Boilers under cloudy skies

Jason_13

I have been installing boiler for about 20 years and want the best for my customer. Not only the best product but the best value. I do not at this time sell condensing boilers but am considering it. I am not sure if it is the best value or not. Please help me clerify this so I can offer the best value.
I have been kicking this around in my head for some time and have only gotten more confused. Below you will find my pro's and con's. I will not use brand names.
Condensing Boilers
More up front cost. From the figures I have recieved about $300-$400 dollars
More maintenance. More parts to break down. More compact so more labor time to do the repairs.
More efficient about 94% eff.
Some areas require limestone filter to get rid of condensate. Change this annually I assume.
Smaller internal heat exchanger area could be a problem with scaleing if any small leaks are aquired.
Not a concern with low return water temperatures.
12 year warranty (Not sure if it is pro-rated or not)

Non-condensing
Less maintenance, easier to work on.
Less efficient, about 88% efficient
No condensate to worry about
Larger internal passages
More water volume which can be a plus when working with low temp water which produces longer off cycles and longer run cycles.
Normally requires mixing or injection with low temp water
Already has boiler protection built in.
Lifetime pro-rated warranty

Just a quick thought to summerize the above.
94% efficient as compared to 88% efficient is about 8-1/2% more fuel savings. If the fuel bill is $1200 a year at 8% that would mean only $102 savings a year. That would be about a 4 year payback in just the differance in upfront cost for the boilers at cost. We have not added the mark-up to the boiler yet. Even a small percent mark-up could add another year or two to this payback. Add in more maintenance and less warranty, where is the value? I am not saying there is none I am just looking for clarity on this matter.
Thanks in advance.

Jason_13

I have been installing boiler for about 20 years and want the best for my customer. Not only the best product but the best value. I do not at this time sell condensing boilers but am considering it. I am not sure if it is the best value or not. Please help me clerify this so I can offer the best value.
I have been kicking this around in my head for some time and have only gotten more confused. Below you will find my pro's and con's. I will not use brand names.
Condensing Boilers
More up front cost. From the figures I have recieved about $300-$400 dollars
More maintenance. More parts to break down. More compact so more labor time to do the repairs.
More efficient about 94% eff.
Some areas require limestone filter to get rid of condensate. Change this annually I assume.
Smaller internal heat exchanger area could be a problem with scaleing if any small leaks are aquired.
Not a concern with low return water temperatures.
12 year warranty (Not sure if it is pro-rated or not)

Non-condensing
Less maintenance, easier to work on.
Less efficient, about 88% efficient
No condensate to worry about
Larger internal passages
More water volume which can be a plus when working with low temp water which produces longer off cycles and longer run cycles.
Normally requires mixing or injection with low temp water
Already has boiler protection built in.
Lifetime pro-rated warranty

Just a quick thought to summerize the above.
94% efficient as compared to 88% efficient is about 8-1/2% more fuel savings. If the fuel bill is $1200 a year at 8% that would mean only $102 savings a year. That would be about a 4 year payback in just the differance in upfront cost for the boilers at cost. We have not added the mark-up to the boiler yet. Even a small percent mark-up could add another year or two to this payback. Add in more maintenance and less warranty, where is the value? I am not saying there is none I am just looking for clarity on this matter.
Thanks in advance.

Maine Ken

I have some of the same questions. Just yesterday I heard a factory rep speak briefly about a "Canadian" study that showed that under perfect lab conditions condensing boilers only condense 60% of the time and in the field it is only 30%. If this is true (and I haven't located any documentation) then where o' where is the savings and benefit over a lifetime warranty(non prorated) triple pass, cold start, cast iron boiler?????? How can the condensing units even ccompare with an oil unit with the difference in fuel costs without some huge effeciency difference???

Please can someone enlighten me.

Cliff Brady

Other considerations

Consider standby losses that are nearly 0 with condensing boilers, ie no flew for hot boiler water to waste into. The low standby losses make an indirect DHW tank make more sense.

There is less infiltration with a direct vented condensing boiler for more efficiency also.

Consider exterior chimney maintenance. I am a homeowner with a condensing boiler primarily becauses I wanted to remove the chimney for kitchen remodeling. I have since seen neighbors go through costly contortions designing around their chimenys for their kitchen remodels. Then they went to remodel their basement and spent all kinds of labor boxing around the very old boiler with framing and drywall and access door. A wall hung condensing boiler set off to the side at the beginning of the projects would have made their lives a lot easier and more comfortable from thier standing radiators.

I am sure others will come up with other reasons.

Floyd_5

How 'bout....

the savings of PVC venting over S/S????
No mixing devices or CW boiler protection????
How 'bout the weight difference and my aging back????
How 'bout the idea that in 10 years I may be installing a solar fusion electric producing/heating gizzmo......
Then there are the facts!!!!!!
My house heating bill dropped by more like 30% maybe more, didn't run the numbers yet....but I know it was at least that.
Another situation that i know of I have saved the customer the price of the boiler already since the install in Sept.......savings are more like 60-70% and I can PROVE it.
I have a fire house that's heating for less than some of the firemen's houses......
As with anything your results may vary, however if you want to put your nose to the grindstone and look for uses rather than excuses your will find ways to use and thrive, installing the latest and greatest......

Floyd

Mark Hunt

Where was that study done?


Try calculating a buildings heat loss at different temperatures. Instead of going for broke with design day, try starting at say 60 degrees, and work your way down.

You already know that the heat requirements for those milder days is less. Now look at the output curve of the heat emitters. You already know that they will put out less heat with cooler water.

A condensing, modulating boiler is going to adjust it's input/output accordingly. You can't do that with traditional, fixed rate boilers. You could add outdoor reset to them, but then you have to pipe them in such a way to protect them from those cool water temps.

Take a look at the temperature records for your specific area and see how many times "design day" was actually reached. You might be suprised.

Don't you think it costs more to service a "modern" cast iron or steel boiler today than it did 50 years ago? Electronic ignition, relays,boards, etc.....

That logic would tell us all to go back to gravity hot water systems.

As I said, systems are designed around 180 degree water and the coldest day of the year. What happens to all of those "extra" btu's?

AFUE and "combustion efficiency" are not going to give you a true picture for those days, which out number design day by far in my area.



Mark H

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Phil_6

All I know..

..is that I heat my house with my little MZ for a lot less than my neighbors do. Studies and lab results not withstanding, that's good enough for me. I easily save a couple of hundred bucks a month with gas prices so high here on LI.
I do find it amusing that when we rebuild a big old house into a nice contemporary mansion that people will pay 50 grand for the paint job but take the free Keyspan boiler every time. Then when it's 2-300 bucks a WEEK for gas they are crying.

Oh well, at least I made the right choice ;-)

S Ebels

My humble thoughts

I have the same thoughts as you on a lot of the points you mention. I think one of the biggest challenges we face as "field engineers" is selecting/recommending the right equipment for a given job. I see a lot of guys around here harnessing a condensing boiler to a BB system designed to run at 180*+ usually operated by nothing more than a call for heat from a T-87. No modulation of water temp via outdoor reset or DHW production, just on/off. This would be a very poor setup for a condenser being that it would live in that mode maybe 20% of its life, maximum.

On the other hand I see installers hooking up CI boilers to low temp systems (<140*) with virtually nothing installed for protection of the boiler. Maybe a thermostatic 3-way mix valve to knock down the water temp going out to the zones. They seem to just hope or trust that condensation won't occur when the low temp zone kicks on, I don't know..........

What I'm saying is that different applications require different solutions. An iron boiler is not right for all jobs and neither is a condenser. You as the "designer" have to select the correct equipment for the task at hand based on your hopefully up to date knowledge.

I am a firm believer in the way the Germans run their cast iron products via their proprietery control setups. I have lots of European iron out there connected to systems that never see above 150-160 and spend most of their time at 140 or less. I have yet to encounter a condensation problem. None of these have any form of boiler protection other than what the control provides. These, even in atomospheric applications, will run in the 84-88% range.

On the other hand, when I look at a job that is all low temp (85-120*), I see a prime candidate for a condenser. A system like that will allow maximum performance of the boiler with efficiencies running well into the 95%+ range.
At this point, looking at what's on the market, the only condenser I feel confident recommending as a long lived piece is the Vitodens from Viessmann. It costs more than other condensers of the same input but it is without doubt the best on the market. I think a lot of the condensers hitting the U.S. market may work fine in Europe where they were developed, but, (and that's a huge BUT) typical maintenance in Europe is a lot different than typical maintenance here in the U.S. I have lot's of reservations about product life of these in typical heating systems found in here in the states. Maintenance here consists of a phone call to the technician, (any technician will work) when there is no heat. Until homeowners here understand the value of having their entire system checked every year, I think that condensing equipment is going to get a very bad rap very quickly. Until technicians here understand that proper maintenance consists of proper burner setup followed by annual combustion testing, PH testing and monitoring the entire system there will be a lot of guys cussing out this new fangled &@#$(&amp; junk. There is definitely a sharp learning curve for both technician and homeowner.

Repair costs associated with condensing equipment will be higher due to complexity and non-universal parts. The example is already there to see in the forced air world. Look at the difference in repair costs associated with an atmospheric, standing pilot furnace with gravity air flow compared to a two-stage variable speed high efficiency type. I don't think I have to elaborate on that. It's pretty obvious that efficiency comes at a price.

That being said, how many standing pilot furnaces are sold today? None. Condensing equipment and systems that make them usable are here now and definitely here to stay. You might as well get on the train and enjoy the ride.

Kal Row

dito - especially if you pipe it

primary/secondary/vari-injection with a tekmar 361 control with outdoor reset, – on my most recent one like that, the primary boiler loop cycles between 140-175, and the burner runs 2 min out of 15, and the injection pump supplies 140 degree water to the zones on the average temp day, and I run the zones with tekmar remote sensing thermostats. Base on the fuel bill drop the HO got, he got an annual efficiency increase, that belies the modest 83.4% AFUE of the good old fashioned real simple SlantFin cast iron boiler I put in – the only thing not old-fashioned on the boiler is the flue damper – that keeps it nice and toasty in between cycles.

In that setup, a fully condensing boiler’s efficiency increase could never justify the maintenance cost – I am only “loosing” heat from the flue gas when the boiler is on and the damper is open, and based on the attached table I will loose a max of 25kbtu, for the 2min out of 15 the boiler is running, bid deal!!! - the HO was loosing a lot more than that with his old boiler and improper zoning that allowed the heat gravity to migrate to the top floor and out the open windows – cause the tenants were cooking

Even worse, while the boiler I bought, is “technology” obsolete, it will live and work nicely in that setup for 30 years, the tekmar keeps it from condensing and short cycling, whereas a new fangled condensing boiler, will die in 10-15, and have many quirk failures during that time, and might well be “technology” obsolete in about 3 years – ouch


quirk failures: eg Weil-McLain ULTRA – a boiler which I happen to like – has had lockouts because of power glitches – someone even asked us on the “WALL” how to reset it, just imagine going on a mid winter vacation – and coming home to a busted frozen pipe flooded house – because the power company decided to switch generators and the ULTRA went into lockout – requiring you to push the reset button on the face, but aren’t home to do, ouch!!! – I tell people that they have to put uninterruptible power supplies on these things - but they don’t listen!!! – you need about 3-4 hours – but even a 15min UPS would take care of most power problems – the mid winter vacation, was another forgotten reason, for the popularity of “scorched” air systems – people would turn off the main, open all under-sink doors, and pipe access points, set the system for 55 and go – whereas I was called to repair a few Hydronic systems, this winter, that broke during the overnight setback, due to freezing – one of them I still have to fix – it had one of the baseboard zones returning through the slab the edge of the house – stupid – am probably going to bypass the whole mess with snaked pex.

Maine Ken

I replaced my own CI w/ coil with a triple pass, cold start, indirect hw and have saved 35% on oil for the past heating season. No need for a chimney with DV. With the price of oil compared to gas, with a lifetime warranty w/ CI and far less with condensing I don't understand the push for the condensing units. If gas were less costly than oil and I could convince my customers that they don't need a lifetime warranty I could probably justify pushing the condensing units.

How do you folks get by all of the added expenses when selling systems? Are you in predominantly gas markets????? Where I am oil is KING far and away.

I am not trying to argue or be nit picky, I am simply trying to learn. I am all for the newest, latest, greatest....if it is!

Jason_13

Some comments to the above reply's

First you cannot look at the total fuel saved when trying to decide to use condensing. The question here is why condensing instead of cast iron. I do not mean a chimney vent. The product I use is direct vent, built in primary/secondary and no fear of return water as low as 55º. The unit will handle it. This takes the infiltration issue out as it does not change between condensing or cast iron if both are direct vent. Air from the outside for combustion. The efficiency comparrison would have to be between 88% (mine) and 94% (or what their claim is). Shore there is more maintenance on the newer cast iron products but parts are more standard and more room to work. I understand not everyday is design cold but if the circulator is variable speed pumping the water through the boiler and runs slower when water is colder is that not absorbing more BTU's than if water was zooming through at normal rate? Thus less heat loss out vent. I do know if the condensing boiler is installed in systems where the water runs above 140º alot the boiler is less efficient.
I really appreciate all the reponses and i realize this could go on for a long time. Again I am not against condensing boilers at all just trying to understand the differances.

Kal Row

while your comments are flawlessly logical...

while your comments are flawlessly logical...
we have people out there, with condensing boilers, running at insanely high temps for those types, - yet are saving tons on fuel costs, the only explanation i can come up with is, that the combustion processes and heat-exchange on those, are way way, mo bet-tah, i know that on the ULTRA the fuel air is really mixed up and turbulated, and the flame is swirled around the heat-ex, instead of hitting it directly which always seems to be a problem for cast-iron designs, they also keep the combustion airflow low enough so that they are not actually taking heat out of the 160f returning water,
in the vie$$mann combustion chamber, they are actually recovering the radiant heat from combustion also - and there heat-ex is shaped in a way where they can really extract heat - making it equal in heat-xfer eff to an aluminum one, you got-a see it, it’s amazing what you can do with a hardy metal like stainless!!! (see pic below – the metal grid dome, #1 in pic, actually holds onto the flame and glows massive amounts of infra-red light at the heat ex – really cool if you’ve got tons of euro’s )

and there is also the issue, that the eff rating for old type boiler is only, once they are up to temp, – on avg – they are running at 40%, ouch!!! – so it another reason why your mixed-down-CI – is better, it runs the boiler loop up to operating temp real fast – this is especially important if you are putting it into a gravity conversion job where the water mass is huge!!!

so it not like these units aren’t giving you real value for the money - it's like you say, with a sealed combustion and internally mixed down, cast iron boiler - in your application, they aren’t giving you enough, to even begin to justify the cost diff – had I known you were using mixed-down-CI with sealed-combustion – I would have told you right away – that it’s fine

ps: pls tell us which one your using/considering and if you have/had good/bad experience etc. (I know none of them haven been around too long for any real data) – but many of us are trying to amass collective experience