Upgrade of brand new heating system in Long Island, NY

GRod

Hello,



I am about to close on a new energy star colonial house in Nassau County, NY. The house is about 3,500 sq ft, two floors and a unfinished basement. The system that was placed in my house is the following:

Boiler (Natural Gas): Weil McLain CGi-5 Series 3 -  Direct Vent

Water Heater: HTP Indirect Water Heater SuperStor 50 Gallons

2 Zones: 1st floor and 2nd floor.

Slantfin baseboard - Baseline 2000 throught the home.

PEX Tubing throughout.



I have been reading about condensing boilers and will like to see two things:

1. If it makes economical sense for me to change it to a condesing boiler (either a Viessman, Triangle Tube or Buderus).

2. If I can work out with some business owner who will be willing to take the Weil Mclain and apply credit towards the condensing boiler and installation. After all, its a brand new boiler.



I'm basically going for efficiency and hopping to utilize the new technology such as outdoor resets and indoor feedback systems to save me money over the long run. I will even consider changing to Runtal baseboards.



If anyone can chime along, please do so and Thank You for your help



Thank You

Robert O'Brien

Long Island

We're on LI and install quite a few Viessmann and Triangle Tube,if I had gas available,I'd have one of those in my house! It is a major investment to upgrade,and at todays gas prices would have a long payback. The catch is how long do gas prices stay so low? Who knows,but I have to think it can't last. Nat Grid has rebates and the tax credit is back so that would help a little. Be happy to take a look if you'd like

CMadatMe

Have to Start

With a room by room heat loss. Then measurement of each rooms baseboard. From there, break out the heat loss into zones and calculate water temp needed to supply the board to overcome the heat loss for our outdoor reset curve.



Without it, can't fully answer the question you pose. Can say that the average fuel savings going from conventional to a condensing boiler is 35%-50%..

JeffGuy

Seems to me there's an easier way

There is an easier way to approximate how long your payback is. You only need two things - what was the cost of heating and hot water for your house for a full year? - and what is the cost of the upgrade minus any rebate and trade in. The effiency of your current system is (best-case) 83%; the efficiency of your new system is (best-case) 96%. Cost of new system / ( .13 * Gas cost last year) is the number of years to pay off new system (assuming stable gas cost and consumption same each year).



Two notes: 1. Your system is not brand new - it is used (by definition) - and you will be lucky to get much more than scrap value for it (but maybe you'll get lucky); 2. slant-fin requires higher temp than radiators so you will are unlikely to achieve 96% since you won't be condensing much. Upgrading to radiators would get you closer to 96% since they work at lower temp, but the cost of changing out to new runtal baseboard is going to be very high. Get a quote and figure the payback for that using the same equation - seems unlikely to me that you'll proceed with any of this if you base it purely on payback.

CMadatMe

Disagree

Your taking account btu for btu and we both know that the existing boiler, one, is over sized and two, the modcon is not burning the same btu/hr on each fire as the conventional boiler is. You also are not accounting for the savings from outdoor reset.

JeffGuy

Hmmm

We don't know the boiler is oversize - it is brand new construction and hopefully was done correctly (we have no reason to believe otherwise). Agree not burning same btu/hr, but I don't see how that matters - the important thing is the number of btu produced - the advantage of burning a mod/con at a lower rate should be included in the relative AFUE rating. Also, the outdoor reset is part of the mod/con AFUE rating (isn't it?) - AFAIK that's included in how they get the rating so high.



Just trying to keep it simple - I don't see why you can't compute payback using AFUE alone. AFUE by definition is the projected average thermal efficiency for a complete heating season. If AFUE isn't good enough - why not?

CMadatMe

No

Outdoor reset has nothing to do with AFUE testing! Its based on the same 140 in 120 return as a conventional boiler. Modulation rate has a ton to do with efficiency and fuel savings.



How do I know the boiler is oversized? It's a 3,500 sqft home on Long Island. If the heat loss is more then 80,000 btu/hr I will be just as surprised as I was on Sunday watching the Bronco's secondary falling a sleep..



Question for the poster. How many feet of baseboard is in this home?

JeffGuy

Wait

Hold on, so then outdoor reset is the only difference? In which case adding outdoor reset to a conventional boiler will give you an apples to apples comparison, and allow use of relative AFUE to compute payback again, right?



What is the heating efficiency improvement when using outdoor reset - this must have been measured? If the payback for outdoor reset is so huge, then he could add outdoor reset to his existing boiler - that will cost a couple hundred and not many thousands of dollars and should pay for itself almost immediately. And after doing that, then he can compare AFUE ratings, right?

CMadatMe

It's Not The Same

You need to get your head into "modulation rate" not a fixed rate as his current boiler. Even without an outdoor sensor attached to a condensing boiler it still modulates based on the curve it rides. See attached page 2. I can still be 90 plus % at least on Viessmann Vitodens 200 outside condensing range. So 100 percent load is design temp and 70 is warm wearther shut down. At 35 degrees outside i would be at 50%.



Basic rule of thumb for outdoor reset savings. For every 3 degrees you can run a heating system with less than 180 degree water you get a 1% fuel savings. So if I ran a conventional boiler at 160 instead of 180 I could save 6% before I even turned the boiler on. Problem with older and most conventional boilers is that you are limited to that 140 degree return water temp. I said most because the Burnham Series 2, Series 3, ES2, ESC as well as the Crown AWR use the G Iron which can handle 110 degree return water temp because of the sectional iron design. More pins and each section has a diffuser of sorts in the return that disperses return water evenly across each section. No hot or cold spots.



I've never been a believer in AFUE or boiler efficiency. More concerned with system efficiency. It plays a much larger roll in fuel savings. You can make all the energy in the world as efficient as you want but it's all about how you move and use it that counts.



If I have a condensing boiler that modulates 20,000 btu/hr - 90,000 btu/hr and it's a 32 degree day I may only be producing 40,000 btu/hr where as that conventional boiler is still firing at it 90,000 btu/hr everytime it fires no matter what. How do you measure that?



You'd have to graph the last 10 years of daily temp and start doing some serious math. I've often thought about trying it using an excel spreadsheet but have better thing to do with my time.

SWEI

it is brand new construction and hopefully

... was done correctly (we have no reason to believe otherwise).



Most of us see "reasons to believe otherwise" almost daily.



AFUE does not even come close to quantifying the real-world energy savings a properly installed mod/con boiler and radiant distribution system will deliver.  30% is pretty much a bankable _minimum_ savings.  Highly efficient and comfortable systems based on conventional boilers are entirely possible.  The additional materials and labor for a buffer tank, mixing valve, and proper controls will pretty much eat any cost savings you got on the boiler.  Don't get me wrong -- conventional boilers are not going to disappear from the market anytime soon.  Particularly when expected operating hours are low, they usually represent the best value decision.  But when annual operating hours get into the thousands, the math changes dramatically.

GRod

I have to move there first....

I still have not closed on the house...in a few weeks I should be there. Once Im there, Im going to be using the heating system that was installed.



This house is an energy star house meaning that proper insulation was used using both spray foam and fiberglass insulation. The builders HVAC engineer desinged both the A/C and heating requierements for the house. Once I'm there, I'll measure how mush feet of baseboard I have in both the 1st and 2nd floor.



Also, if I decide to do this, I plan to do this in the summer.



Regarding the baseboards, what about these two companies that seem more adequate for mod/con boiler:

http://www.aimradiantheating.com/store/slimline.html

http://www.hydronicalternatives.com/default.aspx

Myson Select Radiators



Will these be cheaper than Runtal?

JeffGuy

Comparison

The cost of a brand-new conventional boiler is zero in this case - because he is buying a house that was just built and includes a new 83% AFUE boiler. He doesn't need to replace his boiler - he is asking whether it makes financial sense to junk this new boiler and put in a newer one so he can slightly increase his efficiency from 83% to 96%.



This is like deciding whether it makes sense to take a free 2012 Corolla, or to pay $20K for a 2012 Prius. It's true that he will get better mileage with the Prius and save on the cost of gasoline, but the payoff time will be way out in the future and many many miles down the road. It just doesn't make sense. It DOES make sense to wait until the free boiler he already has needs major work or replacing and THEN buy the most fuel-efficient boiler he can find.



The AFUE ratings are designed to answer exactly this type of question. (He isn't talking about putting in radiant heat - that would be REALLY expensive as a retrofit).

GRod

Makes alot of sense

I totally understand your logic there. I was just trying to see if anyone will take the current boiler and apply some credit towards the new one. However, I am realizing that it may be hard to get. And I will really have to change the baseboards.



I think the best bang-for-your-buck could be addition of controllers such as a Beckett Aquasmart or similar management controller for the current boiler .

CMadatMe

AFUE Ratings

They are, why and how? Yes, there are degree day formulas that can be used with AFUE but is it realistic or just smoke and mirrors? How many conventional cast iron boiler systems have you worked on that are set up to maintain a water temperature supply of 140 and return of 120?



I also love how some use a vehicle in a debate concerning ROI considering it is the worst investment with zero payback. It actually cost you money. We will spend 30K on a vehicle at a blip of a dime but we worry about payback in a heating or cooling system.

Roland_18

Upgrade to mod-con.......

Hi GRod,

I don't have any credentials regarding heating, I'm just a home owner (on L.I.)

If it were me, I'd use the system as is for a couple of years and keep track of your gas usage. As has been suggested, do a heat loss for the house to see what you actually need as far as b.t.u.'s. You could hire some one with the equipment to evaluate how well insulated and air tight the house really is. You may be surprised to find areas that are under insulated. Air infiltration is as bad as not enough insulation.

I'm not familiar with the model boiler you will have, but, unless the installer really knew how to size it, it's probably too big for your needs. Than again, it has to produce your potable hot water as well. Too big a boiler will cause short cycling and possible reduced appliance life.

Definately consider adding outdoor reset. Depending on the model, you may be able to reduce the temperature of the water flowing through the baseboards. As it is now, the boiler is probably circulating 180-200 degree water.

A mod-con boiler is a nice thing to have, provided it's installed by a concientious professional. Prepare for sticker shock when you get the estimates. Don't get me wrong, I'd have one if I could swing the cost. When my present atmospheric boiler coughs, I'm going mod-con. If you have the scratch to spend, by all means go for it.

I the mean time, educate yourself. Read past posts of those who asked these same questions.

Good luck, Roland

RobG

Heat Loss

Can you get a copy of the heat loss that was performed by the design engineer? It should not be proprietary as would have been submitted to the AJH for permitting. Please post it here. As well, take pictures of the boiler and associated piping and post them. The photos would at least give us an idea of if it was installed correctly and the heat loss / manual J will let us know the important design details of your home.

Rob 

icesailor

Savings:

You are starting with a house that is supposedly state of the art with insulation, windows, and energy saving features. It is "Energy Star" rated.

After going through all of your thoughts and dreams of what you would like to do to save energy, AFTER you spend the money on the upgrades, I doubt from experience that your savings will be enough for a nice tip after an expensive meal at a nice restaurant.

Its like education. The more you know, the harder it is to find the pearls. The laws of diminishing returns.

SWEI

investment

Given that the house is tight and the existing boiler is paid for, I'd probably look at adding a solar thermal system before I replaced the boiler.  Pipe the existing conventional boiler into the storage tank with appropriate controls and you shouldn't see too many hours on it, plus it will run nice long cycles when it does fire.  This assumes you have winter sunshine.

Mad Dog_2

It would behoove you to...........................

Atleast get Robert O'Brien in for a consultation. He'll steer you right and is super-sharp. Mad Dog

Paul Pollets

Builder's Special

You can bet the home has granite countertops and a Sub-Zero reefer. One of these days US builders will get it and spend another $3-7K for a better hydronic setup that truly reflects efficiency. Nahhhhh..."costs too much".



Yes, pearls are hard to find.

GRod

I will try...

That makes sense. I will try to get the manual J for the house...or at least attempt to since builders are somewhat difficult on getting information like this. I will aslo take pics and post them here in the near future.



Thanks