace was firing at 850,000btu's, not horribly oversized, maybe 20% like most heating systems are. Actual calculated heating load for this building was 511,000 btus, just a tad above the rated output of the Vitola's. The main thing is that furnace had one firing rate. Full bore and off. The new system can fire at 50% and 100% and the 50% rate meets the need 95 days out of 100. When you have a piece of equpment that fires at one rate, and most people do, it hardly ever runs at peak efficiency. Multiple or better yet modulating btu inputs are another key factor.

3. Outdoor reset and constant circulation do a lot to increase efficiency and comfort levels allowing lower thermostat settings. I have living breathing proof on this job. Two of the rooms in this building are used for preschool age kids in the HeadStart program. The teachers and the kids complained about feeling cold even when the room temp was 72* with the old system. With the new system the radiators are "on" 95% of the time. Nice even heat. Constant. Comforting. This past winter the teachers said that rarely did they ever see the heat higher than 68-70* but they were comfortable while wearing regular shirts instead of sweaters. Besides that, the heat output from a radiator is much more comfortable than warm air blowing into a room. Chalk one up for appropriately sized radiators, constant circ and OD reset.




4. Underground ductwork should be banned. We calculated that about 11-12% of the output of the old furnace was lost in the ground under the building. it blew 130-140* air into ducts laying in 50* soil. The same thing happens in most homes with uninsulated duct running through an unconditioned space, like a 55-60* basement.

That's about it other than the actual efficiency difference in the equipment and heat delivery system. It's not rocket science, you just have to think eachstructure through whether it's 1,500 or 15,000 sq ft. There is no one size fits all heating plan.