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Thread: Converting oil to gas. Have 10 year Weil Mclain. Would appreciate advice and costs.

  1. #31
    In the Trades Tom Sawyer's Avatar
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    In forty years of doing this I can honestly say that I have only run into two boilers that were absolute crap. One from Slant Fin and the other from Burnham. I'll admit to haveing favorites and that some are easier to service than others but properly installed 99% of them will outlast their warranty by decades.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  2. #32
    In the trades Dana's Avatar
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    Can we assume those are models no longer offered?

    I've seen plenty of the low end ~78% AFUE Burnham P20x series (now set up to run 82%) with 25+ years on 'em (not that I'd go out of my way to buy one.) I even scrapped one fully functioning with only ~15 years of service on it due to gross oversizing, when I got around to dealing with the system at the house where I'm currently living. The thermocouple on the standing pilot needed replacing at about age 12 (no bfd- expected, in fact), and the automatic flue damper developed an intermittency due to a cold solder on the printed circuit board at about the same time, which I repaired by reflowing the solder rather than replacing the unit. The basic boiler underneath had no issues, looked clean, burned cleanly. I didn't test the combustion efficincy, but it was probably still hitting around 80%. The ES2 & ESC series are probably not that different underneath the fancier controls and new tin, but I don't know that for sure. The 3-section Burnham PVG (same output & efficiency specs as the ESC) in my nieces place has about 5 years on it now (running ~130-135F return water) with no detectable signs of problems. I'd expect something in the controls or maybe the blower to maybe get funky by age 20-25, but those are component-swap repairs.

  3. #33
    DIY Member jefferson17's Avatar
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    Hi Dana,

    >> Yep- the real heat loads are a lot lower than most people think they are.

    I know that you have some very fancy tool - and I'm guessing that normal folk like me don't have access to it. I had a thought - would you consider looking at that spreadsheet that I used before? I bet it wouldn't take all that much time, to tweak it up and make it much more accurate than it is now. Even if it is designed to be a touch conservative, that would be much better than the additional 20K BTU (36% oversized). People could REALLY use a GOOD and easy to use tool. There's not much out there today. What do you think?


    >> When stepping down that much in boiler size and with high-mass radiation you can't use really deep overnight temperature setbacks as an economizing strategy. But some of the "learning" thermostats like he Nest ... It's probably not the first place to spend the money ... but they can be pretty nice once you've buttoned up the house and have the new boiler setup dialed in, and would probably save at least 50 therms/year, but probably not 100 unless you're out of the house a lot.

    More excellent info? Is there any end to your knowledge and helpfulness? This is great stuff. Given our situation, and how our zones are piped, I only drop the Night temp to say 67 from 70. I bought several programmable Lux thermostats (m-f, sat, sun) w/ wake, away, back, night) 4 years ago. They are nice for $35 and great compared to the super old dial types that were still here!

    Yeah sounds good. Those basement band joists need some attention and I've got lots of uninstalled soft fiberglass ceiling tiles that need a new home!

    >> Complaints about cracked or rusting boilers not getting full warranty treatment after 10+ years of service need to be taken with a grain of salt. Many of those types of issues can be a result of improper installation that may have lacked adequate cool return water protection. Ignition system failures can often be traced to short-cycling due to gross oversizing for the amount of radiation (particularly on multi-zoned systems.) If you look at the negative reviews of any manufacturer's boilers the theme is similar cracked or leaking after x years of service, ignition crapped out in only y ears, but without details about the installation it's hard to say if the fault lies with the manufacturer or the installer. Installer training is often woefully lacking- and folks with plumbing skills aren't automatically hydronic system designers, but often have enough information to be dangerous for getting the full lifespan out of the equipment. It's not uncommon to see a cast iron boiler succumb to condensation from cool return water in 1-2 seasons due to improper system design/installation. But the installer is more likely to blame the manufacturer, replaces the same equipment without changing the system plumbing (charging "labor only") just to have it fail again in 1-2 years, leading the homeowner to launch bitter "lousy manufacturer, went through three boilers in just five years" kinds of complaints. The odds of an established manufacturer's boiler design or quality control being that bad are infinitesimally remote. Odds of something being amiss in the system design or commissioning tweaks are pretty high.

    Your point is VERY well made indeed. So there are lots of homeowners who think "hey this is a garbage boiler" when the likely root cause of a failure or short life span is a bad install / no adjustments to ensure proper return temps, etc. This makes a LOT of sense! Thanks!



    >> That's why you will want to plumb in a system by pass loop with ball valves and tweak the return water up to 110F a few minutes into a cold start. Even though the ESC series tolerates 110F return water. It WON'T tolerate 90-100F return water on a regular basis, but it would take awhile for the failure to occur, and you have enough radiation with enough emittance & mass that it's likely that direct-pumped with no radiation bypass you'd be getting a lot of sustained sub-110F return water events during the shoulder seasons, when the radiators can actually cover the load at 110F.[/QUOTE]

    Dana: I know you are saying something really IMPORTANT here but I also know that I'm not really following it well enough.

    Ultimately it's OUR boiler and we need to know that the heating system including valves etc are tweaked to ensure that our boiler has a long and reliable lifespan.

    Let's please assume an ESC3 with Burnham's 50g indirect (only $120 more than their 35g). We'll get $300 back afterwards for the boiler. We'd be CRAZY to do a gas conversion.


    When you talk about a cold start - is that only just the start of the season?

    I'm not following what you mean about "plumbing in a system bypass loop with ball valves and tweak the return temp to 110 on a cold start". I sorta have a GUESS about what your intentions might be but I'm hoping you have one of your amazing diagrams??? (hint, hint).


    RUNNING HEALTH DURING SEASON?
    After it's up and running, it sound like I must simply make sure the return pipe back to the boiler is at LEAST above X. I can easily measure that. Is that 120? 130? I'm good at doing what I'm told - just ask Amy

    The currently 2 active zones all have cast iron rads, and all valves are set to wide open. I believe that these will need to be adjusted down - to slow the rate of flow. Is this correct? Is there a good process to follow? I would think that I'll need to keep checking daily for the first 1-2 weeks then perhaps only weekly for the next few months - to tweak it if need be.

    THANKS SO MUCH!

  4. #34
    In the trades Dana's Avatar
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    The fancy tools I personally tend use for first-cut heat loads are standard spreadsheets, and I'll calculate the U-factors from engineering tables. Most tools aren't dramatically different from that behind the user interface, but have a limited range of U-factors. The pro-tools have better range of pre-calculated U-factors and take a stab at site-factors for solar gain, etc but the biggest error in any of these methods tends to be in the infilration/ventilation rates.

    The important issue about cold start protection:

    In the beginning, you have something on the order of 500-1000lbs water-equivalent thermal mass of radiator-iron & water at about 65-68F. Can't estimate the real thermal mass without a better description of the radiator and plumbing sizes, but we'll run with 1000lbs for now. It might be as little as half that, but it might be more. If this was originally a gravity-feed coal fired system with 4"-6" plumbing it's going to be a lot MORE than 1000 lbs.

    With 60,000 BTU/hr of boiler output, that's (60K/60 minutes=) 1000 BTU/minute, which is plenty for heating up just the boiler from 65F to 110F in short time- a few 10s of seconds probably less than two minutes. But to raise the 1000 lbs of system mass the 40F degrees from 70F to 110F takes (1000 lbs x 40F =) 40,000 BTU, and at 1000 BTU/minute that's a 40 minute burn at sub-110F return water, ignoring for the moment the heat being given up from the radiators to the room. When it's only 45-50F out you'll have a real heat load, but that load is a fraction of what it is at +15F, and it's quite likely that the radiators will emit sufficient heat to satisfy the thermostat without the radiators themselves reaching 110F, which means the return water will be under 110F, and damaging to the boiler.

    This is a standard problem with multiple solution approaches, boiler bypass and radiation bypass loops being tried & true standbys. One variation of radiation bypass looks like this:



    In this configuration the system pump is pumping toward the bypass loop. A ball valve located where the valve marked "differential pressure bypass valve" is enough, since yours is a one-zone radiation system, and the flow isn't changing. Closing the ball valve would mean 100% of the pumped volume is going toward the radiators, and 100% of the return water entering the boiler is coming from said radiators. If you crack open the ball valve a bit boiler output water is mixes in with that cool return water, raising the temp of the water entering the boiler. Open it up more, the temp of the water entering the boiler rises. The size of the plumbing on that branch loop needs to be substantial but it really depends on he pumping head of the entire system. A 1" diameter bypass branch might cut it, but maybe not ona super low-head system. A real hydronic designer would do the math on the system's pumping head and the pump volume, etc, but most boiler installers would go with whatever worked the last time. A 1.5" bypass plumbing would likely be more than enough, but wide open you may get almost no flow to the radiation- it has to be dialed so that even with a large slug of cool water in the system the temp at the return port on the boiler stabilizes above 110F in the first 5 minutes or so.

    Rather than a ball valve (=cheap) this can be implemented with a thermostatic mixing valve (= less cheap) at the intersection of the radiation return and bypass branch and often is, if higher temps are required on the radiation on design day, but I'm going to presume based on just a WAG that you'll never need to hit even as high as 140F at the rads. With the flow split a fixed 50/50 between radiation and bypass at a 70F cold start you'll get your 110F water with the boiler output at 150F you'd have, a sane, comfortable 40F delta-T on the boiler, and as the system temp rises that delta-T will vary a bit as the delta-T across the radiation first shrinks to something like 20-30F with higher temp return water. When the radiation is returning 120F water and the boiler output creeps up the delta-T on the boiler will shrink a bit too. Getting the pump sizing right so this all works, delivers the heat while keeping the delta-T on the boiler under 50F (the likely max operating limit- didn't look it up) under all circumstances is a key part of the design too, but probably not hard to hit. I don't know if that boiler comes with a pump pre-installed, but if it does you may or may not need to swap it depending on your actual system design. (60KBTU/hr with a 40F delta-T is ~3 gpm- you may need it to be more like 4-6gpm starting at a lower delta-T, feeding more boiler of the boiler output back in the bypass to achieve your 110F+ cold start.)

    Dead-cold system starts will happen multiple times per year, and tepid-starts will be the norm during the shoulder season. If you tweak the bypass flow such that the mix of return water and boiler output is above 110F a few minutes into a cold start, it'll be above 110F pretty much all the time, and you won't destroy the boiler. With most gas boilers you'd want to set that to 130F+, but the internal plumbing on the ESC takes care of it from 110F & up.

    But getting it there is up to the system designer- if that's going to be YOU, it's time to start reading up on it. These tend to not be design-by-web-forum kinds of projects. You have pretty good idea of the heat load, and if you measure up your radiation you'll be able to get a pretty good idea of what your max water temps on the system need to be, and how you need to design the flows to meet all boundary conditions. It doesn't have to be modeled to the n-th degree to work, but it takes more than a coupla napkins and a crayon to get there, and it will take tweaking & measuring while commissioning the system to ensure you don't run into condensation trouble.

    If you're plumbing it in yourself it doesn't hurt to add some thermometers on both the output and return ports to the boiler. Otherwise using a wrap of hockey tape on the bit of plumbing where you want to know the temp for spot-checking with an infra-red thermometer makes it easy-it'll be accurate enough for your purposes.

    Unless you have two thermostats and two pumps, the adjustable valves you have are there for adjusting the flow to balance the temperatures between what you're calling "zones". In general you'd want one to be wide open, the other throttled back just enough that the temperatures in the different parts of the house served by the two radiator loops track reasonable.

  5. #35
    In the Trades Tom Sawyer's Avatar
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    Long since gone. The Burnham was the Fiesta. Steel boiler with a tankless coil in the top that would leak at the gasket and rot the boiler out. I can't recall the slant fin boiler but it was a 2 section, wet base cast iron with a carlin 100 crd in it.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  6. #36
    DIY Member jefferson17's Avatar
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    Hi Dana,

    Once again – THANK YOU! You are so incredibly helpful and I can't stress enough how thankful we are to benefit from your expertise and knowledge!

    Quote Originally Posted by Dana View Post
    The fancy tools I personally tend use for first-cut heat loads are standard spreadsheets, and I'll calculate the U-factors from engineering tables. Most tools aren't dramatically different from that behind the user interface, but have a limited range of U-factors. The pro-tools have better range of pre-calculated U-factors and take a stab at site-factors for solar gain, etc but the biggest error in any of these methods tends to be in the infilration/ventilation rates.
    For grins and giggles I did a rework that way and came up w/ a heat loss of just under 50K – including the entire 1000 sq ft basement not only the original section.

    Here's kinda a dumb question. Is is appropriate or potentially useful for me to re-work my heat loss to not count the addition in the back – which uses only the dedicated Fujitsu heat pumps (12K BTU per room with shared 24K condenser) for each of the 2 family rooms (one on top of the other – above the rear basement addition underneath them)?

    Or is it better to include the rear addition in a total heat loss calculation, regardless that it has its own heating system (but the addition isn't “closed off” and some heat will make it's way from the original Victorian section through doorways and such)? There is 2 feet of solid masonry between the original section and the addition. The 1st level has a single doorway connecting to the rear addition: 36x84. There are 2 picture windows there that are incredibly well sealed - they are nearly soundproof. If we close that one door almost nothing gets through. The other area, 2nd floor, has 2 doorways connecting them – same dimensions: big single french doors w/ 15 panes in each.

    Quote Originally Posted by Dana View Post
    The important issue about cold start protection:

    In the beginning, you have something on the order of 500-1000lbs water-equivalent thermal mass of radiator-iron & water at about 65-68F. Can't estimate the real thermal mass without a better description of the radiator and plumbing sizes, but we'll run with 1000lbs for now. It might be as little as half that, but it might be more. If this was originally a gravity-feed coal fired system with 4"-6" plumbing it's going to be a lot MORE than 1000 lbs.

    With 60,000 BTU/hr of boiler output, that's (60K/60 minutes=) 1000 BTU/minute, which is plenty for heating up just the boiler from 65F to 110F in short time- a few 10s of seconds probably less than two minutes. But to raise the 1000 lbs of system mass the 40F degrees from 70F to 110F takes (1000 lbs x 40F =) 40,000 BTU, and at 1000 BTU/minute that's a 40 minute burn at sub-110F return water, ignoring for the moment the heat being given up from the radiators to the room. When it's only 45-50F out you'll have a real heat load, but that load is a fraction of what it is at +15F, and it's quite likely that the radiators will emit sufficient heat to satisfy the thermostat without the radiators themselves reaching 110F, which means the return water will be under 110F, and damaging to the boiler.

    This is a standard problem with multiple solution approaches, boiler bypass and radiation bypass loops being tried & true standbys. One variation of radiation bypass looks like this:



    In this configuration the system pump is pumping toward the bypass loop. A ball valve located where the valve marked "differential pressure bypass valve" is enough, since yours is a one-zone radiation system, and the flow isn't changing. Closing the ball valve would mean 100% of the pumped volume is going toward the radiators, and 100% of the return water entering the boiler is coming from said radiators. If you crack open the ball valve a bit boiler output water is mixes in with that cool return water, raising the temp of the water entering the boiler. Open it up more, the temp of the water entering the boiler rises. The size of the plumbing on that branch loop needs to be substantial but it really depends on he pumping head of the entire system. A 1" diameter bypass branch might cut it, but maybe not ona super low-head system. A real hydronic designer would do the math on the system's pumping head and the pump volume, etc, but most boiler installers would go with whatever worked the last time. A 1.5" bypass plumbing would likely be more than enough, but wide open you may get almost no flow to the radiation- it has to be dialed so that even with a large slug of cool water in the system the temp at the return port on the boiler stabilizes above 110F in the first 5 minutes or so.

    Rather than a ball valve (=cheap) this can be implemented with a thermostatic mixing valve (= less cheap) at the intersection of the radiation return and bypass branch and often is, if higher temps are required on the radiation on design day, but I'm going to presume based on just a WAG that you'll never need to hit even as high as 140F at the rads. With the flow split a fixed 50/50 between radiation and bypass at a 70F cold start you'll get your 110F water with the boiler output at 150F you'd have, a sane, comfortable 40F delta-T on the boiler, and as the system temp rises that delta-T will vary a bit as the delta-T across the radiation first shrinks to something like 20-30F with higher temp return water. When the radiation is returning 120F water and the boiler output creeps up the delta-T on the boiler will shrink a bit too. Getting the pump sizing right so this all works, delivers the heat while keeping the delta-T on the boiler under 50F (the likely max operating limit- didn't look it up) under all circumstances is a key part of the design too, but probably not hard to hit. I don't know if that boiler comes with a pump pre-installed, but if it does you may or may not need to swap it depending on your actual system design. (60KBTU/hr with a 40F delta-T is ~3 gpm- you may need it to be more like 4-6gpm starting at a lower delta-T, feeding more boiler of the boiler output back in the bypass to achieve your 110F+ cold start.)

    Dead-cold system starts will happen multiple times per year, and tepid-starts will be the norm during the shoulder season. If you tweak the bypass flow such that the mix of return water and boiler output is above 110F a few minutes into a cold start, it'll be above 110F pretty much all the time, and you won't destroy the boiler. With most gas boilers you'd want to set that to 130F+, but the internal plumbing on the ESC takes care of it from 110F & up.

    But getting it there is up to the system designer- if that's going to be YOU, it's time to start reading up on it. These tend to not be design-by-web-forum kinds of projects. You have pretty good idea of the heat load, and if you measure up your radiation you'll be able to get a pretty good idea of what your max water temps on the system need to be, and how you need to design the flows to meet all boundary conditions. It doesn't have to be modeled to the n-th degree to work, but it takes more than a coupla napkins and a crayon to get there, and it will take tweaking & measuring while commissioning the system to ensure you don't run into condensation trouble.

    If you're plumbing it in yourself it doesn't hurt to add some thermometers on both the output and return ports to the boiler. Otherwise using a wrap of hockey tape on the bit of plumbing where you want to know the temp for spot-checking with an infra-red thermometer makes it easy-it'll be accurate enough for your purposes.

    Unless you have two thermostats and two pumps, the adjustable valves you have are there for adjusting the flow to balance the temperatures between what you're calling "zones". In general you'd want one to be wide open, the other throttled back just enough that the temperatures in the different parts of the house served by the two radiator loops track reasonable.
    AH! I think I “get it” now! That is GREAT – THANKS! For us, a Solid, Simple, and Idiot-Proof (me) design is best with one of your fancy thermostatic mixing valves. I shouldn't be in the mix - something bad/expensive would eventually happen. It's much better to have some good technology protecting our boiler automagically, avoiding cold water shock so that it has a long life.

    I had another heating guy come out here the other day and he was the ONLY out of the bunch who mentioned that this should be done to protect the boiler. He also suggested we get a circulation pump to keep the hot water (shower water) from the new indirect water heater up to the front of the house, so that people wouldn't have to wait any longer than they do now for hot water to the showers (extra 50' or so in pex). That made sense to me and once I figure out what to buy I'll get one and plumb it in w/ Pex, and put in a dedicated return Pex, so that we don't end up with warm water in the cold pipe.

    The ESC3 lists it's input/output pipes as 1.25”. Does the thermostatic protection valve need to also be 1.25 or can it be say 1” or 3/4”? My GUESS is that any pipe that handles the flow rate is still ok but that's just a guess and I wouldn't want some inspector to fail me, if I chose the wrong thing.

    Some (most) of the 1.25 models seem pretty expensive but I want to do the “right thing” here. I've found a few things and would appreciate advice as to what models might be a good fit for the ESC3.

    It's really hard for a layman (and calling myself that is generous) to know what is or isn't proper. THANKS! Are ANY of these appropriate for the ESC3? If not, I'd love a few recommendations and I'll just buy one.

    http://www.pexsupply.com/Tekmar-712-...alve-4866000-p

    http://www.pexsupply.com/Honeywell-S...alve-Lead-Free

    http://www.amazon.com/Honeywell-V804...c+boiler+valve

    http://www.amazon.com/ThermoMix-High...c+boiler+valve

    >> Unless you have two thermostats and two pumps, the adjustable valves you have are there for adjusting the flow to balance the temperatures between what you're calling "zones". In general you'd want one to be wide open, the other throttled back just enough that the temperatures in the different parts of the house served by the two radiator loops track reasonable.

    Yes we do – 2 zones each w/ it's own thermostat and pump. There is a 3rd zone but it may never see use again, unless the heat pumps have an issue.

    THANKS very very much!

    Jeff

  7. #37
    In the trades Dana's Avatar
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    The boiler is best sized for the loads it is actually serving, so the zones served by the mini-splits need not be include in the calculation even if you hook up those baseboards to the system as backup.

    With two circulation pumps it's usually awkward to implement a radiation-bypass loop, and you'll often have to resort to other methods of boiler protction, such as boiler-bypass. In a boiler bypass configuration it pumps away from the bypass branch rather than toward is. This is somewhat less protective than radiation bypass, but can usually still get the job done. A key thing to get right on the boiler bypass is to deliver the minimum flow requirements for the boiler under all conditions so that the delta-T on the boiler itself stays withing spec. (A 60K boiler with a 50F max delta-T needs about 2.5 gpm as the absolute minimum.)



    In the event that you are so over-radiated for the load that the water temps are too low to meet the return water flow & temp requirements with a boiler bypass you may need to add a pump and set it up primary/secondary loops which is also a standard way to deal with it:



    A number of system architectures can work, but to figure out the most optimal scheme in YOUR case requires knowing the heat load, the total radiation size, and the boiler output, from which all temperatures and pumping requirements can be determined. An unsophisticated installer who either doesn't understand that it's necessary or ignores the particulars can screw it up royally without half trying, which is why it's good to have a handle on it ahead of time to vet their choices. Don't be afraid to ask them which configuration they're going with and why. (You might even convince them to actually do the math this time! :-) )

    If you use a thermostatic valve on the bypass loop it's OK to go with 1" (or even 3/4") rather than 1.25", provided it's rated for the both min & max flows you actually pump. The pumping head presented by the valve itself is relatively low, but if the radiation flows need to be exceptionally high pumping a high velocity through the thermostatic valve may become an issue (don't go with a 1/2" version.) There are probably several suitable 1" 3-way mixing valves that would do it.

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