Refurbish or replace boiler

[tbird6391]

Hello

Our home is equipped with a 3 zone hydronic system. The boiler is a 1958 HB Smith - Mills fitted with a Roberts Gordon 302-21 gas conversion burner. I love this system as with the Powerpile gas valve, opening the flow valves will gravity feed and heat the house with no power. And it is reliable. It has served nearly 60 yearswith maybe a few hundred dollars worth of repairs to the controls.

The system was combustion tested the other week and the numbers look good (1-2 ppm CO).

While it is currently functioning properly, I do have concerns regarding the burner due to its age (Original to the 1958 boiler). Specifically, the condition of the gas valve, and regulator. Another issue is a crack in the approximately 12-15 inch diameter ceramic diffuser sitting on top of the burner in the combustion chamber.

Ideally, I would like to rebuild or replace the burner with another Powerpile unit and add some safety features to the boiler such as low water cutoff, and whatever else may be available to improve its safety. Reason being here in southwest Connecticut we have a history of week long power outages.

And I would need to find a reasonable, licensed tech willing and able to do this.

The other option obviously is to replace the boiler. Which I hate to do because of the new ones needing electricity.

So what are your thoughts about upgrading the existing equipment vs replacement. I am aware of the efficiency gains, etc, however my priorities are not so much that as reliability. I want to set my temp and be done.

I know it will be tough to find a new unit that will run as long as this one has without any problems, but what new units come closest? Simplicity of controls, rugged construction, quality components are key.

I see the new stuff and while it is shiny and clean, it looks kind of wimpy compared to the old Smith.

And for this I would need to locate a top notch installer to do the job.

Any and all opinions welcome.

Thanks!

 

[BadgerBoilerMN]

First; where is it. Size of house, fuel bills, your age.

In general a gravity boiler will run 4-500 degrees Fahrenheit up an unlined brick chimney. This equates to 40-50% of the fuel. Not to mention the NOx and SOx produced, read "acid rain".

The cost of electricity to drive a typical low-efficiency <86% atmospheric boiler with a circulator, available when your boiler was installed, is less than $25.00/year with an expected lifespan of 20.

The mere pumping of warm water will decrease your fuel bill since it takes more energy (fuel) to drive water with heat than with an electrically driven pump.

We have replaced many gravity boilers and second or third time conventional boilers with pumps in homes exceeding the century mark. Our only option for such homes is a condensing boiler, with at least one pump, a fancy computer, outdoor reset and an average fuel bill some 40% lower than the boilers we replace.

The cost of bi-annual maintenance is typically offset by fuel savings. You get someone to install a "modern" gravity boiler with slightly improved combustion efficiency and safety features but you will be paying more for heat than you should.

If you ran this same question past your local mechanic in reference to you your 1958 Ford sedan he would just give you a smile.

 

[Sponsor]

 

[tbird6391]

First; where is it. Size of house, fuel bills, your age.

In general a gravity boiler will run 4-500 degrees Fahrenheit up an unlined brick chimney. This equates to 40-50% of the fuel. Not to mention the NOx and SOx produced, read "acid rain".

The cost of electricity to drive a typical low-efficiency <86% atmospheric boiler with a circulator, available when your boiler was installed, is less than $25.00/year with an expected lifespan of 20.

The mere pumping of warm water will decrease your fuel bill since it takes more energy (fuel) to drive water with heat than with an electrically driven pump.

We have replaced many gravity boilers and second or third time conventional boilers with pumps in homes exceeding the century mark. Our only option for such homes is a condensing boiler, with at least one pump, a fancy computer, outdoor reset and an average fuel bill some 40% lower than the boilers we replace.

The cost of bi-annual maintenance is typically offset by fuel savings. You get someone to install a "modern" gravity boiler with slightly improved combustion efficiency and safety features but you will be paying more for heat than you should.

If you ran this same question past your local mechanic in reference to you your 1958 Ford sedan he would just give you a smile.

 

[tbird6391]

Thanks for the reply, Badger.
The house is 2600 sq ft 2 story located in southwestern CT. I'm in my 50s, 2nd generation to own it since new. Wife tells me the gas bills for the last 2 months were $200 and $235 respectively. this winter has been mild, last year it was brutal so one month the gas was about $500. And $500 is about half of what we spent for oil one month at our last house when it was over $4.00/gallon. (1800 sq ft 5 miles away with a 2003 oil boiler)

The system is actually pumped in its normal state. When I mentioned gravity feed, I was referring to the capability it has to run off the grid in case the electric goes out, simply by turning a couple of valves. My concerns about the electricity were not that of cost, rather the week long power outages we get here due to tropical storms or noreasters.

If we end up replacing it, which we probably will, i am currently partial to the conventional cast iron boiler. It seems simpler, more rugged and less tempermental than some of the newer high tech options, plus I want to continue using the existing masonry chimney, rather than having something new sticking out the side of the house. And I want to retain the indirect water heating capability.

So i'm looking for information about who makes the best boilers on the market... ones that last the longest and you don't have to mess with. All American made.

You wrote condensing boilers were the only option for some of your jobs. Why? I'm curious to learn more about this.

58 Ford... now if that won't start you clean the points, set with a matchbook, and you're good to go, but it wont have any seatbelts. Our '11 explorer has all the bells and whistles and touch screens and airbags and such, but you don't need any of that when you're waiting for the tow truck.

Rick

 

[BadgerBoilerMN]

It is a puzzle. It does come down to the individual and his house.

I can't argue for a ModCon, say 10k installed when you have a $250.00 peak fuel bill. If your new ModCon were perfectly sized, installed and maintained the $500/yr I save you will not pay for it. With the blackouts gravity backup does seem attractive and any decent american boiler will last 30 yrs.

Dana and I both agree on the EC3 from Burnham, the best of the low-efficiency hogs if you will.

 

[tbird6391]

It's looking like perhaps I should replace the unit. It's about 3 degrees here with 30 mph winds gusting to 40 and the old girl is running so much it's making me a bit nervous.

I tried finding the Burnham ec3, to no avail. Peerless makes an ec3 but for oil. Is that Burnham an ESC? The esc7 136000 BTU shows up as $3300.

I had a tech and salesman from a large hvac contractor recommending a Weil McLain 140000 BTU ($2100). Plus install and removal.

Now after reading about the WM with their elastomer seals and ties to China I can't get too excited about those. I see they last about 10-15 years plus they give you crap if you have a warranty issue.

But now you have me interested in a high efficiency unit, at least for educational purposes. The state will give me a $750 rebate if I get 90% AFUE with temp reset or purge control.

So the first question is, how much are the superior quality mod cons relative to conventional
Do they cost more to install
How long is the typical service life
Do any of these use common controls such as Honeywell, and other parts the gas company techs would keep in their vans.
What parts might be good to have as spares and how much would such an inventory cost
Can you fill them with antifreeze
Can you use the existing chimney (30 ft) Ours needs a liner anyways. I see varying info on this.
Can you do indirect hot water heating

I need it properly sized too. The 140000 BTU is based on Sq ft only. Is there some free calculator you might recommend? And a good tutorial on them.

Sorry, I do know lots of questions.

Thanks
Rick

 

[Leon82]

They have the es2 and series 3 the dash number I think is boiler sections. They start at -3 approx 60k btu

ESC is direct vent
Torrco and winelston shelton are distributors if I recall (a couple online sources also)

http://www.usboiler.net/us-boiler-product-io-manuals-documents.html

 

[John Molyneux]

I think you're asking good questions but a boiler isn't like most other household appliances where you can or should just go to Consumer Reports to pick the best one.

My advice is to focus on choosing the best contractor and have them install what they're most experienced with and can support. Bosch, Triangle Tube, Lochinvar, NTI, Utica, Viessmann, HTP, etc. all make excellent equipment (and many are made here in New England). Proper sizing and installation is probably more important than the brand of the appliance.

Installation not only includes the hardware (boiler, piping, pumps, etc.) but making sure the software (ODR curves, etc) is optimized for your unique situation. The sneaky little secret about an AFUE rating is that it's based on a laboratory test that doesn't represent real-world conditions. A label that says it's 95% efficient really only means it has the potential to be that efficient if it's properly sized, matched to your system and properly tuned. It breaks my heart how many modcons get installed that never even approach 90% efficiency because consumers and contractors don't really know or care how they work. It's like buying a Prius -- gas mileage depends on how you drive it.

Manufacturers obviously can't know what your house looks like so they set the factory defaults to make sure that a) you get heat and b) you don't damage the boiler. The installer can make an educated guess about where to set your ODR and pump speed based on a good heat loss calculation, but even then it's only a guess. Most of us find it takes the better part of a heating season to really dial it in for maximum efficiency. You probably don't want to pay for repeated service calls to have them do that for you so you have to learn yourself. It's easy and well worth it but not every consumer will want to make the effort.

And then there's the equally important aspect of what the rest of your system looks like, including amount and type of radiation and the quality of your building envelope. I reduced my heat loss by 25% last year with some air sealing and insulation work. Maybe you'll find you want to spend less on the boiler and invest the balance on the envelope. Have you looked at state or utility rebate opportunities that might cover an energy audit and maybe even some upgrades? I paid for my whole project (boiler and air sealing/insulation) with a combination of rebates and a low-interest energy efficiency loan with no money out of pocket. And I got a higher rebate because I installed a "95% efficient boiler," so that's a factor you should look at too.

Cost and efficiency (and carbon emissions!) are important but one thing that isn't stressed as much as I think it should be is comfort. I honestly can't believe the difference in how comfortable my house is with a modcon sending out a stream of gently heated water that keeps the radiators at a relatively constant temperature compared with the old on/off monster I had.

Chimney: you can definitely use your existing chimney as a race but you absolutely must follow the manufacturer's requirements for safety and other reasons. I used Centrotherm Flex which is a polypro liner. That probably cost me an extra $1,000 compared with going out through a wall but made sense for my situation.

Heat loss calcs: Do one. Don't make such an important decision based on somebody's rule of thumb. (Although a rule of thumb that may actually be pretty accurate is that most existing boilers are at least twice as big as they need to be.)

Slantfin has a free program you can download and use on your smart phone. It tends to be very conservative.

The easier and more accurate way is to measure your actual historic fuel use relative to Heating Degree Days over a portion of a heating season (like a couple months). Search here for posts from Dana for instructions on how to do that. The simple explanation is that you compare how many BTU's you used over a given period relative to weather data for the same period (i.e. your weather adjusted fuel use). With a couple gas bills, a little math and using your existing boiler as a measuring device you can come up with a surprisingly accurate estimate of your design day heat loss. Then you can look at the amount (EDR) of radiation you have and determine whether you can heat your house with the low water temps that make a modcon efficient.

I did my heat loss 3 ways: Slantfin came in at 39,000 BTU/hr; a Manual J analysis as part of an energy audit came it at 29,000; and the actual fuel use method came in at 30,000. I just calculated a year-over-year comparison after my insulation work and my heat loss is now about 22,000 BTU/hr for a 1940 1,400 sq ft cape in Maine. Even my 57,000 BTU Bosch, which is the smallest model they sell here, is somewhat oversized, but at least it can modulate down to around 10,000. It replaced a boiler rated at 140,000 BTU/hr.

 

[tbird6391]

Thanks for your thoughtful reply, John. There certainly are many things to consider.

A major benefit you described I was not aware of, the comfort aspect. Sounds pretty nice. I am going to give some serious thought to this now. But I'm still having trouble with the potential for not having heat due to some part that goes out and having to wait for that. I just have to get past this obsession I have for Simplicity.

Setting it up and tuning it actually sounds like a lot of fun. My training is in both mechanical and software engineering so I'd actually get to use some of that for a change.

The contractor issue is of the most concern no matter what we decide to do. Based on some of my more recent experiences, when I hear the word "contractor" I envision the clown car pulling up, and they all pile out to distract me while the leader picks my pocket. No offense intended to any *legitimate* contractors who may read this.

I will definitely dig into the heat loss calculations and get that all figured out. If these can modulate down, I would think it's better to have it somewhat oversize, (10-20% or so) in terms of less strain on the equipment near the design temp?

 

[John Molyneux]

With a modcon, 'strain on the equipment' is mostly related to cycling. Steady state means less wear and tear. And if you're making DHW with an indirect the boiler's going to cycle up to max fire anyway when the tank is being recharged. And that's what you want. And that's what the boiler's engineered to do. Doesn't really matter whether it's running at low fire or high fire.

Others can opine on this too but the ideal size might be 1.2X design day heat load with the ability to modulate as low as possible. 8,000 to 10,000 seems to be about the bottom end of what current technology can do, which is kind of amazing when you think about it. That's about what the 'medium' size burner on my gas range can do.

The low end of the range particularly important in a multi-zone system. You design the max output based on the whole house design day load but you want the min-fire to be able to take care of your smallest zone on a non-design day without cycling too much.

In an ideal world your boiler would run continuously during the heating season, modulating up and down based on outside temperature. The Outdoor Reset Curve tells the boiler to send out water that's just warm enough to keep the house cozy. It sends out warmer water as it gets colder and vice versus. For example, one way to set the ODR is to set the t-stat at 80 and then live with it over a number of days while you tweak the ODR curve until the boiler is keeping the house at your desired comfort level. In other words, the ODR runs things and your thermostat is nothing more than a high limit switch.

Of course in the real world there are other factors besides outdoor temp that affect real-time heat load -- solar gain, wind, cooking, having a fire, running the dishwasher, etc. Some boiler manufacturers deal with this using indoor feedback in addition to or in lieu of ODR. Or you can just set the ODR as best you can so that the boiler will cycle some, but not excessively.

I don't know if the current generation of modcons is really any less reliable than any other modern boiler.

Can't help you with contractors but Badger's website has some helpful advice and he offers some consultation services that might be useful. (I have no experience with him other than having benefited from many of his posts and the free expertise he donates to this site.) Google badgerboiler in Minnesota.

 

[Cpeters]

It's looking like perhaps I should replace the unit. It's about 3 degrees here with 30 mph winds gusting to 40 and the old girl is running so much it's making me a bit nervous.

I tried finding the Burnham ec3, to no avail. Peerless makes an ec3 but for oil. Is that Burnham an ESC? The esc7 136000 BTU shows up as $3300.

I had a tech and salesman from a large hvac contractor recommending a Weil McLain 140000 BTU ($2100). Plus install and removal.

Now after reading about the WM with their elastomer seals and ties to China I can't get too excited about those. I see they last about 10-15 years plus they give you crap if you have a warranty issue.

But now you have me interested in a high efficiency unit, at least for educational purposes. The state will give me a $750 rebate if I get 90% AFUE with temp reset or purge control.

So the first question is, how much are the superior quality mod cons relative to conventional
Do they cost more to install
How long is the typical service life
Do any of these use common controls such as Honeywell, and other parts the gas company techs would keep in their vans.
What parts might be good to have as spares and how much would such an inventory cost
Can you fill them with antifreeze
Can you use the existing chimney (30 ft) Ours needs a liner anyways. I see varying info on this.
Can you do indirect hot water heating

I need it properly sized too. The 140000 BTU is based on Sq ft only. Is there some free calculator you might recommend? And a good tutorial on them.

Sorry, I do know lots of questions.

Thanks
Rick

I'm going through the same thing. I have a 1977 burnham oil coverted to gas. 140,000 btu. Condensing units cost 3-4x as much and most of the people posting here will be living to see them replaced. I was told 600 btu per linear foot of finned baseboard. I'm in central jersey and would rather oversize than undersize.

 

[Dana]

An ESC-3 already would be oversized or you maybe by as much as 2x (but probably more like 1.5x.) The heat load of a typical 2x4 framed 1970s house at Trenton's +15F or New Brunswick's +10F outside design temp is about 40,000 BTU/hr. At the ~52,000 BTU/hr output of the ESC-3 you'd be completely covered down to about -5F or a bit lower before it even started to give up ground. It's a ~$2300-2500 direct vented boiler that would also cost you another couple hundred in stainless exhaust.

The atmospheric drafted version, the ES2-3 is about $1800-2K and puts out 59,000 BTU/hr, which would take you down into negative double digits without losing ground.

A 50-60K mod-con may cost 1.5-2x as much, but it'll save you more than the full purchase price of the boiler in less than 15 years in fuel cost, and it'll be more comfortable.

A 100K or bigger mod con boiler would usually be a mistake, since at your average load it won't even modulate.